______________________________________________________________________________________ 

SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 

FOR THE LONG TERM 2 AND STAGE 2 DBP RULES 

Office of Water (4601) 

EPA 815-R-07-017 

March 2007 
U.S. Environmental Protection Agency 

Office of Water (4601) 

1200 Pennsylvania Avenue NW 

Washington, DC 20460 

EPA 815-R-07-017 

http://www.epa.gov/safewater/disinfection/stage2/compliance.html

March 2007 
Simultaneous Compliance Guidance Manual 3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules

Purpose: 

 The purpose of this guidance manual is to provide technical information for water 

systems and states to assist them with complying with the Stage 2 Disinfectant and Disinfection 

Byproducts Rule, the Long Term 2 Enhanced Surface Water Treatment Rule, and other Safe 

Drinking Water Act (SDWA) regulations. This guidance is not a substitute for applicable legal 

requirements, nor is it a regulation itself. Thus, it does not impose legally binding requirements 

on any party, including EPA, states, or the regulated community. Interested parties are free to 

raise questions and objections to the guidance and the appropriateness of its use in a particular 

situation. Although this manual describes many methods for complying with SDWA 

requirements, the guidance presented here may not be appropriate for all situations, and 

alternative approaches may provide satisfactory performance. The mention of trade names or 

commercial products does not constitute endorsement or recommendation for use. 

Authorship: 

 This manual was developed under the direction of EPA’s Office of Ground Water and 

Drinking Water and was prepared by The Cadmus Group, Inc. and HDR, Inc. Questions 

concerning this document should be addressed to: 

Sarah Bahrman 

Office of Ground Water & Drinking Water 

U.S. Environmental Protection Agency 

Mail Code 4607M 

1200 Pennsylvania Avenue NW 

Washington, DC 20460-0001 

Email: Bahrman.Sarah@epamail.epa.gov 
Simultaneous Compliance Guidance Manual 4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules

Acknowledgments: 

Gary Burlingame ― Philadelphia Water Department 

Chris Hill ― Malcolm Pirnie, Inc. 

Rick Sakaji ― California Department of Health Services 

David Schendel ― Malcolm Pirnie, Inc. 

Ann Arbor Utilities 

City of Englewood, Colorado 

Gulf Coast Water Authority 

City of Higginsville, Missouri 

Kansas City Water Services 

Owenton Water Works and Kentucky American TriVillage 

Palm Beach County Water Utilities Department 

City of Poughkeepsie, New York 

Skagit County Public Utility District #1 

City of Tampa, Florida 

Washington Suburban Sanitary Commission 

Village of Waterloo, New York 

City of Wilmington, North Carolina 
Simultaneous Compliance Guidance Manual i March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Table of Contents 

Table of Contents ........................................................................................................................... i 

List of Exhibits ...............................................................................................................................v 

List of Abbreviations and Acronyms ......................................................................................... vi 

1. Introduction........................................................................................................................... 1-1 

1.1 What is the purpose of this guidance manual? ............................................................. 1-1 

1.2 What is “Simultaneous Compliance”?.......................................................................... 1-2 

1.3 Does this manual address compliance with environmental regulations other 

 than SDWA regulations? .............................................................................................. 1-2 

1.4 Who should use this guidance manual? How should it be used? ................................ 1-2 

1.5 How is this manual organized?..................................................................................... 1-7 

1.6 Can I rely on this guidance manual alone to make compliance decisions?................ 1-11 

1.7 Are there quick references I can use to screen for potential simultaneous 

 compliance problems? ................................................................................................ 1-11 

1.8 Where can I get help achieving simultaneous compliance? ....................................... 1-12 

1.9 What additional resources are available?.................................................................... 1-12 

2. Quick Reference Materials for Simultaneous Compliance............................................... 2-1 

3. Improving and Optimizing Current Operations ............................................................... 3-1 

3.1 Source Management ..................................................................................................... 3-2 

3.1.1 Advantages of Source Management................................................................ 3-4 

3.1.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Source Management Changes ................................................................. 3-5 

3.1.3 Recommendations for Gathering More Information..................................... 3-10 

3.2 Distribution System Best Management Practices....................................................... 3-11 

 3.2.1 Advantages of Distribution System BMPs.................................................... 3-16 

 3.2.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Distribution System BMPs.................................................................... 3-17 

 3.2.3 Recommendations for Gathering More Information..................................... 3-19 

3.3 Moving the Point of Chlorination............................................................................... 3-21 

 3.3.1 Advantages of Moving the Point of Chlorination ......................................... 3-22 

 3.3.2 Potential Operational and Simultaneous Compliance Issues 

 Associated with Moving the Point of Chlorination...................................... 3-23 

 3.3.3 Recommendations for Gathering More Information..................................... 3-28 

3.4 Decreasing pH............................................................................................................. 3-30 

 3.4.1 Advantages of Decreasing pH....................................................................... 3-30 

 3.4.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Decreasing pH....................................................................................... 3-32 

 3.4.3 Recommendations for Gathering More Information..................................... 3-35 

3.5 Reducing Chlorine Dose under Warm Water Conditions .......................................... 3-37 

 3.5.1 Advantages of Reducing Chlorine Dose under Warm Water Conditions..... 3-37 

 3.5.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Reducing Chlorine Dose under Warm Water Conditions..................... 3-38 

 3.5.3 Recommendations for Gathering More Information..................................... 3-39 

3.6 Modifying Pre-sedimentation Basin Operations......................................................... 3-41 
Table of Contents (continued) 

Simultaneous Compliance Guidance Manual ii March 2007 

For the Long Term 2 and Stage 2 DBP Rules

 3.6.1 Advantages of Modifying Pre-sedimentation Basin Operations................... 3-41 

 3.6.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Modifying Pre-sedimentation Basin Operations ................................... 3-42 

 3.6.3 Recommendations for Gathering More Information..................................... 3-43 

3.7 Enhanced Coagulation ................................................................................................ 3-44 

 3.7.1 Advantages of Enhanced Coagulation .......................................................... 3-44 

 3.7.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Enhanced Coagulation........................................................................... 3-46 

 3.7.3 Recommendations for Gathering More Information..................................... 3-51 

3.8 Enhanced Softening .................................................................................................... 3-53

 3.8.1 Advantages of Enhanced Softening .............................................................. 3-54 

 3.8.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Enhanced Softening............................................................................... 3-55 

 3.8.3 Recommendations for Gathering More Information..................................... 3-58 

4. Installing New Total Organic Carbon or Microbial Removal Technologies................... 4-1 

4.1 Granular Activated Carbon........................................................................................... 4-1 

 4.1.1 Advantages of GAC ........................................................................................ 4-2 

 4.1.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Using GAC.............................................................................................. 4-3 

 4.1.3 Recommendations for Gathering More Information....................................... 4-6 

4.2 Microfiltration/Ultrafiltration ....................................................................................... 4-8 

 4.2.1 Advantages of MF/UF..................................................................................... 4-8 

 4.2.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with MF/UF..................................................................................................... 4-9 

 4.2.3 Recommendations for Gathering More Information..................................... 4-11 

4.3 Nanofiltration.............................................................................................................. 4-13 

 4.3.1 Advantages of Nanofiltration ........................................................................ 4-13 

 4.3.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Nanofiltration ........................................................................................ 4-14 

 4.3.3 Recommendations for Gathering More Information..................................... 4-17 

4.4 Other Microbial Removal Technologies..................................................................... 4-19 

 4.4.1 Advantages .................................................................................................... 4-20 

 4.4.2 Potential Operational and Simultaneous Compliance Issues ........................ 4-21 

 4.4.3 Recommendations for Gathering More Information..................................... 4-23 

5. Alternative Disinfection Strategies...................................................................................... 5-1 

5.1 Chloramines.................................................................................................................. 5-1 

 5.1.1 Advantages of Chloramines ............................................................................ 5-1 

 5.1.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Chloramines ............................................................................................ 5-3 

 5.1.3 Recommendations for Gathering More Information..................................... 5-10 

5.2 Ozonation.................................................................................................................... 5-13 

 5.2.1 Advantages of Ozonation .............................................................................. 5-13 

 5.2.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Ozonation .............................................................................................. 5-15 

 5.2.3 Recommendations for Gathering More Information..................................... 5-21 

5.3 Ultraviolet Light (UV)................................................................................................ 5-24
Table of Contents (continued) 

Simultaneous Compliance Guidance Manual iii March 2007 

For the Long Term 2 and Stage 2 DBP Rules

 5.3.1 Advantages of UV ......................................................................................... 5-24 

 5.3.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with UV Disinfection .................................................................................... 5-25 

 5.3.3 Recommendations for Gathering More Information..................................... 5-30 

5.4 Chlorine Dioxide......................................................................................................... 5-32 

 5.4.1 Advantages of Chlorine Dioxide................................................................... 5-32 

 5.4.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Chlorine Dioxide Use............................................................................ 5-34 

 5.4.3 Recommendations for Gathering More Information..................................... 5-39 

5.5 Primary and Residual Disinfectant Use...................................................................... 5-41 

 5.5.1 Noteworthy Issues About Disinfectant Combinations .................................. 5-44 

 5.5.2 Recommendations for Gathering More Information..................................... 5-44 

6. Making Compliance Decisions............................................................................................. 6-1

6.1 Introduction................................................................................................................... 6-1 

6.2 Issues to Consider When Making a Compliance Decision........................................... 6-2 

6.3 Tools for Gathering Information................................................................................... 6-7 

6.3.1 Water Quality Monitoring ............................................................................... 6-7 

6.3.2 Hydraulic and Water Quality Modeling for Distribution System ................... 6-9 

6.3.3 Desktop Evaluations...................................................................................... 6-11 

6.3.4 Bench-Scale Testing...................................................................................... 6-12 

6.3.5 Pilot Testing .................................................................................................. 6-15 

6.3.6 Full-Scale Applications ................................................................................. 6-16 

6.3.7 Cost Estimation ............................................................................................. 6-18 

6.3.8 Community Preferences ................................................................................ 6-20 

6.4 Basic Approach for Implementing Regulatory Compliance Projects......................... 6-21 

7. References.............................................................................................................................. 7-1 

7.1 References Organized by Topic.................................................................................... 7-1 

7.1.1 General ............................................................................................................ 7-1 

7.1.2 Formation and Control of Chlorinated DBPs.................................................. 7-9 

7.1.3 Corrosion....................................................................................................... 7-10 

7.1.4 Source Management ...................................................................................... 7-13 

7.1.5 Distribution System Management ................................................................. 7-14 

7.1.6 Problem Organisms in Water Treatment....................................................... 7-16 

7.1.7 Pre-sedimentation.......................................................................................... 7-17 

7.1.8 Enhanced Coagulation and Enhanced Softening........................................... 7-17 

7.1.9 GAC............................................................................................................... 7-19 

7.1.10 Membranes .................................................................................................... 7-20 

7.1.11 Riverbank Filtration ...................................................................................... 7-21 

7.1.12 Chloramines................................................................................................... 7-22 

7.1.13 Ozone............................................................................................................. 7-25 

7.1.14 Ultraviolet Light ............................................................................................ 7-27 

7.1.15 Chlorine Dioxide ........................................................................................... 7-28 

7.1.16 Tools for Gathering More Information ......................................................... 7-29 

7.1.17 Chlorination................................................................................................... 7-35 

7.2 Comprehensive List of References............................................................................. 7-38 
Table of Contents (continued) 

Simultaneous Compliance Guidance Manual iv March 2007 

For the Long Term 2 and Stage 2 DBP Rules

Appendices

Appendix A. Summary of Pertinent Drinking Water Regulations ...................................... A-1 

Appendix B. Case Studies ....................................................................................................B-1

Appendix C. Guidance for Evaluating Potential Impacts of Treatment Changes on 

 Distribution Systems .......................................................................................C-1 

Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and 

 Copper Rule Compliance .............................................................................. D-1 

Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance .....E-1 

Appendix F. Considerations for Systems Complying with the Ground Water Rule ...........F-1 
Simultaneous Compliance Guidance Manual v March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

List of Exhibits 

Exhibit 1.1 Existing SDWA Regulations as of March, 2007.................................................... 1-4 

Exhibit 1.2 Organization of the Chapters.................................................................................. 1-8

Exhibit 1.3 Organization of the Appendices............................................................................. 1-9 

Exhibit 1.4 Treatment Technologies and Operational Changes Addressed in this 

 Guidance Manual ................................................................................................. 1-10 

Exhibit 1.5 EPA Guidance Manuals under Development....................................................... 1-14 

Exhibit 2.1 Checklist for Identifying Key Operational and Simultaneous 

 Compliance Issues.................................................................................................. 2-2 

Exhibit 2.2 Technology Alternatives and How They Potentially Affect Water Quality .......... 2-3 

Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies: 

 Summary of Benefits and Potential Conflicts ........................................................ 2-6 

Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications................... 2-12 

Exhibit 2.5 Case Studies in this Guidance Manual and Issues they Address ......................... 2-13 

Exhibit 2.6 Tools for Gathering System-Specific Information on Different Compliance 

 Techniques ........................................................................................................... 2-16 

Exhibit 3.1 Typical Chlorine Points of Application and Uses................................................ 3-21 

Exhibit 3.2 Percent Reduction in DBP Formation by Moving Point of Chlorination ............ 3-22 

Exhibit 3.3 Effects of pH Changes on CT Required for 0.5-Log Inactivation of 

 Giardia lamblia.................................................................................................... 3-31 

Exhibit 3.4 Impacts of pH on Formation of DBPs.................................................................. 3-31 

Exhibit 3.5 Required CT for 0.5-Log Inactivation of Giardia lamblia by 

 Free Chlorine at pH 7.0 ........................................................................................ 3-38 

Exhibit 3.6 Effect of the Change of Water Quality Parameters Due to Enhanced 

 Softening on Corrosion of Piping System Materials............................................ 3-55 

Exhibit 5.1 Comparison of Required CT (mg-min/L) values for Inactivation of 

 Viruses and Giardia by Free Chlorine and Monochloramine at 

 pH 7 and 10oC........................................................................................................ 5-8 

Exhibit 5.2 Required CT values (mg-min/L) for Chemical Disinfectants at 10°C................. 5-14 

Exhibit 5.3 Ratio of CT values for Inactivation of Viruses and Cryptosporidium at 10°C.... 5-27 

Exhibit 5.4 Required CT Values for Inactivation of Microorganisms by Chlorine 

 Dioxide Compared with Other Chemical Disinfectants at 10o

C and 

 pH 6-9 (in mg-min/L)........................................................................................... 5-33 

Exhibit 5.5 Effect of Temperature on the CT Required for Cryptosporidium Inactivation 

 by Chlorine Dioxide ............................................................................................. 5-36 

Exhibit 5.6 Summary of Potential Benefits and Adverse Effects Associated with Different 

 Combinations of Primary and Residual Disinfectants ......................................... 5-42 

Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR 

 and/or LT2ESWTR ................................................................................................ 6-3 

Exhibit 6.2 Application of Information Gathering Tools at Various Project 

 Implementation Stages ......................................................................................... 6-22 
List of Abbreviations and Acronyms (continued) 

Simultaneous Compliance Guidance Manual vi March 2007 

For the Long Term 2 and Stage 2 DBP Rules

List of Abbreviations and Acronyms 

AOC assimilable organic carbon 

APHA American Public Health Association 

AMTA American Membrane Technology Association 

As(III) arsenite 

As(V) arsenate 

AWWA American Water Works Association 

AwwaRF American Water Works Association Research Foundation 

BAT best available technology 

BLS below land surface 

BMPs best management practices 

BDOC biodegradable dissolved organic carbon 

C disinfectant concentration in mg/L (in CT calculations) 

CDPHE Colorado Department of Health and Environment 

CFE combined filter effluent 

CIS Customer Information System 

CO2 carbon dioxide 

CaCO3 calcium carbonate 

CPE comprehensive performance evaluation 

CT disinfectant concentration x contact time, a measure of 

disinfection performance 

CTA comprehensive technical assistance 

CWS community water system 

DBP disinfection byproduct 

DBPR Disinfectants and Disinfection Byproducts Rule 

DCWASA Washington D.C. Water and Sewage Authority 

DE diatomaceous earth 

DO dissolved oxygen 

DIC dissolved inorganic carbon 

DOC dissolved organic carbon 

DOP demonstration of performance 

EBCT empty bed contact time 

EPA U.S. Environmental Protection Agency 

FBRR Filter Backwash Recycling Rule 

GAC granular activated carbon 

GPM gallons per minute 

GWR Ground Water Rule 

GWUDI ground water under the direct influence of surface water 

H2CO3 carbonic acid 

HCO3

-

 bicarbonate 

HAA haloacetic acid 

HAA5 the sum of five HAA species (monochloroacetic, 

dichloroacetic, trichloroacetic, monobromoacetic, and 
List of Abbreviations and Acronyms (continued) 

Simultaneous Compliance Guidance Manual vii March 2007 

For the Long Term 2 and Stage 2 DBP Rules

dibromoacetic acids) 

HACCP Hazard Analysis and Critical Control Point 

HOCl hypochlorous acid 

HPC heterotrophic plate count 

HRT hydraulic residence time 

ICR Information Collection Rule 

ISO International Organization for Standardization 

IESWTR Interim Enhanced Surface Water Treatment Rule 

IFE individual filter effluents 

LCR Lead and Copper Rule 

LRAA locational running annual average 

LT1ESWTR Long Term 1 Enhanced Surface Water Treatment Rule 

LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule 

MCL maximum contaminant level 

MCLG maximum contaminant level goal 

M/DBP microbial disinfection byproducts 

MF microfiltration 

MGD millions gallon per day 

MIB 2-methylisoborneol 

MRDL maximum residual disinfection level 

MRDLG maximum residual disinfection level goal 

MWCO molecular weight cutoff 

N.d. no date 

ND non-detectable 

NF nanofiltration 

NOM natural organic matter 

NPDES National Pollutant Discharge Elimination System 

NTNCWS non-transient non-community water system 

NTU nephelometric turbidity unit 

OCl hypochlorite ion 

OCCT optimal corrosion control treatment 

O&M operations and maintenance 

ORP oxidation reduction potential 

PAC powder activated carbon 

PACl polyaluminum chloride 

POTW publicly owned treatment works 

PWS public water system 

RAA running annual average 

RCAP Rural Community Assistance Partnership 

RCRA Resource Conservation and Recovery Act 

RMP Risk Management Plan 

RO reverse osmosis 

SDS simulated distribution system 

SCADA Supervisory Control and Data Acquisition 

SOC synthetic organic chemicals 

SDWA Safe Drinking Water Act 

Stage 1 D/DBPR Stage 1 Disinfectants and Disinfection Byproducts Rule 

Stage 2 D/DBPR Stage 2 Disinfectants and Disinfection Byproducts Rule 
List of Abbreviations and Acronyms (continued) 

Simultaneous Compliance Guidance Manual viii March 2007 

For the Long Term 2 and Stage 2 DBP Rules

SUVA specific ultraviolet absorbance 

SWTR Surface Water Treatment Rule 

T contact time in minutes (in CT calculations) 

TCR Total Coliform Rule 

TDS total dissolved solids 

TENORM technologically enhanced naturally occurring radioactive 

materials 

THM trihalomethane 

TTHM total trihalomethane (sum of chloroform, BDCM, DBCM, and 

bromoform) 

TTHMFP total trihalomethane formation potential 

TOC total organic carbon 

TOP Texas Optimization Program 

TSO total system optimization 

UF ultrafiltration 

UFC uniform formation conditions 

UPS universal power supply 

UV ultraviolet light 

UVT ultraviolet light transmittance 

VOC volatile organic compound 

WEF Water Environment Foundation 

WFP water filtration plant 

WTP water treatment plant 

WWTP wastewater treatment plant 
Simultaneous Compliance Guidance Manual 1-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 The Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) and the Stage 

2 Disinfectants and Disinfection Byproducts Rule (DBPR) were developed and promulgated 

together to address risk trade-offs between two different types of contaminants: microbial 

pathogens and disinfection byproducts. The U.S. Environmental Protection Agency (EPA) 

recognizes that systems may encounter compliance issues with the Stage 2 DBPR when making 

changes to comply with the LT2ESWTR, and vice versa. In addition to the challenges of 

complying with the suite of microbial/disinfection byproduct (M/DBP) rules simultaneously, a 

water system must also ensure that changes in treatment to comply with those rules do not 

adversely affect compliance with other drinking water regulations. 

This chapter answers the questions: 

 1.1 What is the purpose of this guidance manual? 

 1.2 What is “Simultaneous Compliance”? 

 1.3 Does this manual address compliance with environmental regulations other than 

Safe Drinking Water Act regulations? 

 1.4 Who should use this guidance manual? How should it be used? 

 1.5 How is this manual organized? 

 1.6 Can I rely on this guidance manual alone to make compliance decisions? 

1.7 Are there quick references I can use to screen for potential simultaneous 

compliance problems? 

 1.8 Where can I get help achieving simultaneous compliance? 

 1.9 What additional resources are available? 

1.1 What is the purpose of this guidance manual? 

 The purpose of this guidance manual is to 

help water systems and their regulators identify 

and mitigate potential simultaneous compliance 

issues that may arise when systems make changes 

to comply with the LT2ESWTR and/or the Stage 2 

DBPR. The manual lists possible ways that 

simultaneous compliance issues could be 

addressed. In addition, tools are recommended and 

described to help determine if potential issues may 

affect a given system. 

 Another key purpose of this manual is to provide a clearinghouse of information, 

directing the reader to helpful resources. It would not be practical for one document to contain 

comprehensive technical and operational information for all of the Stage 2 DBPR and 

LT2ESWTR compliance treatment technologies. Each public water system (PWS) has different 

1 Introduction 

This manual addresses 

simultaneous compliance issues 

that may arise as systems make 

treatment changes to comply 

with the LT2ESWTR and/or the 

Stage 2 DBPR.
1. Introduction 

Simultaneous Compliance Guidance Manual 1-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

source water, existing treatment processes, distribution system materials, layout, storage, 

operations, and other characteristics that should be evaluated and addressed by the system in 

conjunction with the state and if necessary outside technical consultants, to ensure long-term 

compliance. EPA has designed this manual to raise potential simultaneous compliance issues, 

and directs readers to other references for more in-depth information. 

 After the draft version of this manual was released for public comment in September of 

2006, the Ground Water Rule (GWR) was promulgated in November of 2006. Most 

simultaneous compliance issues faced by systems using disinfection to comply with the GWR 

are already covered in the main body of this manual. EPA has identified a few issues, however, 

that may be unique, such as when ground water systems add disinfection for the first time. 

These issues and recommendations for addressing them are included in a new appendix 

(Appendix F). 

1.2 What is “Simultaneous Compliance”? 

 For the purposes of this guidance manual, simultaneous compliance means compliance 

with all existing Safe Drinking Water Act (SDWA) regulations, as summarized in Exhibit 1.1. 

Two-page fact sheets for many of the regulations are included in Appendix A. While systems 

may be concerned with issues pertaining to emerging contaminants, this guidance manual is not 

designed to address these concerns and does not discuss these issues. 

1.3 Does this manual address compliance with environmental regulations 

other than SDWA regulations? 

 In addition to SDWA regulatory issues, systems should always weigh operational issues 

and compliance with other environmental regulations when considering a treatment change. 

While this document provides some discussion of non-SDWA regulations and other compliance 

challenges (e.g. discharge permits, sludge disposal), readers should seek additional guidance and 

other technical references for addressing these compliance issues. 

1.4 Who should use this guidance manual? How should it be used? 

 This manual should be used by public 

water systems that already know they need to 

make a change to comply with the requirements 

of the LT2ESTWR and/or the Stage 2 DBPR. 

The manual is targeted to water system 

managers, engineers, consultants, and regulators. 

It assumes that readers have a technical 

background and some familiarity with water treatment processes (for readers without this 

background, see Section 1.8 for how to obtain technical assistance). 

This manual is for systems that 

already know they need to make 

a change in operations or 

treatment. 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 This manual should be used as a technical resource as systems select a treatment 

alternative or operational change. Example 1.1 shows how managers of a hypothetical system 

could use this manual to help inform their decision-making about treatment changes to comply 

with the LT2ESWTR. Example 1.2 shows how a regulator working with the same hypothetical 

system could also use this guidance manual as a technical resource. 

Before considering a treatment or operational change to achieve compliance with the 

LT2ESWTR and/or Stage 2 DBPR, water systems should make sure their sources are wellmanaged for both for quantity and quality and existing treatment processes are working well. 

For surface water systems, treatment plant performance should be optimized for disinfectant 

byproduct (DBP) precursor removal, filtered water turbidity should be well-controlled, and 

disinfectants should be applied for sufficient time and at sufficient concentrations for inactivation 

of microbial pathogens. All water systems should actively manage their distribution systems to 

meet water demand and provide consistently good water quality. EPA encourages systems to 

take advantage of existing voluntary programs in place including the Partnership for Safe Water, 

Qualserve, and Areawide Optimization. Appendix E describes these and other programs that can 

be used to achieve simultaneous compliance. 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 1.1 Existing SDWA Regulations as of March, 2007

Rule/Memo Date of 

Promulgation 

Contaminant of 

Concern 

Rule Summary 

Information Available 

from EPA

Ground Water Rule (GWR) November 

2006 

Source Water 

Microbial 

Pathogens 

Fact Sheet, included in 

Appendix A 

Long Term 2 Enhanced Surface 

Water Treatment Rule 

(LT2ESWTR) 

January 2006 Source Water 

Microbial 

Pathogens 

Fact Sheet, included in 

Appendix A 

Stage 2 Disinfectants and 

Disinfection Byproducts Rule 

(Stage 2 DBPR) 

January 2006 Disinfection 

Byproducts 

Fact Sheet, included in 

Appendix A 

Arsenic and Clarifications to 

Compliance and New Source 

Monitoring Rule 

January 2001 Arsenic Quick Reference Guide, 

included in Appendix A 

Lead and Copper Rule (LCR) June 1991 Lead and Copper Quick Reference Guide, 

Included in Appendix A 

LCR Clarification of 

Requirements for Collecting 

Samples and Calculating 

Compliance 

November 

2004 

Lead and Copper Fact Sheet, included in 

Appendix A 

Total Coliform Rule (TCR) June 1989 Distribution 

System Microbial 

Pathogens

Quick Reference Guide, 

included in Appendix A 

Stage 1 Disinfectants and 

Disinfection Byproducts Rule 

(Stage 1 D/DBPR) 

December 1998 Disinfectants and 

Disinfection 

Byproducts 

Quick Reference Guide, 

included in Appendix A 

Interim Enhanced Surface Water 

Treatment Rule (IESWTR) 

December 1998 Source Water 

Microbial 

Pathogens 

Quick Reference Guide, 

included in Appendix A 

Long Term 1 Enhanced Surface 

Water Treatment Rule 

(LT1ESWTR) 

January 2002 Source Water 

Microbial 

Pathogens 

Quick Reference Guide, 

included in Appendix A 

Filter Backwash Recycling Rule 

(FBRR) 

June 2001 Filter Backwash 

(Microbial 

Pathogens) 

Quick Reference Guide, 

included in Appendix A 

Surface Water Treatment Rule 

(SWTR) 

June 1989 Source Water 

Microbial 

Pathogens 

Summary information on 

the web at 

http://www.epa.gov/safewa

ter/therule.html#Surface 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Example 1.1 How this Manual can Help Water System Personnel Better Understand 

Their Choices 

System A is a community water system serving filtered surface water to 11,000 people. Based on 

source water Cryptosporidium data the system has begun to collect, System A will likely be placed in 

the second LT2ESWTR bin and therefore will need an additional 1.0 log Cryptosporidium removal or 

inactivation. The system hired an engineer to conduct a feasibility study. The engineer 

recommended three possible compliance options: 

• Bank filtration 

• Bag filters 

• Ozone 

Before discussing any of them with their state regulator or recommending any of them to their water 

board, System A wanted more information on each technique. In addition to worrying about costs 

and operational challenges, the staff is concerned that making a change to comply with LT2ESWTR 

might put them out of compliance with another drinking water regulation. 

System A picks up this Simultaneous Compliance Guidance Manual and 

• Refers to Chapter 2 for summaries of the issues that pertain to these three treatment 

alternatives. 

• Reads Section 4.4 Other Microbial Removal Technologies in Chapter 4 for information 

on simultaneous compliance issues associated with bank filtration and bag filters. 

• Reads Section 5.2 Ozonation in Chapter 5 for information on simultaneous compliance 

issues associated with ozone. 

• Gets additional references about bank filtration, bag filters, and ozone from Chapter 7. 

• Reviews Section 5.5 Primary and Residual Disinfectant Use in Chapter 5 to see what 

issues might arise using the combination of ozone as primary disinfectant and free 

chlorine as residual disinfectant. 

• Based on their reading, System A want to know more about whether they might have 

distribution system biofilm problems from switching to ozone. They refer to Appendix C 

Guidelines for Evaluating Potential Impacts of Treatment Changes on Distribution 

Systems and read the section on adding ozone and the section on installing ozone without 

subsequent biological filtration. 

• System A decides it would be beneficial to know how each of the treatment alternatives 

could be evaluated more before installation. They read through Section 6.3 Tools for 

Gathering Information and identify tools that may be helpful for evaluating the three 

alternatives. 

While they still have many questions for their engineer and have not yet chosen a treatment 

technique, System A’s managers feel more prepared to discuss the pros and cons of each alternative. 

They have identified questions they would like answered before they take the next step. 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

Example 1.2 How This Manual Can Help Regulators Understand Potential 

Simultaneous Compliance Issues 

The state is scheduled to meet with System A to discuss the possibility of installing ozone treatment 

to comply with the LT2ESWTR. The state’s engineers are concerned that this change could 

potentially make it difficult for System A to comply with other regulations. They’re particularly 

concerned with bacteriological regrowth in the distribution system. 

They pick up this Simultaneous Compliance Guidance Manual and 

• Read Section 5.2 Ozonation in Chapter 5 for information on simultaneous compliance 

issues associated with ozone. 

• Refer to Appendix C Guidelines for Evaluating Potential Impacts of Treatment Changes 

on Distribution Systems and read the section on adding ozone and the section on 

installing ozone without subsequent biological filtration. 

• Read Case Study #10: Ozonation for an example of how one water system used ozone to 

control microbial regrowth potential in the distribution system. 

The regulators have many questions for System A, but are more prepared to discuss the prospect of 

ozone as a way for the system to comply with their Cryptosporidium treatment requirement.
1. Introduction 

Simultaneous Compliance Guidance Manual 1-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

1.5 How is this manual organized? 

 Exhibits 1.2 and 1.3 summarize the contents of each chapter and appendix in this 

guidance manual. 

 Chapter 2 provides tables that summarize the potential benefits and conflicts of 

LT2ESWTR and Stage 2 DBPR compliance technologies, operational issues that should be 

considered, and tools that systems can use to evaluate a treatment technology’s potential for 

causing simultaneous compliance problems. 

 Chapters 3 through 5 of the manual are organized by treatment technology. This enables 

the reader to refer to a particular section for a comprehensive discussion of simultaneous 

compliance issues related to that treatment technique. For example, if the reader is considering 

installing chloramines to achieve compliance with the Stage 2 DBPR, the reader should refer to 

Section 5.1 for a discussion of pertinent simultaneous compliance issues that relate to using 

chloramines. Exhibit 1.4 provides brief descriptions of the treatment technologies and 

operational changes identified as compliance options in this guidance manual. 

 Within Chapters 3 through 5, each section on a treatment technique is organized as 

follows: 

• A summary of Advantages of the treatment technique;

• Potential Operational and Simultaneous Compliance Issues, including 

recommendations for addressing each issue; and 

• Recommendations for Gathering More Information, including suggestions for 

additional monitoring, tools that are available for collecting additional system 

information, and a short description of related case studies.

Chapter 6 identifies issues that should be considered before a change in treatment or 

operations is made. It also describes tools available to help systems collect information that is 

applicable and helpful for making their compliance decisions. 

 Chapter 7 provides a complete reference list, grouped by subject and also listed 

alphabetically. Most of the subject headings in Chapter 7 correspond to specific treatment 

technologies. Exceptions include technical references for DBP formation, technical references 

for corrosion, and general water treatment references. 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 1.2 Organization of the Chapters

Ch #... Is titled... and has information on...

2 Quick Reference Materials for 

Simultaneous Compliance 

• A checklist to help systems quickly identify simultaneous 

compliance issues 

• Tables summarizing compliance, operational, and water quality 

issues for each compliance technology 

• Tables summarizing tools and pertinent case studies 

3 Improving and Optimizing 

Current Operations 

• Source Management 

• Distribution System Best Management Practices 

• Moving Point of Chlorination 

• Decreasing pH 

• Reducing Chlorine Dose Under Warm Water Conditions 

• Modifying Presedimentation Basin Operations 

• Enhanced Coagulation 

• Enhanced Softening 

4 Installing New Total Organic 

Carbon or Microbial Removal 

Technologies 

• Granular Activated Carbon 

• Microfiltration/Ultrafiltration (MF/UF) 

• Nanofiltration 

• Other Microbial Removal Technologies 

5 Alternative Disinfection 

Strategies 

• Chloramines 

• Ozone 

• Ultraviolet Light 

• Chlorine Dioxide 

• Primary and Secondary (residual) Disinfectant Use 

6 Making M/DBP Compliance 

Decisions 

Tools available for: 

• Water Quality Monitoring 

• Hydraulic and Water Quality Modeling for Distribution 

Systems 

• Desktop Evaluations 

• Bench-Scale Testing 

• Pilot Testing 

• Full-Scale Applications 

• Cost Estimation 

• Community Preferences 

7 References Technical references grouped by subject and also listed 

alphabetically 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 1.3 Organization of the Appendices 

Appendix... is titled... and has information on...

A Summary of Pertinent 

Drinking Water 

Regulations 

Summaries of major EPA drinking water regulations in the 

form of 2-page fact sheets and quick reference guides. 

B Case Studies Case studies illustrating simultaneous compliance challenges 

that water systems have encountered when implementing 

treatment techniques to help comply with one or more of the 

M/DBP rules. 

C Guidelines for Evaluating 

Potential Impacts of 

Treatment Changes on 

Distribution Systems 

Summary of issues that may arise in the distribution system 

as a result of changes made during treatment. 

D Tools for Evaluating 

Impacts of Treatment 

Changes on Lead and 

Copper Rule Compliance 

Tools that can be used to test impacts of a water quality 

change on corrosion, which can result in violations of the 

LCR. References for further information are also included. 

E Innovative Management 

Tools for Achieving 

Simultaneous Compliance 

Existing and developing programs that can help water 

systems comply with regulations and produce consistently 

high quality water. Contains descriptions of performancedriven optimization programs and integrated management 

approaches that consider treatment processes and operating 

practices throughout the entire water system. 

F Considerations for 

Systems Complying with 

the Ground Water Rule 

Considers unique challenges that may emerge when systems 

make treatment or source changes to comply with the GWR. 

Contains a brief overview of the GWR and a discussion of 

corrective actions that could create simultaneous compliance 

issues. 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 1.4 Treatment Technologies and Operational Changes Addressed in this 

Guidance Manual1 

Technology or Operational Change Description 

Source Management (sec. 3.1) Management techniques that manipulate a source(s) to provide 

water with the lowest concentration of DBP precursors or 

pathogens possible. 

Distribution System Best Management 

Practices (sec.3.2) 

Management techniques designed to maintain the integrity of the 

distribution system and limit or reduce microbial growth, DBPs, 

or incursion into the distribution system. 

Moving Point of Chlorination (sec.3.3) Moving chlorination further downstream in the plant to a point 

where more DBP precursor removal has taken place. 

Modifying pH during Chlorination 

(sec.3.4) 

Lowering the pH of the water during the chlorination process. 

Reducing Chlorine Dose under Warm 

Water Conditions (sec.3.5) 

Lowering the chlorine dose under warmer water temperature 

conditions. 

Modifying Presedimentation Basin 

Operations (sec.3.6) 

Changing operation of presedimentation basins to achieve more 

removal of pathogens by adding coagulant or increasing 

residence time. 

Enhanced Coagulation (sec.3.7) Achieving more organic carbon removal by using higher 

coagulant doses under lower pH conditions. 

Enhanced Softening (sec.3.8) Achieving more organic carbon removal by adding coagulant and 

increasing the lime dose to raise the pH. 

Granular Activated Carbon (sec.4.1) Filtering water through a bed of granular activated carbon either 

by itself or as part of a granular filter. 

Microfiltration/Ultrafiltration 

(MF/UF) (sec.4.2) 

A low pressure membrane process used to remove microbes and 

some organic carbon. 

Nanofiltration (sec.4.3) A pressure membrane process used to remove particles and some 

dissolved organic matter. Nanofiltration uses membranes with 

smaller pores than MF/UF. 

Improved Filtration Performance 

(sec.4.4) 

Changes in the operation of filters to lower the effluent turbidity 

to below 0.10 NTU. 

Slow Sand Filtration (sec.4.4) A gravity filtration process using sand as the filtration medium. 

Diatomaceous Earth Filtration 

(sec.4.4) 

Filtration through a layer of diatomaceous earth placed on a 

permeable membrane. It can be a pressure or vacuum process. 

River Bank Filtration (sec.4.4) A filtration process that uses vertical or horizontal wells drilled 

near a river bank to filter the water through the river bank 

material. 

Bag Filtration (sec.4.4) A filtration process that filters water through a fabric material. 

Cartridge Filtration (sec.4.4) A pressure filtration process that filters water through a 

membrane cartridge. 

Chloramines (sec.5.1) Adding chloramines to the water to achieve disinfection. 

Chloramines are formed by adding chlorine and ammonia 

together in water. 

Ozone (sec.5.2) Adding ozone to water to achieve disinfection. Ozone is 

generated on site using oxygen. 

Ultraviolet Light (sec.5.3) Passing light from ultraviolet lamps through the water to achieve 

disinfection. 

Chlorine Dioxide (sec.5.4) Adding chlorine dioxide to water to achieve disinfection. 

Chlorine dioxide is generated on site. 1 These technologies and operational changes are not necessarily appropriate for every system; rather they 

are approaches that systems may opt to pursue based on a system-specific analysis.
1. Introduction 

Simultaneous Compliance Guidance Manual 1-11 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

1.6 Can I rely on this guidance manual alone to make compliance 

decisions? 

No, this guidance manual alone is not intended to provide comprehensive technical 

guidance for systems making treatment modifications. Instead, systems are encouraged to use 

this manual as a technical resource to identify potential issues and possible solutions to those 

issues. Chapter 6 describes the potential tools for assessing compliance choices. Chapter 7 

provides an extensive reference list, grouped by subject matter, which systems can use to obtain 

more information as they plan treatment modifications. Systems should take into account source 

water characteristics, existing treatment processes, distribution system issues, available 

resources, and other system-specific information in determining the best compliance approach. 

 This guidance manual is just one of many guidance manuals EPA has developed or is 

developing to help systems comply with the rules under the Safe Drinking Water Act. EPA 

recommends systems first visit EPA’s websites for the Stage 2 DBPR 

(http://www.epa.gov/OGWDW/disinfection/stage2) and the LT2ESWTR 

(http://www.epa.gov/OGWDW/disinfection/lt2). These websites have a wealth of technical 

links to assist systems with identifying their compliance requirements and options. Readers can 

also visit http://www.epa.gov/safewater for general regulatory information. 

 In addition, each state may have its own rules and regulations pertaining to treatment 

modifications. For example, many states have review and approval procedures that must be 

followed before making any compliance decisions. Systems should contact their state for further 

information. 

1.7 Are there quick references I can use to screen for potential 

simultaneous compliance problems? 

 Yes, Exhibit 2.1 in Chapter 2 is a one-page checklist that systems can use to quickly 

identify key potential operational and simultaneous compliance issues. This checklist could be 

particularly helpful for small systems or systems with limited resources. Chapter 2 also provides 

the following summary tables to help systems screen for potential issues: 

• Exhibit 2.2 Technology Alternatives and How They Potentially Affect Water Quality 

• Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies: Summary of 

Benefits and Potential Conflicts 

• Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications 

• Exhibit 2.5 Case Studies in this Guidance Manual and Issues They Address 

• Exhibit 2.6 Tools for Gathering System-Specific Information on Different 

Compliance Techniques 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-12 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

1.8 Where can I get help achieving simultaneous compliance? 

 Some water system engineers and managers may need assistance understanding the more 

technically complex portions of this guidance manual. Others may need assistance weighing 

which of the potential issues are likely to occur in their system. EPA encourages these readers to 

seek help from their regulators, technical assistance providers, or consulting engineers. In 

addition, small water system managers are encouraged to seek help from their state, local Rural 

Water Association circuit riders, or the Rural Community Assistance Partnership (RCAP). EPA 

has also published small entity compliance guides for both the LT2ESWTR (USEPA 2007a) and 

the Stage 2 DBPR (USEPA 2007b). 

1.9 What additional resources are available? 

 Chapter 7 contains a comprehensive list of references, grouped by subject. EPA 

references are discussed below. In addition to these many references, the American Water 

Works Association Research Foundation (AwwaRF) is currently developing a decision tool to 

help utilities develop simultaneous compliance strategies (Project #3115). Publication of this 

tool is expected in 2008. 

The 1999 M-DBP Simultaneous Compliance Guidance Manual 

The Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual (USEPA 1999f) was published in conjunction with the promulgation of the Stage 1 

D/DBPR and the Interim Enhanced Surface Water Treatment Rule (IESWTR). The 1999 

manual is organized by regulation, describing how compliance with the Stage 1 D/DBPR or 

IESWTR might affect compliance with another regulation, focusing on one regulation at a time. 

Some readers may be more comfortable with that layout. 

Since several issues discussed in the 1999 manual continue to be issues that present 

challenges to systems trying to comply with the LT2ESWTR and Stage 2 DBPR, readers could 

also refer to the 1999 manual for guidance. The 2007 Simultaneous Compliance Guidance 

Manual, however, provides more up-to-date findings and references. It also focuses more 

Troubleshooting Guides 

Some water systems may encounter problems with their treatment performance or finished water 

quality as they modify treatment to comply with the new regulations. Here are a few troubleshooting 

guides that can help those systems (and systems in general) identify and address treatment 

problems: 

Bevery, R.P. 2005. Filter Troubleshooting and Design Handbook. 425 pp. Denver: AWWA.

 

Lauer, W.C. 2004. Water Quality Complaint Investigator's Field Guide. 102pp. Denver: AWWA.

Logsdon, G.S., A.F. Hess, M.J. Chipps, and A.J. Rachwal. 2002. Filter Maintenance and Operations 

Guidance Manual. AwwaRF Report 90908. Project #2511. Denver: AwwaRF. 

Tillman, G.M. 1996. Water Treatment: Troubleshooting and Problem Solving. 176 pp. Boca Raton: 

CRC Press LLC. 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-13 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

specifically on those technologies that have been identified as treatment solutions for complying 

with the requirements of the LT2ESWTR and the Stage 2 DBPR. 

Additional EPA References

 In conjunction with promulgation of the IESWTR, Stage 1 D/DBPR, Long Term 1 

Enhanced Surface Water Treatment Rule (LT1ESWTR), LT2ESWTR, and the Stage 2 DBPR, 

EPA has published several guidance manuals that may assist PWSs in resolving potential 

conflicts. Complete references for these guidance manuals are provided in Chapter 7. These 

references include the following: 

• Handbook: Optimizing Water Treatment Plant Performance Using the Composite 

Correction Program (USEPA 1998a) 

• Disinfection Profiling and Benchmarking Guidance Manual (USEPA 1999a) 

• Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b) 

• Uncovered Finished Water Reservoirs Guidance Manual (USEPA 1999c) 

• Guidance Manual for Compliance with the Interim Enhanced Surface Water 

Treatment Rule: Turbidity Provisions (USEPA 1999d)

• Unfiltered Water Supply Systems Guidance Manual (USEPA 1999e) 

• Guidance Manual for Conducting Sanitary Surveys of Public Water Systems; Surface 

Water and Ground Water Under the Direct Influence (GWUDI) (USEPA 1999g) 

• Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual 

(USEPA 1999h) 

• Implementation Guidance for the Stage 1 Disinfectants/Disinfection Byproducts Rule 

(USEPA 2001a)

• Low Pressure Membrane Filtration for Pathogen Removal: Application, 

Implementation, and Regulatory Issues (USEPA 2001h)

• Controlling Disinfection By-Products and Microbial Contaminants in Drinking Water 

(USEPA 2001c) 

• Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 Enhanced 

Surface Water Treatment Rule (USEPA 2006b) 

• Membrane Filtration Guidance Manual (USEPA 2005b) 

• Long Term 1 Enhanced Surface Water Treatment Rule Turbidity Provisions 

Technical Guidance Manual (USEPA 2004h) 
1. Introduction 

Simultaneous Compliance Guidance Manual 1-14 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• Complying with the Long Term 2 Enhanced Surface Water Treatment Rule: Small 

Entity Compliance Guide (USEPA 2007a)

• Complying with the Stage 2 Disinfectants and Disinfection Byproduct Rule: Small 

Entity Compliance Guide (USEPA 2007b)

 Several additional guidance manuals are under development and will be published to help 

water systems comply with the requirements of the Stage 2 DBPR, LT2ESWTR and the Ground 

Water Rule. Information on these manuals is provided in Exhibit 1.5. 

Exhibit 1.5 EPA Guidance Manuals under Development 

Rule Guidance Manual Weblink for Updates 

LT2ESWTR Microbial Toolbox Guidance Manual 

LT2ESWTR Implementation Guidance 

http://www.epa.gov/safewa

ter/disinfection/lt2/complia

nce.html

Consecutive Systems Guidance Manual for 

the Stage 2 DBPR

Operational Evaluation Guidance Manual

Stage 2 DBPR 

Stage 2 DBPR Implementation Guidance 

http://www.epa.gov/safewa

ter/disinfection/stage2/com

pliance.html

Consecutive Systems Guidance Manual for 

the GWR 

Source Water Monitoring Guidance Manual 

Source Water Assessment Guidance Manual 

Corrective Actions Guidance Manual 

Sanitary Survey Guidance Manual 

Complying with the GWR: Small Entity 

Compliance Guide 

GWR 

GWR Implementation Guidance 

http://www.epa.gov/safewa

ter/disinfection/gwr/compli

ancehelp.html
Simultaneous Compliance Guidance Manual 2-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 This Chapter provides matrices that can be used as screening tools by systems and states 

to quickly identify potential simultaneous compliance issues, while the later chapters provide a 

detailed discussion of these issues. 

• Exhibit 2.1 (page 2-2) is a checklist that can be used to quickly identify potential 

operational and simultaneous compliance issues. It may be particularly useful for 

small systems or systems with limited resources. 

• Exhibit 2.2 (starting on page 2-3) provides a summary of how different compliance 

technologies may affect water quality. For example, while switching from chlorine 

to UV will increase inactivation of Cryptosporidium, it may decrease inactivation for 

viruses. Note that the changes shown in this exhibit may or may not occur at a 

specific water system; they are listed so that systems and states will be aware of them 

and the possibility that they UmayU be an issue. 

• Exhibit 2.3 (starting on page 2-6) summarizes simultaneous compliance issues for 

individual LT2ESWTR and Stage 2 DBPR compliance technologies. For some 

treatment strategies listed, no significant impact on drinking water regulations is 

anticipated. Systems may, however, encounter other challenges, such as an increase 

in waste residuals or a reduction in the quantity of treated water that can be produced. 

• Exhibit 2.4 (starting on page 2-12) identifies potential operational issues for 

individual LT2ESWTR and Stage 2 DBPR compliance technologies. Note that the 

operational issues shown in this exhibit may or may not occur at a specific water 

system; they are listed so that systems and states will be aware of them and the 

possibility that they UmayU be an issue. 

• Exhibit 2.5 (starting on page 2-13) provides summary information on each of the case 

studies in Appendix B. The case studies give real-world examples of how systems 

have dealt with simultaneous compliance issues with past regulations and in 

anticipation of the Stage 2 DBPR and LT2ESWTR. 

• Exhibit 2.6 (page 2-16) lists tools that can be used to gather more information on how 

a system may be affected by a treatment change. 

2 Quick Reference Materials 

for Simultaneous Compliance 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-2 For the Long Term 2 and Stage 2 DBP Rules 

If you are considering a treatment modification or a new treatment to meet the LT2ESWTR or Stage 2 DB

can help you see if you might have problems complying with other drinking water regulations. If you answer “yquestions, go to the section in Chapter 3, 4, or 5 that addresses your treatment change. There you will find a list osimultaneous compliance issues, suggestions for how to address them, and other helpful information. If you are answer any of these questions or need help understanding the water quality impacts of a treatment change, consu

technical assistance provider, or a consulting engineer. 

Exhibit 2.1 Checklist for Identifying Key Operational and Simultaneous Compliance 

Yes No

□ □

Will you be getting less CT (measured as log inactivation) for any regulated microorganism (i.Cryptosporidium) as a result of the treatment change? If you answered “yes” and are a surface 

must conduct disinfection benchmarking and profiling. If you are a ground water system requireinactivation, you must continue to meet 4-log inactivation. 

□ □ Will the treatment change cause an increase (seasonal or permanent) in organic carbon at any 

disinfectant addition? If yes, you could potentially have problems complying with the Stage 1 DDBPR, or the TCR. 

□ □ Will the treatment change the pH and/or alkalinity of your finished water? If yes, your finishe

corrosive and you could have problems complying with the LCR. 

□ □ Will you be using a different residual disinfectant or a different concentration of residual disin

residual changes can impact TCR and LCR compliance. 

□ □ Will the treatment change affect the quality of water being filtered? A change in coagulation o

affect filter performance and compliance with the LT1ESWTR or IESWTR. 

□ □ Will the treatment change result in higher or lower concentrations of inorganics, such as man

aluminum, sulfate, chloride, or sodium in your finished water? If yes, your water could becomyou could have problems complying with the LCR. You could also have aesthetic problems. 

□ □ Will the treatment change cause an increase in production of waste residuals (e.g., enhanced c

cause your system to produce more sludge)? This will not typically cause any rule violations buincreased land disposal area, and increased residual production can present operational challenge
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-3 For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 2.2 Technology Alternatives and How They Potentially Affect Water Qua

Inactivation 

of microbial 

pathogens 

pH alkalinity disinfectant 

residualP1P iron or manganese turbidity NOM DBPs corrosiv

Source ManagementP2P May decrease if 

colder water 

is used 

may 

increase or 

decrease 

may 

increase 

or 

decrease 

 may 

increase 

 may 

decrease

may 

decrease 

may 

increase 

decreas

Distribution System BMPs 

may 

increase 

 may 

increase if 

flushing 

not done 

properly 

 TTHM may 

decrease; 

HAA5 may 

decrease or 

increase 

may 

decreas

Moving the Point of Chlorination Downstream 

May 

decrease 

 may 

increase or 

decrease 

may 

increase 

 decrease 

Decreasing pH Increase 

(for chlorine 

only) 

decrease may 

decrease 

 TTHM may 

decrease, 

HAA5 may 

increase 

may 

increas

Reducing Chlorine Dose Under Warmer Water Conditions 

may 

decrease 

may 

increase or 

decrease 

 may 

decrease 

 decrease 

Presedimentation may 

decrease 

may 

decrease 

may 

decrease

may 

decrease 

Enhanced Coagulation 

may 

increase 

decrease may 

decrease 

 manganese 

may 

increase 

may 

increase 

or 

decrease 

decrease decrease may 

increas

Softening/ Enhanced Softening 

may 

increase, 

may 

decrease due 

to high pH 

increase may 

increase 

 may 

decrease 

may 

decrease 

may 

decrease

HAA5 may 

decrease, 

TTHM may 

increase 

concret

corrosio

may 

increas
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-4 For the Long Term 2 and Stage 2 DBP Rules 

Inactivation 

of microbial 

pathogens 

pH alkalinity disinfectant 

residualP1P iron or manganese turbidity NOM DBPs corrosiv

GAC may 

increase 

due to 

GAC fines 

decrease decrease 

Microfiltration/ Ultrafiltration 

 may 

decrease 

decrease may 

decrease 

Nanofiltration may 

decrease 

may 

decrease 

 decrease decrease may 

decrease

decrease increas

Bank Filtration may 

increase 

Bag Filtration may 

decrease 

may 

decrease 

Cartridge Filtration 

may 

decrease 

may 

decrease 

Second Stage Filtration 

may 

decrease 

decrease may 

decrease

may 

decrease 

 

Slow Sand Filtration 

may 

decrease 

may 

decrease 

may 

decrease

may 

decrease 

DE Filtration may 

decrease 

may 

decrease 

Improved Filter Performance 

may 

decrease 

decrease may 

decrease

may 

decrease 

ChloraminesP3P decrease may 

increase 

 TTHM and 

HAA5 will 

decrease 

may 

increase 

decreas

OzoneP3P increase for 

protozoa 

 may 

decrease, but 

increase in 

bromate 

may 

increase 

decreas

UV DisinfectionP3P UV dose is 

low for 

protozoa, 

need higher 

dose for 

viruses 

 decrease 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-5 For the Long Term 2 and Stage 2 DBP Rules 

Inactivation 

of microbial 

pathogens 

pH alkalinity disinfectant 

residualP1P iron or manganese turbidity NOM DBPs corrosiv

Chlorine DioxideP3P increase for 

protozoa, 

decrease for 

viruses 

 may 

decrease if 

followed 

by filtration

 TTHM and 

HAA5 

decrease, 

chlorite will 

be formed 

P1P Refers to the disinfectant residual in distribution system water. P2P For the purpose of this guidance, source management refers to techniques water systems can use to manipulate their wa

with Stage 2 DBPR or LT2ESWTR regulations. In this context, source management does not refer to source water protewatershed efforts to improve water quality. The source management techniques discussed in this section are operationawater systems to use the source with the least amount of natural organic matter (NOM), or selecting a blend of sources tmost effective treatment for organics and turbidity removal. Source management strategies can affect raw water quality 

finished water quality directly (e.g., blending or alternating sources). P3P Water quality changes for alternative disinfectants are compared to conditions when free chlorine is used. 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-6 For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies: 

Summary of Benefits and Potential Conflicts 

Used for Compliance 

with System Potential Issues 

Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description

Source Management 

X X • may reduce DBP precursors 

• may reduce disinfectant demand • can improve treatability of raw water  for turbidity and/or DBP precursor  removal • may reduce pathogen and particle  loading 

• water temperature change may affect CT and  coagulation/flocculation • may introduce new contaminants (e.g. iron,  manganese, sulfide) • raw water pH change can adversely affect wate treatment and/or corrosion control • may increase coagulant demand • may increase disinfectant demand • change in aesthetic quality may generate  customer complaints 

Distribution System BMPs 

X • targets specific problem areas 

• can improve microbial control 

• can reduce corrosion 

• can reduce nitrification 

• improves chlorine residual 

 maintenance 

• can stir up sediments • issues with disposal of chlorinated water • lining materials may leach into water • less storage available for emergencies • increased water loss 

Moving the Point of Chlorination Downstream 

X • reduces DBP concentrations 

• reduces amount of disinfectant used • can facilitate monthly total organic  carbon (TOC) source water  monitoring 

• May impact ability to meet CT requirements • increases chances of filter fouling • may reduce Asiatic clam or zebra mussel  control • provides less effective treatment for iron or  manganese • may limit coagulation and filtration  effectiveness • may need to increase disinfectant dosage, which  could produce more DBPs 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-7 For the Long Term 2 and Stage 2 DBP Rules 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Decreasing pH X • same inactivation can be achieved 

 with lower disinfectant dose or  shorter free chlorine contact time • lower pH may reduce some DBPs 

• may increase HAA5 

• can adversely affect treatment plant equipment 

• may impact settling and sludge dewatering • can cause corrosion problems 

• may be difficult to maintain a residual 

Reducing Chlorine Dose under Warm Water Conditions 

X • Comparable pathogen inactivation 

 with less chlorine • Reduction in TTHM and HAA5  Formation 

• Higher disinfectant residual needed for  addressing seasonal pathogens • Distribution system impacts if finished water  chlorine concentration is decreased 

Presedimentation X • removes Cryptosporidium

• can remove DBP precursors 

• reduced solids loading and enhanced 

 stability of water 

• algal growth in basins can increase DBP  precursors • removal of solids difficult 

Enhanced Coagulation 

X • may improve disinfection 

 effectiveness • can reduce bromate formation by  reducing pH • can reduce DBP formation • can enhance arsenic and radionuclide  removal 

• may adversely impact finished water turbidity • lower pH can cause corrosion problems • may see increased inorganics concentrations in  finished water • issues with disposal of residuals 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-8 For the Long Term 2 and Stage 2 DBP Rules 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Softening/ Enhanced Softening 

X X • removes DBP precursors 

• two stage plants can achieve 

Cryptosporidium removal credit 

• lower corrosion impacts 

• options for disinfection are limited • may increase scaling in treatment plant and 

 distribution system piping • higher TTHM formation at high pH (may be 

 offset by lower precursors) • pH adjustment may be needed for distribution  system and for disinfection effectiveness • increased sludge volume and change in sludge 

 characteristics 

Granular Activated Carbon (GAC) 

X X • removes DBP precursors 

• can remove taste and odor  compounds • if used as secondary filter, can be  used to receive Cryptosporidium 

removal credit 

• removes AOC after ozone when used  as biological filter 

• may release previously adsorbed compounds • bacteria can be released • fines can foul downstream processes at startup • can limit the ability to pre-chlorinate • chlorate can be formed when GAC comes into  contact with chlorine dioxide • ammonia added before GAC may increase  nitrification 

Microfiltration/ Ultrafiltration 

 X • removes bacteria and protozoa 

• can lower DBPs by allowing lower 

 disinfectant doses • can remove arsenic 

• may have increased loss of process water • can be fouled by organics and minerals • additional training required 

Nanofiltration X X • removes microbial pathogens 

 including viruses • can remove DBP precursors • removes arsenic 

• can increase corrosiveness of water • issues with reject stream • can be fouled by organics and minerals • additional training required 

Watershed Control Program 

X X • removes microbial pathogens 

• reduces DBP precursor loading • reduces chemical contamination 

• none known 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-9 For the Long Term 2 and Stage 2 DBP Rules 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Bank Filtration X • removes microbial pathogens 

• decreases turbidity • decreases DBP precursors • relative ease of use 

• hydraulic issues • iron/manganese problems • clogging 

Bag Filtration X • removes microbial pathogens 

• relative ease of use 

• hydraulic issues • filter fouling 

Cartridge Filtration 

X • removes microbial pathogens 

• relative ease of use 

• hydraulic issues • disposal issues • filter fouling 

Second Stage Filtration 

X X • reduces particulate matter 

• reduces DBP precursors • removes microbial pathogens • reduces assimilable organic carbon  (AOC) 

• hydraulic issues • increased residuals 

Slow Sand Filtration 

X • removes microbial pathogens 

• may reduce DBP precursors 

• hydraulic issues 

Diatomaceous Earth (DE) Filtration 

X • removes microbial pathogens • hydraulic issues 

Improved Filter Performance 

X • removes microbial pathogens 

• reduces chemical contaminants • improves aesthetic quality 

• increased residuals • disposal issues 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-10 For the Long Term 2 and Stage 2 DBP Rules 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Chloramines X • reduce DBPs 

• may improve biofilm control • may increase ability to maintain  disinfectant residual throughout  distribution system • may reduce occurrence of Legionella in hot water systems 

• nitrification may occur in distribution system • may cause corrosion problems with some 

materials 

• potential taste and odor problems if improper 

ratio is used 

• weaker disinfectant • can be difficult to blend with chlorinated 

sources 

• ozone and GAC can lead to faster residual deca• must remove for dialysis patients, fish owners 

and industrial users. 

Ozone X X • inactivates Cryptosporidium and 

Giardia

• does not form TTHM or HAA5 • effective pre-oxidant • increases UV transmittance of water • disinfection not pH dependent • can oxidize taste and odor  compounds • may aid coagulation if fed before  coagulant addition point 

• may form bromate • forms smaller organic compounds • does not provide a residual in the distribution  system • may increase dissolved oxygen in the water • can form taste and odor compounds • can cause corrosion to materials exposed to gas • ozone bubbles can hinder filter performance if 

not operated properly 

• switching to ozone and biofiltration can cause 

the release of manganese from filters 

• requires additional training 

Ultraviolet (UV) Disinfection 

X X • inactivates Cryptosporidium and 

Giardia

• does not produce regulated DBPs • effectiveness not pH or temperature  dependent 

• much higher doses needed to inactivate viruses • does not provide a residual • substances in water can interfere with UV  disinfection • potential for lamp breakage • power quality problems can cause loss of  disinfection • requires additional training 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-11 For the Long Term 2 and Stage 2 DBP Rules 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Chlorine Dioxide X X • achieves some Cryptosporidium

 inactivation • less TTHM and HAA5 formation  than with chlorine • oxidizes iron and manganese • disinfection not pH dependent • chlorite residual may inhibit growth  of nitrifying bacteria in the  distribution system (benefit when  using in combination with  chloramines) 

• forms chlorite which may be a concern for MCL  compliance • reduced effectiveness at low temperatures 

• chlorine dioxide Maximum Residual 

Disinfectant Level (MRDL) limits application dose 

• can form brominated DBPs • degrades under UV light • residual dissipates quickly • potential odor problems • requires additional training and safety concerns 

Brief descriptions of the treatment alternatives discussed here and later in this guidance manual are provided in Exhibit 1.4. 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-12 For the Long Term 2 and Stage 2 DBP Rules 

Topic is marked with an “X” 

if it may be a concern for the 

treatment modification 

Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications 

Treatment Modification 

Production Capability 

Compatibility with Treatment 

Facilities 

Residual/Disposal Issues 

Site Specific Issues 

Distribution System Materials 

Distribution System Operations 

Environmental Issues 

Consumer Driven Issues 

Preference of Operation Staff 

Consecutive System 

Requirements 

Source Management X X X X X X X X X Distribution System BMPs X X X X X X X Moving Point of Chlorination Downstream X X X X X X 

Decreasing pH X X X X X X X 

Decreasing Chlorine Dose Under Warm Water Conditions X X X X X 

Presedimentation X X X X X 

Enhanced Coagulation X X X X X X X X 

Softening/Enhanced Softening X X X X X X X 

Granular Activated Carbon X X X X X X X 

Microfiltration/Ultrafiltration X X X X X X X 

Nanofiltration X X X X X X X X X 

Bank Filtration X X X 

Other Microbial Removal Technologies (improved filter performance, bag filtration, cartridge filtration, second stage filtration, slow sand filtration, DE filtration) 

X X X X X 

Chloramines X X X X X X X 

Ozone X X X X X X X 

UV Disinfection X X X X X 

Chlorine Dioxide X X X X X 

P1PIt is important to note that costs are associated with any modification or new treatment. This column is meant to identify changes th

costly compared to others. Also note that some distribution system BMPs, such as looping dead end pipes, can have relatively high 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-13 For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 2.5 Case Studies in this Guidance Manual and Issues they Address 

Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

1 Improving and 

Optimizing Current Operations 

Owenton Water Works and Kentucky American TriVillage 

Owenton, Kentucky <10,000 1 Surface Wate

(reservoir) 

2 Decreasing pH Public Utility District 

#1 

Skagit County, Washington 

70,000 12 Surface Wate

(reservoir) 

3 Presedimentation Kansas City Water 

Services 

Kansas City, Missouri >600,000 240 Surface Wate

(river, ground water under the direct influence of surface water

4 Switching 

Coagulants 

Hillsborough River Water Treatment Plant 

Tampa, Florida >450,000 100 Surface Wate

(river) 

5 Enhanced 

Coagulation - Problems with Copper Pitting 

Washington Suburban Sanitary Commission 

Montgomery and Prince Georges County, Maryland 

1,600,000 167 Surface Wate

(rivers) 

6 Enhanced 

Coagulation - Managing Radioactive Residuals 

Allen Water Filtration Plant 

Englewood, Colorado 48,000 8.5 Surface Wate

(river, creek, diversions) 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-14 For the Long Term 2 and Stage 2 DBP Rules 

Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

7 GAC for TOC 

Removal 

Higginsville Water Treatment Plant 

Higginsville, Missouri <10,000 2 Surface Wate

(reservoir) 

8 Nanofiltration 

Membrane Technology for TOC Removal 

PBCWUD Water Treatment Plant #9 

West Palm Beach, Florida 

132,000 27 Ground Wate

(surficial aquifer) 

9 Modifying 

Chloramination Practices to Address Nitrification Issues 

Ann Arbor Utilities Ann Arbor, Michigan 115,000 20 Surface Wate

(river, wells) 

10 Ozonation Ann Arbor Utilities Ann Arbor, Michigan 115,000 20 Surface Wate

(river, wells) 

11 Ozonation and 

Biological Filtration 

Sweeney Water Treatment Plant 

Wilmington, North Carolina 

75,000 25 Surface Wate

(river) 

12 UV Disinfection Poughkeepsie Water 

Treatment Facility 

Poughkeepsie, New York 

75,000 16 Surface Wate

(river) 

13 Chlorine Dioxide for 

Primary Disinfection and Chloramines for Secondary Disinfection 

Gulf Coast Water Authority 

Texas City, Texas 92,000 12 Surface Wate

(river) 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-15 For the Long Term 2 and Stage 2 DBP Rules 

Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

14 Chlorine Dioxide for 

Primary Disinfection and Chloramines for Secondary Disinfection 

Village of Waterloo Water Treatment Plant 

Waterloo, New York <10,000 2 Surface Wate

(lake) 
2. Quick Reference Materials for Simultaneous Compliance 

Simultaneous Compliance Guidance Manual 2-16 For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 2.6 Tools for Gathering System-Specific Information on Different Compliance T

Compliance Techniques 

Water Quality Monitoring 

Hydraulic and WQ 

Modeling for DS 

Desktop Evaluation 

Bench-Scale: Disinfectant 

Demand and Decay 

Bench-Scale: DBP 

Formation and Decay 

Bench-Scale: Taste and 

Odor Profiles 

Bench-Scale: Jar/Column 

Testing Procedures 

Bench-Scale: Internal 

Corrosion Assessment 

Pilot Testing 

Full Scale Applications 

Source Management X X X Distribution System BMPs X X X X Moving the Point of Chlorination Downstream X X X X X X X X Decreasing pH X X X X X X X X Decreasing Chlorine Dose Under Warm Water Conditions X X X X X Presedimentation X X X Enhanced Coagulation X X X X X X X Softening/Enhanced Softening X X X X X X X X GAC X X X X X X Microfiltration/Ultrafiltration X X X X X X Nanofiltration X X X X X X Other Microbial Removal Technologies including Bank Filtration X X X X X Chloramines X X X X X X X Ozone X X X X X X X UV Disinfection X X X X Chlorine Dioxide X X X X X X 
Simultaneous Compliance Guidance Manual 3-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

 Public water systems (PWSs) will 

generally find that improving and optimizing 

current operations is the best first step as they 

consider changes to ensure continued compliance 

with LT2ESWTR and Stage 2 DBPR. There are 

several reasons for this. 

• Operational changes to optimize 

existing processes can often achieve 

significant reductions in DBPs and 

pathogens, improve disinfection, and 

improve water quality without major 

capital improvements. These changes 

may be enough to achieve compliance; 

• Operators are familiar with existing 

processes, which will simplify the 

transition; 

• Even if improving and optimizing current operations does not get a system in 

compliance by itself, it may allow for the use of a less expensive or simpler 

technology to ensure compliance; and 

• If existing technologies are not optimized, adding a new technology may not have the 

desired effect or may cost more to operate. 

 This chapter addresses ways that water systems might change how they operate their 

existing facilities to achieve compliance with the Stage 2 DBPR and LT2ESWTR. These 

changes can be made individually or in combination to improve and optimize current operations 

as a whole. Improving filter turbidity performance is in Chapter 4 instead of this chapter because 

of the similarity of issues between this option and other filtration options included in Chapter 4. 

 Several options described in this chapter are ways in which water systems might modify 

their existing chlorination practices. Before making any significant changes to disinfection 

practices, systems that are required (by the IESWTR, LT1ESWTR, and LT2ESWTR) to develop 

a disinfection profile must calculate a disinfection benchmark for the treatment configuration 

currently in place. To learn more about disinfection profiling and benchmarking, refer to EPA’s 

Disinfection Profiling and Benchmarking Guidance Manual (1999a). 

3 Improving and Optimizing 

Current Operations 

OPERATIONAL PRACTICES 

COVERED IN THIS CHAPTER 

 

• Source Management 

• Distribution System Best 

Management Practices 

• Moving Point of Chlorination 

• Modifying pH During Chlorination 

• Modifying Chlorine Dose Under 

Different Temperature Conditions 

• Modifying Pre-sedimentation 

Basin Operations 

• Enhanced Coagulation 

• Enhanced Softening 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.1 Source Management 

 For the purpose of this guidance, the term 

source management refers to techniques that water 

systems can use to manipulate their water source or 

sources to comply with Stage 2 DBPR or 

LT2ESWTR regulations. In this context, source 

management does not refer to source water protection 

or other long-term watershed efforts to improve water 

quality. The source management techniques 

discussed in this section are operational changes made 

by water systems to use the source with the least 

amount of contaminants, such as pathogens and 

natural organic matter (NOM), or selecting a blend of 

sources to try to achieve the most effective treatment for organics and turbidity removal. 

Examples of source management include: 

• Selecting the optimum depth from which to draw water. Systems using lake or 

reservoir sources should have multi-level intakes. This flexibility allows the system 

to draw water from different depths or 

locations, depending on the source 

water quality during that time of year 

or for other reasons (e.g. algal bloom, 

storm upsets, etc); 

• Blending various sources. Systems 

that have multiple sources may 

consider blending surface and ground 

water sources to attain the best blended 

raw water for compliance. If blended 

prior to treatment, all water must be treated to surface water standards; 

• Alternating between sources. Systems with multiple sources may consider alternating 

between surface water and ground water sources depending on source water quality at 

a given time. Systems may also temporarily discontinue use of a source for a period 

of time when negative impacts are expected or water quality is poor; and 

• Using the optimum intake. Systems may have more than one intake they can use to 

draw from a source. By determining the intake with the highest water quality for 

each particular time period, the system can obtain the optimum water quality year 

round. 

 Many systems have one or more source management options available to them, while 

others have limited opportunities to manage their source water quality in this way. Those 

systems that think they could benefit from greater source management flexibility are encouraged 

to diversify their options as feasible when they are planning capital improvements. 

Water system managers should 

check with their primacy agency 

before making any source 

management changes. Approval 

of the primacy agency may be 

required before a water system 

modifies or switches its raw water 

source. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Source management may be considered as a temporary, seasonal, or permanent solution 

depending on physical or chemical characteristics of the source; the need to reduce disinfection 

byproduct (DBP) precursors, Cryptosporidium and/or turbidity; the availability of alternate, 

additional, or new sources; and the impact the water chemistry change has on the rest of the 

system. For example, a system may only have seasonal issues with DBP precursor 

concentrations and, therefore, may decide to apply one or more source management techniques 

on a seasonal basis. 

 Many factors can have a temporary or seasonal impact on surface water quality and can 

impact organic loading, turbidity, and pathogen concentrations entering the plant. If these 

impacts are understood and flexibility is built into the plant intake and operations, the system 

may be able to use source management strategies to comply with the Stage 2 DBPR and 

LT2ESWTR and avoid or mitigate simultaneous compliance issues. These factors include: 

• Seasonal turnover - In colder climates many reservoirs and lakes experience turnover 

during the spring and fall. When this occurs, sediment, organic matter and 

particulates at the bottom of the reservoir can be stirred up and re-suspended. This 

can lead to an increase in organic load, algal blooms causing taste and odor, turbidity, 

and higher pathogen concentrations entering the plant; 

• Precipitation events - Heavy rainfall or snowmelt can wash organic matter and 

particulates from soils into surface water sources. A runoff event upstream of the 

intake can result in an increase in organic load and pathogens entering the plant; 

• Algae blooms - Seasonal algae blooms that occur in lakes and reservoirs can impact 

NOM levels and raw water pH in water nearer to the surface. Decayed algae can 

contribute organics to sediment that later become problematic during turnover. Algae 

blooms can also interfere with filter operation and may interfere with analysis for 

Cryptosporidium and Giardia; 

• Point source discharges - Discharges from wastewater treatment plants, water 

treatment plants, and industrial discharges upstream of the intake can increase the 

organic load and pathogens in source water. This becomes more significant when 

stream flow decreases and there is less dilution; and 

• Nonpoint sources of pollution - Nonpoint discharges of pollution can impact the 

organic load in the source water. They can also increase microbial contaminants such 

as Cryptosporidium and increase nutrients that can cause algal blooms. Many such 

sources of pollution are intermittent or seasonal and, if the system is aware in 

advance, adverse impacts can be avoided by temporarily discontinuing use of the 

source. 

If a ground water is used to supplement a surface water source on a seasonal basis, the quality of 

the ground water should be considered, including its pH, iron and manganese concentrations, 

oxidation reduction (redox) potential of the water, and any nearby contaminant plumes. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Jar testing should be conducted 

when a system is considering a 

source water change. 

3.1.1 Advantages of Source Management 

 By using source management techniques, a PWS may be able to: 

• Reduce DBP precursors in the raw water (reduction in raw water organic load); 

• Reduce turbidity or pathogen levels in the raw water; 

• Reduce oxidant or chlorine demand in the raw water and amount of disinfectant 

used; and 

• Improve treatability of raw water for turbidity and/or DBP precursors. 

 While changes to the source may be advantageous for minimizing DBP precursor 

concentrations or turbidity, any major changes in the source water entering plants are likely to be 

accompanied by corresponding changes in other raw water chemistry. These may include 

changes in pH, temperature, alkalinity, organics, inorganics, radionuclides, etc. As a result, these 

changes will have an impact on the treatment processes employed by the system and may impact 

the distribution system as well. Therefore, when a source water change is considered, water 

quality monitoring and jar testing should be conducted to determine the impacts the change in 

water chemistry will have on the plant, as well as the 

stability of the distribution system. Some, but not all 

of these are included in Section 3.1.2. 

Reduce DBPs

 Selecting a source water or combination of source waters containing the least amount of 

or more treatable organic matter can reduce finished water DBP concentrations. The water 

chemistry of stratified lakes and reservoirs can change seasonally and vary significantly 

depending on water depth. Different depths in a stratified source may contain different 

concentrations of organics with different characteristics (e.g., particulate vs. dissolved, high vs. 

low molecular weight). Water systems can use this to their advantage by determining the depth 

containing the lowest DBP precursor concentrations or precursors that are most easily removed, 

and then draw their source water from this depth. Systems should keep in mind, however, that 

the depth producing the lowest concentration of DBP precursors may change seasonally. It is 

important for an effective source management program to include routine monitoring to detect 

changes in water quality at different intake depths and guide decision-making. Section 3.1.3 

provides some suggestions for additional monitoring that can help in this way. 

 Blending sources can also produce lower finished water DBP concentrations if the 

additional source used in blending contains lower concentrations of DBP precursors. 

Reduce turbidity or pathogen level 

 Turbidity and pathogen concentrations can 

vary depending on the location, timing, and 

characteristics of the particles or pathogens. For 

example, stratified reservoirs can have different 

Routine reservoir monitoring can 

help a system select the best 

intake depth for minimizing 

DBPs.
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

turbidity levels at different elevations, especially during algae blooms. Certain pathogens can 

also concentrate in one location of a reservoir. By being aware of the concentrations of particles 

and pathogens at various locations in the water source the system can plan its withdrawals to 

minimize the concentrations of these contaminants. 

Reduce Amount of Disinfectant Used

 Organic matter, inorganic matter, and biota such as algae in water usually present a 

chlorine demand. If an alternative water source is used that is well-oxygenated and has lower 

concentrations of organic matter, iron, and manganese, the water is likely to have a lower 

chlorine demand than the poorer quality water previously used. 

Raw Water Treatability

 By drawing water from different depths in a stratified source, blending sources or 

alternating sources, the raw water chemistry may also be manipulated to provide optimum 

conditions for water treatability resulting in increased particulate removal. For example, systems 

that have minimal alkalinity in the source water may find that blending another source water 

with higher alkalinity may improve coagulation (when using alkalinity-dependent coagulants), 

resulting in a reduction in DBP precursors and turbidity. In this situation, however, systems 

should keep in mind that increasing alkalinity would in turn increase the amount of chemical 

needed to lower the pH and effectively remove total organic carbon (TOC). 

 Different types of organic matter in water can be removed more or less effectively during 

coagulation. In general, water containing primarily non-humic organic matter is less amenable 

to enhanced coagulation. This type of water is also more likely to have a lower specific 

ultraviolet absorbance (SUVA) concentration. By monitoring for NOM indicators such as 

SUVA in their source water alternatives, water systems can pick the water that can be treated 

more effectively for NOM removal and, possibly, reduce DBP concentrations in the finished 

water. 

 By avoiding water with algal blooms, systems can improve the coagulation properties of 

the water. Avoiding algal blooms can also reduce taste and odor compounds that are difficult to 

remove during conventional treatment. 

3.1.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Source Management Changes 

 Any changes to the raw water as a result of source management are likely to affect the 

raw water chemistry and in some way impact treatment processes. While the goal may be to 

minimize organic and/or pathogen loading or provide optimum conditions for DBP precursor and 

turbidity removal, adverse changes in the raw water chemistry may include: 

• Water temperature changes affecting CT (concentration H contact time)

calculations and coagulation and flocculation; 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• Introduction of new contaminants or higher concentrations of existing 

contaminants (e.g., iron, manganese, sulfide); 

• Variation in raw water pH adversely affecting water treatment; 

• Reduction in coagulation effectiveness or increased coagulant demand because 

of other chemistry changes (e.g., alkalinity, type of turbidity); 

• Changes in source water quality impacting corrosion control effectiveness; 

• Increased disinfectant demand for water under reduced conditions (e.g., little or 

no dissolved oxygen); and 

• Changes in aesthetic quality may generate customer complaints. 

Again, as noted in section 3.1.1, water quality monitoring should be conducted to determine the 

impacts of changes in water chemistry. Section 3.1.3 lists additional parameters that systems can 

monitor to guide their source management decisions. General suggestions for addressing some 

of these issues that may arise as a result of source changes are provided below. 

Changes in Water Temperature

 If a water system's managers opt to draw from a lower level in a thermally stratified 

reservoir during warmer months in order to decrease DBP precursors at the plant, the water 

temperature may be considerably lower than the system typically experiences. It is not unusual 

in northern parts of the U.S. for water temperatures near the top of a reservoir to be at least 10 

degrees C higher than temperatures near the bottom. As water temperature decreases, pathogen 

inactivation using most disinfectants is less effective, and therefore the required CT must be 

increased. Since the system’s contact time (T) is generally set, the disinfectant concentration (C) 

may need to be increased when operating at maximum capacity. Therefore, the benefit gained 

by changing the source to one with lower DBP precursors may be offset by the required increase 

in disinfectant concentration, and little gain in terms of reducing finished water DBPs may be 

realized. Alternatively, the lower temperature may slow down DBP formation reactions and 

residual decay reactions that may mitigate the effect of temperature to some degree. 

 The converse, however, may also apply. If a system draws from a higher level in the 

reservoir and there is a corresponding higher temperature, this may result in more efficient 

inactivation and therefore less required CT. 

 Colder water temperatures also result in slower floc formation in the coagulation process 

and therefore, decreased efficiency of turbidity removal (Faust and Aly 1998). 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Recommendations for Addressing this Issue

 Systems may need to increase their CT when using a colder water source. Frequently a 

system's T is set, especially when a system is operating at maximum capacity in the summer 

months. Therefore, the disinfectant residual concentration may need to be increased in the 

treatment plant. 

 Changes in temperature may require changes in coagulant dose, mixing speeds, and other 

factors related to coagulation. To determine the impact colder water temperature may have on 

the coagulation process, systems should conduct jar tests with the modified source water to 

determine optimum conditions for coagulation based on the new water temperature and 

chemistry. As the source water temperature and/or water chemistry changes, additional jar tests 

should be conducted to determine the optimum conditions based on the new temperature or water 

chemistry change. 

Introducing New Contaminants or Higher Concentrations of Existing Contaminants 

 Contaminants such as arsenic, dissolved iron, dissolved manganese, or hydrogen sulfide 

may be introduced or their concentrations may be increased depending on source management 

decisions. For example, in the summer months a system may alternate its surface water source 

with a ground water source to produce water lower in DBPs. This may, however, introduce 

contaminants into the source water for which there is not adequate treatment in place for 

removal, or the contaminant may deplete chemicals used in the treatment process that are needed 

for other purposes (e.g., dissolved iron may deplete chlorine meant to be used for disinfection). 

For systems using thermally stratified sources, drawing from a lower depth to avoid high 

turbidities may introduce water with higher concentrations of dissolved organics or soluble 

metals. 

 Another potential problem with a system introducing new contaminants or contaminants 

at higher concentrations is the potential for increasing contaminant concentrations in the residual 

waste streams of certain treatment processes. For example, if higher arsenic concentrations are 

introduced in a conventional surface water plant, the arsenic will be oxidized and removed, and 

will be concentrated in the sludge and backwash water. 

 Recommendations for Addressing this Issue

 To address the problem of introducing or increasing contaminant concentrations in the 

source water, systems should analyze the water chemistry of the alternate source for typical 

constituents and suspected contaminants. Systems can then compare the alternate source's water 

chemistry with the original source and consider the possible impacts prior to making source 

changes. Section 3.1.3 provides some suggestions for additional monitoring to assist with this 

decision making process. Once the new source water chemistry has been characterized, systems 

using coagulants should conduct jar tests to determine if contaminant concentrations negatively 

impact the treatment process. Several tests may be necessary to determine a source management 

option that works best for meeting all treatment goals. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Problems with a Change in Raw Water pH

 A water system may change its source to decrease DBP precursors at the plant, but the 

change may also affect the pH of the raw water. Variations in raw water pH will affect CT, 

coagulation effectiveness for certain coagulants, and possibly DBP formation, unless pH is 

controlled ahead of and through the treatment plant. 

 For systems that use chlorine to disinfect, pathogen inactivation is very dependent on pH. 

As pH increases, inactivation is less efficient, and therefore the required CT must be increased. 

Since the system's contact time is frequently set, the disinfectant concentration (C) may need to 

be increased when operating at maximum flow. As with the impact from temperature, the 

benefit gained by changing the source to one with lower precursors may be offset by the required 

increase in disinfectant concentration. Under these circumstances, little gain may be realized. 

 Variations in the raw water pH can affect the coagulation process. The pH may no longer 

be in the optimum range for coagulation using pH-dependent coagulants such as alum. Less 

effective coagulation is likely to result in less DBP precursor removal, leaving more DBP 

precursors available for reaction with chlorine or other disinfectants downstream in the treatment 

process. If the pH of the source water is low and alum is used for coagulation, aluminum ions 

may pass through the filters if alum is overdosed. A more detailed discussion of aluminum 

solubility can be found in section 3.4.2. 

 Recommendations for Addressing this Issue

 If the source water pH changes, water systems should conduct jar tests to determine 

optimum coagulation/flocculation conditions based on the new pH. Systems should ensure that 

corrosion control is adjusted accordingly if the pH change persists in water entering the 

distribution system. 

Reduced Coagulant Effectiveness

 If source management is used to reduce DBP precursors, the turbidity of the raw water 

may increase as a result. An increase in turbidity may result in increased coagulant demand and, 

possibly, increased alkalinity demand. Water with increased turbidity may be more difficult to 

treat, especially for systems that are not optimized or are nearing the design capacity of the 

coagulation process. Higher influent turbidity can also lead to higher settled water turbidity and 

problems with filtration. 

 Recommendations for Addressing this Issue

 Systems should characterize the source water chemistry of the proposed new source or 

blend of sources to ensure there are no negative impacts related to the coagulation process. Jar 

tests should be performed if parameters that impact coagulation such as turbidity, alkalinity, pH, 

or temperature change significantly. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Changes in Corrosion Control Effectiveness

 Systems using source management options such as blending various sources or 

alternating between sources may experience changes in source water quality. This is especially 

true for systems that switch from ground water to surface water, or vice versa. Fluctuations or 

permanent changes to source water quality may impact the effectiveness of existing corrosion 

control practices. 

 Recommendations for Addressing this Issue

 Systems should characterize the source water chemistry of the proposed new source or 

blend of sources to evaluate the impact of dissimilar waters on corrosion control. Systems may 

need to make changes to their corrosion control process if there are differences in water quality. 

Increased Disinfectant Demand for Waters under Reduced Conditions

 When drawing from lower reservoir depths or from ground water sources, the water may 

be under reduced conditions (with low or no dissolved oxygen (DO)). Dissolved iron, 

manganese, and hydrogen sulfide may be present in these waters. The dissolved oxygen level at 

which these agents become a problem is site specific and depends on other water quality 

parameters such as pH and iron speciation. These reducing agents are readily oxidized by 

disinfectants and, therefore, increase the disinfectant demand. In addition, dissolved iron and 

manganese precipitate when oxidized, creating more turbid water and increasing the particle load 

onto the filters. 

 Recommendations for Addressing this Issue

 Water systems should be aware of the DO concentration and oxidation reduction 

potential of the source water they are using. Chlorine dose should be adjusted to accommodate 

the increased chlorine demand due to reduced conditions. Alternatively, systems may consider 

periodic use of an additional oxidant, such as potassium permanganate, as a pretreatment to 

oxidize reduced iron, manganese, or sulfide (Cooke and Kennedy, 2001). Aerating the water 

before it is treated can be another effective way to eliminate reduced conditions. 

 Once they are oxidized, the inorganic chemicals that were formerly dissolved are likely to 

precipitate. Water systems should carefully review their filter effluent turbidities to ensure that 

additional particle loading is not stressing the filters. Systems should also conduct jar tests to 

determine how to adjust their coagulant dose to improve removal of the additional particle load. 

Changes in Aesthetic Quality May Generate Customer Complaints 

 When drawing from lower reservoir depths or changing to a groundwater source, systems 

may draw in hydrogen sulfide, iron, manganese and other compounds that may cause taste and 

odor problems. An increase in hardness may also generate customer complaints. 

 Recommendations for Addressing this Issue
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Systems that draw from anoxic layers in stratified reservoirs or from anoxic groundwater 

may want to add a pre-oxidant to oxidize compounds such as iron, manganese, and hydrogen 

sulfide (Cooke and Kennedy, 2001). Changes in hardness should be considered and lowered if 

they become problematic by blending sources or by softening processes. Some systems may 

want to notify customers of a source water change to explain why they may be seeing a change 

in water characteristics at the tap. 

3.1.3 Recommendations for Gathering More Information 

See Additional References

 Readers can turn to Section 7.1.4 in Chapter 7 for technical references associated with 

source management. 

Consider Additional Monitoring

 Source management changes are likely to affect raw water chemistry. Additional 

monitoring can help systems understand how treatment processes and other components of a 

PWS will be affected by changes in the raw water chemistry. Water quality monitoring can also 

be used for making source management decisions. For example, a system that monitors water 

quality at its various intake depths can use measurements such as turbidity or TOC to decide 

which intake gates to open and use. Many of these parameters can be monitored in real time to 

provide immediate feedback into plant operation. 

 Systems choosing to use any of the source management options discussed in this section 

should consider monitoring the applicable following parameters at a location before water enters 

the treatment plant: 

9 Dissolved Oxygen 

– Ground water and stratified surface water sources 

– DO profiles of lakes or reservoirs at the intake location using a field meter 

9 Temperature 

– All sources 

– Temperature profiles of lakes or reservoirs at the intake location using a field 

meter 

9 pH 

– All sources 

– pH profiles of lakes or reservoirs at the intake location using a field meter 

9 Secchi disk depth 

– Lakes and reservoirs to determine water clarity 

9 Oxidation-reduction (redox) potential 

– Ground water and stratified surface water sources using a field meter, if possible 
3. Improving and Optimizing Current Operations 

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For the Long Term 2 and Stage 2 DBP Rules 

9 Turbidity 

9 Alkalinity 

9 NOM measured as TOC or SUVA 

9 Dissolved iron 

9 Dissolved manganese 

9 Hydrogen sulfide 

9 Other chemicals known to be problematic for ground or surface water sources in the 

area 

9 Chlorophyll a and algal counts 

Consider Other Tools 

 In addition to water quality monitoring, there are multiple tools available in Chapter 6 to 

help systems evaluate and improve their current water system in relation to the compliance issues 

they may face when modifying their operation or treatment practices. For example, the 

AwwaRF report “Design of Early Warning and Predictive Source-Water Monitoring Systems” 

(Grayman et al. 2001) provides guidance on the development of source water quality monitoring 

systems that allow utilities to predict water quality events in the source water. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 

3.2 Distribution System Best Management Practices 

 The overall objectives of distribution system best management practices (BMPs) are to 

maintain the quality of the treated water while also meeting water quantity, pressure, and service 

reliability goals. If there is a significant increase of DBP concentrations from the finished water 

to the distribution system, systems should consider implementing BMPs to lower DBP levels in 

the distribution system. BMPs that can be particularly effective in reducing DBP formation in 

the distribution system include: 

• Water age management strategy 

• Booster disinfection 

• Water main flushing program 

Other BMPs that are important for overall management of distribution system water quality 

include but are not limited to a pressure management strategy, backflow prevention program, 

procedures to prevent contamination during installation and repair of water mains, a pipeline 

rehabilitation and replacement program, and finished water storage facility inspection and 

cleaning program. These BMPs are also discussed briefly below. 
3. Improving and Optimizing Current Operations 

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For the Long Term 2 and Stage 2 DBP Rules 

 Water systems should prioritize the implementation of BMPs based on their system 

conditions and needs. BMPs are particularly important for systems purchasing water from other 

systems because the purchasers normally have limited flexibility for improving the water quality 

entering the distribution system. Some systems may face operational and simultaneous 

compliance issues when implementing distribution system BMPs, as discussed later in this 

section. 

Water Age Management Strategy 

 As water travels through the distribution system, chlorine continues to react with NOM to 

form DBPs. Thus, increased water age can lead to higher DBP concentrations1. Other water 

quality problems associated with increased water age include reduced disinfectant residual, 

increased microbial activity, nitrification, and/or taste and odor problems. 

 Water systems should develop an overall strategy to manage the water age in their 

distribution systems. Establishing a water age goal is system-specific depending on system 

design and operation, water demands, and water quality (e.g. DBP formation potential). In the 

US, the average distribution system retention time is 1.3 days and the average maximum 

retention time is 3.0 days based on a survey of 800 medium and large water utilities (AWWA 

and AwwaRF 1992). 

 Water age can be controlled through a variety of techniques including management of 

finished water storage facilities, looping of dead-ends, and re-routing of water by changing valve 

settings. Additional guidance is provided in the AwwaRF report, Managing Distribution System 

Retention Time to Improve Water Quality (Brandt et al. 2004). 

• Improve Mixing in Storage Facilities. Improving mixing in finished water storage 

facilities can help eliminate stagnant zones. Old water in stagnant zones can often 

have very high DBPs and no or low disinfectant residual. This water can be released 

into the system during periods of high demand. Mixing can be improved by 

increasing inlet momentum, changing the inlet configuration, increasing the fill time, 

and by installing mixing devices within the storage facility. Hydraulic experts should 

be consulted to determine which of these strategies will work for a given tank design 

and configuration. Additional information is provided in an AWWA publication, 

Physical Modeling of Mixing in Water Storage Tanks (Roberts et al. 2006). 

• Minimize the Hydraulic Residence 

Time in Storage Facilities. Increasing 

volume turnover reduces the average 

hydraulic residence time (HRT) in 

finished water storage facilities, thereby 

reducing DBP formation, loss of 

disinfectant and microbial growth. 

Kirmeyer et al. (2000b) recommend a 

 

1

 The extent of DBP formation in the distribution system is dependent on many factors and is site-specific. TTHM 

levels typically increase with water age. Because HAA5 can biodegrade, however, HAA5 concentration may 

decrease with advanced water age in areas of the distribution system with low or non-detectable disinfection 

residuals and increased microbial activity. See Section 7.1.2 for references on DBP formation. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-13 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

complete turnover every three to five days but suggest that water system’s establish 

their own turnover goal based on system-specific needs and goals. Turnover can be 

accomplished by increasing the water level fluctuation or drawdown between fill and 

draw cycles. The water level should be lowered in one continuous operation not 

small incremental drops throughout the day. Converting tanks to eliminate common 

inlet/outlet configurations can also reduce average HRT. 

• Decommission Storage. Decommissioning storage facilities may be an appropriate 

strategy to reduce water age if existing facilities are oversized and not needed for 

emergency conditions, fire protection, or for maintaining system pressure. A 

professional engineer should review system needs, system design, and operation to 

determine if the existing storage capacity is appropriate. 

• Minimize Hydraulic Residence Time in Pipes. Minimizing the HRT in pipes can 

help reduce the time available for DBP formation, although it is possible for an 

increase in HAA5 to occur because of less biological degradation. Reducing HRT 

can also minimize disinfectant residual loss and allow systems to use a lower overall 

residual concentration, thereby reducing DBPs. Systems can reduce HRT and 

disinfectant loss through physical system improvements such as looping dead ends, 

installing blow-offs, and replacing oversized pipes. These can be expensive, 

however, and cost-prohibitive for some systems. 

 

Booster Disinfection

 

 Booster disinfection can improve disinfectant residual maintenance and minimize 

formation of DBPs by allowing systems to reduce the chlorine residual leaving the treatment 

plant and feed chlorine at select locations in the distribution system to maintain a residual. 

Systems can reduce the booster disinfectant dosage rate by first reducing the disinfectant demand 

within the piping system through various maintenance programs. For example, periodic flushing 

of the water mains removes loose sediment. Cast iron pipes can be cleaned and lined with 

materials that are less prone to microbial growth or have less potential for consuming oxidants. 

Develop and Implement a Water Main Flushing Program 

 A water main flushing program helps to keep the system clean and free of sediment, 

reduces the disinfectant demand of pipe surfaces, and removes stagnant water and any untreated 

or contaminated water that enters the system (Kirmeyer et al. 2000b). Flushing can also be used 

to address water quality deterioration at dead-ends. If a dead-end is unavoidable, industry and 

regulatory guidance recommend fitting dead-ends with hydrants or blow-offs for flushing 

purposes (Friedman et al. 2005). 

Minimum elements of a flushing program are outlined in the AWWA G200 Standard 

(AWWA 2004e) and include: (1) a preventive approach including spot flushing to address local 

problems or customer concerns and routine flushing to avoid water quality problems; (2) use of 

an appropriate flushing velocity to address water quality concerns; and (3) written procedures for 

all elements of the flushing program including water quality monitoring, regulatory requirements 

and specific flushing procedures. 
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For the Long Term 2 and Stage 2 DBP Rules 

Kirmeyer et al. (2000b) developed an approach to assist utilities with developing, 

implementing, and evaluating the effectiveness of flushing programs. The program includes four 

steps: 

• Step 1: Determining the Appropriateness of Flushing as Part of a Utility 

Maintenance Program. In this step, the water system conducts a self-assessment to 

determine if flushing is needed to maintain distribution system water quality and what 

type of flushing is warranted. For example, yes answers to the following questions 

would indicate a need for flushing: 

- Do you experience frequent water quality-related customer complaints? 

- Do you have difficulty maintaining a disinfectant residual in portions of the 

distribution system? 

- Does sediment accumulate in finished water storage facilities? 

If the water system determines that flushing is needed, a second self-assessment can 

help determine the feasibility of conducting an effective flushing program. Questions 

to consider prior to initiating flushing may include: 

- Will hydraulic constraints prevent the achievement of desired flushing velocities? 

- Is enough water available to flush at desired velocities for desired duration? 

- What are the requirements for disposing of the water? 

• Step 2—Planning and Managing a Flushing Program. In this step, the water 

system identifies flushing objectives, determines the most effective flushing 

approach, and establishes specific flushing procedures. Flushing objectives may 

involve both water quality considerations as well as hydraulic and maintenance 

considerations. One or more flushing approaches may be appropriate, unidirectional, 

conventional, and/or continuous blow-off depending on system configuration and 

flushing objectives. Each approach can be implemented on a comprehensive, systemwide basis or on a more limited “spot” basis. Other important planning activities 

include notifying customers of flushing activities and identifying sensitive users that 

may be impacted by temporary water quality changes as a result of flushing; 

• Step 3—Implementing a Flushing Program and Data Collection. Water quality 

monitoring and documentation of costs provide information needed to evaluate the 

program (Step 4); and 

• Step 4—Evaluating and Revising a Flushing Program. Kirmeyer et al. (2000b) 

suggest that experimenting with flushing velocities, duration, and frequency may help 

the water system establish a flushing program that meets water quality goals within 

their operating budget. Additional guidance is provided in an AwwaRF report, Cost 

and Benefit Analysis of Flushing

(DeNadai et al. 2004).

Care should be taken regarding disposal of 

disinfected water. The AwwaRF report Guidelines 

for the Disposal of Chlorinated Water (Tikkanen et 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-15 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

al. 2001) provides strategies for removing chlorine and choramine from water during flushing. 

See Section 3.2.3 for additional information. 

In some cases, flushing may not be adequate to clean water mains. Techniques such as 

pigging may be needed to remove accumulated material. 

Other BMPs for Maintaining Distribution System Water Quality 

• Pressure Management Strategy. Pressure losses can occur in the distribution 

system as a result of events such as flushing, main breaks, power outages, service line 

breaks, and fires. Pressure transients (also called pressure surges or water hammer) 

can occur when an abrupt change in water velocity occurs, due to a sudden valve 

closure, pump shutdown or loss of power. The resulting pressure wave, with 

alternating low and high pressures, travels back and forth through the distribution 

system until the pressure is stabilized. Low pressure conditions in the distribution 

system can allow a flow reversal or backflow of non-potable water to enter the system 

from a cross connection or other source. Pressure transients can also create hydraulic 

disturbances that allow biofilm material on pipe surfaces to enter the bulk water. 

Industry guidelines suggest that system pressure should be maintained within the 

range of 35 to 100 psi at all points in the distribution system (AWWA 1996). The 

AWWA G200 standard indicates that the minimum residual pressure at the service 

connection under all operating conditions should be > 20 psi (AWWA 2004c). 

Written standard operating procedures for pump, hydrant and valve operation under 

routine and emergency conditions can help minimize sudden changes in water 

velocity that impact system pressure; 

• Backflow Prevention Program. The National Research Council (2006) ranked cross 

connections and backflow events as the highest priority concern for water 

distribution systems. Systems should have cross connection control and backflow 

prevention programs that meet state regulatory requirements and adhere to industry 

guidelines (AWWA 2004c); 

• Program to Prevent Contamination During Installation and Repair of Water 

Mains. Contamination of the distribution system following water main breaks or new 

installations was identified as a high priority issue by the National Research Council 

(2006). The AWWA Standard C651-05 (AWWA 2005c) provides a method for 

disinfecting newly constructed water mains or water mains that have undergone 

repairs. Pierson et al. (2001) developed comprehensive best practices to prevent 

microbiological contamination of water mains covering topics such as site conditions; 

condition and storage of materials; general construction/repair practices; preparing for 

service; and project closeout; 

• Pipeline Rehabilitation and Replacement Program. A comprehensive program to 

assess and upgrade water mains will help maintain water quality and to provide 

reliable service. Pipe replacement and various types of pipe lining can help improve 

water quality as well as increase carrying capacity of pipes. AWWA Standard G200 

(AWWA 2004c) and several AwwaRF publications provide guidelines for program 

elements; and 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-16 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• Finished Water Storage Facility Inspection and Cleaning Program. Regular 

inspection of storage facilities provides information needed to plan facility 

maintenance and to minimize contaminant entry to the system. Kirmeyer et al. 

(2000b) identifies three types of inspections - routine, periodic and comprehensive. 

Routine inspections, conducted on a daily to weekly basis, are primarily a visual 

inspection of the tank’s structural integrity and the site’s security. Periodic 

inspections, conducted every one to four months, require climbing the tank to visually 

inspect areas not normally accessible from the ground. Comprehensive inspections 

are conducted every three to five years depending on state requirements and industry 

guidelines. Comprehensive inspections evaluate the structural condition of storage 

facility components including interior features. Kirmeyer et al. (2000b) recommends 

that covered facilities be cleaned every three to five years, and uncovered storage 

facilities be cleaned once or twice per year. The cleaning frequency should be set 

based on system-specific information such as inspection reports and water quality 

monitoring data. 

3.2.1 Advantages of Distribution System BMPs 

 Depending on treatment and distribution system configuration and characteristics of DBP 

formation, distribution system BMPs may be less expensive ways to achieve compliance with the 

Stage 2 DBPR compared to advanced treatment options. Other advantages to implementing 

distribution system BMPs include: 

• Target specific problem areas 

• Improve microbial control 

• Improve chlorine residual maintenance 

• Reduce corrosion 

• Reduce nitrification 

Target Specific Problem Areas

 Many of the BMPs such as flushing, booster disinfection, and management of finished 

water storage facilities can target specific problem areas rather than apply a solution to the entire 

system. This is an efficient way to improved water quality in the distribution system. 

Improve Microbial Control

 In additional to reducing DBP formation, most BMPs will improve microbial control by 

helping to maintain a disinfectant residual and/or reducing biofilms and sediments that encourage 

biological growth. Improved microbial control can result in fewer Total Coliform Rule 

violations, fewer violations of the Surface Water Treatment Rule requirement to maintain a 

disinfectant residual, and less potential for microbiologically-induced corrosion. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-17 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Improve Chlorine Residual Maintenance

 The National Research Council (2006) ranked loss of disinfectant residual as a medium 

priority concern for water distribution systems because “...it is an indirect health impact that 

compromises the biological integrity of the system and promotes microbial regrowth.” Long 

hydraulic residence times, microbial growth, and corrosion products will all deplete the 

disinfectant residual. The BMPs seek to reduce these factors and will therefore result in higher 

and more consistent residuals throughout the distribution system. 

Reduce Corrosion

 Corrosion can cause Lead and Copper Rule compliance problems, aesthetic problems, and 

may eventually lead to leaks that can be sources of contamination to the system. Corrosion of 

cast iron pipes can provide a habitat for microorganisms and increase the likelihood of TCR 

violations. Some BMPs, such as pipe replacement or lining, can reduce corrosion. 

Reduce Nitrification 

 The occurrence of nitrification in chloraminated systems can be reduced through the use of 

distribution system BMPs. Reducing water age and controlling microbial growth will help 

reduce nitrification episodes by slowing the decay of chloramines and providing less free 

ammonia for nitrification. 

3.2.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Distribution System BMPs 

 Challenges of implementing the BMPs depend largely on the specific BMP. Examples of 

these challenges include: 

• Re-suspension of sediments 

• Issues with disposal of disinfected water 

• Lining materials leaching into the water 

• Less storage available for emergencies 

• Increased water loss 

Re-suspension of Sediments

 Some BMPs such as increasing storage pumping rates, using blow-offs, or flushing of 

pipes can cause re-suspension of sediments that had settled in the storage facilities or pipes. 

These sediments can cause temporary aesthetic complaints and may also contain microbes or 

particulate metals such as lead, copper, and iron. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-18 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Recommendations for Addressing this Issue

 A properly implemented flushing program can remove the sediments from the pipes and 

can result in a positive long-term impact. There are many references listed in the Section 7.1.5, 

Distribution System Management, that can that can be used to plan, design, implement, and 

monitor an effective flushing program (AWWA 2002; AWWA 2005b; Kirmeyer et al. 2000b). 

Issues with Disposal of Disinfected Water

 When flushing water distribution mains or draining storage facilities prior to cleaning or 

inspections, utilities should be aware of state or local regulations on disposal of chlorinated or 

chloraminated water. If flushed water flows directly into natural waters, systems may need to 

remove the disinfectant chemicals prior to discharge to protect the aquatic environment. The 

National Pollution Discharge Elimination System is a Federal program established under the 

Clean Water Act, aimed at protecting the nation’s waterways from point sources of pollution. 

Effluent limitations vary depending on receiving water characteristics (use classification, water 

quality standards, flow characteristics) and discharge characteristics (flow, duration, frequency). 

 Recommendations for Addressing this Issue

 The AwwaRF report, Guidelines for the Disposal of Chlorinated Water (Tikkanen et al. 

2001) provides information on dechlorination techniques in use by water systems. Some utilities 

use straightforward field methods such as a bag filled with a de-chlorinating agent placed in the 

flowing water, while other systems have sophisticated metering and storage equipment installed 

in trailers. 

Lining Materials Can Leach Into Water

 Some lining materials can leach chemicals into the water if not properly handled or 

applied. 

 Recommendations for Addressing this Issue

 It is important to make sure the lining material has been independently certified against 

NSF/ANSI Standard 61. Manufacturers' instructions and appropriate standards should be 

followed in lining the pipe and returning it to service as well. In addition to following the 

certifying agency’s and manufacturer's recommendations, many utilities will conduct their own 

water quality tests for compounds of interest including VOCs and taste and odor-causing 

compounds before a new lining is returned or released to service. 

Less Storage Available for Emergencies

 Removing finished water storage facilities from service, while reducing DBPs and 

improving microbial control, can result in less storage available for emergencies such as drought, 

earthquakes, main breaks, firefighting, etc. To a lesser extent, some of the other finished water 

storage BMPs can also reduce the amount of storage available for such events. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-19 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Recommendations for Addressing this Issue

 Before changes are made to finished water storage, an analysis should be made of system 

demand and pressure needs and fire flow requirements. This analysis should review appropriate 

fire ordinances to determine the amount needed. In addition, emergency storage requirements 

should be addressed. Hydraulic models in combination with source planning can help determine 

the amount of water to be maintained in storage in various parts of the system. Section 6.3 

identifies several hydraulic models that may be helpful. 

Increased Water Loss 

 Flushing programs will lead to a loss of water. This is an added expense and could be 

troublesome in areas where sufficient water supply is a concern. 

 Recommendations for Addressing this Issue

 The advantages of system flushing often outweigh the cost of lost water. Systems may, 

however, want to minimize water loss through careful design of the flushing program. For 

example, Friedman et al. (2003) found that systems that had previously conducted one round of 

high velocity unidirectional flushing (> 5fps) within the last 4-6 years had likely removed all 

loose, compacted and adhered deposits and may not benefit from additional high velocity 

flushing. Use of automatic flushing devices may help control flushing volume and reduce water 

loss. Examining customer complaint and water quality records can help to focus flushing to the 

areas and times where they are most needed. A public outreach program can help minimize 

customer perceptions that the utility is wasting water when they observe flushing activities in 

progress. Additional guidance may be found in an AwwaRF report, Cost and Benefit Analysis of 

Flushing (DeNadai et al. 2004). 

3.2.3 Recommendations for Gathering More Information 

Read the Case Study

 For more information on simultaneous compliance issues associated with distribution 

system BMPs, see Case Study #1 - Improving and Optimizing Current Operations starting on 

page B-5 of Appendix B. This case study describes how two small PWSs with high THM 

concentrations were able to comply with the requirements of the Stage 1 D/DBPR and Stage 2 

DBPR by adjusting their coagulation methods and changing the point of chlorination, while also 

optimizing distribution operations to minimize water age and optimizing booster chlorine use. 

See Additional References

Readers can turn to Section 7.1.5 in Chapter 7 for technical references associated with 

Distribution System BMPs. 

Consider Additional Monitoring 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-20 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 The following are some suggestions for additional monitoring that may benefit water 

systems implementing distribution system BMPs: 

9 Take routine measurements of chlorine residual and heterotrophic plate count (HPCR2A) in water leaving storage tanks and other distribution system locations with long 

residence times and in chloraminated systems. Online chlorine analyzers at storage 

facilities may be helpful; 

9 Monitor water quality at dead-end mains. Monitoring parameters may include 

disinfectant residual, turbidity, coliform bacteria, HPC counts, and DBPs; 

9 Increase measurements of total coliform, HPC, chlorine residual, and turbidity in 

distribution system locations during flushing; 

9 Periodically monitor pipe metals (e.g., iron if cast iron pipes are used, lead if lead 

solder is used) in distribution system regions where corrosion is suspected; and 

9 Monitor pertinent chemicals and odor downstream of pipes that have been recently 

lined or replaced. 

The Stage 2 DBPR Initial Distribution System Evaluation Guidance Manual (USEPA 

2006a) provides distribution system water quality monitoring requirements for the Stage 2 DBPR 

and can be used to identify locations that tend to have high DBP levels. 

The AwwaRF report, “Guidance Manual for Monitoring Distribution System Water 

Quality” (Kirmeyer et al. 2002), can be used to assist water utilities in implementing a 

distribution system water quality data collection and analysis program. 

Consider Other Tools 

In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their operation or treatment practices. Examples of tools 

that can be used when distribution system best management practices are used for Stage 2 DBPR 

compliance include: 

• Computer hydraulic and water modeling software, such as EPANET (USEPA 2002b), 

that can be used to simulate hydraulic detention time and water quality in the 

distribution system; and 

• The AWWA manual “Computer Modeling of Water Distribution Systems” (AWWA 

2004a) that provides step-by-step instructions for the design and use of computer 

modeling for water distribution systems. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-21 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.3 Moving the Point of Chlorination 

 At conventional surface water treatment plants, chlorine 

can be added for prechlorination at either the raw water intake or 

flash mixer, for intermediate chlorination ahead of the filters, for 

postchlorination at the clearwell, or for rechlorination of the 

distribution system. While inactivation of pathogenic organisms 

is its primary function, chlorine is used in drinking water 

treatment for several other purposes, including: 

• Control of nuisance Asiatic clams and zebra mussels 

• Oxidation of iron and manganese 

• Improved coagulation 

• Taste and odor control 

• Prevention of algal growth in sedimentation basins and filters 

• Color removal 

Exhibit 3.1 summarizes the typical uses for each point of chlorine application. 

Exhibit 3.1 Typical Chlorine Points of Application and Uses 

Point of Application Typical Uses

Raw Water Intake Zebra mussel and Asiatic clam control, control 

biological growth 

Flash Mixer or Rapid Mix (prior to sedimentation) Disinfection, iron and manganese oxidation, 

improved coagulation1, taste and odor control, 

oxidation of hydrogen sulfide, algae control 

Filter Influent Disinfection, control biological growth in filter, 

iron and manganese oxidation, taste and odor 

control, color removal 

Filter Clearwell Disinfection, disinfectant residual 

Distribution System Maintain disinfectant residual 

Source: Alternative Disinfectants and Oxidants Guidance Manual, USEPA 1999b. 1

Not included as a typical use in the above reference, but documented by research

 Public water systems with conventional treatment might consider moving the application 

point for chlorine downstream within the plant to a point after DBP precursors have been 

removed. Depending on the treatment plant, THM formation potential can be decreased by up to 

50 percent as a result of precursor removal during coagulation and sedimentation (Singer and 

Chang 1989). 
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Simultaneous Compliance Guidance Manual 3-22 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.3.1 Advantages of Moving the Point of Chlorination 

 By moving the point of chlorination downstream in the treatment process, a PWS can: 

• Reduce DBP concentrations in the finished water 

• Reduce amount of disinfectant used 

• Facilitate monthly TOC source water monitoring 

Reduces DBPs

 Summers et al. (1996) presented the results from four studies evaluating the impact of 

pretreatment on DBP formation. Jar tests were conducted to simulate water treatment through 

rapid mix, coagulation, flocculation, and sedimentation. Chlorine was added at various points in 

the jar testing to simulate the impact of various dose points on production of DBPs. The results 

demonstrate the benefits of delaying the point of chlorination downstream in the treatment train 

to take advantage of precursor removal during flocculation and sedimentation processes. Exhibit 

3.2 summarizes the results from this study. 

Exhibit 3.2 Percent Reduction in DBP Formation by Moving Point of Chlorination 

Chlorination Point TTHM 

Baseline (%)

TTHM 

Enhanced (%)

HAA5 

Baseline (%)

HAA5 

Enhanced (%)

Pre rapid mix Baseline 17 Baseline 5

Post rapid mix 2 21 5 21

Mid flocculation 9 36 14 36

Post sedimentation 21 48 35 61

Notes: Source: USEPA 1997 based on Summers et al. 1996 

Baseline = Baseline coagulant (alum) dose for optimal turbidity removal (~30 mg/L) 

Enhanced = Enhanced coagulant (alum) dose for optimal TOC removal (~ 52 mg/L)

 Exhibit 3.2 also includes a comparison of total trihalomethane (TTHM) and haloacetic 

acid (five) (HAA5) concentrations when enhanced coagulation was used, and the benefits of 

enhanced coagulation for reducing DBP production. The TTHM formation reduction of 21 

percent by moving the chlorination point to post sedimentation is more than doubled to 48 

percent by enhanced coagulation. The reduction in HAA5 formation increases from 35 to 61 

percent under enhanced coagulation with post sedimentation chlorination. Therefore, DBP 

control by selecting the optimal dose location and conditions, along with enhanced precursor 

removal, can significantly reduce DBP formation. For a more detailed discussion of enhanced 

coagulation and its simultaneous compliance issues, refer to Section 3.7 of this manual. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-23 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Reduces Amount of Disinfectant Used

 If a system moves its point of chlorination downstream after a significant amount of 

organic matter has been removed, the chlorine demand of the water will be lower. In some 

cases, the system may be able to take advantage of the reduced chlorine demand to reduce the 

overall chlorine dose needed to achieve the required CT. The system would benefit not only in 

reduced chemical costs, but may also reduce operational costs if they decrease their number of 

chlorine injection points. 

Facilitates Source Water TOC Monitoring

 The Stage 1 D/DBPR requires surface water systems (or systems using ground water 

under the direct influence of surface water) using conventional filtration treatment to monitor 

each treatment plant for TOC removal. Systems are required to collect TOC samples from the 

source and the treated water. Source water TOC samples must be collected prior to any 

treatment, including chlorination. 

 Some PWSs that are required to conduct TOC sampling prechlorinate at or near the 

source water intake. These systems currently have to turn off their chlorination in order to 

collect a proper source water TOC sample. Although it’s a minor benefit of moving chlorination 

downstream in the treatment process, those systems would no longer have to turn off their 

chlorination in order to collect their source water TOC sample. 

3.3.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Moving the Point of Chlorination 

 Many PWSs benefit from other functions of prechlorination in addition to its use as a 

disinfectant. Chlorine can oxidize iron and manganese, improve coagulation, enhance color 

removal, improve taste and odor, as well as control biological growth at different stages of 

treatment. Because it has several other functions, some PWSs may find that there are drawbacks 

to moving the point of chlorination further downstream in the treatment process. Moving the 

point of chlorination further downstream in the treatment process can: 

• Raise issues with meeting CT requirements 

• Increase filter fouling 

• Limit Asiatic clam or zebra mussel control 

• Limit coagulation and filtration effectiveness 

• Provide less effective treatment for iron and manganese 

• Affect pH of water being treated, possibly requiring adjustment of water 

treatment chemistry 

This section discusses these issues and provides some recommendations for addressing them. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-24 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

CT Issues

 Disinfection effectiveness is measured in terms of CT. If a PWS receives CT credit for 

contact time prior to filtration and then moves its point of chlorination further downstream in the 

treatment process, the system will likely have to increase its C to accommodate reduced T. 

Systems should carefully evaluate their disinfection profiles to ensure that they continue to meet 

benchmarking requirements. Guidance is provided in the Disinfection Profiling and 

Benchmarking Guidance Manual (USEPA 1999a). 

 If concentration of disinfectant is increased, high disinfectant residuals may persist into 

the distribution system. A public water system, however, must maintain disinfectant residual 

concentrations that meet the MRDL requirements of the Stage 1 D/DBPR. The running annual 

average (RAA) of the free chlorine residual measured in the distribution system must not exceed 

the 4.0 mg/L MRDL. Also, if the chlorine residual in the delivered water is increased, the 

number of customers that will notice a chlorinous odor may increase and generate more frequent 

customer complaints. 

 Recommendations for Addressing this Issue

 Systems should examine hydraulic conditions and maximize contact time where possible. 

Clearwells can be modified (e.g., baffling and/or improved inlet and outlet structures added) to 

improve their hydraulic performance. Constructing additional storage or dedicated disinfection 

contact basins can also increase CT. 

 A water system should evaluate the CT that it can achieve downstream of the new 

application point to ensure that sufficient CT can be maintained once the point of chlorination 

has been moved. The evaluation should be done for the organism for which the disinfectant is 

least effective. A system may also want to break up its CT segments into smaller segments. For 

example, if the section from the raw water intake until the filters had been considered as a single 

section for performing CT calculations and the point of chlorination is moved until after the 

flocculation basin, a system can still receive some credit for section between the flocculation 

basin and the filters. See the Disinfection Profiling and Benchmarking Guidance Manual

(USEPA 1999a) for more details on calculating CT and using segments. This evaluation should 

review seasonal impacts on CT (e.g., cold water conditions when higher CT values are needed or 

if the water’s pH increases during algae blooms in the warmer water months). 

 If having too high of a residual in the distribution system is an issue a system may be able 

to extend its contact time instead. Reducing chlorine demand may also help to achieve the 

required inactivation with a lower chlorine dose. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-25 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Potential for Increased Filter Fouling

 Prechlorination is often used to minimize operational problems associated with biological 

growth in water treatment plants. Prechlorination can prevent slime formation on filters, pipes, 

and tanks, and reduce potential taste and odor problems associated with such slimes. It can also 

prevent algal growth which can clog filters and cause turbidity problems. Many sedimentation 

and filtration facilities operate with a small chlorine residual to prevent growth of algae and 

bacteria in the launders and on the filter surfaces. 

 Recommendations for Addressing this Issue

 If a system is concerned about the potential for algal growth and filter fouling after 

prechlorination is stopped, there are alternatives the system can consider. If chlorine is being 

added before the coagulation and flocculation steps, 

operators may want to consider moving the chlorination 

point so that it follows these steps but comes before 

filtration. Adding chlorine immediately before the 

filters may be an effective way for the system to prevent 

filter fouling, yet not allow the chlorine to come into 

contact with the water when the water still contains 

unsettled DBP precursors (see case study No. 1 in 

Appendix B). 

 

 Systems may be able to eliminate the prechlorination step at certain times of the year, and 

return to prechlorination when microbial fouling is more likely to occur during the treatment 

process, such as when there is algal growth in the source water. They may also consider 

continuing to prechlorinate, but adjusting the prechlorination dose depending on source water 

conditions or water temperature. 

 Lastly, a system may consider using an alternative preoxidant, such as potassium 

permanganate or chlorine dioxide. These oxidants can provide benefits similar to chlorine in 

terms of iron, manganese, or algae control without forming significant amounts of TTHM or 

HAA5. They can also reduce chlorine demand before chlorination is applied. Readers should 

refer to the Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b) for more 

information. 

Asiatic Clam and Zebra Mussel Control

 The Asiatic clam (Corbicula fluminea) was introduced to the United States from 

Southeast Asia in 1938 and now inhabits almost every river system south of 40E latitude 

(Problem Organisms in Water Treatment: Britton and Morton 1982, Counts 1986). This mollusk 

has invaded many source waters, clogging source water transmission systems and valves, 

screens, and meters; damaging centrifugal pumps; and causing taste and odor problems. 

 The zebra mussel (Dreissena polymorpha) population in the United States has expanded 

very rapidly. Zebra mussels have been found in the Great Lakes, Ohio River, Cumberland River, 

Arkansas River, Tennessee River, and the Mississippi River south to New Orleans (Lange et al. 

1994). 

Adding chlorine immediately 

before the filters may be an 

effective way for the system to 

prevent filter fouling from 

biological growth.
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-26 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Many PWSs add chlorine at their intakes to control Asiatic clam and zebra mussel 

growth. For those systems with intakes a significant distance from their treatment plants, 

prechlorinating for zebra mussel control may allow a substantial amount of time for TTHM or 

HAA5 formation prior to any precursor removal process. 

 Recommendations for Addressing this Issue

Asiatic Clams 

 Systems that add chlorine to control Asiatic clams and have problems with elevated 

TTHM or HAA5 concentrations may want to consider using an alternative oxidant, such as 

monochloramine or chlorine dioxide, to control clam growth in their systems. If 

monochloramine is used, water systems using the monochloramine to also satisfy CT 

requirements will need to perform a disinfection benchmark, bearing in mind that the CT 

required for viral inactivation using chloramines is substantially greater than that for chlorine, 

and should ensure that adequate disinfection is being provided after switching disinfectants. 

 Cameron et al. (1989) compared the 

effectiveness of free chlorine, potassium 

permanganate, monochloramine, and chlorine 

dioxide for controlling the juvenile Asiatic clam. 

Monochloramine was found to be the best for 

controlling juvenile clams without forming DBPs. Further research showed that the 

effectiveness of monochloramine increased greatly as the temperature increased (Cameron et al. 

1989). Belanger et al. (1991) showed that pre-formed monochloramine with excess ammonia 

was more effective for controlling Asiatic clams than either total residual chlorine, 

monochloramine, bromine, or copper. Chlorination at 0.25 to 0.40 mg/L total chlorine residual 

at 20 to 25E C controlled clams of all sizes, but the same dosage had minimal effect at 12 to 15E

C. 

Zebra mussels 

 Systems with elevated DBPs may also want to consider using an alternative zebra mussel 

control strategy. Permanganate has been found to be effective for zebra mussel control and has 

been used. Chlorine dioxide and ozone have shown promise as effective oxidants that can be 

used for zebra mussel control. Antifouling coatings can work by slowly releasing into the water 

a toxic substance, often an organo-metallic compound that prevents the zebra mussel larvae from 

settling on the pipes. PWSs should check with their State if they are considering a chemical 

control method, to make sure that the chemical is approved for use in a drinking water supply. 

Monochloramine was found to 

work well for controlling juvenile 

clams without forming DBPs. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-27 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 There are many other approaches to zebra mussel control being developed and tested. 

These methods include: 

• The use of electrical fields to kill veligers (zebra mussel larvae) 

• Ultrasonic treatment to prevent settlement 

• Oxygen deprivation 

• Sand infiltration beds 

• Thermal control (AWWA 2003c) 

In addition, some polymers have been tested recently that show promise. 

Coagulation and Filtration Effectiveness

 Research has shown that using a preoxidant ahead of coagulation can have a positive 

effect on coagulation and filtration with respect to particle removal (Becker et al. 2004). By 

moving chlorination to a point after filtration, a water system may find that it needs to develop 

new strategies for turbidity and particle control. 

 Recommendations for Addressing this Issue

 Water systems moving chlorination to a point after filtration that can no longer achieve 

low filter effluent turbidity values or particle counts may want to consider using a preoxidant 

other than chlorine to improve filter performance. The strongest preoxidants have shown the 

maximum benefit to filtration, so a system can achieve similar benefits by applying chlorine 

dioxide or ozone. Systems that choose to do this should consult the Section 5.4 (chlorine 

dioxide) or Section 5.2 (ozone) of this guidance manual to determine possible effects of these 

steps. 

Iron and Manganese Control

 Although not harmful to human health at the low concentrations typically found in water, 

iron and manganese can cause staining and taste problems. Iron and manganese compounds are 

treated by oxidation to produce a precipitate that is subsequently removed by sedimentation and 

filtration. Systems with high manganese levels should also be aware that a manganese coating 

may have developed on their filters when pre-oxidation was practiced. This layer could dissolve 

if pre-oxidation is no longer practiced and/or the pH drops (Angara et al 2004). 

 Recommendations for Addressing this Issue

 Systems should be careful to consider how eliminating prechlorination may impact other 

removal mechanisms during the treatment process. Some may be able to use an alternative 

oxidant or reduce their prechlorination dose if the chlorine dose required for iron or manganese 

removal is lower than what is currently being added. The oxidation of iron and manganese can 

usually be accomplished while maintaining a minimum residual. Potassium permanganate is an 

effective alternative oxidant to chlorine for iron and manganese oxidation and does not result in 

TTHM or HAA5 formation. Various alternatives are discussed in greater detail in the 

Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b) and the Guidance 

Manual for Enhanced Coagulation and Precipitative Softening (USEPA 1999h). 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-28 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Problems with a Change in pH

 Moving the point of chlorination or 

eliminating prechlorination may result in a change in 

water pH. Adding gaseous chlorine decreases 

water’s pH, whereas adding hypochlorite increases 

water’s pH. 

 Recommendations for Addressing this Issue

 Water systems that use a coagulant should consider whether the elimination of 

prechlorination and the resulting change in pH would require the system to adjust its coagulant 

dose or add other chemicals to control pH. Systems with corrosion control should also consider 

whether a pH change due to the elimination of prechlorination would require the system to alter 

its corrosion control chemical dose. Impacts of pH changes on compliance and operational 

issues are described in Section 3.4. 

3.3.3 Recommendations for Gathering More Information 

Read the Case Study

 For more information on simultaneous compliance issues associated with moving the 

point of chlorination and how to address them, see Case Study #1 - Improving and Optimizing 

Current Operations starting on page B-5 of Appendix B. This case study describes how two 

small PWSs with high THM concentrations were able to comply with the requirements of the 

Stage 1 D/DBPR and Stage 2 DBPR by adjusting their coagulation methods and changing the 

point of chlorination, while also optimizing distribution operations to minimize water age and 

optimizing booster chlorine use. 

See Additional References

 Readers can turn to Sections 7.1.1, 7.1.2, 7.1.6, and 7.1.17 in Chapter 7 for technical 

references associated with moving the point of chlorination. 

Consider Additional Monitoring

 The following are some suggestions for additional monitoring that may benefit water 

systems moving their point of chlorination: 

9 Water systems that reduce or eliminate prechlorination should carefully review pH 

data to ensure that treatment processes and materials will not be adversely affected; 

9 Systems with the potential for iron or manganese problems that move, reduce, or 

eliminate prechlorination should consider monitoring for those metals at the entry 

point to the distribution system. Those systems with clearwells and long residence 

Impacts of pH changes on 

compliance and operational 

issues associated with pH are 

described in Section 3.4. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-29 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

times may want to check whether iron or manganese solids are accumulating in the 

clearwell; 

9 Customer complaint monitoring can be traced along with color and taste and odor 

evaluations to make sure aesthetic quality has not been lost; and 

9 The impact of algal blooms on sedimentation and filter performance can be tracked 

by measuring turbidity and/or particle counts before and after filtration. Spikes in 

turbidity or particle counts may indicate a problem with algal blooms. 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their operation or treatment practices. Examples of tools 

that can be used when moving the point of chlorination is used as a Stage 2 DBPR compliance 

technique include: 

• The AwwaRF report “Internal Corrosion of Water Distribution Systems” (AwwaRF 

and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

testing protocols that can be used to evaluate the impacts of pH changes on corrosion 

potential. Such pH changes may occur if a utility switches disinfectants; 

• The paper “Predicting the Formation of DBPs by the Simulated Distribution System” 

published by Koch et al. (1991) can be used to predict the amounts of DBPs that 

would form in a distribution system. Key parameters (including chlorine dosage, 

incubation temperature, and incubation holding time) are chosen to simulate the 

conditions of the treatment plant and the distribution; and 

• The second version of “Water Treatment Plant Model” (USEPA 2001h) developed by 

EPA that assists utilities with implementing various treatment changes while 

maintaining adequate disinfection and meeting the requirements of the Stage 2 

DBPR. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-30 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.4 Decreasing pH 

 Pathogen inactivation by chlorine is affected by 

pH. This is because the germicidal efficiency of 

hypochlorous acid (HOCl) is much higher than that of 

hypochlorite ion (OCl G), and the distribution of chlorine 

species between HOCl and OClG is determined by pH. Because HOCl dominates at low pH 

values (< 7.5), chlorination provides more effective disinfection at low pH. At high pH values (> 

8.0), OCl G dominates, which causes a decrease in disinfection efficiency. 

 Public water systems can reduce their pH to increase disinfectant efficiency, enabling 

them to lower their disinfectant dose and still achieve the same amount of disinfection, thereby 

potentially limiting DBP formation. The system may want to raise the pH again before it enters 

the distribution system to avoid corrosion problems within the distribution system. The ease and 

desirability of changing pH will depend on the alkalinity and pH of the existing water. Many 

other treatment processes can also be affected by changing pH, so careful consideration should 

be given before any change is made. 

 The pH can also impact reactions between chlorine and NOM, resulting in conditions that 

favor either TTHMs or HAA5 formation. At higher pH, more THMs tend to be formed. Lower 

pH tends to favor HAA formation. This information can be used by systems to influence TTHM 

or HAA5 formation at the plant or in the distribution system by controlling the pH. Systems that 

have high TTHM levels but relatively low HAA5 may be able to reduce TTHM formation by 

lowering pH. However, these systems will need to pay special attention to corrosion issues. 

3.4.1 Advantages of Decreasing pH 

 Advantages to decreasing pH include: 

• The same inactivation can be achieved with a lower disinfectant dose or shorter 

contact time 

• Can reduce formation of some DBPs 

Same CT Can Be Achieved with Lower Disinfectant Dose 

 Virus inactivation studies have shown that 50 percent more contact time is required at pH 

7.0 than at pH 6.0 to achieve comparable levels of inactivation with chlorine. These studies also 

demonstrated that an increase in pH from 7.0 to 8.8 or 9.0 requires six times the contact time to 

achieve the same level of virus inactivation (Culp and Culp 1974). 

 In general, Giardia is the organism that drives the CT required at a water system. Exhibit 

3.3 illustrates how pH affects the CT required for 0.5-log inactivation of Giardia lamblia. At a 

pH of 7.0, CT required for free chlorine is 19 mg-min/L. For a pH of 6.5, the CT required is 16 

mg-min/L. At a contact time of 16 minutes, this corresponds to a reduction in required free 

chlorine residual concentration from 1.2 mg/L at a pH of 7.0 to 1.0 mg/L at a pH of 6.5. 

Pathogen inactivation by 

chlorine depends on pH. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-31 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 3.3 Effects of pH Changes on CT Required for 0.5-Log Inactivation of 

Giardia lamblia

Temperature pH CT Required for 0.5 log 

inactivation of Giardia 

lamblia

Contact time 

(minutes) 

Free Chlorine 

Residual needed to 

meet CT Required 

10 oC 7.0 19 16 1.2 mg/L 

10 oC 6.5 16 16 1.0 mg/L 

Source: Adapted from CT tables in 40 CFR 141.74 National Primary Drinking Water regulations. 

Can Reduce DBP Formation

 The pH of water can impact the formation of halogenated byproducts (Reckhow and 

Singer 1985, Stevens et al. 1989). Exhibit 3.4 compares formation of byproducts at three pH 

levels (adapted from Stevens et al., 1989). Note that TTHM show generally lower formation at 

the lowest pH level. The formation of HAAs, however, generally increases at lower pH levels. 

Exhibit 3.4 Impacts of pH on Formation of DBPs 

Conditions of Formation

Byproduct Chlorination at pH 

5.0

Chlorination at pH 

7.0

Chlorination at pH 

9.4

TTHM Lower Formation Basis for Comparison Higher Formation 

Trichloroacetic Acid 

(one of the HAA5) 

Similar Formation Similar Formation Lower Formation 

Dichloroacetic Acid 

(one of the HAA5) 

Similar Formation - perhaps slightly higher at pH 7 

Source: adapted from Stevens et al. 1989

 Other studies show that limiting pH levels in the distribution system to less than 8.2 may 

help to limit TTHM formation (Edwards and Reiber 1997). Four LCR compliance strategy case 

studies showed that TTHM increases were less than 20 percent if the pH shift implemented for 

lead and/or copper corrosion control was near neutral (7.0) to less than 8.2. When the pH was 

shifted from near neutral to greater than 8.5, TTHM production increased as much as 40 percent. 

At one plant, TTHM increases due to pH adjustment ranged from 2 percent at a pH of 8.1 to 43 

percent at a pH of 8.7. HAA production was shown to decrease about 10 percent for all of the 

pH increases implemented (Edwards and Reiber 1997). 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-32 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.4.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Decreasing pH 

 Potential issues associated with reducing pH to enhance chlorine disinfection include: 

• May increase HAA5 formation; 

• Can adversely affect treatment plant structures and coatings (i.e., corrosion of 

pipes, tanks, etc.); 

• Can affect treatment chemistry, sludge dewatering, and inorganic solubility; 

• Can cause problems with corrosion control and LCR compliance; and 

• If chlorine dose is reduced during primary disinfection, it may be difficult to 

maintain secondary disinfection levels throughout the distribution system. 

HAA5 May Increase

 Lower pH conditions may result in higher HAA5 concentrations. Reckhow and Singer 

(1985) studied humic acid chlorination in laboratory tests and found that trichloracetic acid 

concentrations reached a maximum when the water was in the acidic pH range. When pH levels 

were increased, trichloroacetic acid concentrations decreased and chloroform (a key component 

of TTHM) concentrations increased. Other studies, such as Stevens et al. (1989), have not found 

comparable increases in HAA5 concentrations when pH levels decreased from neutral to slightly 

acidic. 

 Recommendations for Addressing this Issue

 In general, pH values in distribution systems are unlikely to fall in the acidic range given 

the requirements of the Lead and Copper Rule and good corrosion control practices. Systems 

can conduct simulated distribution system (SDS) studies to simultaneously evaluate impacts of 

pH adjustment on both TTHM and HAA5 formation. The results of these bench-scale tests can 

help identify the optimal pH for balancing the need to control both TTHM and HAA5. 

 Systems can also evaluate pH fluctuation trends throughout their distribution systems. 

For poorly buffered waters, the pH can tend to drift upward as the water reacts with cement-lined 

pipes. Increases in pH throughout the distribution system would tend to favor TTHM formation 

and reduce HAA5 formation. 

Adverse Effects on Treatment Plant Materials

 If pH levels are lowered to enhance disinfection, components of the treatment plant may 

be adversely affected by the acidic conditions. Metal components of the plant may corrode; 

plastic or rubber components may deteriorate more quickly; cement/concrete leaching and 

deterioration may be exacerbated. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-33 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Recommendations for Addressing this Issue

 Systems should evaluate the effects of decreased pH on treatment plant components, such 

as pipes and linings. Based on their evaluation, systems should adjust the: 

• maintenance schedules, 

• materials, or 

• point of pH adjustment 

so that the chances of leaks, leaching, or equipment failure are minimized. 

Adverse Effects on Treatment Chemistry, Inorganics Solubility, Settling, and Sludge Dewatering

 Reducing the water pH can cause problems with increased solubility of inorganics, and 

may result in increased iron and manganese levels. Lower treated water pH can also result in 

recalcification of lime-softened waters, resulting in increased turbidity. Variation of pH levels 

can affect treatment chemistry and impact settling and sludge dewatering. System operators 

should carefully consider the impacts of pH adjustment before implementing such a significant 

change to their treatment process. 

 Manganese is typically removed from water using direct oxidation/coagulation/filtration 

or filter adsorption/oxidation (i.e., green sand). Chlorine is sometimes used for the oxidation 

step of this process. A low pH hinders the direct oxidation process because the rate of 

manganese oxidation increases as pH increases. The oxidation process for manganese is affected 

at a pH below about 6.2 (USEPA 1999h). Therefore, systems using chlorine or potassium 

permanganate for manganese oxidation should be aware that, if the pH is reduced before 

manganese oxidation, more time may be needed for the manganese to be removed. Manganese 

has also been found to accumulate on filter media of systems that use iron coagulants. This 

manganese layer can be released if pH and disinfectant conditions change across the filter. 

Manganese release was found to increase at pH’s as high as 7 and to be rapid at pH 6 (Wert et al. 

2005). 

 The minimum solubility of aluminum occurs at a pH of 6.2 to 6.5. Those water systems 

that use alum as a coagulant and operate at a pH of less than 6.0 that do not increase their pH 

before filtration may be impacted by the solubility of aluminum at this low pH. If the pH is not 

adjusted before filtration, aluminum carryover problems may result. 

 Recommendations for Addressing this Issue

 Systems with high manganese levels that lower the pH prior to filtration may want to 

consider using an oxidant that is less pH dependent to oxidize manganese, such as ozone. 

Alternatively, a system could choose to lower the pH after oxidation and filtration. Maintaining 

a chlorine residual across the filter should prevent manganese from being released in systems 

using iron coagulants. 

 Systems using alum as a coagulant can adjust pH to greater than 6.5 before the filters to 

avoid aluminum passing into the distribution system. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-34 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Water systems should carefully 

research the implications of 

using a corrosion inhibitor before 

adding it as a treatment step. 

Appendix D provides additional 

guidance for systems evaluating 

their corrosion control options 

and information on proper 

piloting procedures. 

A drop of one pH unit may cause 

the desorption of some metal ions, 

or cause significant dissolution of 

carbonate or oxyhydroxide 

mineral scales on lead, copper, iron 

or other pipe surfaces (Shock 

2005). 

Corrosion Control and LCR Problems

 A lower pH in the distribution system can increase corrosion of cement linings and iron 

pipe. It can also favor corrosion of lead and copper plumbing, causing LCR compliance 

problems. Corrosion of unlined cast iron water mains can favor microbial regrowth, which can 

affect TCR compliance. 

 Any changes in the pH levels historically 

maintained in a distribution system can disrupt 

films and scales that have accumulated on natural 

corrosion surfaces. These films and scales have 

formed over long periods of time and may be 

helping to passivate the corrosion process from 

further development. A decrease of one pH unit 

may cause the desorption of some metal ions, or 

cause significant dissolution of carbonate or 

oxyhydroxide mineral scales on lead, copper, iron or other pipe surfaces (Shock 2005). 

Although the disruption of films or scales in the distribution system may not result in a direct 

violation of either the DBP or microbial rules, the disruption could cause aesthetic problems or 

the release of microbes. Disruption of scale can also cause maintenance problems in utility 

facilities such as tanks, valves, and pumps, as well as in customer sprinkler systems and 

commercial facilities. 

 Recommendations for Addressing this Issue

 If pH is lowered during disinfection, systems with pipe materials susceptible to corrosion 

should consider adjusting pH upward and possibly adjusting alkalinity before the water enters 

the distribution system to reduce corrosion of pipe materials. If finished water pH is reduced, the 

system should consider other corrosion control strategies. 

 Systems can control corrosion by optimizing pH, 

alkalinity, and dissolved inorganic carbon (DIC). 

Another alternative is to add a corrosion inhibitor that is 

phosphate- or silica-based to form a protective coating 

on pipes. As inhibitor effectiveness is dependent on 

pipe material and water quality, any system considering 

using a corrosion inhibitor to offset the effects of lower pH should carefully research the options. 

Some utilities, however, have elected not to use phosphate-based corrosion inhibitors because the 

publicly owned treatment works (POTW) receiving the wastewater has phosphorus limits in their 

national pollutant discharge elimination system (NPDES) and sludge disposal permits. 

 Regardless of the type of corrosion treatment 

used, it should be tested before it is introduced, if 

possible. Pilot testing is discussed in more detail in 

Section 6.3.5 of this manual. Large systems should 

have completed corrosion control studies, as required 

by the LCR. Smaller water systems may have 

conducted studies if required by the state. Any 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-35 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

system that subsequently changes their treatment must notify the state and may be required to 

conduct a new corrosion control study. In any event, LCR corrosion control studies should be 

used as a starting point to assess the impacts of changes in distribution system water quality on 

corrosion and LCR compliance and determine the best corrosion control treatment strategy. 

Appendix D provides additional guidance for systems evaluating their corrosion control options 

and information on proper testing procedures. 

Reduced Disinfectant Residual Concentration 

 Systems that are considering lowering their disinfectant dose to take advantage of 

additional CT credit at a lower pH should consider impacts on maintaining the desired 

disinfectant residual level throughout the distribution system. A lower disinfectant dose may 

mean a lower disinfectant residual concentration leaving the treatment plant if the system does 

not have a chlorine dose point after the clearwells. 

 Recommendations for Addressing this Issue

 Additional chlorine will be needed prior to entry to the distribution system, or through 

booster disinfection, to account for the decrease in chlorine during primary disinfection. 

3.4.3 Recommendations for Gathering More Information 

Read the Case Study 

For more information on simultaneous compliance issues associated with modifying pH, 

see Case Study #2 Modifying pH During Chlorination starting on page B-11 of Appendix B. 

This case study describes how one PWS used pH depression via carbon dioxide injection ahead 

of the flocculation basins to reduce DBPs and DBP precursors. The system was also able to 

increase coagulation efficiency, increase CT throughout the treatment plant (allowing for 

reduced chlorine injection), and increase and stabilize pH levels in the distribution system by 

increasing the buffering capacity following caustic soda addition. Their greatest operation issue 

was a need for a pressurized solution feed to solubilize CO2. 

See Additional References

 Sections 7.1.2, 7.1.3, and 7.17 in Chapter 7 contain technical references associated with 

DBP formation, corrosion, and chlorination, including references on how each process is 

affected by pH. General water treatment references in Section 7.1.1 can also provide useful 

information. 

Consider Additional Monitoring 

 The following are some suggestions for additional monitoring that may benefit water 

systems that are reducing their pH during chlorination: 

9 If alum is used as a coagulant and pH is not adjusted back up before filtration, 

systems should test periodically for aluminum in the finished water; 
3. Improving and Optimizing Current Operations 

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For the Long Term 2 and Stage 2 DBP Rules 

9 Systems should perform routine pH and alkalinity monitoring at significant locations 

throughout the treatment plant, especially after corrosion control chemicals have been 

added; 

9 Where it may be a problem, systems should perform periodic monitoring of iron and 

manganese in the finished water; 

9 Systems can perform additional HPC and total coliform monitoring in the distribution 

system near locations where there is reason to believe that scale may have been 

dislodged; and 

9 Systems can track customer complaints, color, and turbidity in the distribution system 

if there is reason to believe that changes in pH can affect scales and films. 

The purpose of these monitoring suggestions is specifically to address and prevent potential 

simultaneous compliance issues. 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their operation or treatment practices. Examples of tools 

that can be used when modifying pH during chlorination is used for Stage 2 DBPR compliance 

include: 

• The SDS and material-specific (MS-SDS) procedures described by Koch et al (1991) 

and Brereton and Mavinic (2002), respectively, which describe bench-scale and pilotscale tests that can be used to evaluate DBP formation under varying chlorine, 

temperature, and pH conditions; 

• The AwwaRF report “Internal Corrosion of Water Distribution System” (AwwaRF 

and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

testing protocols that can be used to evaluate changes in corrosion potential due to pH 

changes; 

• The AwwaRF report “Optimizing Corrosion Control in Water Distribution Systems” 

(Duranceau, et. al 2004) which provides techniques for instantaneous corrosion 

monitoring; 

• The “Guidance Manual for Monitoring Distribution System Water Quality” 

(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a 

distribution system water quality data collection and analysis program; and 

• The second version of “Water Treatment Plant Model” (USEPA 2001h) developed by 

EPA that assists utilities to implement various treatment changes while maintaining 

adequate disinfection and meeting the requirements of Stage 2 DBPR. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-37 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Systems should 

ensure that they 

continue to meet CT 

requirements 

3.5 Reducing Chlorine Dose under Warm Water Conditions 

 In general, as temperature increases, chlorine reaction kinetics increase. The increased 

kinetics mean that disinfection effectiveness will improve, but it also means that TTHM and 

HAA5 will form more quickly. This section discusses the advantages and disadvantages of 

reducing chlorine residual concentration at the treatment plant during periods of warm water 

temperature. 

3.5.1 Advantages of Reducing Chlorine Dose under Warm Water Conditions 

 By reducing the chlorine residual at the treatment plant during warm water conditions, 

systems can achieve: 

• Comparable pathogen inactivation with less chlorine 

• Reduction in TTHM and HAA5 formation 

Comparable Pathogen Inactivation with Less Chlorine

 Systems that use the same chlorine dose throughout the year at their plant to meet CT 

requirements may be getting significantly higher log inactivation for Giardia and viruses in the 

summer months than in winter months. This is especially true in temperate regions with seasonal 

changes in source water temperature. Exhibit 3.5 shows how water temperature affects the 

amount of CT required to achieve 0.5-log Giardia lamblia inactivation. Note, for example, how 

the CT required at 5.0E C and a free chlorine residual of 1.0 mg/L is 25 mg-min/L. But when the 

water temperature increases to 20E C and a free chlorine residual of 1.0 mg/L is used, the CT 

required for 3-log Giardia lamblia inactivation decreases to 9 mg-min/L. Systems may be able 

to provide sufficient CT in the summer months using a lower concentration of free chlorine than 

the concentration they are using during the winter to provide the same pathogen protection. 

 Disinfectant residual should not be lowered below the 

point of compliance with the CT requirements dictated by the 

SWTR (USEPA 1989). Systems should carefully evaluate their 

disinfection profiles to ensure that they meet benchmarking 

requirements and refer to guidance provided in The Disinfection 

Profiling and Benchmarking Guidance Manual (USEPA 1999a). 

Reduction in TTHM and HAA5 Formation 

 By reducing the chlorine residual at the treatment plant when water temperatures 

increase, systems may be able to reduce the formation of TTHM and HAA5. Krasner et al. 

(1990) found that the median TTHM concentrations in 35 systems were highest for those 

systems with the highest water temperature. 
3. Improving and Optimizing Current Operations 

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For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 3.5 Required CT for 0.5-Log Inactivation of Giardia lamblia by Free 

Chlorine at pH 7.0 

Free chlorine residual (mg/L) 0.5° C 5.0° C 10.0° C 15.0° C 20° C 25° C

≤ 0.4 33 23 17 12 9 6 

 0.6 33 24 18 12 9 6 

 0.8 34 24 18 12 9 6 

 1.0 35 25 19 13 9 6

Adapted from 40 CFR Part 141 National Primary Drinking Water Regulations § 141.74

3.5.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Reducing Chlorine Dose under Warm Water Conditions 

 Some potential issues associated with reducing the chlorine residual concentration at the 

plant under warm temperature conditions are: 

• Higher disinfectant residual needed for addressing seasonal pathogens (e.g., 

water is used for recreational purposes, flowing waters with permitted 

wastewater discharges when flows are low); 

• Distribution system impacts if finished water chlorine concentration is decreased. 

Seasonal Variability of Pathogen Concentrations in the Source Water

 Pathogen concentrations may increase in some surface water sources during the summer 

months. Concentrations of viruses and enteric bacteria are of particular concern, especially if the 

source water is also used for recreational activity. Other pathogens such as Cryptosporidium

have been found to peak during spring runoff. 

 Recommendations for Addressing this Issue

 Systems should evaluate uses of their source water and examine historical data to 

determine if there is a trend in pathogen occurrence in the warmer months. Systems should also 

consider consulting with their states to determine if others have collected data for the same 

source. Many systems will soon have Cryptosporidium and/or E. coli data available for their 

source as a result of the LT2ESWTR source water monitoring requirements. If data are not 

available, systems may want to collect surveillance fecal coliform or E. coli samples at their 

intake to track whether they should be concerned about increased microbial risk. 

Distribution System Issues if Chlorine Residual in Finished Water is Decreased 

In cases where systems do not add chlorine again after primary disinfection, reducing the 

chlorine dose at the treatment plant during warmer months may result in lower finished water 

chlorine residual concentrations. Lower finished water residual levels combined with the faster 
3. Improving and Optimizing Current Operations 

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For the Long Term 2 and Stage 2 DBP Rules 

decay rate of chlorine in the warmer months may make it difficult for some systems to meet the 

SWTR requirement of maintaining a detectable residual throughout the distribution system. 

 Distribution systems are also more susceptible to microbial growth during periods of 

warmer water temperature. Studies have shown that increased water temperatures and 

corresponding increases in organic matter can enhance coliform re-growth in the distribution 

system (LeChevallier et al. 1996). 

 A reduction in chlorine concentration will generally result in a lower oxidation reduction 

potential (ORP) of the water. ORP is a fundamental characteristic of the water that influences 

corrosion reactions on metal pipes. In cases where lead oxide (PbO2) compounds have formed 

on lead service lines, reductions in ORP can cause dissolution of PbO2 under certain conditions 

(Lytle and Schock 2005; Schock and Giani 2004). Reductions in ORP can also cause manganese 

deposits on pipes to dissolve, potentially depositing again on plumbing fixtures and staining 

laundry. 

 Recommendations for Addressing this Issue

 If systems are having difficulty maintaining their chlorine residual in the distribution 

system to meet SWTR requirements, control microbial growth, and ensure compliance with the 

TCR, they can consider using the distribution system BMPs identified in section 3.2 to reduce 

disinfectant decay (such as flushing) and to reduce water age (such as improving mixing in 

storage facilities and installing blowoffs). Booster disinfection may also be a good strategy for 

maintaining a residual in remote areas of the distribution system. 

 If reducing the chlorine dose at the treatment plant during periods of warm water 

temperatures will result in significantly lower chlorine residual in the finished water, systems 

should consider using various tools and/or monitoring to determine how the change could impact 

corrosion of metals in the distribution system. Systems could conduct additional monitoring 

determine the range of ORP levels in the distribution system prior to the change. Appendix D 

describes various tools that can be used to assess the potential impact of treatment changes on 

LCR compliance. Systems should also carefully monitor customer complaints to determine if 

manganese deposits have become a problem. 

3.5.3 Recommendations for Gathering More Information 

See Additional References

 Readers can turn to Sections 7.1.1, 7.1.4, and 7.1.17 in Chapter 7 for general references 

associated with disinfection, technical references related to distribution system management, and 

technical references related to chlorination. 

Consider Additional Monitoring

 The following are some suggestions for additional monitoring that may benefit water 

systems that are reducing their chlorine dose: 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-40 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

9 Routine raw and finished water monitoring for E. coli and total coliform, especially 

during the periods when the system is reducing its chlorine dose; 

9 Increased chlorine residual measurements throughout the distribution system; 

9 Increased HPC and total coliform surveillance monitoring in the distribution system; 

9 Chlorine demand monitoring prior to chlorine addition for secondary disinfection to 

make sure stable water is sent into the distribution system; and 

9 Inspection of distribution system pipe scales (including service lines and domestic 

plumbing) to see if reductions in disinfectant residual and/or lower redox potential 

may cause a problematic change in scale integrity and metal release. 

The purpose of these monitoring suggestions is specifically to address and prevent potential 

simultaneous compliance issues. 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their operation or treatment practices. Examples of tools 

that can be used when varying the chlorine dosage is used for Stage 2 DBPR compliance include: 

• The Disinfection Profiling and Benchmarkng Guidance Manual (USEPA 1999a) 

describes how systems can develop a disinfection profile and identify their 

benchmark. It also provides guidance on what constitutes a significant change in 

disinfection practices. 

• The Guidance Manual for Monitoring Distribution System Water Quality (Kirmeyer 

et al. 2002) which can be used to assist water utilities in implementing a distribution 

system water quality data collection and analysis program; 

• The Standard Method 2350 (Oxidant Demand/Requirement) (APHA 1998) that 

provides step-by-step instructions for the determination of chlorine demand during 

various water quality conditions; and 

• The paper “Predicting the Formation of DBPs by the Simulated Distribution System” 

(Koch et al. 1991) that can be used to closely monitor and predict changes in DBP 

formation in the distribution system due to frequent chlorine dose changes. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-41 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.6 Modifying Pre-sedimentation Basin Operations 

 Pre-sedimentation basins are basins placed before the rapid 

mix chamber and the flocculation basins. Their purpose is to allow 

large particles and debris to settle out before the main coagulation 

process and before any disinfectant is added. Pre-sedimentation 

basins provide a buffer to turbidity fluctuations and can lower DBP 

precursors entering the plant. Existing basins can be modified to 

increase Cryptosporidium removal by adding a coagulant or 

increasing residence time. 

3.6.1 Advantages of Modifying Pre-sedimentation Basin Operations 

 The advantages of pre-sedimentation basins include: 

• Can lower DBP precursors prior to the addition of disinfectants; 

• Can possibly achieve 0.5 log of Cryptosporidium removal credit under the 

LT2ESWTR; and 

• Reduce solids loading and improve stability of water quality for downstream 

treatment processes. 

Lower DBP Precursor Concentrations

 By modifying pre-sedimentation basins, systems can remove additional DBP precursors 

and decrease TTHM and HAA5 formation. Pre-sedimentation basins are especially useful to 

systems with high levels of solids in their raw water 

or highly fluctuating turbidity. Addition of a 

coagulant in the pre-sedimentation basin may 

increase the removal of DBP precursors. 

Cryptosporidium Removal Credit

 Systems with pre-sedimentation basins can receive 0.5-log removal credit for 

Cryptosporidium. In order to get the credit for the pre-sedimentation basin, all of the plant’s 

water must pass through the basin and a coagulant must be added whenever the basin is 

operating. Alternatively, systems can conduct their LT2ESWTR monitoring for 

Cryptosporidium after the pre-sedimentation basin to determine their treatment bin. If a system 

monitors for bin selection after the pre-sedimentation basin, it cannot get the 0.5 log 

Cryptosporidium removal credit for the basin. These systems may, however, end up in a lower 

treatment bin due to Cryptosporidium removal in the pre-sedimentation basin. See the

LT2ESWTR Microbial Toolbox Guidance Manual (USEPA N.d.e) for additional information on 

receiving the removal credit. 

Addition of a coagulant in the 

pre-sedimentation basin may 

increase the removal of DBP 

precursors. 
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For the Long Term 2 and Stage 2 DBP Rules 

Solids should be removed on 

a regular basis to prevent 

interference with plant 

performance and compliance 

with regulatory requirements.

Reduce solids loading and improve water stability 

Pre-sedimentation basins allow extra time before the water enters the treatment process. 

This will allow particles suspended by flow to settle out before entering the main treatment train. 

It will also help to dampen turbidity and particle concentration fluctuations caused by storm 

events. This will reduce solids loading and fluctuations on downstream processes which can 

improve process performance. 

3.6.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Modifying Pre-sedimentation Basin Operations 

 Potential issues associated with using pre-sedimentation basins include: 

• Algal growth in pre-sedimentation basins can increase DBP precursors 

• Removal of settled solids can be difficult 

Algal Growth

 Algae can grow in uncovered pre-sedimentation basins that are not treated with a 

disinfectant. The algae can add NOM to the water, increasing the chlorine demand, and can 

negate DBP precursor removal obtained during pre-sedimentation. Algae are also known to 

produce taste and odor compounds and interfere with flocculation/sedimentation and filtration. 

 Recommendations for Addressing this Issue

 There are several ways to prevent algae growth in pre-sedimentation basins. Potassium 

permanganate addition has been used with mixed success in efforts to stop algae growth and 

control resulting tastes and odors. Covering basins to block ultraviolet (UV) light will also 

prevent algae growth. Although this can be a more expensive solution, floating covers are 

available that can provide a lower-cost alternative. 

Removal of Settled Solids

 Solids that accumulate in the bottom of presedimentation basins should be removed 

periodically. This is especially true when a 

coagulant is added. If a coagulant is not added, 

systems may be able to manage solids with periodic 

manual removal. Systems may not be able to use a coagulant if they cannot add solids removal 

equipment to the basin. Although it presents additional costs to the plant, solids removal should 

not interfere with plant production if it is done on a regular basis. 

 

 Recommendations for Addressing this Issue

 If a coagulant is not used, systems should consider using two basins, taking one off-line 

while the other is being cleaned to avoid stirring up sediment and allowing it to enter the plant. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-43 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Solids should be removed on a regular basis to prevent interference with plant performance and 

compliance with regulatory requirements. Solids can be removed in various ways such as using 

a sloped floor and center drain or specially designed vacuums or pumps. Removal can be 

accomplished manually by regular cleaning or dredging. 

3.6.3 Recommendations for Gathering More Information 

Read the Case Study 

 For more information on simultaneous compliance issues associated with presedimentation basins and how to address them, see Case Study #3 Pre-sedimentation starting on 

page B-19 of Appendix B. This case study describes how one PWS was able to monitor effluent 

from their pre-sedimentation basins to determine their Cryptosporidium bin classification for the 

LT2ESWTR. Operational issues include problems with algae blooms, which the system was 

typically able to control by adding potassium permanganate to the basins. 

See Additional References

 Readers can turn to Section 7.1.1 in Chapter 7 for general technical references associated 

with water treatment. The final LT2ESWTR Microbial Toolbox Guidance Manual (USEPA 

N.d.e) provides additional information on pre-sedimentation. 

Consider Additional Monitoring

 

The following are suggestions for additional monitoring that may benefit water systems using 

pre-sedimentation: 

9 Turbidity measurements as water leaves the pre-sedimentation basin and enters the 

treatment plant, in order to detect impacts of sediment buildup or short-circuiting on 

water quality entering the plant; and 

9 If algae growth is a problem, routine algal counts, chlorophyll a measurements, or 

Secchi disk depth readings as feasible, to guide algae management efforts. 

The purpose of these monitoring suggestions is specifically to address and prevent potential 

simultaneous compliance issues. 
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For the Long Term 2 and Stage 2 DBP Rules 

3.7 Enhanced Coagulation 

 One way to remove NOM is to practice enhanced 

coagulation. Enhanced coagulation has been shown to be an 

effective strategy for reduction of DBP precursors for many 

systems (Krasner and Amy 1995). Reduction of pH to between 5 

and 6 and/or use of higher coagulant doses has been found 

effective in reducing TOC to required levels (Krasner and Amy 

1995). Enhanced coagulation can include one or more of the 

following operational changes: 

• Increasing coagulant dose 

• Changing coagulant 

• Adjusting pH (using acid to lower the pH as low as 5.5) 

• Improving mixing or applying moderate dosage of an oxidant 

• Adding a polymer 

 As one part of the treatment process is modified, PWSs should consider the impacts on 

subsequent processes and within the distribution system. Systems considering whether enhanced 

coagulation may be an effective way to reduce DBPs should refer to the Guidance Manual for 

Enhanced Coagulation and Precipitative Softening (USEPA 1999h). 

 This section discusses the advantages and disadvantages of enhanced coagulation, and 

provides recommendations for how systems may be able to address and minimize the 

disadvantages. 

3.7.1 Advantages of Enhanced Coagulation 

 Some advantages of enhanced coagulation include: 

• May improve disinfection effectiveness 

• Can reduce DBP formation 

• Can reduce bromate formation 

• Can enhance arsenic and radionuclide removal 
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Simultaneous Compliance Guidance Manual 3-45 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Improved Disinfection Effectiveness 

 All public water systems with a surface water source or a ground water source under the 

direct influence of surface water must achieve a 3.0 log Giardia removal/inactivation and 4.0 log 

virus removal/inactivation. Enhanced coagulation can improve disinfection effectiveness in 

three ways: 

• Lower the pH during disinfection to improve chlorine effectiveness 

• Reduce disinfectant demand 

• Remove particles to which pathogens are attached 

The pH may be suppressed artificially using an acid or may be the result of heavy alum or ferric 

coagulant doses. 

 Chlorine is pH-sensitive, being more effective at low pH values (see Section 3.4 for a 

more complete discussion of chlorine sensitivity to pH). Therefore, a decrease in pH results in 

greater inactivation of Giardia and viruses. For example, a system with a 1.0 mg/L chlorine 

residual decreasing its pH from 7.0 to 6.5 at a temperature of 10o

C would lower its CT 

requirement for 3 log Giardia inactivation from 112 mg-min/L to 94 mg-min/L. Ozone also 

exhibits increased performance at lower pH values (Carlson et al. 2000). Conversely, chlorine 

dioxide can be less effective at low pH values and less monochloramine is formed at lower pH. 

 The removal of NOM through enhanced coagulation may allow increased disinfectant 

efficiency by decreasing the demand on the disinfectants exerted by organics (Carlson et al. 

2000). The amount of NOM removed will vary depending on the pH, coagulant, coagulant dose, 

and NOM properties. The amount of NOM removal for a given system can be determined using 

jar tests. Alternatively, computer models are available that can predict organic removal given the 

pH, coagulant dose, and organic properties (Edwards 1997). For a system to realize this benefit, 

the system should inject the disinfectant at a location in the treatment process where NOM 

removal has been achieved. This operational scenario may allow the system, in consultation 

with its regulatory agency, to reduce the amount of disinfectant used compared to dosages 

required prior to practicing enhanced coagulation. A reduction in the amount of disinfectant 

applied should result in fewer DBPs being formed. The system should, however, ensure that the 

necessary microbial inactivation is maintained at all times by measuring: 

• The disinfectant residual 

• Flow, temperature, and pH 

• Calculating the resulting inactivation contact times and CTs being achieved 

 Increased removal of organic particles obtained using enhanced coagulation can have the 

added benefit of removing additional microbial pathogens. For example, States et al. (2002) 

found that enhanced coagulation with filtration could achieve 5.0 log removal of 

Cryptosporidium compared to an estimated 2.0 log removal by filtration without coagulation. 

Reduced DBP Formation 

 Enhanced coagulation improves the removal of DBP precursors in a conventional water 

treatment plant. The removal of TOC (a surrogate measure of NOM) by coagulation has been 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-46 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

demonstrated in several laboratory research, pilot demonstrations, and full-scale studies 

(Chowdhury et al. 1997, Edwards 1997). Removal of TOC can result in a decrease in TTHM 

and HAA5 formation. In fact, the Stage 1 D/DBPR uses TOC to define enhanced coagulation 

for DBP precursor removal regulatory requirements. The actual reduction in TOC can vary 

widely. Systems can obtain a better idea of the removal they can obtain by using jar tests. 

 Reduced pH, which is usually characteristic of enhanced coagulation, has also been 

demonstrated to result in a reduction in formation of chloroform (Singer 1999). A more detailed 

discussion of this topic is provided in Section 3.4. 

Reduced Bromate Formation 

 The reduction of pH that is commonly practiced as part of enhanced coagulation can 

result in better control of bromate formation for those systems using ozone. Williams et al. 

(2003) indicated that a pH of about 6.5 provided effective reduction of bromate formation. The 

effectiveness of bromate control at lower pH values depends on the source water, particularly its 

alkalinity. 

Arsenic and Radionuclide Removal

 Compliance with the new arsenic maximum contaminant level (MCL) of 0.010 mg/L 

may require systems to consider treatment modifications for improved arsenic removal. Some 

systems may realize improved arsenic removal by using a ferric coagulant as part of the 

enhanced coagulation process. Scott et al (1995) observed that arsenate (As(V)) removal was in 

the range of 80 to 95 percent for a ferric coagulant dose ranging from 3 to 10 mg/L. Alum 

coagulation has been shown to remove arsenic, but at higher doses (up to 20 mg/L) Removal of 

arsenite (As(III)) is much less efficient than As(V), though iron coagulants are still more 

effective at removing As(III) than alum coagulants (Hering et al. 1996; Edwards 1997). 

Modified coagulation is identified by EPA as a Best Available Technology (BAT) for the 

Arsenic Rule. 

 Enhanced coagulation may also provide better radionuclide removal since radionuclides, 

such as uranium, have been shown to be removed by coagulation/filtration (Sorg 1988). Systems 

will want to understand fully their requirements for disposal of residuals containing 

radionuclides and check with their State or Primacy Agency for instructions on special handling 

or disposal of residuals containing radionuclides. 

3.7.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Enhanced Coagulation 

 Potential issues associated with enhanced coagulation include: 

• Adverse impacts to filtration process 

• Corrosion concerns 

• Increased concentrations of inorganics in the finished water 
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Simultaneous Compliance Guidance Manual 3-47 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• Additional issues with residual disposal 

This section discusses these issues briefly and provides suggestions for reducing their impacts. 

Adverse Impacts to Filtration Process

 In most cases, lowering the pH and/or increasing coagulant feed will result in lowering 

turbidity in the finished water. However, lower pH levels can sometimes lead to the formation of 

a less dense, more fragile floc. This type of floc can carry over from the clarifier and may result 

in shorter filter run times or premature filter breakthrough (Singer 1999). A lower pH and higher 

coagulant dose may also result in restabilization of particles. These conditions can create upsets 

in solids blanket-type clarifiers (Carlson et al. 2000). 

 Premature filter breakthrough as a result of higher particle loading to the filter could 

result in shorter filter runs or, if a system does not adjust its operations in response to the higher 

particle loading, the system might not meet the turbidity limits established by the IESWTR and 

LT1ESWTR. This may also trigger individual filter follow-up actions as required by IESWTR 

and LT1ESWTR. Conversely, enhanced coagulation may have a positive effect on subsequent 

treatment steps, resulting in lower finished water turbidity, potentially longer filter runs, and 

better compliance with effluent turbidity limits. 

 Recommendations for Addressing this Issue

 Systems may want to pilot test different coagulants to identify the coagulant type and 

dose that produces the most stable, settleable floc. Lovins et al. (2003) found that ferric sulfate 

produced a larger, more durable and more settleable floc relative to alum in Peace River water, a 

high DOC water, at a pH of around 7.5. 

 Systems should consult the Enhanced Coagulation and Enhanced Precipitative Softening 

Guidance Manual (USEPA 1999h) for recommendations on how to maintain low turbidity while 

performing enhanced coagulation. 

Corrosion Concerns

 Corrosion control within the distribution system and water treatment plant can be affected 

by a change in pH, change in the chloride to sulfate ratio, change in organics concentration, or a 

significant change in the alkalinity of the finished water (Carlson et al. 2000). Any of these 

conditions can occur as a result of enhanced coagulation and can potentially create compliance 

issues with the LCR or result in degradation of plant facilities. 

 Enhanced coagulation lowers TOC. Changes in TOC have been found to have differing 

impacts on corrosion. Schock et al. (1996) found that in some cases, NOM can form soluble 

complexes with lead which can increase corrosion. In other cases, NOM was found to coat the 

pipes and lower corrosion rates. Edwards et al. (1996) have reported similar results for copper 

corrosion. Edwards et al. (2004) found that lower TOC in combination with higher aluminum 

may cause pinholes leaks in copper piping. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-48 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Enhanced coagulation can lower alkalinity. The effect of an alkalinity change depends 

on the initial alkalinity; for water with moderate to low alkalinity, a decrease in alkalinity can 

increase corrosion. Lower alkalinity can also damage concrete in pipes or in basins and 

reservoirs. Systems are encouraged to maintain a minimum alkalinity of 10 to 20 mg/L as 

calcium carbonate. If the initial alkalinity is high, however, a decrease may be beneficial since a 

decrease in alkalinity can also decrease copper corrosion rates. 

 Enhanced coagulation lowers pH. Lower pH generally increases corrosion rates. 

Changing distribution system pH can also alter the condition of pre-existing scale. The lower the 

initial pH, the smaller the pH change needed to affect the corrosion rate. At an initial pH of 7, a 

pH change of 0.2 can affect corrosion, while with an initial pH of 9 it takes a pH change of over 

0.5 to significantly affect corrosion (AWWA 2005a). Softened scale can break off and release 

any material contained in the scale into the distribution system water. 

 Lower pH can also have adverse impacts within the treatment plant. Cement can degrade 

in acidic conditions. Metals in pipes and pumps may also be susceptible to corrosion. 

 If aluminum coagulants are used and filtration is not optimized, efforts to perform 

enhanced coagulation may result in increased aluminum concentrations. Aluminum can increase 

corrosion of lead and copper, though it will decrease corrosion of copper byproducts. 

 The increased use of coagulants in enhanced coagulation will raise the concentration of 

the anion, either sulfate or chloride, and will affect the chloride to sulfate ration. A low chloride 

to sulfate ratio has been shown to decrease corrosion rates (Edwards et al.1999). 

 Recommendations for Addressing this Issue

 Systems should consider adjusting their pH upward before the water enters the 

distribution system in order to reduce corrosion of pipe materials. Systems will want to identify 

the optimum pH within the distribution system that 

enables compliance with the LCR and does not result 

in substantial increases in DBP levels. 

 There are several options available to increase 

pH. These include addition of lime, caustic soda, soda 

ash, and sodium bicarbonate. Another possible method of increasing pH is to filter using 

limestone or other alkaline media. Each of these techniques has advantages and disadvantages 

that will depend on the water quality of the water being adjusted and the distribution system 

materials that must be protected. For example, soda ash raises alkalinity as well as pH. The 

increased alkalinity can cause increased corrosion of some materials (Kirmeyer et al. 2002). The 

reference tools listed at the end of this section provide more guidance on proper selection of pH 

adjustment techniques. 

 If the system cannot readjust the pH to a high enough level using caustic to prevent 

corrosion, it can consider adding a corrosion inhibitor (i.e., a substance that is phosphate- or 

silica-based) to the finished water to form a protective coating on the pipes. 

Water systems should carefully 

research the implications of 

using a corrosion inhibitor before 

adding it as a treatment step. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-49 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Water systems should carefully research the implications of using a corrosion inhibitor 

before adding it as a treatment step. Some utilities have elected not to use phosphate-based 

corrosion inhibitors because the POTW receiving the wastewater violated phosphorus limits in 

their disposal permits. Zinc toxicity to wastewater treatment biota can also be a concern. Lime 

addition can potentially cause turbidity problems if the dosing and mixing are not done properly. 

Conversely, research has shown that corrosion control often has the added benefit of controlling 

biological growth in the distribution system, which can lead to improved compliance with the 

TCR. 

 Regardless of the type of corrosion inhibitor used, it should be carefully pilot-tested 

before it is introduced. Large water systems were required to conduct corrosion control studies 

under the LCR. Smaller systems may have conducted studies if required by the state. Any 

system that subsequently changes their treatment must notify the state and may be required to 

conduct a new corrosion control study. In any event, LCR corrosion control studies should be 

used as a starting point to assess the impacts of changes in distribution system water quality on 

corrosion and LCR compliance and determine the best corrosion control treatment strategy. 

Appendices C and D provide additional guidelines for systems evaluating their corrosion control 

options and information on proper piloting procedures. 

 Systems should also monitor inside the plant for signs of corrosion of concrete or metal. 

If corrosion is noticed, corrosion may be prevented by applying an epoxy coating. For metals 

such as pipes and pumps or metal rebar in concrete structures, using a sacrificial anode is an 

option in addition to epoxy coatings. Exterior fittings in buildings should be painted to reduce 

corrosion. Finally, materials compatible with the anticipated pH and water quality in the plant 

should be specified when designing new processes. 

Increased Inorganics in Finished Water

 Enhanced coagulation can cause an increase in inorganics, such as manganese, 

aluminum, sulfate, chloride, and sodium in the finished water. The low pH that frequently 

results from enhanced coagulation reduces the oxidation rate of manganese from the dissolved 

state (Mn2+) to the solid form (MnO2) that allows it to be removed during sedimentation and 

filtration. Ideally, manganese is completely oxidized before the coagulation step, and enhanced 

coagulation should not deter manganese removal. Systems should note, however, that even very 

low concentrations of manganese (e.g., 0.05 mg/L) in the finished water could result in aesthetic 

problems. 

 Manganese may also be present in concentrations above the secondary standard of 0.05 

mg/L if high dosages of ferric coagulants are used (Carlson et al. 2000). Ferric chloride and 

ferric sulfate coagulants can contain relatively high concentrations of manganese. If a water 

system switches from low doses of ferric or alum to high doses of ferric, the coagulant itself may 

significantly increase the amount of dissolved manganese in the water. 

 The presence of high concentrations of sulfate or chloride may affect the corrosivity of 

the water (Carlson et al. 2000). The mass ratio of chloride to sulfate can also affect the 

corrosivity of the water. Edwards et al. (1999) found that of 24 utilities surveyed, none of the 

utilities with a chloride to sulfate ratio of less than 0.58 exceeded the lead action level, while 64 

percent of utilities with a ratio greater than 0.58 exceeded the lead action level. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-50 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Increased aluminum in the distribution system may result when high alum dosages are 

used in an effort to perform enhanced coagulation. Increased aluminum can lead to aesthetic 

problems, such as solids precipitation, in the distribution system (Carlson et al. 2000). Increased 

alum can be kept from passing through filters by addition of filter aids and more frequent 

backwashing. More frequent backwashing, however, has costs and other implications. 

 Recommendations for Addressing this Issue

 System operators should consider their source water specifically when making choices 

about coagulant use. Systems should jar test and, ideally, pilot test under different water quality 

conditions the coagulants that they are considering before making full-scale coagulant treatment 

changes. NSF and manufacturer recommendations should be followed in coagulant dosing. 

Specifications for coagulants and other treatment chemicals should also specify allowable 

concentrations of trace contaminants. Section 6.3 describes some ways systems can test their 

water to determine which coagulant is best suited for their water quality and particular treatment 

needs. Systems with a high chloride to sulfate ratio may be able to mitigate corrosion by 

switching from a chloride-based coagulant to a sulfate-based coagulant. 

Residuals Handling

 Because more coagulant is added and more organics are being removed, enhanced 

coagulation will likely result in the production of more waste residuals. The conditions for 

existing disposal of water treatment plant (WTP) sludge should be reviewed and even 

renegotiated, and increased costs of waste disposal should be factored into a system’s decision. 

 

 If the source water has high concentrations of hazardous contaminants such as arsenic, 

the waste residuals may concentrate these contaminants to the extent that the waste is considered 

unfit for disposal in a sanitary landfill. Some states have stricter limits on toxics concentrations 

in waste residuals disposed of in sanitary landfills, and exceeding any of those limits could cause 

the waste to be classified as hazardous. In addition, some states have additional disposal 

requirements for residuals that have been characterized as technologically enhanced naturally 

occurring radioactive material (TENORM) that can further complicate disposal. 

 Recommendations for Addressing this Issue

 Systems will likely experience higher costs with managing an increased residual load. 

Depending on how residuals are managed, additional facilities may need to be constructed or 

new permits may be necessary. Aluminum is toxic to aquatic life, so increased alum use may 

result in limitations on the discharge of the residual stream to surface water bodies. 

 Systems should properly analyze the sludge that results from enhanced coagulation for 

increased metals and other contaminants that may create issues with final sludge disposal. The 

regulatory agency should be consulted regarding disposal of residuals if hazardous chemicals are 

concentrated in the residuals. EPA has recently released A Regulator’s Guide to the 

Management of Radioactive Residuals from Drinking Water Treatment Technologies, (USEPA 

2005c) which deals with the issue of radioactive compounds concentrated in residuals. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-51 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Typically, ferric sulfate sludges are more easily dewatered as compared to alum sludges 

(Thompson and Paulson 1998). 

3.7.3 Recommendations for Gathering More Information 

Read the Case Studies 

Four case studies in Appendix B describe simultaneous compliance challenges faced by 

utilities using enhanced coagulation. 

Case Study #1 - Improving and Optimizing Current Operations starting on page B-5 of 

Appendix B describes how two small PWSs with high THM concentrations were able to comply 

with the requirements of the Stage 1 D/DBPR and Stage 2 DBPR by adjusting their coagulation 

methods and changing the point of chlorination, while also optimizing distribution operations to 

minimize water age and optimizing booster chlorine use. Their greatest operation issue was a 

need for increased attention to solids removal as a result of enhanced coagulation 

Case Study #4 Switching Coagulants starting on page B-23 describes how a system 

could simultaneously comply with the TOC removal requirements of the Stage 1 D/DBPR and 

the turbidity removal requirements of the IESWTR by switching coagulants. The system found 

that enhanced coagulation with ferric sulfate not only increased TOC removal significantly, but 

also reduced turbidity levels in the finished water. The major problem experienced in 

implementing the treatment modification was the control of manganese and corrosion in the 

rapid mix chamber due to the addition of sulfuric acid.

Case Study #5 Enhanced Coagulation-Problems with Copper Pitting starting on page 

B-29 describes a system that experienced pinhole leaks in their copper piping following 

alterations to the coagulation process. The system implemented orthophosphate addition to 

address the pinhole leaks, which also had an effect on finished water turbidity and iron release 

from unlined cast iron mains. 

 Case Study #6 Enhanced Coagulation - Managing Radioactive Residuals starting 

on page B-33 provides a discussion of a system's options for disposing of radioactive 

residuals resulting from enhanced coagulation. As a result of enhanced coagulation, 

radionuclides can become concentrated in residuals at levels that require special 

consideration for regulatory approval of sludge disposal. 

See Additional References

 Readers can turn to Section 7.1.8 in Chapter 7 for technical references associated with 

using enhanced coagulation. 

Consider Additional Monitoring

 The following are some suggestions for additional monitoring that may benefit water 

systems using enhanced coagulation: 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-52 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

9 Routine turbidity or particle count monitoring of water leaving the sedimentation 

basin to ensure that a consistently stable and dense floc is forming; 

9 Routine finished water pH and alkalinity monitoring to help ensure that corrosion 

control is being implemented correctly; and 

9 Periodic aluminum measurements in the finished water to watch for aluminum 

carryover from the combination of alum floc and low pH. 

The purpose of these monitoring suggestions is specifically to address and prevent potential 

simultaneous compliance issues. 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their operation or treatment practices. Examples of tools 

that can be used when enhanced coagulation is used for Stage 2 DBPR compliance include: 

• The “Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual” 

(USEPA 1999h) that provides recommended procedures for conducting jar testing to 

determine the optimum coagulation conditions for achieving desirable total organic 

carbon removal and coagulated/settled water turbidity; 

• The AwwaRF report “Internal Corrosion of Water Distribution System” (AwwaRF 

and DVGW-Technologiezentrum Wasser 1996), which provides bench-scale and 

pilot testing protocols that can be used to evaluate changes in corrosion potential due 

to changes in pH; 

• EPA’s Environmental Technology Verification Program collects performance data on 

many environmental technologies, including enhanced coagulation. Reports for each 

technology can be found on the website at: 

http://www.epa.gov/etv/verifications/verification-index.html; 

• The “Guidance Manual for Monitoring Distribution System Water Quality” 

(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a 

distribution system water quality data collection and analysis program; 

• The second version of “Water Treatment Plant Model” (USEPA 2001h) developed by 

EPA that assists utilities with implementing various treatment changes while 

maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR; 

and 

• The Partnership for Safe Water publishes many materials useful in optimizing filter 

performance. More information can be found on their website at: 

http://www.awwa.org/science/partnership/. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-53 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.8 Enhanced Softening 

 Precipitative softening with lime addition is typically practiced with the objective of 

removing hardness in the form of calcium and magnesium from water. Total hardness removal 

goals vary among treatment plants. Lime softening processes are generally divided into three 

distinct groups: 

• Conventional lime softening to remove calcium carbonate where only lime is fed; 

• Lime-soda softening to remove calcium carbonate and noncarbonate hardness by 

feeding both lime and either soda ash or potassium carbonate; and 

• Excess lime softening to remove both calcium and magnesium (and sometimes silica) 

by adding an excess of lime. 

 All softening plants operate at higher pH levels than conventional coagulation plants. 

Calcium carbonate begins to precipitate above pH of 9.5 and as the pH increases above 10, 

magnesium hydroxide precipitation increases. 

 Softening has some similarities to 

coagulation with respect to the mechanisms 

operating to remove particles and TOC, so that 

when coupled with appropriate settling, DBP 

precursors can be removed effectively by 

softening. Generally, removal of TOC in 

softening is enhanced by the addition of a small amount of coagulant. The regulatory 

requirement for enhanced softening in the Stage 1 D/DBPR is based on the assumption that 

raising the lime dose will foster the precipitation of CaCO3 and the associated coprecipitation of 

precursors. The resulting increase in pH causes increased precursor removal, presumably by 

promoting stronger interactions between the precursors and calcium ions. In addition, the 

increase in pH may be sufficient to precipitate magnesium hydroxide, which strongly adsorbs 

precursors (Randtke 1999; Shorney and Randtke 1994). 

 When the pH of softening is changed significantly, differences in process chemistry 

affect the nature of the solids that are formed with respect to settling and dewatering 

characteristics. Enhanced softening criteria do not require plants to alter the softening process to 

the extent that major changes in settling conditions and solids handling are generally required. A 

plant is considered to be practicing enhanced softening if it meets the appropriate TOC removal 

target in the 3x3 TOC removal matrix. Most softening plants have raw water alkalinity above 

120 mg/L as CaCO3, so that they are classified in the right hand column of the matrix, but a few 

fall into the classification for influent with alkalinity of 60 – 120 mg/L. Plants that cannot meet 

the removal requirements in the 3x3 matrix may remain in compliance by removing a minimum 

of 10 mg/L of magnesium as CaCO3. Alternatively, softening plants that reduce their finished 

water alkalinity to 60 mg/L are in compliance with enhanced softening. 

Generally, removal of TOC in 

softening is enhanced by the 

addition of a small amount of 

coagulant. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-54 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

3.8.1 Advantages of Enhanced Softening 

 The main advantages of enhanced softening are: 

• Adequate removal of TOC 

• Two stage plants may achieve additional Cryptosporidium removal credit 

• Lower corrosion impacts 

Adequate Removal of TOC 

 Softening plants typically do not have difficulty meeting the TOC removal requirements 

of the 3x3 matrix in the Stage 1 D/DBPR. Information from a survey of softening plants (Clark 

et al. 2000) indicated that operational data showed TOC being removed at least at the level 

defined by the matrix, and this is substantiated by the data from the Information Collection Rule 

(ICR). Since plants were not necessarily striving to meet the enhanced softening criteria during 

the ICR sampling period, apparently the standard operating scheme for most softening plants 

actually falls within the criteria of “enhanced softening” as defined by the rule (Clark et al. 

2000). 

 The only instances reported by softeners which lead to difficulty in removing TOC occur 

when raw water alkalinity drops significantly causing the calcium hardness:carbonate alkalinity 

ratio to be elevated. This situation can arise when surface water is diluted by major rain events 

or when a blend of ground and surface water is altered in proportions. In these cases, some 

addition of carbonate alkalinity in the form of soda ash or potassium carbonate may be warranted 

to facilitate the softening reactions and the coprecipitation of organic material. Softening utilities 

are expected to be able to meet the requirements of the Stage 2 DBPR as effectively, or more so, 

as conventional coagulation plants (USEPA N.d.e). 

Two Stage Plants May Achieve Additional Cryptosporidium Removal Credit 

 Plants that include a two-stage lime softening process are eligible for an additional 0.5-

log Cryptosporidium removal credit toward compliance under LT2ESWTR if chemical addition 

and hardness precipitation occur in two separate and sequential softening stages prior to 

filtration. The two-stage process must consist of a second clarification step between the primary 

clarifier and filters. Both clarifiers must treat all of the plant flow. Refer to the LT2ESWTR 

Toolbox Guidance Manual (USEPA N.d.e) for a description of the requirements for receiving 

this credit. 

Lower Corrosion Impacts

 Softening systems have an advantage with respect to managing corrosion for two reasons. 

Since the softening process takes place at a pH above 10, systems generally add carbon dioxide 

to reduce pH and stabilize the water prior to distribution. Selection of an appropriate finished 

water pH goal takes into consideration the optimum pH for corrosion control. At the same time, 

softening systems generally produce water that tends to develop scale in the distribution system. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-55 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

If the scale formation is not managed appropriately, it can be a liability with respect to flow 

restriction, but from a corrosion control standpoint, scale formation is a distinct benefit. 

 As noted in EPA’s “Enhanced Coagulation and Enhanced Precipitative Softening 

Guidance Manual” (USEPA 1999h), the information in Exhibit 3.6 is intended only to 

characterize existing and future corrosion control strategies. The figure can be used proactively 

to anticipate problems that may develop if enhanced softening is used. 

Exhibit 3.6 Effect of the Change of Water Quality Parameters Due to Enhanced 

Softening on Corrosion of Piping System Materials 

Parameter Potential Impact on Corrosion of Material

Change 

Resulting From 

Enhanced 

Softening

Pb Cu Fe Pb from 

Brass

Concrete

TOC ▼ ► ►1

▼2 ▼ ▼ ► ▲

Alkalinity ▼ ► ► ► ▲ ► ▼ ► ▲ ►

Ca Hardness ▼ ► ► ▲ ► ► ▲

pH ▲ ► ▼ ► ▼ ► ▼ ► ▼ ► ► 1 applies to copper 

2

 applies to copper by-products ▼= decrease ▲= increase ►= same (no change)

Source: USEPA’s Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual (USEPA 1999h)

3.8.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Enhanced Softening 

 Potential issues associated with enhanced softening include: 

• Options for disinfection are limited 

• Higher TTHM formation at high pH 

• Can cause scaling 

• pH adjustment required for distribution and for disinfection effectiveness 

• Increased sludge volume and changes in sludge characteristics 

This section briefly describes these issues and provides suggestions for minimizing their impacts.
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-56 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Disinfection considerations 

 One of the most complex issues facing softening plants with respect to regulatory 

compliance is selection and implementation of disinfection processes. Disinfection with 

chlorine, chloramines, chlorine dioxide, and ozone requires specific consideration of issues that 

arise in high pH waters. 

 Based on data from an AWWA survey of 

softening plants completed in 1997 to inform the 

regulatory development process, more than one third 

of softening plants predisinfect with chlorine, ozone, 

or a combination of chlorine/chloramines and they 

take CT credit for some or all predisinfection contact 

time. In addition, the survey indicated that the 

finished water pH in softening plants ranges from 7.5 

to 10, with approximately half reporting average 

finished water pH greater than 9. CT values for inactivation of Giardia by free chlorine and 

chloramines are not identified for pH levels greater than 9 in the SWTR Guidance (USEPA 

1991). Thus, the state must evaluate disinfection credit using chlorine or chloramines through 

the softening portion of the treatment process on a case-by-case basis to ensure that the total 

treatment processes achieve at least 3-log treatment of Giardia and 4-log treatment of viruses. 

Some softening plants have resolved this problem by providing appropriate contact time after 

softening and pH reduction to meet required CT values with their selected disinfectant. 

 Use of chlorine dioxide in softening plants is governed by the regulated levels for 

chlorine dioxide and chlorite. Chlorine dioxide reacts with many organic and inorganic 

constituents in water. It disinfects by oxidation, but does not chlorinate. Chlorine dioxide 

functions as a highly selective oxidant due to its unique, one-electron transfer mechanism where 

it is reduced to chlorite. The reactions produce chlorite and chlorate as endpoints. In drinking 

water, chlorite (ClO2

-

) is the predominant reaction endpoint, with approximately 50 to 70 percent 

of the chlorine dioxide converted to chlorite and 30 percent to chlorate (ClO3

-

) and chloride (Cl-) 

(USEPA 1999h). The balance between these two species varies frequently and is affected by the 

exposure to bright sunlight, aeration, and recarbonation, among other factors (Gates 1997). The 

disproportionation of ClO2 is accelerated by increased pH, which means that the addition of lime 

soon after the addition of ClO2 may result in minimal disinfection time and development of both 

chlorite and chlorate (Hoehn 1993). There may be situations in which chlorine dioxide can be 

used as a preoxidant in softening plants, but they would be governed by the contact time 

available prior to the addition of lime and initiation of the softening process. 

 Ozone use at high pH (above pH 7) will form significant bromate when bromide is 

present in the water. Ozonation at lower pH can control the formation of bromate, but will 

increase the formation of brominated organic byproducts produced from the interaction between 

hypobromous acid and NOM, producing an overall increase in TTHM by weight (Reckhow 

1999). In softening plants, the use of ozone generally requires reduction of pH from the 

softening pH (between 10 and 11) to a pH between 6 and 7. To obtain such a shift in pH, 

significant amounts of acid are often consumed. Thus, unless a unique water quality concern 

requires use of ozone, other disinfection options should be considered. 

The state must evaluate 

disinfection credit using 

chlorine or chloramines 

through the softening 

portion of the treatment 

process on a case-by-case 

basis.
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-57 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Higher THM Formation 

 In addition to increasing with chlorine dose and presence of DBP precursors, THM 

formation has been shown to be higher with increasing chlorination pH. Some HAAs, in 

contrast appear to have lower formation at higher pH (Singer 1999). A number of softening 

plants have constructed a large chlorine contact chamber/clearwell to provide disinfection 

contact time after the pH of the water is lowered from the softening pH to a pH that minimizes 

DBP production. 

 Many raw water sources that are treated by softening contain significant levels of 

bromide. As plants practice enhanced softening to remove precursors, the ratio of the amount of 

bromide in the water to the amount of TOC goes up because bromide is not removed by 

softening. Research has shown that as the ratio of bromide to TOC increases the percentage of 

brominated DBPs increases. Thus, when bromide-containing enhanced softened water is 

disinfected with chlorine, formation of brominated THMs increases, resulting in a higher total 

weight of THMs formed. Thus, softening plants may be forced into a balancing of TOC removal 

with DBP formation to optimize the finished water DBP formation based on speciation of the 

THMs and total weight of TTHM. 

 Recommendations for Addressing this Issue

 If softening plants have problems complying with the proposed Stage 2 DBPR TTHM 

MCLs, three possible alternatives should be considered. 

• Systems may be able to reduce finished water pH somewhat to reduce the TTHM 

formation potential in the system. Changes in system pH should be cautiously 

undertaken to ensure that the existing system scale is not altered significantly, 

softened, or stripped from pipes, thereby causing major operational problems; 

• Systems may be able to utilize alternative disinfectants, including chloramines, 

chlorine dioxide, or ozone. Chloramines are best suited for use as a distribution 

system residual although some softening plants operate with a chloramine residual 

carried through the softening process. Chlorine dioxide and ozone disinfection 

should be evaluated with care in both quantity and placement to ensure that neither 

chlorate nor bromate MCLs are violated. Use of UV for disinfection may reduce the 

level of chlorine or chloramine residual required for residual disinfection in the 

distribution system; and 

• Softening plants may also evaluate the possible conversion from conventional 

softening to membrane softening. The use of microfiltration followed by 

nanofiltration can remove TOC as well as provide softened water, thereby reducing 

the DBP formation potential. Cost may be a factor that prohibits a system from 

making this change. In addition, membrane conversion can necessitate the need to 

consider other simultaneous compliance issues such as ensuring that distribution 

system chemical equilibrium is not altered in a way that will cause either corrosion or 

scale sloughing. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-58 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Scaling 

 Depending on the raw water quality and the physical configuration of the treatment 

processes in a softening plant, the addition of extra lime to provide enhanced softening 

conditions can lead to increased scaling conditions in both the treatment plant and the 

distribution system piping. In general, if the Langelier Saturation Index (LSI) is positive, the 

water is oversaturated with CaCO3 and has the potential to precipitate and form scale. 

pH Adjustment Required for Distribution and for Disinfection Effectiveness 

 Most softening plants adjust pH to meet finished water pH goals, to meet pH 

requirements for disinfection effectiveness after the completion of the softening process, and to 

satisfy distribution system chemical equilibrium. As the pH of softening is increased in an effort 

to remove more TOC, the quantity of chemical required for pH adjustment increases. 

Historically, the finished water pH in softening plants has ranged between 7.5 and 10. 

Increased Sludge Volume and Changes in Sludge Characteristics 

 Significant increases in lime doses will result in increased lime sludge production. 

Residuals production may also increase when lime addition results in a pH greater than 10.25 in 

plants with significant magnesium present that have not historically softened at pH greater than 

10. At that pH, the magnesium hydroxide is precipitated along with calcium carbonate. If 

significant noncarbonate hardness exists, then addition of soda ash may be necessary, resulting in 

increased residuals production and higher sodium levels in the finished water. In addition, the 

handling and dewatering characteristics may be significantly altered (Randtke et al. 1999). 

 In the softening process, calcium carbonate forms a dense crystal that is negatively 

charged, while magnesium hydroxide forms large, light floc that has a high surface area and 

positive surface charge. This difference in particle characteristics is what makes magnesium 

hydroxide a better adsorbent for dissolved precursors; however magnesium hydroxide solids 

have settling and dewatering characteristics that are quite different from calcium carbonate 

solids. In fact, softening plants that are designed to settle calcium carbonate may very well have 

inadequate settling time to settle magnesium hydroxide. If the previous softening pH was less 

than 10.25 and the water has significant magnesium, then enhanced softening in which the pH is 

increased to greater than 10.25 can cause formation of magnesium hydroxide, which may not be 

effectively removed in the settling process, or may change the characteristics of the process 

solids. 

3.8.3 Recommendations for Gathering More Information 

See Additional References

 Readers can turn to Section 7.1.8 of Chapter 7 for technical references associated with 

enhanced softening 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-59 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Consider Additional Monitoring

 The following are some suggestions for additional monitoring that may benefit softening 

systems. The purpose of these monitoring suggestions is specifically to address and prevent 

potential simultaneous compliance issues. 

9 Routine LSI measurements, or another comparable calcium carbonate saturation 

index, of water entering the distribution system to monitor the potential for excess 

scale formation. Weekly measurements may be sufficient when raw water quality is 

relatively consistent. More frequent checks may be useful under changing raw water 

conditions. 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their operation or treatment practices. Examples of tools 

that can be used when enhanced softening is used for Stage 2 DBPR compliance include: 

• The “Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual” 

(USEPA 1999h) that provides recommended procedures for conducting jar testing to 

determine the optimum coagulation and softening conditions for achieving desirable 

total organic carbon removal and coagulated/settled water turbidity; 

• The AwwaRF report “Internal Corrosion of Water Distribution System” (AwwaRF 

and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

testing protocols that can be used to evaluate changes in corrosion potential due to 

changes in pH; 

• The “Guidance Manual for Monitoring Distribution System Water Quality” 

(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a 

distribution system water quality data collection and analysis program; and 

• The second version of “Water Treatment Plant Model” (USEPA 2001h) developed by 

EPA that assists utilities with implementing various treatment changes while 

maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
3. Improving and Optimizing Current Operations 

Simultaneous Compliance Guidance Manual 3-60 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Simultaneous Compliance Guidance Manual 4-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

TREATMENTS COVERED 

 

• Granular Activated Carbon 

• Microfiltration/Ultrafiltration 

• Nanofiltration 

• Other Microbial Removal Technologies 

After improving and optimizing current operations, some water systems will still need to 

install a new type of treatment in order to comply with the Stage 2 DBPR and/or the 

LT2ESWTR. This chapter describes treatment technologies that can be installed to remove DBP 

precursors and microbial pathogens. Advantages of using each treatment are described, along 

with summaries of operational and simultaneous compliance issues associated with the 

treatment. General recommendations for 

addressing those issues are provided, 

along with recommendations for gathering 

more information. While most of the 

issues presented in the following sections 

address simultaneous compliance 

concerns, some additional operational and 

aesthetic issues are discussed. 

 

4.1 Granular Activated Carbon 

The main benefit of granular activated carbon (GAC) is that it is effective in adsorbing 

and removing organic compounds from water. Removing organic matter lowers DBPs, taste and 

odor complaints, and microbial activity in the distribution system. Additionally, if GAC is used 

in series with a conventional filter, as illustrated below, systems may be able to receive 

additional Cryptosporidium removal credit under the LT2ESWTR. The main drawbacks to 

using GAC are the possibility of release of bacteria or carbon fines into the system, the 

possibility of chromatographic peaking, and its reaction with disinfectants. These issues are 

discussed in more detail in Section 4.1.2. 

 

 GAC can be used as an additional layer on top of an existing filter (GAC cap), or it can 

be placed in a separate contactor. Design will vary depending on whether it is used as a separate 

adsorber or if it is added as a filter cap. Its efficiency is determined by the contact time and the 

4 Installing New Total Organic Carbon 

or Microbial Removal Technologies 

Rapid Mix Flocculation/ 

Sedimentation

Filtration

Caustic

Storage

Coagulant

Interstage GAC Filter

Pumping 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

Simultaneous Compliance Guidance Manual 4-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Using GAC in a second filter can: 

 

• lower DBP precursors and other organics 

• help meet the Stage 2 DBPR requirements 

• achieve Cryptosporidium removal credit for 

the LT2ESWTR 

relative adsorption strength of the compounds that are to be removed. Some physical removal by 

filtration will occur in GAC beds as well. 

4.1.1 Advantages of GAC 

 Advantages of GAC include: 

• Removes DBP precursors 

• Can remove taste and odor compounds 

• If used as a secondary filter, the system may be able to receive a 0.5-log 

Cryptosporidium removal credit 

• Can be used as a biologically active filter after ozone to remove assimilable 

organic carbon (AOC)

DBP Precursor Removal

 DBP precursor removal before the addition of a disinfectant can significantly lower DBP 

production and ease compliance with the Stage 2 DBPR. GAC10, a GAC contactor with a 10 

minute empty bed contact time (EBCT), is considered a best available technology (BAT) for the 

Stage 1 D/DBPR. GAC10 in combination with enhanced coagulation or enhanced softening or 

GAC20 are considered BATs for the Stage 2 DBPR. GAC has been found to reduce total organic 

carbon (TOC) by 30 to 90 percent depending on the contact time, the nature of the organic 

matter, and other parameters (USEPA 2003d and references therein). Generally, AOC is 

removed relatively quickly while other organic fractions take longer to remove. 

Taste and Odor Removal

 Because many taste and odor compounds are organic, the ability of GAC to adsorb 

organics also makes it a useful treatment technique in this respect. For example, GAC has been 

found to remove 30 to 40 percent of geosmin from drinking water (Youngsug et al. 1997). The 

removal efficiency was increased to 80 percent or more with the addition of ozone or peroxone. 

Similar reductions can be achieved for 2-methylisoborneol (MIB). 

Cryptosporidium Removal

 Systems can receive a 0.5-log 

Cryptosporidium removal credit for having 

a second set of filters in series in a 

conventional treatment plant. Both a GAC 

contactor and a conventional dual media 

filter with a GAC cap are eligible for this 

credit. In both cases the Cryptosporidium is 

removed through physical filtration onto the 

filter media. The filter must treat the entire 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

Simultaneous Compliance Guidance Manual 4-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

flow of the plant to obtain the credit. Refer to the LT2ESWTR Toolbox Guidance Manual

(USEPA N.d.e) for a description of rule requirements for receiving credit. 

Removes AOC After Ozone

 Ozonation often results in organic matter becoming AOC, which serves as a food source 

for microbes. This can cause difficulties with compliance with the Total Coliform Rule (TCR) 

and can lead to nitrification problems. GAC, acting as an adsorbent, can remove some AOC 

before it enters the distribution system. 

 Additionally, systems can take advantage of the high surface area per mass ratio of GAC 

and the fact that it adsorbs organics to operate the GAC filter in biologically active mode. By 

not having a disinfectant residual in the water passing through the filter and allowing biological 

growth, the system can achieve high removals of AOC. Using biologically active GAC filters 

after ozonation can reduce biological growth in the distribution system and lower DBPs. See 

Section 5.2 for further details on the use of biological filtration with ozone. 

4.1.2 Potential Operational and Simultaneous Compliance Issues Associated 

with Using GAC 

 

 Potential issues associated with GAC use include: 

• Can limit the ability to prechlorinate; 

• Previously adsorbed compounds can be released; 

• Bacteria can be released; 

• Carbon fines released from GAC filters can foul downstream processes; 

• Chlorate can be formed when GAC comes in contact with chlorine dioxide; and 

• Ammonia added before a GAC filter has been found to increase nitrification in 

the distribution system.

 This section briefly describes each of these issues and provides some suggestions for 

addressing them. 

Limits Ability to Pre-chlorinate

 Most disinfectants react quickly when they come into contact with GAC. This leads to a 

rapid loss of disinfectant residual, and in the case of chlorine, can lead to a faster depletion of the 

GAC. 
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 Recommendations for Addressing this Issue

 Systems should not use GAC filters at the same time as achieving CT for purposes of 

meeting disinfection requirements. Disinfectants should be added after the GAC filter. If the 

disinfectant addition points are moved, an evaluation of the CT throughout the plant must be 

made and any effects of moving the disinfection point, such as changes in coagulation and 

precipitation, pre-oxidation of contaminants, and growth of algae should be evaluated. If preoxidation is needed in treatment before GAC, alternative oxidants (e.g., potassium 

permanganate) or lower chlorine doses should be used so as not to carry a residual onto the 

GAC. 

Release of Adsorbed Compounds

 Organic materials adsorbed onto GAC will generally remain on the GAC until it is 

regenerated. But if a stronger adsorbing compound passes through the GAC when the GAC is 

relatively saturated, and the GAC does not have a significant number of free adsorption sites, 

weaker binding compounds can be expelled. It is possible for the concentration of these expelled 

compounds to be higher than the original concentration. This phenomenon is referred to as 

chromatographic peaking. Strongly adsorbing compounds that can have this effect include 

hydroxide used to adjust pH, or chloride as a byproduct of chlorination. 

 Recommendations for Addressing this Issue

 To avoid chromatographic peaking and the desorption of contaminants from the GAC, 

pH adjustment should be made after the GAC filter. Chlorine should also generally be added 

after the GAC filter, both to avoid chromatographic peaking and to lower DBP formation. Any 

other sudden changes in water chemistry entering the GAC contactor should be avoided as well. 

If sudden swings in water chemistry are unavoidable, then GAC regeneration frequency should 

be increased and the filter effluent should be monitored carefully to prevent breakthrough of any 

contaminants. 

Release of Bacteria

Studies have found that the average number of bacteria in the effluent of GAC filters can 

be significantly higher than influent levels (Parson et al. 1980; Klotz et al. 1976), indicating that 

heterotrophic bacteria growth may occur within the filters. For systems using GAC filtration that 

have inadequate post-GAC disinfection, bacteria may enter the distributon system. The primary 

concern with this potential bacteria release is the possible presence of pathogenic 

microorganisms. Other concerns include the possible presence of ammonia-oxidizing bacteria 

that could trigger a nitrification event if ammonia is present, and bacteria growth in distribution 

system biofilms. 

 Recommendations for Addressing this Issue

 The amount of bacteria in the effluent of GAC systems can often be reduced by proper 

backwashing and GAC regeneration frequencies. However, some bacteria are still likely to be 

shed from GAC filters. Introducing a disinfectant residual in the filter itself is not recommended 

because most disinfectants react with GAC, spending the GAC and not penetrating the full depth 
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of the bed. The best strategy to deal with bacteria shed from GAC filters is to add a disinfectant 

after the GAC filter. 

Release of Carbon Fines

 Small particles of carbon are usually present in GAC filters when they are first installed. 

These carbon fines appear gray or black and can cloud the water. If carbon fines from GAC 

filters are released into the product water, they can interfere with downstream treatment 

processes, particularly fouling of membrane filters and absorbing ultraviolet (UV) light in UV 

disinfection units, and cause poorer performance of these subsequent treatment steps. 

 Recommendations for Addressing this Issue

 GAC filters should be placed after membrane or UV disinfection processes to avoid 

problems associated with the release of carbon fines. If this is not possible, proper backwashing 

procedures, good maintenance of the filter underdrains, and more frequent cleaning of the UV 

reactor or membrane unit can help to minimize the problem. 

Formation of Chlorate

 Chlorine dioxide, in addition to losing its residual, will form chlorate when it comes into 

contact with GAC. Chlorate can further react to form chlorite, a DBP regulated by the Stage 1 

D/DBPR. 

 Recommendations for Addressing this Issue

 Chlorine dioxide should be added after the GAC filters to avoid the formation of chlorate. 

If chlorine dioxide is used for pre-oxidation, it should be added far enough ahead of the GAC 

filter that no residual enters the contactor. If the treatment sequence first has conventional 

filtration and then the GAC filter, adding the chlorine dioxide prior to the first set of filters will 

usually solve the problem. 

Nitrification with Chloramines

 Systems that add ammonia prior to a GAC contactor have been found to have more 

frequent incidents of nitrification in the distribution system (Krasner et al. 2003). This may be 

caused by the ammonia stimulating growth of nitrifying bacteria on the GAC media and seeding 

the distribution system with these bacteria, though the research has not been conclusive. 

 Recommendations for Addressing this Issue

To reduce the potential for nitrification, systems using ammonia to form chloramines or 

to raise pH should add the ammonia after the GAC filters.
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4.1.3 Recommendations for Gathering More Information 

Read the Case Study 

For more information on simultaneous compliance issues associated with GAC and how 

to address them, see Case Study #7 - Granular Activated Carbon for TOC removal starting on 

page B-39 of Appendix B. This case study describes how a utility used GAC to address high 

levels of atrazine in its source water and high TTHM levels in its finished water. The system 

was able to reduce their atrazine levels 30 to 60 percent and their UV254 levels 20 percent six 

months after installing the GAC cap. The greatest operational issue faced by the system was a 

build up of inorganic precipitates on the GAC filter, and occasional taste and odor episodes. 

See Additional References

 Readers can turn to Chapter 7 for more references on this topic. Section 7.1.1 includes 

general references on water treatment, Section 7.1.2 contains references on controlling DBP 

formation, and section 7.1.9 contains references on GAC use. 

Consider Additional Monitoring

The following are some suggestions for additional monitoring that may benefit water 

systems implementing GAC. Note that the purpose of these monitoring suggestions is 

specifically to address and prevent potential simultaneous compliance issues. Water system 

managers should discuss process control monitoring with the GAC manufacturer or their 

engineer. 

9 Periodic monitoring of volatile organic chemicals (VOCs) and synthetic organic 

chemicals (SOCs), as appropriate, in water leaving the GAC unit to detect 

breakthrough and desorption of contaminants; 

9 Turbidity or particle count measurements of the GAC effluent, especially when new 

or re-activated carbon is first being used; and 

9 Heterotrophic plant counts (HPC) in water leaving the GAC units to watch for an 

increase in bacteria numbers. 

Consider Other Tools 

 In addition to water quality monitoring, there are additional tools described in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their treatment practices. Examples of tools that can be 

used when GAC is used for Stage 2 DBPR compliance include: 

• The AwwaRF report “Prediction of GAC Performance Using Rapid-Small Scale 

Column Tests” (Crittenden 1989) that describes the use of RSSCT techniques to 

predict full-scale GAC’s useful lifetime when it is used to remove dissolved organic 

matter from a drinking water source. This report also demonstrates how to use pilotscale testing data to further refine the RSSCT prediction; 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

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• The “Handbook of Public Water Systems” (HDR Engineering, Inc. 2001) which 

provides detailed engineering design aspects of various drinking water treatment 

processes including granular activated carbon; 

• EPA’s ICR Treatment Study Database contains the results of 63 pilot studies of GAC 

plants. It can be found on the web at: 

www.epa.gov/safewater/data/icrtreatmentstudies.html; 

• The second version of “Water Treatment Plant Model” (USEPA 2001i) developed by 

EPA in 2001 that assists utilities with implementing various treatment changes, while 

maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR; 

and 

• Various cost estimation models that can be used to estimate the cost of constructing 

and operating a new GAC facility (See Section 6.3.7). 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

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An advantage of MF/UF is that it can achieve 

high removal rates of bacteria, Giardia and 

Cryptosporidium. This allows a system to 

lower its disinfectant dose and possibly reduce 

its finished water DBP concentrations. 

4.2 Microfiltration/Ultrafiltration 

Microfiltration/Ultrafiltration (MF/UF) is a lowpressure membrane technology. The membranes remove 

particulate matter larger than the membrane pore size. MF 

membranes generally operate at slightly lower pressure and 

have larger pore sizes than UF membranes. In some cases, 

MF/UF membranes will be used together, with the MF 

membranes acting as a pre-filter for the UF membranes. 

MF/UF units are often supplied on skid mounted assemblies 

that can easily be installed and have high degrees of automation. 

4.2.1 Advantages of MF/UF 

 Advantages of MF/UF include: 

• Removes bacteria and 

protozoa 

• Can lower DBPs by allowing 

lower disinfectant doses

• Can remove particulate arsenic

Bacteria and Protozoa Removal

 Membrane processes remove all particles larger than the pore size of the membrane, 

provided the membrane integrity is not compromised. Bacteria, Cryptosporidium oocysts, and 

Giardia cysts can all be reliably removed by MF/UF. Although MF membranes do not generally 

remove viruses, some UF membranes can remove viruses. MF/UF units that are challenge-tested 

before installation and undergo membrane integrity tests qualify for additional Cryptosporidium

removal credit as determined based on testing results. See the LT2ESWTR Toolbox Guidance 

Manual (USEPA N.d.e) for more information. Systems should also consult with their state to 

determine applicable credits and requirements. 

 If surface water systems use MF/UF instead of chemical disinfection to get 

inactivation/removal credit, they must add a disinfectant such as chlorine or chloramines to 

maintain a disinfectant residual in the distribution system. 

DBP Reduction

 Because MF/UF can achieve high levels of microbial removal, systems installing MF/UF 

can lower their disinfectant dose and still achieve the same level of microbial protection. The 

lowered disinfectant dose may result in lower DBPs and aid in meeting Stage 2 DBPR 

requirements. 
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If TOC is high after filtration, it can be lowered 

through other pretreatment techniques, including: 

• Pre-sedimentation 

• Enhanced coagulation 

• GAC filtration (less often) 

Arsenic Removal 

 MF/UF membranes do not have a small enough molecular cut-off weight to remove 

dissolved or colloidal arsenic. They can, however, remove particulate arsenic. The removal will 

depend on the size distribution of particles the arsenic is bound to and the pore size of the 

membrane. A coagulation step prior to the membranes will help to improve arsenic removal. 

Electrostatic repulsion can also help increase arsenic removal in MF/UF systems. The increase 

in removal will depend on the charge of the membrane, the oxidation state of the arsenic, and the 

pH of the water. Removal rates have been shown to vary between 5 and 70 percent (Amy, et al. 

2000). 

 

4.2.2 Potential Operational and Simultaneous Compliance Issues Associated 

with MF/UF 

 Potential issues associated with MF/UF use include: 

• Can be fouled by organics and minerals 

• Increased loss of process water

• Additional training required

 This section provides brief descriptions of these issues and suggestions for minimizing 

their impacts. 

Membrane Fouling

 Membranes can be fouled by organic matter, iron, manganese, and carbonate deposits. 

Sources of these fouling compounds include source water and treatment chemicals. Ground 

water systems that do not treat their water before it passes through the MF/UF unit may have 

particular problems with iron, manganese, and other minerals. This is especially true if the 

ground water is anoxic and is exposed to the atmosphere during pumping or an aeration process, 

resulting in dissolved minerals settling out. 

 Recommendations for Addressing this Issue

 Systems with high TOC can 

reduce fouling by placing the MF/UF 

after existing sedimentation and/or 

filtration processes. If TOC is high 

even after filtration, TOC can be 

lowered by adding other pretreatment 

techniques. Pretreatment to lower 

TOC levels includes: presedimentation, enhanced coagulation, 

and, less often, GAC filtration. TOC removal can often be accomplished by good coagulation 

before the membranes. If iron-based coagulants are used, jar testing should be carried out to 
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ensure optimal dosing and settling, because iron-based coagulants can foul some membranes. 

GAC filtration removes much of the organic matter, although not all organic compounds are 

adsorbed easily. A cartridge filter may need to be installed before the MF/UF unit, however, to 

prevent carbon fines from entering the membrane unit. 

 Systems that aerate their ground water to oxidize iron, manganese or other compounds 

should remove any precipitated minerals before the water reaches the MF/UF unit to prevent 

fouling. The manufacturer of the MF/UF unit and other utilities with experience using the same 

units should be consulted before a system makes any changes to the chemistry of the treated 

water, since many treatment chemicals can also foul membranes. 

Regardless of the pretreatment involved and the quality of the water, membranes will 

eventually foul and will need to be cleaned. Cleaning the membranes will improve performance 

and prolong membrane life. The appropriate length between cleanings can be determined by 

monitoring the long-term decrease in productivity and backwash efficiency. 

Loss of Process Water

 Membrane processes produce reject streams as well as backwash water. Therefore, the 

amount of wastewater that has to be handled can be higher than that produced during 

conventional filtration. Although improvements have been made in efficiency, some water 

systems lose as much as 15 percent of the process water as a waste stream. Other membrane 

projects have been bid with approximately 92 percent recovery in summer and 90 percent 

recovery in winter (Sarah Clark, personal communication). In a recent survey of MF/UF 

systems, however, the median value for feed water recovery was 95 percent (Adham et al. 2005). 

 Recommendations for Addressing this Issue

 To handle the higher quantities of process water produced by MF/UF units, systems may 

need to increase the capacity of their wastewater storage and residuals processing facilities. This 

is especially true of systems that recycle their reject water. 

 To minimize the lost water, systems may also be able to recycle some of the reject stream 

if the membranes are added onto a conventional treatment train. In this case, the recycle must be 

sent to the head of the plant according to the Filter Backwash Recycling Rule (FBRR), unless the 

State approves an alternate location. The effect of additional particle loading should be taken 

into account when determining coagulant dosing and filter loading rates. 

Additional Training Required

MF/UF membranes are significantly different to operate than other water treatment units. 

The control parameters are different; the State will determine the parameters that the system 

must monitor to demonstrate regulatory compliance. 
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Recommendations for Addressing this Issue

Systems should consult with their state to determine what parameters will need to be 

monitored for approval and regulatory compliance. Systems should also work with the state and 

the vendor to provide adequate training for operators. 

4.2.3 Recommendations for Gathering More Information 

See Additional References

 Readers can turn to chapter 7 for further references on this topic. Section 7.1.1 contains 

general references on water treatment, and section 7.1.10 contains references on membranes, 

including MF/UF. 

Consider Additional Monitoring 

 The following are some suggestions for additional monitoring that may benefit water 

systems implementing MF/UF. Note that the purpose of these monitoring suggestions is 

specifically to address and prevent potential simultaneous compliance issues. Water system 

managers should discuss process control monitoring with the MF/UF manufacturer and other 

experienced utilities. 

9 Periodic monitoring of iron, manganese, and other minerals in the water entering the 

MF/UF unit to detect an increase in minerals that may need to be addressed by pretreatment; 

9 Particle counting to indirectly monitor membrane integrity and determine if a direct 

integrity test should be conducted; 

9 Total organic carbon (TOC) in the membrane unit’s influent and effluent to track 

removal performance; 

9 Heterotrophic plate counts (HPC) in the membrane unit’s effluent if membrane 

integrity is lost; and 

9 Membrane autopsies on any failed membranes to determine the cause of failure and 

determine possible corrective actions. 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their treatment operations. Examples of tools that can be 

used when MF/UF membranes are used for LT2ESWTR and Stage 2 DBPR compliance include: 

• The “Membrane Filtration Guidance Manual” (USEPA 2005b) provides general 

recommendations for membrane pilot testing; 
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• The AwwaRF report “Integrated Membrane Systems” (Schippers et al. 2004) that 

provides guidance on the selection, design, and operating an integrated membrane 

system that can function as a synergistic system for removing microbiological 

contaminants and DBP precursors; 

• The AwwaRF report “Integrating Membrane Treatment in Large Water Utilities” 

(Brown and Hugaboom 2004) that provides guidance to issues related to the 

integration of low pressure membranes into larger water treatment facilities, including 

membrane layout, piping, cost comparison, and operations and maintenance; 

• EPA’s Environmental Technology Verification Program collects performance data on 

many environmental technologies, including MF/UF. Reports for each technology 

can be found on the website at: http://www.epa.gov/etv/verifications/verificationindex.html; 

• The second version of “Water Treatment Plant Model” (USEPA 2001i) developed by 

EPA in 2001 that assists utilities with implementing various treatment changes while 

maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR; 

and 

• Various cost estimation models, such as WTCost©, 2003, that can be used to estimate 

the cost of implementing a new membrane facility (see Section 6.3.7). 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

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Nanofiltration’s main advantage is that it 

can remove virtually all particulate matter 

as well as larger dissolved compounds, 

including some dissolved organic matter. 

4.3 Nanofiltration 

 Nanofiltration is a membrane process that 

physically removes contaminants from water that are larger 

than the pore size of the membranes. Nanofiltration uses 

pore sizes and operating pressures that fall between those 

of UF and reverse osmosis. 

 Nanofiltration’s main advantage over MF/UF is that 

it can remove virtually all particulate matter as well as 

larger dissolved compounds, including dissolved organic 

matter. In addition to meeting all removal requirements for pathogens, it leads to lower DBPs by 

removing DBP precursors. Its main disadvantages are that it can be fouled by organics or 

precipitated minerals, it can increase corrosiveness of the water, it has a large reject stream, and 

it requires additional training. 

4.3.1 Advantages of Nanofiltration 

 Some advantages of nanofiltration include: 

• Significant removal of bacteria, 

protozoa, and viruses 

• Can remove organics that act as

DBP precursors

• Removes arsenic

Significant Removal of Bacteria, Protozoa, and Viruses

 Nanofiltration has small pore sizes that exclude essentially all particulate matter, as long 

as the membrane is intact. Therefore, nanofiltration units that are capable of being integrity 

tested may receive credit for Cryptosporidium removal under LT2ESWTR. 

Removes DBP Precursors

 Nanofiltration can remove dissolved organic compounds that serve as DBP precursors. 

When little or no bromide ion was present in the source water, nanofiltration membranes with 

molecular weight cutoffs (MWCOs) of 400 to 800 daltons were shown to effectively control 

DBP formation (Laine et al. 1993). Nanofiltration with the same pore size produced higher 

bromoform concentrations when bromide was present, although total THMs decreased. 

Membranes with smaller pore sizes controlled bromoform formation better but required 

pretreatment to avoid membrane fouling. 
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DBP formation may be lowered even further if the state allows the system to reduce its 

disinfectant dose and the amount of primary disinfection because of the high microbial removal 

rate of the nanofiltration units. When this is the case, nanofiltration can accomplish both high 

pathogen removal and low DBP formation. 

Removes Arsenic 

 Nanofiltration membranes can remove both dissolved and particulate arsenic through size 

exclusion and electrostatic repulsion. Removal rates will depend on the surface charge of the 

membrane, speciation of the arsenic, dissolved organic concentration, and pH. Oxidized arsenic 

(V) is removed much more efficiently than reduced arsenic (III). Single element tests have 

found rejection rates for arsenic (V) between 80 and 95 percent (Amy et al. 2000). Other tests on 

pilot scale membranes have found the removal can decrease to between 65 and 75 percent over 

time (Malcolm Pirnie 1992, Chang et al. 1994). 

4.3.2 Potential Operational and Simultaneous Compliance Issues Associated 

with Nanofiltration 

 Potential issues associated with nanofiltration include: 

• Can be fouled by organics and precipitated minerals 

• Can increase corrosiveness of water 

• Issues with reject stream

• Additional training required

 This section briefly describes these issues and provides suggestions for addressing their 

impacts. 

Membrane Fouling

 Organics and precipitating minerals can foul nanofiltration membranes and cause them to 

operate inefficiently, shortening their useful life. Fouling also increases operating pressures and 

causes more frequent backwashing, which raises operating expenses. Fouling agents can come 

from the source water or be introduced as part of the treatment process. Ground waters that are 

not filtered before the water passes through the membranes may have more difficulties with 

fouling due to high mineral concentrations. 

 Recommendations for Addressing this Issue

 If nanofiltration membranes are being used in conjunction with a conventional filtration 

plant, the membranes should be placed after the filters to allow for the maximum removal of 

fouling compounds before water passes through the membranes. Treatment processes that can 

change the chemistry of the water should be located downstream of the nanofiltration unit if 
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If coagulants or disinfectants are added prior 

to membranes, the system should consult the 

membrane manufacturer and other 

experienced utilities to determine if the 

chemicals will cause fouling or otherwise 

damage the membranes. 

possible. These include pH adjustment and disinfectants. Systems should bear in mind, 

however, that nanofiltration generally works better at acid pH. 

 If the treatment train in place is not sufficient to reduce fouling compounds, some sort of 

pretreatment will be required. The simplest pretreatment is often adding a cartridge filter before 

the membranes. If the water being treated is anoxic ground water, aeration may be considered to 

oxidize and precipitate any minerals before the cartridge filter. Other options for pretreatment 

include enhanced coagulation and pre-sedimentation. If enhanced coagulation is used, jar testing 

should be conducted to optimize the dose to ensure that unflocculated coagulant does not enter 

the membrane unit. 

 Regardless of the pretreatment involved and the quality of the water, membranes will 

eventually foul. Cleaning the 

membranes is necessary for 

improving performance and 

prolonging membrane life. The 

appropriate length between 

cleanings can be determined by 

monitoring the long-term decrease 

in productivity and back wash 

efficiency. 

Increase Corrosiveness

 Nanofiltration can soften water by removing minerals such as calcium and magnesium. It 

can also result in a lowering of the pH of the water. The less alkaline, lower pH water will be 

more corrosive to distribution system piping and other process equipment, while not providing a 

passivating layer as harder water can. The lower pH can also shift the carbonate equilibrium to 

produce carbon dioxide. In groundwaters, hydrogen sulfide can also pass through the 

membranes. All these factors combine to increase the corrosiveness of the water. 

Increased corrosiveness can cause problems with Lead and Copper Rule (LCR) 

compliance. Depending on the magnitude of the pH drop, it may also affect the disinfection 

efficiency of the secondary disinfectant as well. See Section 3.4 for more discussion of 

disadvantages associated with lowering water pH. It is also possible that the removal or minerals 

such as calcium can be so significant as to cause the water to taste significantly different to 

customers, possibly generating customer complaints. 

Recommendations for Addressing this Issue

 The simplest way to avoid problems associated with a low pH is to adjust the pH after the 

membranes. The fittings for the membrane unit, as well as any equipment between the 

nanofiltration unit and the point where the pH is readjusted, should be made of materials that can 

resist the lower pH of the water. Water systems should also adjust the alkalinity after 

nanofiltration to prevent changes in pH in the distribution system that can enhance corrosion. 

Passive treatment technologies, such as neutralizing filters or limestone contactors, are one way 

to achieve a good pH and carbonate balance in membrane-treated waters. 
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Aeration may help to remove any sulfide or carbon dioxide accumulated as well as raise 

oxygen levels to oxidize the sulfide to sulfate. Adding a disinfectant after the membranes can 

also aid in oxidizing sulfide. 

 Another approach some systems have taken is to only pass part of the influent stream 

through the NF unit and blend that NF product with water that has not received NF treatment. 

However, this negates the microbial treatment credit of NF and would require an alternative 

microbial treatment on the stream not treated by NF. 

Issues with Reject Stream

 Membrane processes produce a reject stream as well as backwash water. Therefore, the 

amount of wastewater that has to be handled can be significantly higher than that produced 

during conventional filtration. Although improvements have been made in efficiency, losing 10 

to 20 percent of the process water as a waste stream is not unusual. The amount of process water 

lost can be reduced by a second membrane unit in series with the first unit. 

Due to the small pore size associated with nanofiltration, other feed water constituents 

will also be removed. As a result, divalent salts, some metals, and some soluble organic carbon 

may be concentrated in the waste stream. This may increase the cost associated with disposing 

of the waste stream compared to disposal costs associated with MF, UF, and conventional 

treatment processes. If regulatory limits or plant locations prohibit sending the waste stream to a 

receiving body or wastewater treatment plant, costs for waste handling and disposal can be 

substantial. 

Recommendations for Addressing this Issue

To handle the higher quantities of waste water produced by nanofiltration units without 

causing upset to the system, utilities may need to increase the capacity of their wastewater 

storage and residuals processing facilities. This is especially true of systems that recycle their 

reject water. If water is recycled, the Filter Backwash Recycling Rule (FBRR) requires that it be 

recycled to the head of the plant unless the State approves an alternate location. 

Water systems using nanofiltration will most likely need to increase the amount of water 

they withdraw from their source to account for their process water losses. This could be an issue 

in arid regions where water is scarce and water restrictions are in place. 

Disposal of the reject stream to the ocean may be a good option since the salinity of brine 

is typically not an issue. Otherwise systems will need to discuss the possibility of disposing of 

the brine to the sanitary sewer which may have limits on brine or on certain metals and may 

involve additional charges. 

Additional Training Required

NF membranes are significantly different to operate than other water treatment units. 

The control parameters are different; the State will determine the parameters that the system 

must monitor to demonstrate regulatory compliance. 
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Recommendations for Addressing this Issue

Systems should consult with their state to determine what parameters will need to be 

monitored for approval and regulatory compliance. Systems should also work with the state and 

the vendor to provide adequate training for operators. 

4.3.3 Recommendations for Gathering More Information 

Read the Case Study 

For more information on simultaneous compliance issues associated with nanofiltration 

and how to address them, see Case Study #8 - Nanofiltration Membrane Technology for TOC 

Removal starting on page B-43 of Appendix B. This case study describes the challenges faced 

by one PWS switching to nanofiltration in response to growing demands for water and the 

implementation of new drinking water standards. Specifically, the NF plant would facilitate the 

removal of hardness, color, TOC, and its related chlorinated DBPs. The greatest operational 

issue involved numerous leaks in the acid feed system, and sagging in the micron cartridge filter 

housings and the string-wound filter. 

See Additional References

 Readers can turn to chapter 7 for further references on this topic. Section 7.1.1 contains 

general references on water treatment, and section 7.1.10 contains references on membranes, 

including NF. 

Consider Additional Monitoring

 The following are some suggestions for additional monitoring that may benefit water 

systems implementing nanofiltration. Note that the purpose of these monitoring suggestions is 

specifically to address and prevent potential simultaneous compliance issues. Water system 

managers should discuss process control monitoring with the manufacturer of their nanofiltration 

units or their engineer. 

T The pH of water leaving the nanofiltration unit should be monitored to ensure that 1) 

CT is being calculated accurately; and 2) chemical dosages for corrosion control are 

correct; 

T Hardness and alkalinity of water leaving the nanofiltration unit should be measured to 

ensure that chemical dosages for corrosion control are correct; 

T TOC in the NF influent and effluent should be monitored to measure removal 

effectiveness; 

T Particle counting should be conducted to indirectly monitor membrane integrity and 

determine if a direct integrity test; 

T HPC should be measured in the NF effluent to identify breakthrough; 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

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For the Long Term 2 and Stage 2 DBP Rules 

T Membrane autopsies should be performed on any failed membranes to determine the 

cause of failure and determine possible corrective actions; and 

T Taste and odor quality should be measured to ensure customer acceptance. 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their treatment operations. Examples of tools that can be 

used when nanofiltration is used for Stage 2 DBPR compliance include: 

• The AwwaRF report “Integrated Membrane Systems” (Schippers et al. 2004) that 

provides guidance on the selection, design, and operation of an integrated membrane 

system that can function as a synergistic system for removing microbiological 

contaminants and DBP precursors; 

• The AwwaRF report “Integrating Membrane Treatment in Large Water Utilities” 

(Brown and Hugaboom 2004) that provides guidance on issues related to the 

integration of low pressure membranes into larger water treatment facilities, including 

membrane layout, piping, cost comparison, and operations and maintenance; 

• The AwwaRF report “NOM Rejection by, and Fouling of, NF and UF Membranes” 

(Amy et al. 2001) that provides information on the selection of appropriate 

nanofiltration membranes to achieve high NOM rejection, and also presents 

information on how water quality (such as the presence of calcium and pH) and 

operational condition might affect NOM rejection by NF membranes; 

• EPA’s Environmental Technology Verification Program collects performance data on 

many environmental technologies, including nanofiltration. Reports for each 

technology can be found on the website at: 

http://www.epa.gov/etv/verifications/verification-index.html; 

• EPA’s ICR Treatment Study Database contains the results of 36 pilot studies of 

nanofiltration plants. It can be found on the web at: 

www.epa.gov/safewater/data/icrtreatmentstudies.html; 

• The second version of “Water Treatment Plant Model” (USEPA 2001i) developed by 

EPA in 2001 that assists utilities to implement various treatment changes while 

maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR; 

and 

• Various cost estimation models, such as WTCost©, 2003, that can be used to estimate 

the cost of implementing a new membrane facility (see Section 6.3.7). 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

Simultaneous Compliance Guidance Manual 4-19 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

The LT2ESWTR Toolbox Guidance 

Manual will provide more information 

on the advantages and disadvantages 

of different Cryptosporidium oocyst 

removal technologies. 

4.4 Other Microbial Removal Technologies 

 Other microbial removal technologies can be used 

to meet LT2ESWTR requirements. All of the technologies 

listed below use some type of filtration media to remove 

Cryptosporidium oocysts and other microbes from drinking 

water. The LT2ESWTR specifies minimum design and 

implementation criteria for receiving various levels of 

Cryptosporidium treatment credit. The LT2ESWTR 

Microbial Toolbox Guidance Manual (USEPA N.d.e) will 

provide additional guidance for each technology. The state should also be consulted on the 

requirements for obtaining pathogen removal credit for these technologies. Although these 

technologies are not expected to present significant compliance problems with other drinking 

water regulations if implemented properly, there are operational issues that utilities should 

consider if they use these options. These technologies are: 

Bank Filtration

Bank filtration uses vertical or 

horizontal wells drilled near a 

riverbank. The riverbed and 

material between the well and the 

riverbank act as the filtration 

media. It is generally used as 

pretreatment for an existing 

treatment plant. 

Improved Filter Performance

Improved filter performance results from optimizing existing filtration to achieve 

consistently low filter effluent turbidity. In order to meet the lower finished water 

turbidity requirements, systems need a high level of process control from the source 

water intake to the filters. The Guidance Manual for Compliance with the IESWTR: 

Turbidity Provisions (USEPA 1999d) discusses many design and operational aspects 

water systems should consider for achieving low effluent turbidity. 

 Bag Filtration 

Bag filtration is a pressure driven filtration process using a fabric filter media. Flow is 

from inside the vessel to outside the vessel. 

 Cartridge Filtration

Cartridge filters are pressure driven filtration devices that have rigid or semi-rigid filter 

media housed in pressure vessels. Water flows from outside the cartridge filter's vessel to 

the inside. 

 Second Stage Filtration

Second stage filtration involves placing a second set of granular media filters in series 

with an existing set of filters. The media can be rapid sand filters, slow sand filters, or 

GAC filters. 
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For the Long Term 2 and Stage 2 DBP Rules 

Slow Sand Filtration

Slow sand filtration uses sand with a biologically active top layer as a filtration media 

and gravity as the driver at relatively low loading rates. 

 Diatomaceous Earth Filtration

Diatomaceous earth (DE) filtration, often referred to as “pre-coat” filtration, uses a layer 

of diatomaceous earth placed on a permeable cover or porous filter septum to filter water. 

DE filters are operated as either pressure filters or vacuum filters. 

This section briefly describes issues associated with the use of these technologies, 

provides suggestions for addressing those issues, and recommends additional monitoring that can 

be conducted. 

4.4.1 Advantages 

 There are several advantages to these microbial removal technologies. The following 

paragraphs list these advantages and briefly discuss which of these technologies provide each 

advantage. 

• Ease of use (bag filtration, cartridge filtration, bank filtration); 

• Removal of Cryptosporidium and other pathogens (all technologies listed); and 

• Removal of other contaminants/ DBP precursors (bank filtration, second stage 

filtration, slow sand filtration). 

 Most operators are familiar with filtration. Second stage filtration, DE, and slow sand 

filtration can all be easily implemented by any system familiar with conventional filtration. 

Cartridge and bag filters are even easier to use as the only routine maintenance required is 

replacing the cartridge or bag when a pre-set trigger is reached, either a pressure drop or a given 

time. 

 All of these technologies will remove matter that is larger than the filter's effective pore 

size. Therefore, in addition to Giardia cysts and Cryptosporidium oocysts, they will remove 

some other microbial pathogens as well. 

 Some of these technologies can also be effective in removing DBP precursors and other 

organic chemicals. Slow sand filtration can remove some DBP precursors. Second stage 

filtration can offer additional DBP precursor removal, especially when GAC is used as the 

second filter media. Bank filtration often provides additional DBP removal through biological 

activity in the riverbank (Weiss et al. 2003). 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

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For the Long Term 2 and Stage 2 DBP Rules 

4.4.2 Potential Operational and Simultaneous Compliance Issues 

 The disadvantages of these microbial removal technologies include: 

• Hydraulic problems or scouring (all technologies listed); 

• Clogging (cartridge filters, bank filtration); 

• Increased residuals/ backwash (second stage filtration, increased filter 

performance); 

• Iron/manganese problems (bank filtration); and 

• Filter fouling (bag filters, cartridge filters).

 With careful planning, many of the disadvantages of these technologies can be overcome. 

The following paragraphs briefly describe steps that can be taken to mitigate these 

disadvantages. 

Hydraulic Problems or Scouring

 All of these technologies can add significant hydraulic head to a plant’s hydraulic profile. 

Changes in head, especially when filters are restarted, can disturb the filter and cause poor 

performance. 

Bank filtration can experience riverbank scouring during periods of high flow. The 

riverbank scour can remove much of the finer grained sediment responsible for a portion of the 

removal associated with this filtration method. 

Large changes in flow to bag filters or intermittent operation can cause stress on the 

seams of the bag filter and lead to premature failure. 

 Recommendations for Addressing this Issue

 Hydraulic loss due to additional filtration can often be overcome by conducting a 

hydraulic profile of the plant. Pumps can be installed to add additional head. The pumps should 

be installed and operated in such a way as to not cause hydraulic disturbances to surrounding 

processes, such as flocculation. Installing additional storage upstream of filtration is also a way 

to smooth out hydraulic disturbances before they upset the filtration. Filtering to waste can 

eliminate some of the problems associated with filter start-up. 

Clogging

 Bank filtration can also be subject to clogging by biomass growth in the pores or settling 

of finer grained material in the pores. Although this may increase removal efficiency of 

contaminants, it will increase pumping costs and drop yield. If too much coagulant is used 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

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For the Long Term 2 and Stage 2 DBP Rules 

before cartridge filters, they can also clog, necessitating more frequent replacement and higher 

costs. 

Recommendations for Addressing this Issue

 Some types of clogging in bank filtration can be avoided by proper siting of the wells. 

Changes in chemistry in the aquifer that could precipitate minerals and areas of high 

sedimentation should be avoided. Otherwise, some clogging is inevitable and even necessary. 

Systems may have to account for this by designing for higher pumping rates than necessary or 

installing multiple wells. 

Increased Residuals or Backwashing

 Many of these technologies can create disposal problems. Cartridge and bag filters have 

to be disposed of periodically. Second stage filtration will generate additional backwash water 

and residuals that will need to be disposed. Practices to improve turbidity to increase filter 

performance can also lead to increased residuals and backwash water. Systems considering 

replacing their filter bed media as part of an effort to improve filter performance should consider 

whether there will be challenges associated with the disposal of old media that may contain high 

concentrations of metals or other contaminants. 

 If significant amounts of additional backwash and residuals are generated, a system may 

need to change its residuals disposal procedures. This may include treating backwash water 

through the addition of coagulant, or adding new sludge dewatering technologies or other 

residuals handling equipment. 

Recommendations for Addressing this Issue

To handle the higher quantities of process water produced by backwashing filter units, 

systems may need to increase the capacity of their wastewater storage and residuals processing 

facilities. This is especially true of systems that recycle their reject water. Manufacturers can 

also be consulted for disposal recommendations for bag and cartridge membranes. 

Iron and Manganese Problems

 Bank filtration can result in elevated levels of iron and manganese if the portion of the 

aquifer the wells draw from is anoxic. This will allow reduced manganese and iron to dissolve 

and enter the water. 

 Recommendations for Addressing this Issue

 If bank filtration is carried out through an anoxic zone, aeration may need to be added to 

oxidize dissolved iron, manganese, and any other reduced chemical species that could cause 

operational or aesthetic problems. Adding a pre-oxidant such as permanganate, ozone, or 

chlorine can also oxidize iron and manganese. 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

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Filter Fouling

 Cartridge and bag filters can be fouled by biofilm if there is insufficient disinfectant 

residual present to control the growth. This can increase the pressure loss across the filter and 

shorten filter life. 

 Recommendations for Addressing this Issue

 Adding disinfectant before the filters can prevent biofilm growth from clogging bag and 

cartridge filters. Systems should evaluate the potential for DBP formation before taking this 

step. Systems should also confirm that the filter media is compatible with the disinfectant. 

4.4.3 Recommendations for Gathering More Information 

See Additional References

 Readers can turn to chapter 7 for additional references on this topic. Section 7.1.1 

includes general references on water treatment, including filtration, Section 7.1.8 includes 

references on enhanced coagulation and softening, and Section 7.1.11 includes references on 

riverbank filtration. 

Consider Additional Monitoring

 Monitoring is important for determining the performance of these technologies. It can 

provide a good indication of performance and help make operating determinations such as when 

to backwash or replace filters. 

9 Turbidity is used to determine filter performance as well as warn that a filter needs to 

be backwashed. Monitoring of individual and combined filter effluents is required 

for conventional filters. Even if the filter is installed as a second filter or in series 

with another treatment technology, turbidity monitoring should be conducted; 

9 Particle counters can also provide useful information, and can frequently determine 

breakthrough before turbidity measurements can; 

9 Flow measurements help to spot potential hydraulic upset and adjust loading rates 

appropriately; 

9 Pressure measurements are used to indicate how frequently a system needs to 

backwash or whether filter media needs to be replaced; and 

9 Streaming current detectors can be used to detect the charge on particles and optimize 

coagulant dose. 
4. Installing new Total Organic Carbon or Microbial Removal Technologies 

Simultaneous Compliance Guidance Manual 4-24 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Consider Other Tools

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their treatment operations. Examples of tools that can be 

used when implementing the other microbial removal technologies described in this section 

include: 

 The AwwaRF report “Evaluation of Riverbank Filtration as a Drinking Water 

Treatment Process” (Wang, Hubbs and Song 2002) that provides general information 

on the design and operation of a riverbank system that can be used for the removal of 

DBP precursors and microbial contaminants; 

 EPA’s Environmental Technology Verification Program collects performance data on 

many environmental technologies, including diatomaceous earth, cartridge, and bag 

filters. Reports for each technology can be found on the website at: 

http://www.epa.gov/etv/verifications/verification-index.html; 

• The second version of “Water Treatment Plant Model” (USEPA 2001i) developed by 

EPA in 2001 that assists utilities with implementing various treatment changes, while 

maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR; 

• Various cost estimation models that can be used to estimate the costs of designing, 

constructing, and operating one of the technologies described above (see Section 

6.3.7) ;and 

• The Partnership for Safe Water has many resources available for optimizing filter 

performance. More information can be obtained at their website at: 

http://www.awwa.org/science/partnership/. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
Simultaneous Compliance Guidance Manual 5-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ALTERNATIVE DISINFECTION 

STRATEGIES COVERED 

 

• Chloramine 

• Ozonation 

• Ultraviolet Light 

• Chlorine Dioxide 

• Primary and Residual 

Disinfectant Use 

As discussed in previous chapters, some water systems, after improving and optimizing 

current operations, will still need to install a new type of treatment to comply with the Stage 2 

DBPR and LT2ESWTR. Some systems may consider switching to an alternative disinfectant for 

either primary or residual disinfection (or both). This chapter describes potential simultaneous 

compliance issues associated with using any of the following alternative disinfectants: 

• Chloramines 

• Ozone 

• Ultraviolet light (UV) 

• Chlorine dioxide 

Suggestions are also provided for how systems can 

mitigate simultaneous compliance and operational 

issues that are identified. 

 In addition, Section 5.5 of this chapter 

discusses different possible combinations of primary 

and residual disinfectants, and simultaneous 

compliance issues that may arise as a result of using 

the disinfectants in combination. 

5.1 Chloramines 

 Chloramines are formed when free chlorine reacts with ammonia and may be present as 

monochloramine, dichloramine, and/or trichloramine. The chloramine compounds react more 

slowly than free chlorine and as a result, they form fewer DBPs and are more persistent in the 

distribution system. Some studies have shown that chloramine compounds can penetrate 

biofilms more effectively than free chlorine. Monochloramine is generally considered the 

preferred species for disinfection purposes because of its biocidal properties, relative stability, 

and infrequent taste and odor problems (Kirmeyer et al. 2004a). Because monochloramine is a 

weaker disinfectant than free chlorine, it is more frequently used as a residual disinfectant in the 

distribution system. If not properly controlled, the use of chloramines can lead to nitrification 

episodes in the distribution system and may cause taste and odor issues, loss of disinfectant 

residual, and other problems. 

5.1.1 Advantages of Chloramines 

 The use of chloramination to comply with the Stage 2 DBPR presents numerous benefits 

in terms of implementation and operation. Advantages include: 

• Lower DBP formation 

5 Alternative Disinfection Strategies 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• More persistent than free chlorine residuals 

• Biofilm control in the distribution system 

• May reduce occurrence of Legionella

Lower DBP Formation

 Compared to free chlorine, chloramines react more slowly with organic matter resulting 

in lower concentrations of total trihalomethane (TTHM) and haloacetic acid (five) (HAA5). 

Although detectable concentrations of mono- and dichloroacetic acids can be produced, these are 

generally significantly lower than corresponding concentrations produced by free chlorine. 

Replacing chlorine with chloramines as a secondary disinfectant typically reduces TTHM levels 

40 to 80 percent. Depending on the system’s water quality, the actual TTHM reduction can vary 

from 10 to 95 percent (Kirmeyer et al. 2004a). 

 If chlorine is added to the water before ammonia, the byproducts associated with the use 

of free chlorine can be formed, although additional formation will be significantly retarded once 

the ammonia has been added. Because free chlorine is a much more effective disinfectant for 

viruses, surface water systems generally add chlorine early enough in the treatment train so that 

CT requirements for viruses are achieved before the ammonia is added. 

More Persistent than Free Chlorine Residuals 

 Chloramines have a lower oxidation-reduction potential and a slower reaction time than 

free chlorine, so they are less likely to be consumed by reactions with organics and reduced 

metals. Therefore, they are longer lasting in the distribution system and are generally more 

persistent than a free chlorine residual. This characteristic helps to protect distribution system 

water quality, particularly in areas with long detention times. It also helps maintain compliance 

with the Surface Water Treatment Rule (SWTR)’s requirement to maintain a disinfectant 

residual. 

Biofilm Control in the Distribution System

 Studies have shown that chloramine compounds are better able to penetrate the biofilm 

layer and inactivate attached organisms because they are more limited than chlorine in the types 

of compounds with which they will react (USEPA 1992a; Jacangelo, Olivieri, and Kawata 1987). 

LeChevallier, Cawthorn, and Lee (1988a, 1988b) found that chloramines were more effective at 

inactivating biofilm organisms than free chlorine. LeChevallier, Lowry, and Lee (1990) also 

found that, in iron pipes, 3 to 4 mg/L doses of free chlorine did not control biofilm growth. 

Chloramines, however, did control biofilm growth at doses starting at 2 mg/L. Recent research 

suggests that the factors affecting biofilm growth and disinfection are complicated and may 

depend on many factors, thus varying between systems (Ollos, Huck, and Slawson 2003). 
5. Alternative Disinfection Strategies 

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For the Long Term 2 and Stage 2 DBP Rules 

May Reduce Occurrence of Legionella 

Use of monochloramine in water supplies may reduce the occurrence of Legionella 

bacteria and incidence of Legionnaires' disease. Flannery et al. (2006) conducted a 2-year study 

to evaluate whether converting from chlorine to monochloramine for water disinfection would 

decrease Legionella colonization of hot water systems. Water and biofilm samples from 53 

buildings were collected for Legionella culture during 6 intervals. Legionella colonized 60% of 

the hot water systems before monochloramine versus 4% after conversion. The effectiveness of 

chloramines for inactivating Legionella and biofilm bacteria may be related to its ability to 

penetrate the biofilm (Kirmeyer et al. 2004a). 

5.1.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Chloramines 

 Potential issues associated with the use of chloramines include: 

• Nitrification 

• Increased corrosion and metal release 

• Taste and odor issues 

• Weaker disinfectant 

• Blending issues - chloraminated and chlorinated waters 

• Safety concerns 

• Issues with ozonation and GAC filtration 

• Issues for dialysis patients, fish owners, and industrial customers 

 

Nitrification 

Biological nitrification is the oxidation of ammonia to nitrite and then eventually to 

nitrate by bacteria and other organisms. Nitrification adversely impacts the effectiveness of 

chloramines by increasing the chloramine demand, depleting chloramine residuals and thus 

allowing bacterial regrowth (Kirmeyer et al. 2004a). A loss of disinfectant residual in the 

distribution system can result in a violation of the SWTR, and may lead to increased 

vulnerability to contamination. Other adverse effects of nitrification on distribution system 

water quality include: 

• Decrease in dissolved oxygen 

• Increase in nitrite and nitrate levels 

• Decrease in pH 
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Simultaneous Compliance Guidance Manual 5-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• Decrease in alkalinity 

• Decrease in ORP 

 Systems that chloraminate can experience nitrification episodes under certain system 

conditions including but not limited to: 

• Excess free ammonia 

• Low chloramine residual 

• Long water detention times in the distribution system, such as in storage tanks, areas 

with low demand, and dead ends 

• Water temperatures of 25oC - 30oC (Wolfe et al. 1988; Wolfe et al. 1990) 

• A pH in the range 7.0 to 8.0 is optimum for nitrifying bacteria (Kirmeyer et al. 2004a) 

As part of the TCR review process, EPA has published several white papers on issues in 

the distribution system such as nitrification and biofilm growth. These papers can be found at: 

http://www.epa.gov/safewater/disinfection/tcr/pdfs/whitepaper_tcr_nitrification.pdf 

http://www.epa.gov/safewater/disinfection/tcr/pdfs/whitepaper_tcr_biofilms.pdf

The AwwaRF report, Optimizing Chloramine Treatment, Second Edition (Kirmeyer et al. 

2004a) describes the biochemistry of nitrification, its impacts on distribution system water 

quality, and treatment and control strategies. It also describes relevant utility experiences based 

on a project survey and case studies.

 

Recommendations for Addressing this Issue

 Nitrification may be controlled by taking certain preventative measures and by 

implementing corrective actions when monitoring indicates the onset of a nitrification event. 

 

Preventive measure for controlling nitrification were identified in a recent AwwaRF 

survey by 50 water systems that use chloramination (Kirmeyer et al. 2004a). The most important 

preventive measures include: 

• Distribution system flushing 

• Increasing chloramine residual 

• Modifying chlorine-to-ammonia nitrogen ratio 

Additional preventive methods used by survey respondents include maintaining low 

concentrations of residual ammonia at the treatment plant effluent, using a source water with the 

lowest temperature whenever possible, and modifying distribution system hydraulics to 

minimize water age (e.g. improve water circulation, eliminate dead-ends, open valves, increase 

turnover rate in storage facilities). 

Some systems that chloraminate periodically switch to free chlorine disinfection for a few 

weeks or months to reduce the population of nitrifying bacteria in the distribution system. 

However, a recent AwwaRF study (Vikesland et al. 2006) found that “...a periodic switch from a 

chloramine residual to a free chlorine residual may not be sufficient for long-term control of 

nitrification within a chloraminated distribution system. Given the higher levels of DBPs 
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For the Long Term 2 and Stage 2 DBP Rules 

observed following a switch to free chlorine, utilities may be better served by careful 

maintenance of their ammonia feed such that nitrification episodes are minimized.” 

 

 Monitoring programs specific to nitrification should be developed and implemented. 

The AwwaRF report, Guidance Manual for Monitoring Distribution System Water Quality

(Kirmeyer et al. 2002) provides detailed monitoring protocols for nitrification including 

recommended sampling locations, monitoring parameters, and sampling frequencies. 

Monitoring protocols are provided for proactive monitoring to establish a baseline database and 

investigative monitoring in response to a suspected nitrification event. The recommended 

monitoring parameters for the baseline monitoring program include total chlorine, 

monochloramine, free ammonia, total ammonia, nitrite, nitrate, HPCs, and water residence time. 

The investigative monitoring program includes these parameters plus temperature and dissolved 

oxygen. Monitoring locations may include raw water, point-of-entry to the distribution system, 

reservoir inlets/outlets, coliform monitoring stations, selected dead-end sites, and low flow sites, 

depending on the monitoring objective (baseline vs. investigative) and the monitoring parameter. 

 

 In combination with monitoring protocols, Kirmeyer et al. (2002) recommend 

establishing system-specific action levels that will trigger corrective action. For example, 

Kirmeyer et al. (2004) summarized the nitrification action plan for Irvine Ranch Water District 

that included three action levels. In Level 1, a nitrite level of 25 to 49 μg/L triggered a review of 

system operations and additional sampling. In Level 2, an HPC count of 200-500 cfu/mL, a total 

chlorine residual <0.4 mg/L or a nitrite level of 50 to 74 μg/L triggered additional sampling, 

additional analyses for nitrate and free ammonia, and reservoir cycling. Level 3 was triggered by 

an HPC count >500 cfu/mL, a total chlorine residual <0.2 mg/L or a nitrite level >75 μg/L, and 

involved chlorinating and cycling the reservoir, and continued sampling. 

Corrective actions that may be implemented when a nitrification event is occurring were 

also identified in the AwwaRF survey (Kirmeyer et al. 2004a). Pipe flushing was found to be the 

most effective corrective action. Additional corrective methods identified by survey respondents 

include: 

• Blending low-TOC water which possesses a higher and more stable chloramine 

residual with nitrifying water (effective in small tanks); 

• Combining pipe flushing and monitoring until adequate water quality is reestablished; and 

• Modifying distribution system hydraulics (eliminate dead-ends). 

 

Increased Corrosion and Metal Release 

 Nitrification resulting from the use of chloramines can lower the alkalinity and the pH of 

the water in the distribution system. This can prove detrimental for lead and copper control. 

Corrosion products and tubercles also interfere with the disinfection of coliform and 

heterotrophic bacteria, which can lead to increased microbially-induced corrosion. 

Changing from free chlorine to chloramines in the distribution system could potentially 

impact the stability of pipe scales, particularly redox-sensitive minerals such as lead, copper, 
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For the Long Term 2 and Stage 2 DBP Rules 

manganese, and iron. Changes in the solubility and/or permeability of scale materials could 

possibly result in their desorption and release into the bulk water. 

For example, systems with lead service lines could possibly see changes in lead levels as 

a result of a switch to chloramines. Pipe scale analysis has shown that, in some distribution 

systems where free chlorine is used, the corrosion by-products on lead service lines contain 

significant amounts of lead (IV) oxide compounds (Schock 2001; Schock, Wagner and Oliphant 

1996; AwwaRF and DVGW-Technologiezentrum Wasser 1996; Lytle and Schock 2005; Schock 

and Giani 2004; Schock et al. 2005). Lead (IV) oxide scales are highly oxidized and considered 

to be relatively insoluble in water. If a water system switches from a strong oxidant (chlorine) to 

a weaker oxidant (chloramines), the ORP necessary to maintain lead (IV) stability may no longer 

remain. As a result, lead (IV) compounds may be reduced to more soluble lead (II) solids and a 

subsequent increase in lead concentrations in water may be observed. 

The switch to chloramines following historically high levels of chlorine residual (and 

relatively high oxidation reduction potential as described above), along with the absence of a 

reevaluation and modification to corrosion control treatment, is the suspected cause of the LCR 

action level exceedances experienced by Washington, D.C.’s Water and Sewer Authority 

(DCWASA) beginning in 2002. DCWASA made the conversion from free chorine to 

chloramines in late 2000 with the goal of reducing TTHM and HAA5 levels in the distribution 

system. After the conversion to chloramines, elevated lead levels were found in compliance 

samples from homes with lead service lines. To address the lead corrosion problem, the city 

accelerated its lead service line replacement program and began orthophosphate treatment in 

August 2004. The treatment program was successful in reducing elevated lead levels. LCR 

monitoring results for 2005 and 2006 showed that the calculated 90th percentile values were at or 

below the lead action level. 

 There have been some indications that chloramines can corrode brass. Edwards et al. 

(2004) found accelerated brass corrosion in 7 of 8 brass samples tested, and a slight increase with 

chloramines as opposed to free chlorine. Reiber et al. (1993) did not observe any additional 

corrosion of brass in the presence of chloramines above what was seen with free chlorine. 

Ammonia is known to be corrosive to brass and it is possible that excess ammonia and nitrate, 

caused by nitrification, can accelerate brass corrosion. Uchida and Okuwaki (1999) found lead 

corrosion (lead is a component of brass) to be higher in the presence of ammonia and nitrate 

together. Maas et al. (2005) found that fluoridation of water in combination with chloramines 

can cause accelerated brass corrosion. 

 Chloramines have also been found to be corrosive to some elastomer materials. 

Prolonged exposure of elastomer materials, such as those used in gaskets and valve seals, can 

lead to cracking and loss of integrity (Reiber 1991). Although free chlorine can also cause 

corrosion of these materials, chloramines show significantly higher corrosion rates. A recent 

study of chloramine effects on elastomer materials (Bonds 2004) showed that pipe gaskets made 

with vulcanized elastomers do not corrode significantly due to their low surface area to volume 

ratio, even though it was shown that chloramine causes significant corrosion of vulcanized 

elastomers. Components with higher surface area to volume ratios such as flappers or valve 

seats may experience more significant deterioration. Both Reiber (1991) and Bonds (2004) 

found that fluorocarbon elastomers showed the least corrosion of the elastomers tested. 
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For the Long Term 2 and Stage 2 DBP Rules 

Therefore, using fluorocarbon elastomers in components that will receive high exposure to 

chloramines will help prevent failure. 

 Recommendations for Addressing this Issue

 Reiber (1993) noted that materials deterioration by monochloramine is less noticeable 

than by dichloramine. Therefore, maintaining optimal conditions for monochloramine formation 

may help prevent materials deterioration as well as help control nitrification. Optimal conditions 

for monochloramine include pH of 8.3, a temperature of 25oC, and a 4:1 to 5:1 weight ratio of 

chlorine to ammonia (Kirmeyer et al. 2004a). 

Systems can minimize lead corrosion by: 

• Optimizing the pH, alkalinity, and DIC of the water; and 

• Adding a corrosion inhibitor (i.e., a substance that is phosphate- or silica-based) to the 

finished water to form a protective coating on the pipes. 

Systems concerned with brass corrosion can take steps to limit free ammonia and 

nitrification as listed in the section on nitrification. The steps listed above will also help mitigate 

brass corrosion. 

To prevent elastomer corrosion, components such as gaskets and flappers should be made 

of elastomers such as fluorocarbons that have good resistance to chloramines. Education and 

outreach programs can help customers select the appropriate materials. 

Taste and Odor Issues

 Chlorine-based disinfectants have some associated taste and odor impacts. 

Monochloramine has a higher odor threshold and variations in residual concentrations produce 

less noticeable odors than free chlorine. Dichloramine and trichloramine, however, have much 

stronger odors than either monochloramine or free chlorine (Krasner and Barrett 1985). Taste 

and odor problems can also arise from nitrification episodes caused by excess ammonia. Control 

measures to prevent nitrification are discussed earlier in this section. 

 Recommendations for Addressing this Issue

 To prevent the formation of dichloramine and trichloramine that cause taste and odor 

problems, the chlorine to ammonia ratio should be carefully controlled and pH should be kept 

above 7.0. When the chlorine to ammonia ratio exceeds 5:1, dichloramine frequently begins to 

form. In general, maintaining a ratio between 3:1 and 5:1 should minimize odor problems. 

Blending Chloraminated and Chlorinated Water

 When water with a chloramine residual is mixed with water with a free chlorine residual, 

the chlorine to ammonia ratio changes and the resulting changes in distribution system water 

quality may cause customer complaints and/or possible violations of SDWA regulations. If the 

additional free chlorine raises the ratio to higher than 5:1, dichloramine and trichloramine can 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

form which have low odor thresholds and can cause customer complaints. If the ratio is raised to 

7.6:1 or higher by the additional free chlorine residual, breakpoint reactions can occur. 

Breakpoint reactions can lead to a total loss of disinfectant residual, which can result in a 

violation of the SWTR and possibly the TCR if the residual loss lasts long enough for an 

increase in microbial growth throughout the system. Blending could also cause the water to have 

excess free chlorine, causing DBP formation and a possible violation of the DBPR. 

 Recommendations for Addressing this Issue

 To avoid breakpoint chlorination, utilities mixing waters with chloramines and free 

chlorine residuals should determine the residuals in both waters and determine the chlorine to 

ammonia ratio of the resulting mixture. Some systems have developed computer models to 

predict these ratios. The models should be calibrated to the specific distribution system in order 

to be useful. Keeping the chlorine to ammonia ratio below 5:1 in the chloraminated water, which 

allows an ammonia residual to exist, will allow some addition of water with a chlorine residual 

before problems occur. A system could also choose to add ammonia again at the point where the 

waters are mixed to maintain the chlorine to ammonia ratio in the proper range. In either case, 

the water system also needs to take into account the possibility of excess ammonia causing 

nitrification. Careful monitoring of excess ammonia, free chlorine, and total chlorine residuals 

should be carried out to ensure that appropriate ratios are maintained. 

Weaker Disinfectant

 Monochloramine is a weaker disinfectant than free chlorine as illustrated by the required 

CT values to achieve inactivation of viruses and Giardia cysts (Exhibit 5.1). Both chlorine and 

monochloramine are ineffective against Cryptosporidium oocysts. 

Exhibit 5.1 Comparison of Required CT (mg-min/L) values for Inactivation of 

Viruses and Giardia by Free Chlorine and Monochloramine at pH 7 and 10o

C 

Disinfectant 

2-log 

inactivation 

(99%) of 

viruses

4-log 

inactivation 

(99.99%) of 

viruses

0.5-log 

inactivation 

(68.4%) of 

Giardia

3.0-log 

inactivation 

(99.9%) of 

Giardia

Chlorine 3 6 171 1041

Monochloramine 643 1,491 310 1,850 

1

 CT values are for free chlorine of <0.4 mg/L 

Even at relatively high doses of monochloramine, extremely long residence times are 

required to achieve required levels of inactivation for viruses and Giardia cysts. Systems that 

switch from free chlorine to monochloramine as their primary disinfectant must benchmark for 

virus and Giardia inactivation. 

 Recommendations for Addressing this Issue
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Systems can compensate for the lower disinfecting power of monochloramine by using a 

different disinfectant as the primary disinfectant and using monochloramine to maintain a 

disinfectant residual in the distribution system. Frequently this is done by adding the ammonia 

some time after the chlorine has been added. This allows a period of time for free chlorine 

disinfection. While this scheme will result in higher DBPs than using chloramines as the 

primary disinfectant, it will still result in lower DBP concentrations than when free chlorine is 

used as both a primary and residual disinfectant. One water system found as little as two minutes 

of free chlorine contact time prior to ammonia addition achieved desired inactivation results and 

reduced TTHM by 50 percent over free chlorine alone (Means et al. 1986). Another system used 

an hour of free chlorine contact time before converting to chloramines without exceeding TTHM 

regulatory levels (Gianatasio 1985). 

 Systems with very high TOC may wish to avoid free chlorine altogether. These systems 

can switch to a different primary disinfectant such as ozone, UV, or chlorine dioxide. See 

Sections 5.2, 5.3, and 5.4 for more details on these disinfectants, and their advantages and 

drawbacks. 

Safety Concerns

 Various safety issues should be considered when switching to chloramines, depending on 

the type of ammonia used. High concentrations of ammonia can form an explosive mixture of 

trichloramine when it reacts with chlorine. Ammonia gas is also toxic if released to the 

atmosphere in sufficient concentrations. Ammonium sulfate does not have as many safety issues 

as either anhydrous ammonia or aqueous ammonia, but it is considerably more expensive and 

should be kept dry to avoid feed problems. 

Recommendations for Addressing this Issue

 To avoid the possibility of an explosive reaction between bulk chlorine and bulk 

ammonia, the two chemicals should be stored in separate rooms. Feed points and pipes for 

chlorine and ammonia should also be placed at least five feet apart (USEPA 1999b). 

 To avoid the release of ammonia into the atmosphere, several precautions should be 

taken. Anhydrous ammonia should be stored in pressurized containers away from temperature 

extremes (temperatures greater than 125o

F will cause pressure buildups in the tank). Aqueous 

ammonia tanks should be vented to keep pressure from building up from ammonia volatilization. 

Keeping the temperature low will also help to prevent volatilization, which can cause vapor lock 

in pumps. Buildings where ammonia is stored should be well-ventilated and should include 

storage areas for respirators just outside the ammonia storage area. If large amounts of ammonia 

are stored, an emergency scrubber should also be installed. Additional safety precautions are 

detailed in the report, Optimizing Chloramine Treatment, 2nd ed. (Kirmeyer et al. 2004a). 

Issues with Ozonation and GAC Filtration

 Wilczak et al. (2003) found that ozone use prior to chloramination increases the 

assimilable organic carbon concentration and could destabilize the chloramine residual, leading 

to problems with chloramine residual concentrations at the ends of the distribution system. 
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Simultaneous Compliance Guidance Manual 5-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Adding chloramines before a GAC filter may lead to nitrification in the GAC filter. It 

has been found that a reaction between chloramines and GAC may free up ammonia and 

encourage the growth of ammonia oxidizing bacteria in the GAC filters (Tokuno 1999). 

 Recommendations for Addressing this Issue

 Installing a GAC filter after ozone to remove AOC, then allowing a few minutes of free 

chlorine contact time to oxidize any remaining organics before ammonia is added can be a more 

reliable way to allow the formation of a stable chloramine residual. Chloramines should not be 

added prior to GAC filters. 

Issues for Dialysis Patients, Fish Owners, and Other Customers

 Chloramines can be toxic to dialysis patients and must be removed before water is used 

in dialysis machines. Chloramines are also toxic to fish and therefore must be removed from the 

water before it is used for pet fish or before water is discharged to natural fish habitats. The 

removal of chloramines from tap water is more difficult to achieve, and more costly, than free 

chlorine. This also impacts water customers who produce foods, beverages, and 

pharmaceuticals. 

 Recommendations for Addressing this Issue

 Because the process for removing chloramines is different from that for removing 

chlorine, dialysis patients and fish owners should be notified in advance of the switch to 

chloramines. Water systems may also want to consider adding special notification language for 

fish owners and dialysis patients in their consumer confidence reports, so that the information is 

provided on an annual basis. Information on how other systems conducted community outreach 

before, during, and after treatment with chloramines are presented in the AwwaRF document, 

Optimizing Chloramine Treatment, Second Edition (Kirmeyer et al. 2004a). 

5.1.3 Recommendations for Gathering More Information 

Read Case Studies 

Three case studies in Appendix B address simultaneous compliance issues for systems 

that switched to chloramines as part of an effort to reduce DBP concentrations: 

• Case Study #9 - Modifying Chloramination Practices to Address Nitrification 

Issues on page B-51 describes a surface water system serving 115,000 people that 

took steps to control nitrification in the distribution system after switching to 

chloramines; 

• Case Study #13 - Chlorine Dioxide for Primary Disinfection and Chloramines for 

Secondary Disinfection on page B-75 describes a surface water treatment plant in a 

wholesale system serving seven municipalities and approximately 92,000 people. 

The treatment plant switched from chlorine to chlorine dioxide as its primary 
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Simultaneous Compliance Guidance Manual 5-11 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

disinfectant and from chlorine to chloramines for residual disinfection. In addition, 

the system uses chlorine dioxide intermittently as a pre-oxidant in its raw water. 

Among the challenges the system has encountered is being able to achieve sufficient 

Cryptosporidium inactivation to be granted LT2ESWTR credit and still comply with 

the Stage 1 DBPR’s chlorite MRDL; and 

• Case Study #14 - Chlorine Dioxide for Primary Disinfection and Chloramines for 

Secondary Disinfection on page B-81 describes a small surface water system that 

achieves its required CT with chlorine dioxide and maintains its disinfectant residual 

in the distribution system with chloramines. 

See Additional References

 Readers can find more references on this topic listed in the following sections of 

Chapter 7: 

• Section 7.1.1 includes general references on water treatment 

• Section 7.1.2 includes references on controlling DBP formation 

• Section 7.1.3 includes several references on corrosion/disinfection interrelationships 

• Section 7.1.5 includes references on using distribution system BMPs to control water 

quality in the distribution system. 

• Section 7.1.12 includes additional references on chloramines. 

Of particular note, the new publication Fundamentals and Control of Nitrification in 

Chloraminated Distribution Systems (M56), published by AWWA in 2006, provides background 

information on the occurrence and microbiology of nitrification and offers current and practical 

approaches to nitrification prevention and response. 

Consider Additional Monitoring

 

 Additional monitoring may benefit water systems using chloramines to address and 

prevent potential simultaneous compliance issues. Specific guidelines on monitoring to detect 

potential nitrification events is discussed previously in Section 5.1.2. 

Consider Other Tools 

Additional tools listed in Chapter 6 may help systems evaluate and improve their current 

water system in relation to the compliance issues they may face when modifying their treatment 

operations. Readers are encouraged to read through Chapter 6 before making any final 

compliance decisions. The following AwwaRF reports provide additional information: 

• Optimizing Chloramine Treatment, Second Edition (Kirmeyer et al. 2004a) describes 

chloramine chemistry, the advantages and disadvantages of chloramination, an 

approach for evaluating conversion to chloramines, and design and implementation 

issues for chloramine feed systems. It also describes relevant utility experiences 

based on a project survey and case studies. 
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Simultaneous Compliance Guidance Manual 5-12 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• Internal Corrosion of Water Distribution System (AwwaRF and DVGWTechnologiezentrum Wasser 1996) provides bench-scale and pilot testing protocols 

that can be used to evaluate changes in corrosion potential due to the switch to 

chloramines. 

• Optimizing Corrosion Control in Water Distribution System (Duranceau, Townley, 

and Bell 2004) provides techniques for instantaneous corrosion monitoring. 

• Tools and Methods to Effectively Measure Customer Perceptions (Colbourne 2001) 

describes tools that allow utilities to measure customer perceptions and changes in 

their opinions toward the use of chloramines. 

• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000) provides capital and 

O&M cost calculations for various water treatment processes based on user inputted 

design parameters.
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-13 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

5.2 Ozonation 

 Ozone is a powerful chemical disinfectant and an alternative to free chlorine. It is an 

unstable gas that is generated on-site, using either air or liquid oxygen. It is very effective at 

disinfecting many microbes and as a pre-oxidant. It can, however, convert bromide to bromate, a 

DBP regulated by the Stage 1 D/DBPR. It also oxidizes organic matter into smaller molecules, 

which can provide a more easily degradable food source for microorganisms in the distribution 

system. Because of its instability in water, ozone cannot be used to provide a disinfectant 

residual in the distribution system. Furthermore, ozone can produce odor compounds such as 

aldehydes and ketones.

5.2.1 Advantages of Ozonation 

The main advantages of ozone are: 

• Effective against pathogens 

• Does not form chlorinated DBPs 

• Effective pre-oxidant 

• Can oxidize taste and odor compounds 

• Can raise UV transmittance of water and UV disinfection effectiveness 

• Independent of pH 

• Can aid coagulation 

Effective Against Many Microbes

 Ozone is a highly effective disinfectant because of its high oxidation potential. It is the 

strongest of all the commonly used chemical disinfectants. It is most effective against viruses 

and slightly less effective against Cryptosporidium oocysts. As with most chemical 

disinfectants, the degree of microbial inactivation is temperature dependent. Inactivation is 

greater at higher temperatures. 

 Exhibit 5.2 shows the required CT values at 10o

C for inactivation of various microbes for 

each of the commonly used chemical disinfectants. Comparing the CT values shows the relative 

effectiveness of the disinfectants. 
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Simultaneous Compliance Guidance Manual 5-14 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 5.2 Required CT values (mg-min/L) for Chemical Disinfectants at 10oC 

Disinfectant 4-log 

Inactivation 

(99.99%) of 

Viruses

3-log 

Inactivation 

(99.9%) of 

Giardia

1-log Inactivation 

(99.9%) of 

Cryptosporidium

Ozone 1 1.43 9.9

Chlorine1 6 104 N/A

Chlorine 

Dioxide

4.2 23 277

Source: USEPA 2003a 

N/A - these disinfectants are ineffective against Cryptosporidium 1 at pH = 7.0 and chlorine residual = 0.4 mg/L

The exhibit shows that ozone is the most effective disinfectant against all three microbes 

listed. In addition to satisfying microbial disinfection requirements, ozone can aid in compliance 

with the Stage 2 DBPR by eliminating chlorine as a primary disinfectant and lowering the 

required dose of secondary disinfectant. Systems with DBP concentrations above a certain 

threshold that switch to ozone from another primary disinfectant are required by the IESWTR, 

LT1ESWTR, and LT2ESWTR to benchmark for Giardia, Cryptosporidium, and viruses. More 

details on disinfection profiling and benchmarking can be found in the Disinfection Profiling and 

Benchmarking Guidance Manual (USEPA 1999a). 

Does Not Form Chlorinated DBPs

 Ozone by itself does not form chlorinated DBPs. Therefore, using ozone instead of 

chlorine for primary disinfection can lower DBP formation and aid in compliance with the Stage 

2 DBPR. Ozone can react with bromide, however, to form bromate, which is a non-chlorinated 

DBP with an MCL of 10 ppb set under the Stage 1 D/DBPR (see section 5.2.2 of discussion of 

bromate formation). 

Effective Pre-oxidant

Ozone’s high oxidation potential also means it acts well as a pre-oxidant. It can be used 

to oxidize iron and manganese so they can be removed through coagulation and sedimentation. 

Ozone can oxidize arsenic (III) to arsenic (V) which enhances its removal. Many organic 

compounds are oxidized by ozone as well. If the dose is high enough, ozone can even 

completely mineralize some organics, lowering the concentration of DBP precursors and aiding 

in Stage 2 DBPR compliance. 

Can Oxidize Taste and Odor Compounds 

 Ozone is especially useful in oxidizing taste and odor compounds such as geosmin and 2 

-methylisoborneol (MIB). The efficiency of ozone at degrading geosmin and MIB is further 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-15 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

increased if hydrogen peroxide is added in addition to the ozone, a process referred to as 

peroxone. 

Raises UV Transmittance of Water

Low UV transmittance (UVT) of the water will result in less efficient UV disinfection. 

Ozone treatment before UV can oxidize those compounds that absorb UV, thereby increasing 

transmittance and UV’s disinfection effectiveness. Although it may be cost-prohibitive to install 

both UV and ozone, a system with one of the two technologies in place may benefit from 

installation of the other. This arrangement would require either chlorine or chloramines to 

maintain a distribution system residual. 

Independent of pH 

 The disinfection efficiency of ozone, unlike chlorine, does not depend on pH for the 

range of pH values normally encountered in water treatment. This enables plants to adjust pH to 

optimize coagulation, prevent corrosion, or alter DBP formation reactions without losing 

disinfection capability. It also removes some of the seasonal variability that is usually found in 

disinfection benchmarks. Note, however, that bromate formation is impacted by the pH of the 

water. This is discussed in more detail in Section 5.2.2. 

Can Aid Coagulation

 Some systems have reported improvements in coagulation when they added ozone prior 

to coagulation (Reckhow et al. 1993, Stolarik and Christie 1997). Other systems have found no 

change or even increases in filtered water turbidity after ozonation. The interaction between 

ozonation and coagulation is complex and entails the interaction of many parameters. Therefore, 

results will vary significantly from plant to plant. Systems should conduct bench-scale and 

preferably pilot-scale tests to determine how ozone will affect the systems water quality. Note 

that adding ozone after coagulation and sedimentation may have the advantage of lowering 

ozone demand allowing the same CT with a lower ozone dose. 

5.2.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Ozonation 

 The main operational and simultaneous compliance issues associated with ozone are: 

• May form bromate 

• Forms smaller organic compounds 

• Does not provide a residual in the distribution system 

• May increase dissolved oxygen in the water 

• Can form taste and odor compounds 
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Simultaneous Compliance Guidance Manual 5-16 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• Can increase corrosion 

• Ozone bubbles can hinder filter performance 

• Switching to ozone with biological filtration may cause manganese release from 

filters 

• Requires additional training 

This section summarizes these issues and provides recommendations for some ways to 

address them.

May Form Bromate

 If bromide is present in the source water, it can react with ozone to form bromate. In the 

presence of organic matter, ozone can also form brominated THMs and HAAs. The Stage 1 

D/DBPR requires compliance with a 10 μg/L MCL for bromate. Therefore, systems considering 

installing ozone should evaluate whether compliance with the bromate MCL may be an issue. 

 Whether bromate or brominated organic DBPs form depends on the pH and organic 

content of the water. Lower pH water and high DOC concentrations tend to favor the formation 

of brominated organic compounds. Systems using ozone may be able to reduce their chlorine 

dose, however, and as a result improve compliance with TTHM and HAA5 MCLs. Higher pH 

and low dissolved organic concentration generally lead to greater bromate formation. 

 Recommendations for Addressing this Issue

 There are several techniques that public water systems can use to control disinfection 

byproduct formation when bromide ion is present. These include: 

• Optimizing the pH 

• Keeping the ratio of ozone to DOC low 

• Adding ammonia 

 Lowering the pH favors formation of brominated organic compounds over bromate. 

Performing ozonation at a pH below 7 will lower the formation of bromate. This is a particularly 

good option for systems that have low DOC concentrations and do not have problems with high 

TTHM or HAA5 concentrations in their finished water. If DOC concentrations are high, 

however, this method of bromate control may result in exceeding HAA5 or TTHM MCLs. 

Systems also need to consider other effects of lowering pH such as increased corrosion, impacts 

on the effectiveness of secondary disinfectants, and impacts on coagulation. (See Section 3.4 for 

a more complete discussion of the effects of changing pH.) 

 If the ratio of ozone to DOC is kept low, the formation of bromate and brominated 

organic compounds can be reduced. This can be done by either lowering the ozone dose or by 

lowering DOC concentrations. Lowering the ozone dose would mean increasing the contact 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-17 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

An effective way to 

remove smaller organic 

compounds is biological 

filtration. 

time, unless the system currently achieves more than the required CT. The ability to extend the 

contact time will depend on the ozone demand and decay of the water as well as operational 

limitations. Determining the ozone demand and decay rate of a given water before ozone is 

installed will help determine the possibilities of this option. DOC can be lowered by removing it 

prior to the ozone addition. If a system does not need to use ozone for pre-oxidation, it may 

want to add the ozone after sedimentation, or even after filtration, to achieve a lower ozone to 

DOC ratio. It is not typical, however, to ozonate after filtration, because of higher AOC 

concentrations being introduced into the distribution system and the related problems of TCR 

compliance and nitrification that may occur. If a system needs to pre-oxidize, a small dose of 

ozone can be added to the raw water and a higher dose can be added after sedimentation or 

filtration. Using biological filtration in this case can be especially effective for lowering DBPs, 

since biological filtration tends to remove aldehydes and other small organic compounds that can 

make up a large fraction of the DOC after ozonation.

Adding ammonia to water containing bromide and ozone will lead to bromamine 

formation. Bromamines react more slowly with organic matter and form fewer brominated 

organic compounds and less bromate. Ammonia addition, however, can lead to nitrification 

problems in the distribution system. See Section 5.1 for more details on controlling nitrification 

when ammonia is added.

 Systems with high bromide concentrations, especially those with high DOC as well, may 

not be able to use ozone even if they adopt these mitigation methods. Systems that use ozone to 

inactivate Cryptosporidium may have an especially hard time, in this regard, because 

Cryptosporidium requires a much higher ozone dose. Since the LT2ESWTR does not grant 

disinfection credit for an ozone residual in the first contact chamber, many systems will want to 

increase their ozone dose to help them gain CT in subsequent chambers. Bromide can be 

removed by the use of anion exchange, but this is generally not a cost-effective solution.

Forms Smaller Organic Compounds 

 Ozone breaks down organic compounds into smaller chain organic molecules, especially 

aldehydes and ketones. These smaller organic molecules often measured as “assimilable organic 

carbon” (AOC) are more readily biodegradable and can increase biological growth downstream 

of the ozone addition point. AOC is a measure of the organic carbon readily available as food 

for microorganisms. Some systems that have added ozone without biological filtration have 

experienced increased AOC and microbial growth in the distribution system (Van der Kooij 

1997). Increased biological growth in the distribution system can lead to higher disinfectant 

demand and potentially TCR violations. Biological growth can also cause increased corrosion, 

possibly leading to violations of the Lead and Copper Rule (LCR) as well as to taste and odor 

problems. 

 Recommendations for Addressing this Issue

 An effective way to reduce AOC is biological 

filtration. Biological filtration can be achieved by not 

having a disinfectant residual in the water entering the 

post-ozone filter. The increased dissolved oxygen that 

results from the ozonation, combined with the high surface 
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Simultaneous Compliance Guidance Manual 5-18 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

area per volume of the filter media, provide conditions for biological growth to occur on the 

filters. The biological growth on the filters then consumes the AOC, using it as a food source. 

Biological filtration has been shown to lower AOC effectively, even when very short residence 

times are used. Longer residence times can lead to the reduction of other organic compounds as 

well (LeChevallier et al. 1992). See Urfer et al. (1997) for more details on biological filtration. 

 Any type of filter media can accommodate biological filtration. Slow sand filters, rapid 

rate dual media filters, and GAC filters have all been successfully used for biological filtration. 

Rapid rate filters have been shown to remove AOC, though they may not remove all of the 

biodegrable dissolved organic carbon (BDOC), which is a portion of organic matter that can still 

be used by microbes as a food source but takes longer for the microbes to metabolize than AOC. 

Slow sand filters and GAC contactors have been shown to remove both BDOC and AOC. GAC 

has the added benefit that it will adsorb or concentrate organics, thus extending the time 

available for the microbes to metabolize the organic matter. 

 Switching to biofiltration can present its own challenges. Although biofilters remove 

turbidity as well as other filters, they have shown higher particle counts than traditional filters. 

They have also shown increased headloss over traditional filters. Systems switching to 

biofiltration may want to consult the AwwaRF report “Optimizing Filtration in Biological 

Filters” (Huck et al. 2000) to design the best biofiltration system. 

Does Not Provide a Disinfectant Residual in the Distribution System

 Ozone reacts very quickly and therefore is not able to provide a residual for use in the 

distribution system. A secondary disinfectant is, therefore, required to maintain a disinfectant 

residual in the distribution system as required by the SWTR. 

 Recommendations for Addressing this Issue

 Chlorine can often be used as an effective residual disinfectant after ozonation. Since 

ozone is used to achieve primary disinfection, lower doses of chlorine can be used as a secondary 

disinfectant, resulting in lower DBP levels. Ozone followed by biological filtration reduces DBP 

precursors, which also leads to lower DBP levels. If biological filtration is not used, the system 

should be careful that the additional smaller organic molecules do not react with chlorine added 

as a secondary disinfectant to produce higher DBP concentration than if chlorine alone were 

added. Chloroform has been found to be higher in some systems which used ozone without 

biological filtration than it was before ozone was implemented. 

 Chloramines can also be used to provide a distribution system residual after ozonation. 

Chloramines will result in lower DBPs than chlorine. As mentioned above, adding ammonia 

with the ozone will provide benefits regarding the formation of brominated DBPs. If this 

approach is taken, chlorine can be added after filtration to form the chloramines. For a full 

discussion on the benefits and drawbacks of chloramines as a secondary disinfectant, see Section 

5.1. 
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Simultaneous Compliance Guidance Manual 5-19 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

May Introduce Dissolved Oxygen into the Water 

 When ozone reacts in water it forms dissolved oxygen. This oxygen may remain 

dissolved in the water. Dissolved oxygen can increase corrosion of metals. It can also cause 

increased growth of aerobic bacteria and problems with TCR compliance. 

 Recommendations for Addressing this Issue

 Corrosion-resistant materials should be used in the ozone feed equipment, the contact 

chamber, and any other plant equipment that comes into contact with the water after ozonation 

and before the dissolved oxygen is dissipated. The best way to prevent dissolved oxygen from 

entering the distribution system is to run the filters in biologically active mode. This will lower 

the dissolved oxygen, as well as remove AOC. 

 Systems using ozone after filtration and unfiltered systems may need to take steps to 

control microbial growth in the distribution system. Control measures include ensuring a 

sufficient residual throughout the system, looping dead ends in the distribution system, and 

minimizing retention time in reservoirs. Systems may also want to raise the pH of the water or 

add a corrosion inhibitor to prevent corrosion. 

Can Form Taste and Odor Compounds 

 Ozone is generally very effective in destroying taste and odors compounds, but in some 

cases ozonation of organic matter forms aldehydes and other compounds that can impart tastes 

and odors to water. 

 Recommendations for Addressing this Issue

 Systems should consider using a GAC filter or biologically active filtration to help 

eliminate aldehydes formed during ozonation, before the water reaches customers. 

Increases Corrosion

 Ozone is corrosive and can corrode steel pipes and fittings, concrete, rubber gaskets, and 

other material with which it comes into contact in the treatment plant. 

 Recommendations for Addressing this Issue

 All material that comes into contact with ozone residual should be resistant to ozone. 

This includes any equipment which might be exposed to off-gassed ozone. Equipment 

manufacturers should be contacted to ensure compatibility of their equipment with ozone. 

Ozone Bubbles Can Hinder Filter Performance

 Ozone can de-gas in the filter and bind to the filter media. This can adversely affect filter 

performance and reduce the effectiveness of filter backwashing. 
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Simultaneous Compliance Guidance Manual 5-20 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Recommendations for Addressing this Issue

 If ozone is injected under pressure, it should be de-gassed before the filters. 

Switching to ozone and biological filtration may cause release of manganese from filters 

 Iron-based coagulants often contain significant amounts of manganese as an impurity in 

the coagulant. When systems that use iron coagulants also pre-chlorinate, a layer of oxidized 

manganese can form on the filter media surface. If the system switches to ozone and stops prechlorinating to achieve biological filtration, this manganese has been found to reduce and be 

released into the filtrate water (Wert et al. 2005, Gabelich et al. 2005). Therefore systems which 

are using or have historically used iron coagulants and switch from chlorine to ozone before the 

filter in order to take advantage of biofiltration may experience elevated manganese levels. In 

some cases these levels of manganese have violated secondary standards for manganese 

(Gabelich et al. 2005). 

 Recommendations for addressing this issue

 Wert et al. (2005) found that the release of manganese from filters was much more at 

rapid at pH 6 than at pH 8. Therefore, maintaining a pH near 8 going through the filter may 

prevent elevated manganese levels. Switching to a coagulant with lower manganese impurity 

concentrations will help future manganese releases but will not solve any already accumulated 

manganese problems. One system found that they were able to clean the manganese from 

anthracite media using a two step process involving acid and hydrogen peroxide (Gabelich et al. 

2005). This process, however, did not remove manganese from sand media. Another option is 

to replace the filter media. 

Requires Additional Training 

 Ozone disinfection is an advanced technology and requires different procedures and 

equipment compared to conventional technologies. There are also safety issues, such as 

containment and destruction of ozone off-gas. 

 Recommendations for Addressing this Issue

 Additional training will be needed to ensure that operators can use equipment correctly. 

They will need to become familiar with additional chemicals used for ozone quench. Operators 

should also be aware of safety concerns related to off-gassing and destruct units. 
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5.2.3 Recommendations for Gathering More Information 

Read Case Studies 

 Two case studies in Appendix B describe simultaneous compliance challenges faced by 

utilities using ozone. 

Case Study #10 - Ozonation on page B-57 describes a surface water system serving 

approximately 115,000 people that installed ozone to control both Cryptosporidium and 

disinfection byproducts. The system was concerned about how ozone might result in increased 

AOC in its finished water, so biofiltration was also installed to address potential problems that 

could have arisen in the distribution system as a result. 

Case Study #11 – Ozonation and Biological Filtration on page B-65 describes a system 

that significantly expanded its capacity at the same time that it installed ozone. Its source is a 

river with high TOC, so this system was also concerned with ozone’s impact on AOC levels in 

the finished water. Four new biological filters were installed and 12 existing filters were 

converted to biological filtration. 

See Additional References

 Readers can turn to Chapter 7 for more references on this topic. Section 7.1.1 includes 

general references on water treatment, Section 7.1.2 includes references on controlling DBP 

formation, and Section 7.1.13 includes references on Ozone. 

Consider Additional Monitoring 

 The following are some suggestions for additional monitoring that may benefit water 

systems using ozone. The purpose of these monitoring suggestions is specifically to address and 

prevent potential simultaneous compliance issues. Water system managers should discuss 

process control monitoring with the manufacturer of their ozonation units or their engineer. 

9 Dissolved organic carbon (DOC) measurements in water being ozonated, and 

calculation of the ozone:DOC ratio. By keeping the ozone:DOC ratio low, formation 

of bromate and brominated organic compounds can be reduced; 

9 AOC and/or BDOC monitoring after biological filtration to verify that they are being 

removed reliably; 

9 If there is no biological filtration treatment step, AOC and/or BDOC monitoring of 

finished water before it enters the distribution system to track whether levels are high 

enough to cause problems with biofilm growth; 

9 HPC measurements at locations throughout the distribution system and in plant 

effluent, to watch for increased biofilm growth; 
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9 Dissolved oxygen at points after ozonation in the treatment plant, as part of an effort 

to control levels and limit corrosion in the plant; 

9 Dissolved oxygen at entry points to the distribution system to make sure it has been 

reduced to acceptable levels and will not induce distribution system corrosion; 

9 Taste and odor in finished water since ozonation can create off-odors; and 

9 Ozone residual in the contactor to ensure proper CT, and after the contactor to ensure 

proper removal and safety. 

Consider Other Tools 

 In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their treatment operations. Examples of tools that can be 

used when ozone is used for Stage 2 DBPR compliance include: 

• The “Guidance Manual for Monitoring Distribution System Water Quality” 

(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a 

distribution system water quality data collection and analysis program; 

• The AwwaRF report “Internal Corrosion of Water Distribution System” (AwwaRF 

and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

testing protocols that can be used to evaluate changes in corrosion potential due to the 

switch to ozonation; 

• The AwwaRF report “Optimizing Corrosion Control in Water Distribution System” 

(Duranceau, Townley, and Bell 2004) which provides techniques for instantaneous 

corrosion monitoring; 

• EPA’s Environmental Technology Verification Program collects performance data on 

many environmental technologies, including ozone. Reports for each technology can 

be found on the website at: http://www.epa.gov/etv/verifications/verificationindex.html; 

• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000) which provides 

capital and O&M cost calculations for various water treatment processes based on 

user inputted design parameters.

• The AwwaRF report “Water Utility Self-Assessment for the Management of 

Aesthetic Issues” (McGuire et al. 2004) which can be used to guide utilities in 

conducting self-assessment of taste and odor issues caused by ozonation and to 

identify subsequent control strategies; 

• The AwwaRF report “Tools and Methods to Effectively Measure Customer 

Perceptions” (Colbourne 2001) which describes tools that allow utilities to measure 

customer perceptions and changes in their opinions toward the use of ozonation; 
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• The AwwaRF report “Ozone-Enhanced Biofiltration for Geosmin and MIB Removal” 

(Westerhoff et al. 2005) which describes the removal of taste and odor compounds 

through the use of biological filtration; and 

• EPA’s Microbial Toolbox Guidance Manual (USEPA N.d.e) which describes 

technologies which can be used for compliance with the LT2ESWTR. The manual 

describes advantages and disadvantages for each technology and lists design and 

operating considerations. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
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5.3 Ultraviolet Light (UV) 

Recent research indicating that UV light can inactivate Cryptosporidium

at relatively low lamp intensities has spurred interest in its use for drinking 

water disinfection. UV light works by damaging the genetic material of 

microorganisms, interfering with the ability of pathogens to replicate and 

therefore with their ability to be infective. Similar to chemical disinfectants, the 

extent of UV inactivation depends on the intensity of the light and the time the 

microorganism is exposed to it. UV is an effective way to disinfect without 

producing regulated DBPs. UV does not provide a residual, however, so it is 

not effective in providing a distribution system residual. Extensive information on the 

mechanisms of UV disinfection and recommendations on UV system design, validation, and 

operation are provided in the UV Disinfection Guidance Manual (USEPA 2006b). 

 If UV is being used as a toolbox option to comply with LT2ESWTR, UV reactors must 

be validated according to state guidelines and operate within the validated parameters. For 

purposes of design and operation, EPA recommends that systems strive to deliver the required 

UV dose at all times during treatment (USEPA 2006b). 

5.3.1 Advantages of UV 

Advantages

 UV light’s advantages include: 

• It can inactivate chlorine-resistant pathogens such as Cryptosporidium oocysts 

and Giardia cysts at relatively low doses; 

• It does not produce regulated DBPs; and 

• Its effectiveness is not pH or temperature dependent.

Inactivates Cryptosporidium and Giardia

 UV disinfection gained attention in the U.S. drinking water market when it was shown 

that it could inactivate Cryptosporidium oocysts and Giardia cysts. This gives UV an advantage 

over chlorine or chloramines, which are ineffective against Cryptosporidium. If properly tested 

and validated, UV is one of the least expensive options for systems that are required to achieve 

additional Cryptosporidium inactivation under the LT2ESWTR (USEPA 2006b). UV can also 

meet SWTR requirements for Giardia inactivation. 

Does Not Produce Regulated DBPs

 UV disinfection, as a photochemical process, does not produce any of the regulated 

byproducts that chemical disinfectants such as chlorine, ozone, and chlorine dioxide produce. 

Surface water systems and systems using GWUDI of surface water may meet Stage 2 DBPR 

requirements by switching to UV disinfection and lowering their doses of chemical disinfectants. 
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Systems making this change will be required to benchmark their disinfection process under 

LT2ESWTR requirements before making the change. See Section 5.3.2 for further discussion of 

UV benchmarking requirements. Systems will also need to continue to meet the residual 

disinfection requirements of the SWTR. 

Not pH or Temperature Dependent

 Research has shown that temperature effects on UV dose-response are minimal (USEPA 

2006b). Dose response is also independent of pH in the range of 6 to 9 (Malley 2000). This 

gives systems more flexibility to adjust pH to control coagulation, or to lower production of 

DBPs without also affecting disinfection efficiency. This could also mean simpler operations if 

the UV dose does not need to be adjusted seasonally (although dose could vary seasonally if the 

levels of UV absorbing compounds in the water being treated vary seasonally). 

5.3.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with UV Disinfection 

 Potential operational and simultaneous compliance issues associated with UV 

disinfection include: 

• Substances in water can interfere with UV disinfection 

• Hydraulic upsets can lower the delivered dose and possibly cause lamp breakage 

• Much higher doses are needed for virus inactivation 

• UV disinfection provides no distribution system residual 

• Power quality problems can disrupt disinfection 

• Requires additional training 

This section provides brief descriptions of these issues and suggestions for addressing them. 

Substances in Water Can Interfere with UV Disinfection

 Because UV disinfection relies on UV light interacting with the organism’s genetic 

material to be effective, any substance that either absorbs or refracts the germicidal UV light can 

interfere with disinfection. A common measure of the fraction of germicidal light (i.e., light 

specifically with a wavelength of 254 nanometers) transmitted through a material is UV 

Transmittance (UVT). The higher the UVT, the better UV light can be transmitted through the 

water and the more effective the treatment. Compounds in source waters that can absorb or 

refract UV light and reduce UVT include humic and fulvic acids, phenols, metals (e.g., iron and 

manganese), and anions (e.g., nitrates) (USEPA 2006b). The LT2ESWTR requires water 

systems to account for UV absorbance of the water during validation testing. 
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 In addition to absorbing UV light and decreasing UVT, compounds in the water can foul 

the external surfaces of the lamp sleeves. The rate of fouling depends on water quality 

characteristics such as hardness, alkalinity, ion concentration, and pH. 

 The presence of disinfectants upstream of UV treatment can impact UV performance. 

Ozone is a strong absorber of UV light and can interfere with disinfection if not quenched prior 

to UV treatment. Ozone treatment, however, can be effective in increasing the UVT. Some 

chlorine residual can be lost if water with a free or total chlorine residual is passed through a UV 

reactor (USEPA 2006b). 

 Recommendations for Addressing this Issue

 Systems should carefully evaluate their water quality during the planning phase for their 

new UV facility. UVT is the most important water quality characteristic affecting UV facility 

design (USEPA 2006b); therefore, care should be taken to characterize UVT during typical 

operations as well as during storm events, seasonal changes, reservoir turnover, and source water 

blends. UV absorbance of the water (i.e., UVT) must be accounted for during validation testing. 

 EPA recommends that systems determine a “fouling factor” during the planning phase to 

account for lower UVT caused by fouling of the lamp sleeves (USEPA 2006b). This factor is 

defined as the estimated fraction of UV light passing through a fouled sleeve compared to a new 

sleeve. UV reactors typically allow for cleaning of lamp sleeves to remove deposited material. 

Three common approaches are off-line chemical cleaning, on-line mechanical cleaning, and online mechanical-chemical cleaning. More frequent lamp cleaning can increase the fouling factor. 

Lamp fouling should be accounted for during validation testing. 

 Systems can modify their treatment to increase UVT and reduce the potential for fouling 

of lamp sleeves. Pre-oxidation and enhanced coagulation are potential treatments that can be 

used for this purpose. Their usefulness should be evaluated on a case-by-case basis. 

Ozone, if used for taste and odor control, will generally be added before the filters and 

will not enter the UV reactor. If this is not the case and an ozone residual is present in the water 

before it enters the UV unit, the ozone should be quenched. Ozone can be quenched by air 

stripping in the last chamber of the ozone contactor, or by using a reducing agent such as 

hydrogen peroxide. Some studies suggest, however, that ozone quenching using hydrogen 

peroxide can be slow in low-alkalinity water (National Research Council 2000). The ozone 

residual should not be quenched with thiosulfate, as thiosulfate also absorbs UV. 

 If chlorine dioxide is being used, it should be added after the UV reactor. See Section 5.4 

for further details on chlorine dioxide use. If corrosion inhibitors that contain UV-absorbing 

compounds are used, they should be added after water has passed through the UV reactor. 

Lamp Breakage

Lamp breaks can be caused by debris in water, temperature variations, water hammer, 

electrical surges, or improper installation (USEPA 2006b). Lamps in most UV reactors contain 

mercury or an amalgam of mercury and another compound such as gallium or indium. If lamps 

break during reactor operations, there is a risk of exposure to mercury. 
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While UV disinfection is highly 

effective against protozoa such 

as Cryptosporidium oocysts, it 

is less effective against viruses. 

 Recommendations for Addressing this Issue

Very few incidents of on-line lamp breaks have been documented. Appendix E of the 

Ultraviolet Disinfection Guidance Manual (USEPA 2006b) provides design and operating 

recommendations to minimize the occurrence of breaks and to develop written procedures to be 

followed if a break does occur. To isolate the mercury, systems can install spring-return actuated 

valves with a short closure time on the reactor inlet and outlet piping. Systems should also 

consider installing a strainer or mercury trap. EPA recommends that systems evaluate the 

applicability of various isolation techniques on a case-by-case basis. 

Virus Inactivation

 While UV disinfection is highly 

effective against protozoa such as 

Cryptosporidium, it is less effective against 

viruses. The LT2ESWTR requires systems 

considering substituting current 

chlorination with UV disinfection to 

benchmark with respect to viruses, Giardia, and Cryptosporidium and consult with the state to be 

sure that sufficient inactivation is maintained. 

 Exhibit 5.3 shows the ratio of CT required for inactivation of viruses and the CT required 

for the inactivation of Cryptosporidium for chlorine dioxide and ozone. This ratio can be 

compared to the ratio of UV dose required for inactivation of viruses and the UV dose required 

for the inactivation of Cryptosporidium. This ratio is much lower for chlorine dioxide and ozone 

compared to UV, meaning that chlorine dioxide and ozone are more effective for inactivation of 

viruses compared to Cryptosporidium, while UV is the opposite. 

Exhibit 5.3 Ratio of CT values for Inactivation of Viruses and Cryptosporidium at 

10o

C 

Ratio of Virus Inactivation to Cryptosporidium Inactivation

Disinfectant 

Ratio of 2-log virus inactivation 

(99.0%) CT to 0.5-log 

Cryptosporidium inactivation CT 

(68.4%) 

Ratio of 4-log virus inactivation 

CT (99.99%) to 3.0-log 

Cryptosporidium inactivation CT 

(99.9%) 

Chlorine 

dioxide 

0.03 0.03 

Ozone 0.10 0.03 

UV1 17.2 15.5 1

 UV doses are in mJ/cm2 and are calculated using safety factors based on the use of low pressure mercury lamps. 

They may vary depending on the reactor validation method. See the Ultraviolet Disinfection Guidance Manual

(USEPA 2006b) for details. 
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 Recommendations for Addressing this Issue

 Systems that adopt UV disinfection will need to take special care to ensure that the virus 

benchmark is achieved. The state should be consulted throughout the planning process to ensure 

that inactivation requirements can be met to achieve the necessary credit. 

 To receive credit for disinfection with UV light, the LT2ESWTR requires water systems 

to demonstrate through validation testing that the UV reactor can deliver the required UV dose. 

The testing must determine a range of operating conditions that can be monitored by the system 

and under which the reactor delivers the required UV dose. At the time of this publication, EPA 

is not aware of an available challenge microorganism that allows for full-scale testing of UV 

reactors to demonstrate 4-log inactivation of viruses at a required dose of 186 mJ/cm2

. 

Methodologies for challenge testing at doses necessary to inactivate UV resistant viruses may be 

developed in the future. 

 

 Until then, UV technology should be used in a series configuration or in combination 

with other inactivation or removal technologies to provide a total 4-log treatment of viruses. 

The second option uses a different treatment to achieve virus inactivation and uses UV only for 

Cryptosporidium and Giardia inactivation. If a chemical disinfectant is used, it could be added 

after the UV reactor to maintain a residual in the distribution system or it could be added prior to 

the UV reactor where it could also serve as a preoxidant. Surface water systems will need to add 

secondary disinfection to comply with the entry point and distribution system residual 

requirements of the SWTR. If a second disinfectant is used also for additional virus inactivation, 

it must achieve the required inactivation before the first customer. Chlorine will provide virus 

inactivation with a relatively low dose, but may produce DBPs and could create problems with 

Stage 2 DBPR requirements. Chloramines will have less DBP formation but will require 

significantly longer contact time in the clearwell to ensure appropriate inactivation before the 

first customer. See Section 5.1 for more details on the use of chloramines. 

 If pre-oxidation is practiced, chlorine, ozone, or chlorine dioxide can be used. Chlorine 

may not be an attractive solution because the production of DBPs. Ozone will likely be cost 

prohibitive unless it is already installed; in which case it would have numerous advantages. 

UV Does Not Provide a Residual

 UV disinfection, because it is not a chemical disinfectant, does not leave a residual and 

cannot be used to meet SWTR requirements regarding entry point and distribution system 

residuals. 

 Recommendations for Addressing this Issue

 Free chlorine or chloramines can be used to maintain a residual disinfectant. Chlorine is 

effective against viruses and bacteria but can cause significant problems with Stage 2 DBPR 

compliance, especially in portions of the distribution system with long residence times where 

organic carbon is present. Chloramines as a residual disinfectant after UV disinfection have the 

potential to provide adequate distribution system residual and very low DBPs. Problems with 
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chloramines include potential issues with nitrification, potential corrosion problems, and taste 

and odor issues if the chlorine-to-ammonia ratio is not maintained properly. 

Power Quality Problems Can Disrupt Disinfection

A UV lamp can loose power in the event of a power interruption, voltage fluctuation, or 

power quality anomaly. Common causes of power quality problems include faulty wiring and 

grounding, weather-related damage, and power transfers to emergency generators or alternate 

feed (USEPA 2006b). Systems are required to monitor lamp status to ensure that reactors are 

operating within validated limits. Loss of power can result in the reactors operating offspecification. 

 Recommendations for Addressing this Issue

 Systems should determine if their facility(s) experience power quality problems or is 

located in a remote area where power quality is unknown. If power quality may be a problem, 

EPA recommends that systems perform a power quality assessment to quantify and understand 

the potential for off-specification operation. Power quality assessments include contacting local 

power suppliers to obtain data on power quality and reliability, obtaining information on the 

power quality tolerance of the UV equipment under consideration, determining how long it will 

take UV reactors to function at full power after a power quality event, and determine if backup 

power or power conditioning equipment is needed (USEPA 2006b). 

Requires Additional Training

 Because UV reactors are operated differently than conventional chemical disinfection, 

training may be needed to ensure proper operation, monitoring, reporting, and maintenance of 

the UV disinfection equipment. 

 Recommendations for Addressing this Issue

 Equipment vendors and state officials should be contacted early in the process regarding 

the appropriate training for UV disinfection. Systems considering UV should check with their 

state to determine whether state-specific monitoring requirements. 
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5.3.3 Recommendations for Gathering More Information 

Read Case Study 

Case Study # 12 – Ultraviolet Disinfection on page B-71 in Appendix B describes a 

surface water system with a 16 MGD plant that converted from chlorine to UV treatment to 

achieve its CT. The system uses a large river as its source and needed to reduce its DBPs. In 

anticipation of LT2ESWTR, it opted for UV because of the additional benefit that UV 

inactivates Cryptosporidium. One of the biggest challenges the system faced with the transition 

was providing the training needed to operate and maintain the UV system. This case study 

describes how the system addressed this and other issues it encountered as one of the first surface 

water systems of its size to switch over to UV. 

See Additional References

 Readers can turn to Chapter 7 for further references on this topic. Section 7.1.1 includes 

general references on water treatment, section 7.1.2 includes references on controlling DBP 

formation, and section 7.1.14 includes references on UV disinfection. 

Consider Additional Monitoring

 The following are some suggestions for additional monitoring that may benefit water 

systems implementing UV disinfection. The purpose of these monitoring suggestions is 

specifically to address and prevent potential simultaneous compliance issues. Monitoring should 

be done before the design process to allow for proper design of the system. Water system 

managers should discuss process control monitoring with the manufacturer of their UV units, 

their engineer, and other experienced utilities. 

9 Monitoring for UV absorbance, which is very important for UV disinfection 

performance and is required by the LT2ESWTR 

9 Periodic measurements of inorganic and organic chemicals, as applicable, in the 

water entering the UV unit. Tracking their concentrations will help a system make 

sure levels are low enough and will not interfere with UV disinfection. Some 

compounds with this potential are: 

- Iron 

- Manganese 

- Calcium 

- Magnesium 

- Aluminum 

- Dissolved Organic Carbon 

- Ozone
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Consider Other Tools 

 In addition to water quality monitoring, there are additional tools listed in Chapter 6 that 

could help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their treatment operations. Examples of tools that can be 

used when UV is used for Stage 2 DBPR compliance include: 

• The “Ultraviolet Disinfection Guidance Manual” (USEPA 2006b) which provides 

guidance on the validation, selection, design, and operation of UV disinfection 

systems; 

• The AwwaRF report “Integrating UV Disinfection Into Existing Water Treatment 

Plants” (Cotton 2005) which provides user-friendly web tools that will assist utilities 

in assessing important disinfection decisions and UV implementation issues; 

• The AwwaRF report “Full Scale Implementation of UV in Groundwater Disinfection 

Systems” (Malley 2002) which provides specific guidance for the selection, design, 

and operation of UV systems; and 

• Various cost estimation models that can be used to estimate the cost of implementing 

a new UV facility. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions. 
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5.4 Chlorine Dioxide 

 Chlorine dioxide is an alternative chemical disinfectant 

that can be used to lower DBP production while maintaining 

adequate levels of inactivation. Because it is unstable, it is 

generated onsite using chlorine dioxide generators. 

 Chlorine dioxide has gained popularity because it 

produces relatively few THMs and HAAs. It is also very 

effective against bacteria, viruses, and Giardia cysts, and can 

provide some inactivation of Cryptosporidium oocysts at higher 

temperatures. The main drawback of chlorine dioxide is that the chlorine dioxide MRDL of 0.8 

mg/L combined with an MCL of 1.0 mg/L for chlorite, the main byproduct of chlorine dioxide, 

limit the dose that can be applied. In addition, low water temperatures can make it more difficult 

to use chlorine dioxide. 

5.4.1 Advantages of Chlorine Dioxide 

 Chlorine dioxide’s advantages include: 

• Effectively inactivates bacteria, virus, and Giardia cysts; can achieve some 

Cryptosporidium oocyst inactivation; 

• Less TTHM and HAA5 formation than chlorine; 

• Effective oxidant for the control of iron, manganese, hydrogen sulfide, and 

phenolic compounds; 

• May treat high-bromide, high-TOC waters better than chlorine or ozone; and 

• Not significantly affected by pH values between 6 and 9.

Effective Disinfectant

 Chlorine dioxide is a strong oxidant and can therefore effectively inactivate a wide range 

of microbes. Exhibit 5.4 compares the required CT values of chlorine dioxide with those of 

chlorine and ozone. Chlorine dioxide is slightly less effective than chlorine against viruses and 

bacteria, but is more effective against Giardia and Cryptosporidium. 
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Exhibit 5.4 Required CT Values for Inactivation of Microorganisms by Chlorine 

Dioxide Compared with Other Chemical Disinfectants at 10oC and pH 6-9 (in mgmin/L) 

Microbe Inactivation Level Chlorine Dioxide Chlorine1 Ozone

Viruses 2-log (99.0%) 4.2 3 0.5 

Viruses 4-log (99.99%) 25.1 6 1.0 

Giardia 0.5-log (68.4%) 4 17 0.23 

Giardia 3.0-log (99.9%) 23 104 1.43 

Cryptosporidium 0.5-log (68.4%) 138 N/A 4.9 

Cryptosporidium 3.0-log (99.9%) 830 N/A 30 

Source: USEPA 2003a 

N/A - not applicable. Chlorine is ineffective against Cryptosporidium.

1 - Chlorine CT values for pH 7

 Chlorine dioxide can achieve some inactivation of Cryptosporidium oocysts. Required 

CT levels for Cryptosporidium inactivation are relatively high though, so achieving more than a 

half log inactivation is unlikely given restrictions on dose. See the following section for a further 

discussion of dose restrictions. Chlorine dioxide can, however, be a relatively low cost 

alternative for systems that require a 0.5 log Cryptosporidium inactivation to comply with the 

LT2ESWTR. 

Less TTHM and HAA5 Formation

 Chlorine dioxide provides a good alternative to chlorine for systems that wish to lower 

the formation of TTHM or HAA5. Pure chlorine dioxide does not form significant amounts of 

TTHM or HAA5. Most chlorine dioxide generators do produce some chlorine as a byproduct, 

however, so some TTHM and HAA5 will still be formed. The DBP of greater concern when 

chlorine dioxide is used is chlorite, which has a 1.0 mg/L MCL. See the discussion in the 

following section for more information on minimizing chlorite formation. Systems 

contemplating changing to chlorine dioxide will be required to perform a disinfection benchmark 

for viruses, Giardia, and Cryptosporidium and consult with the state to ensure adequate 

disinfection levels are maintained. 

Effective Oxidant

 Another advantage to chlorine dioxide is that it is a strong oxidant. It can effectively 

oxidize many compounds including iron and taste and odor compounds. Under the right pH 

conditions it can oxidize arsenic, which is often the first step in arsenic treatment. Oxidation of 

arsenic does not alone result in the removal of arsenic from water, but it enhances its removal 

during additional treatment. Systems that were previously using chlorine to pre-oxidize these 

chemicals may be able to achieve the same goals using chlorine dioxide, and simultaneously 

reduce TTHM and HAA5 to comply with the Stage 2 DBPR. 
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Not Significantly Affected by pH

 The efficiency of chlorine dioxide does not vary significantly in the pH range of 6 to 9. 

This benefits systems trying to meet benchmarks since the CT achieved will not vary with pH. 

This also gives systems more flexibility with their treatment. They can adjust pH values to 

improve coagulation, reduce corrosion, or reduce DBP formation without concern for losing 

disinfection efficiency. It is possible, however, that some plants using enhanced coagulation or 

enhanced softening may fall outside the pH range of 6 to 9. See the following section for further 

discussion of these cases. 

5.4.2 Potential Operational and Simultaneous Compliance Issues Associated 

 with Chlorine Dioxide Use 

Potential issues with using chlorine dioxide include the following: 

• Forms chlorite, a regulated DBP 

• Reduced effectiveness at low temperature 

• Chlorine dioxide MRDL of 0.8 mg/L 

• Can form brominated DBPs 

• Degrades when exposed to UV light 

• Residual dissipates quickly 

• Potential odor problems 

• Requires additional training and safety concerns 

 This section addresses these issues and provides recommendations for addressing them. 

Chlorite Formation

 One of the biggest disadvantages of using chlorine dioxide as a disinfectant is that it 

forms chlorite. The MCL for chlorite was set at 1.0 mg/L by the Stage 1 D/DBPR. Systems 

using chlorine dioxide must monitor daily at the entrance to the distribution system for chlorite. 

They must also collect 3 chlorite samples per month in the distribution system. As much as 70 

percent of the chlorine dioxide added to water can break down to form chlorite. This limits the 

dose of chlorine dioxide that can be used and therefore the amount of inactivation that can be 

achieved. This especially limits Cryptosporidium inactivation, since the required CT values for 

Cryptosporidium are much higher than for other microbes. 

High oxidant demand and high pH also lead to higher chlorite production. If there is 

substantial oxidant demand in a system’s water due to natural organic matter (NOM) or reduced 

metals, the oxidant demand will consume the chlorine dioxide and form chlorite, but the chlorine 
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One of the biggest disadvantages of 

using chlorine dioxide as a 

disinfectant is that it forms chlorite. 

dioxide consumed in this way will not achieve any disinfection. Systems then have to add higher 

chlorine dioxide doses to achieve sufficient inactivation, and as a result generate higher chlorite 

concentrations. 

 Water pH values above 9 also lead to 

increased production of chlorite. Systems 

with high pH as a result of enhanced 

softening or corrosion control may have 

trouble complying with the chlorite MCL. 

 Recommendations for Addressing this Issue

There are several ways to minimize chlorite concentrations. Adding chlorine dioxide 

after the filters, after the oxidant demand has been reduced, can result in lower chlorite 

concentrations. In order to comply with the LT1ESWTR or IESWTR, systems must benchmark 

and check with the state before moving the point of disinfection. Systems using chlorine dioxide 

as a pre-oxidant may also reduce the water’s oxidant demand by using pre-sedimentation before 

chlorine dioxide is injected. 

 Systems that increase pH during treatment should try to do so after the chlorine dioxide 

contact chamber. They may want to reduce the treated water’s pH to below 9 before adding the 

chlorine dioxide. 

 Even if systems control pH and have no oxidant demand outside of microbial 

inactivation, 50 to 70 percent of the chlorine dioxide consumed will form chlorite. This puts an 

effective limit on the dose that can be applied. Most systems will not be able to apply chlorine 

dioxide doses of greater than 1.2 mg/L without risking exceeding the chlorite MCL. Systems 

that cannot achieve the desired inactivation with a chlorine dioxide dose of less than 1.2 mg/L 

may want to consider using another disinfectant in addition to chlorine dioxide to achieve the 

necessary inactivation. Another possibility is that the chlorite could be reduced using a reductant 

such as thiosulfate, which would then allow the use of higher chlorine dioxide doses.

Reduced Effectiveness at Low Temperatures

 The disinfection effectiveness of chlorine dioxide is temperature sensitive. It is much 

less effective at colder temperatures. Exhibit 5.5 shows the temperature sensitivity of chlorine 

dioxide in terms of Cryptosporidium oocyst inactivation. 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-36 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 5.5 Effect of Temperature on the CT Required for Cryptosporidium

Inactivation by Chlorine Dioxide 

Temperature (o

C) CT (in mg-min/L) for 0.5-

log inactivation (69.3%)

CT (in mg-min/L) for 

2.0-log inactivation

1 305 1275 

10 138 553 

25 38 150 

Source: USEPA 2003a

 As a result of this temperature dependence, systems in cold weather climates may not be 

able to use chlorine dioxide to meet the Cryptosporidium inactivation requirements of the 

LT2ESWTR. 

 Recommendations for Addressing this Issue

 Systems may be able to achieve some inactivation by increasing the chlorine dioxide 

dose and then using a reducing agent such as thiosulfate to reduce the chlorite to chloride, or by 

using a second disinfectant. In general though, systems that regularly experience near freezing 

temperatures should probably investigate other disinfection techniques. 

Chlorine Dioxide MRDL

 Chlorine dioxide itself can have health effects at elevated levels. Therefore it has an 

MRDL of 0.8 mg/L. Systems using chlorine dioxide will have to monitor the chlorine dioxide 

residual daily at the entry point to the distribution system, before the first customer. Systems 

using chlorine dioxide may have to limit their doses to prevent exceeding the MRDL. If the 

daily entry point sample exceeds the MRDL, systems are required by the Stage 1 D/DBPR to 

monitor the chlorine dioxide residual in the distribution system. 

 Chlorite can react with excess chlorine in the distribution system to reform chlorine 

dioxide. Some systems may opt to boost with chlorine to maintain a residual in the distribution 

system. If doses are high enough, systems could exceed either the chlorine dioxide MRDL or the 

chlorite MCL. Reformed chlorine dioxide can also volatilize at consumer’s taps and react with 

volatile organics to cause odor problems. 

 Systems that use chloramines for distribution residual may have difficulty measuring 

chlorine dioxide because chloramines can interfere with its measurement. 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-37 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Recommendations for Addressing this Issue

 If chlorine dioxide doses are kept below 1 mg/L, exceeding the MRDL should not be a 

problem. If reformation of chlorine dioxide is not desired, chloramines can be used in the 

distribution system instead of chlorine. If doses much higher than 1.2 mg/L are used, a reducing 

agent can be added to the water before it enters the distribution system to reduce any chlorine 

dioxide residual or chlorite to chloride. This will also prevent formation of chlorine dioxide in 

the system by booster addition of chlorine. 

 If a system intentionally re-forms chlorine dioxide by boosting with chlorine in the 

distribution system, the system should conduct bench scale tests to determine the correct chlorine 

dose to add to achieve an adequate residual without exceeding either the chlorine dioxide MRDL 

or the chlorite MCL. Systems should take into consideration the expected residence time in the 

distribution system. Although some small systems in Canada have maintained adequate 

residuals using doses of 0.4 to 0.6 mg/L of chlorine dioxide, other larger systems have found loss 

of residual at the end of the distribution system using similar doses (Volk et al. 2002b). 

 If a system is using chloramines to maintain a distribution system residual, there are 

amperometric titration techniques which can be used to determine between various chlorine 

species. Systems should consult Standard Methods for the Examination of Water and 

Wastewater (APHA, AWWA, and WEF 1998) for details of the method.

Can Form Brominated DBPs

 Chlorine dioxide can oxidize bromide ions to bromine. The bromine can then react with 

organic matter to form brominated DBPs. Systems with high bromide concentrations that are 

near the Stage 2 DBPR limits for TTHM or HAA5 will need to take this into account. 

 Recommendations for Addressing this Issue

 Systems with high bromide concentrations that are near the Stage 2 DBPR limits for 

TTHM or HAA5 can lower DBP formation by adding chlorine dioxide after the filters, where 

organic concentrations are lower. Enhancing coagulation will also lower the amount of organic 

matter available to react with chlorine dioxide after the filters. Systems that use chlorine dioxide 

for pre-oxidation may be able to achieve some organic removal by using pre-sedimentation 

basins. Systems with very high bromide can remove it using ion exchange columns, but this is 

rarely an economical solution. 

Degrades When Exposed to UV Light

 Chlorine dioxide is sensitive to UV light and will degrade to form chlorate when exposed 

to UV light. This will reduce chlorine dioxide residuals and therefore lower inactivation. 

 Recommendations for Addressing this Issue 

 Systems using chlorine dioxide can prevent degradation by light by covering the contact 

basin. If a building or hard cover are not cost-effective or require too much space, floating 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-38 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

covers can shield the chlorine dioxide from the UV light. The manufacturer should be consulted 

in selecting the cover material to be sure it is compatible with chlorine dioxide. 

 Systems using chlorine dioxide and UV disinfection together should add the chlorine 

dioxide either after the UV reactor or sufficiently ahead of the reactor that there is no residual 

entering the reactor. Systems should not use the residence time of UV reactors to receive contact 

time credit for chlorine dioxide added earlier in the treatment process.

Residual Dissipates Quickly

 Chlorine dioxide is highly reactive and will react with GAC and anthracite in filters. 

Chloride formed by the reaction of chlorine dioxide and GAC can also adsorb to the GAC and 

cause weaker binding elements to be released. See Section 4.1 for more information on GAC 

use. Chlorine dioxide is also volatile and can be lost in rapid mix basins or other unit processes 

that have high turbulence and are exposed to the atmosphere. 

 Recommendations for Addressing this Issue

 Filters should not be used to achieve contact time for chlorine dioxide. Rapid mix basins 

can be used for contact time, but may require higher doses to achieve the same inactivation level. 

Adding the chlorine dioxide after filtration will avoid any unnecessary residual loss and will 

maximize the chlorine dioxide dose that is available for disinfection. 

 Systems adding chlorine dioxide as a pre-oxidant can add the chlorine dioxide in the 

coagulation basins. Systems with low alkalinity may see a slight rise in pH after chlorine 

dioxide addition. 

Potential Formation of Odor-Causing Compounds

 Chlorine dioxide residuals in customers tap water has been found to volatilize at the tap 

and to react with volatile organic compounds (VOCs) in customer’s houses forming compounds 

with particularly bad kerosene-type odor (Hoehn et al. 1990). It can also sometimes give a 

strong chlorinous odor. 

 Recommendations for Addressing this Issue

 The appearance of odors in customer’s homes is difficult to predict and therefore prevent. 

Utilities can keep good customer complaint records and provide public education on what to do 

if such odors occur. Suggestions for dealing with odors in the household include improving 

ventilation and using carbon filters to remove the chlorine dioxide residual. 

Additional Training Needed, Safety Concerns

 The nature of chlorine dioxide and the chemicals used to generate it requires additional 

training and safety precautions to ensure safe operation of the treatment plant. Sodium chlorite is 

often used to generate chlorine dioxide. When acidified, it can produce large amounts of 

gaseous chlorine dioxide. Chlorine dioxide at concentrations greater than 0.1 ppm is toxic and 

can cause shortness of breath, coughing, respiratory distress, and pulmonary edema. Gaseous 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-39 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

chlorine dioxide concentrations greater than 10 percent can be explosive. Sodium chlorite fires 

burn very hot and produce oxygen as a byproduct. 

 Recommendations for Addressing this Issue

 Systems should contact their chlorine dioxide equipment manufacturer to schedule any 

necessary training. Sodium chlorite should be stored away from other chemicals, especially 

acids and reducing agents. It should be stored in an area made of fire resistant materials such as 

concrete. The area should be equipped with monitoring equipment to detect chlorine dioxide and 

other chlorine components in the atmosphere. Proper ventilation and scrubbers should be 

provided in the area. A special plan should be developed to respond to leaks or fires in the area 

and the necessary equipment to implement the plan, including respirators, should be stored and 

accessible outside the sodium chlorite storage area. If more than 1,000 pounds are stored on site 

the plan must be formalized into a Risk Management Plan (RMP) and OSHA’s specific 

requirements for storage of chlorine dioxide must be satisfied. 

5.4.3 Recommendations for Gathering More Information 

Read Case Studies 

Two case studies provided in Appendix B describe systems that switched to chlorine 

dioxide to reduce DBPs in their finished water and the simultaneous compliance challenges they 

encountered when making the switch. 

Case Study #13 - Chlorine Dioxide for Primary Disinfection and Chloramines for 

Secondary Disinfection on page B-75 describes a surface water treatment plant in a wholesale 

system serving seven municipalities and approximately 92,000 people. The treatment plant 

switched from chlorine to chlorine dioxide as its primary disinfectant and from chlorine to 

chloramines for residual disinfection. In addition, the system uses chlorine dioxide intermittently 

as a pre-oxidant in its raw water. Among the challenges the system has encountered is being 

able to achieve sufficient Cryptosporidium inactivation to be granted LT2ESWTR credit and still 

comply with the Stage 1 DBPR’s chlorite MRDL. 

 Case Study #14 – Chlorine Dioxide for Primary Disinfection and Chloramines for 

Secondary Disinfection on page B-81 describes a surface water system serving fewer than 

10,000 people per day that also switched from chlorine to chlorine dioxide for CT and to 

chloramines for residual disinfection. The system, which is challenged by zebra mussels 

clogging its intake, found chlorine dioxide pretreatment works well as a replacement for the 

potassium permanganate previously used. It also adopted a monitoring program to watch for 

nitrification in its extensive distribution system. 

See Additional References

 Readers can turn to Chapter 7 for further references on this topic. Section 7.1.1 contains 

general references on water treatment, section 7.1.2 contains references on controlling DBP 

formation, and section 7.1.15 contains references on chlorine dioxide. 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-40 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Consider Additional Monitoring

 The following are some suggestions for additional monitoring that may benefit water 

systems using chlorine dioxide. The purpose of these monitoring suggestions is specifically to 

address and prevent potential simultaneous compliance issues. Water system managers should 

discuss process control monitoring with the manufacturer of their chlorine dioxide equipment or 

their engineer. 

9 If a system uses chlorine dioxide and has any kind of uncovered storage, chlorine 

dioxide residuals should be measured after the open storage to ensure that a sufficient 

chlorine dioxide residual has been maintained; and 

9 Customer complaints can be monitored to determine if chlorine dioxide residuals are 

causing problems. 

Consider Other Tools 

In addition to water quality monitoring, there are additional tools available in Chapter 6 

to help systems evaluate and improve their current water system in relation to the compliance 

issues they may face when modifying their treatment operations. Examples of tools that can be 

used when chlorine dioxide is used for Stage 2 DBPR compliance include: 

• The “Guidance Manual for Monitoring Distribution System Water Quality” 

(Kirmeyer et al. 2002) which can be used to assist water utilities in implementing a 

distribution system water quality data collection and analysis program, especially for 

chlorite and chlorine dioxide residuals; 

• The AwwaRF report “Internal Corrosion of Water Distribution System” (AwwaRF 

and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

testing protocols that can be used to evaluate changes in corrosion potential due to the 

switch to chlorine dioxide; 

• The Standard Method 2350 (Oxidant Demand/Requirement) (APHA 1998) that 

provides step-by-step instruction for the determination of chlorine dioxide demand; 

• The AwwaRF report “Water Utility Self-Assessment for the Management of 

Aesthetic Issues” (McGuire et al. 2004) which can be used to guide utilities in 

conducting self-assessment on their taste and odor issues caused by ozonation and to 

identify subsequent control strategies; 

• The AwwaRF report “Tools and Methods to Effectively Measure Customer 

Perceptions” (Colbourne 2001) which describes tools that allow utilities to measure 

customer perceptions and changes in their opinions toward the use of chlorine 

dioxide; 

• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000) which provides 

capital and O&M cost calculations for various water treatment processes based on 

user inputted design parameters; and
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-41 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

• EPA’s Microbial Toolbox Guidance Manual (USEPA N.d.e) which describes 

technologies which can be used for compliance with the LT2ESWTR. The manual 

describes advantages and disadvantages for each technology and lists design and 

operating considerations. 

Readers are encouraged to read through Chapter 6 before making any final compliance decisions 

5.5 Primary and Residual Disinfectant Use 

 Different combinations of primary and residual (i.e., secondary) disinfectants can present 

different issues and concerns. For example, when ozone is used as the primary disinfectant 

followed by chloramines as the residual disinfectant, water systems should be aware that 

increased AOC concentrations resulting from ozonation may increase the likelihood of problems 

with nitrification in the distribution system. On the other hand, the chlorite ion produced by 

chlorine dioxide during primary disinfection may actually be effective at inactivating ammoniaoxidizing bacteria and, as a result, reduce nitrification in the distribution system. 

 This section follows a different format than many of the previous sections in this 

guidance manual. Exhibit 5.6 provides a summary table of the potential benefits and 

simultaneous compliance issues of the various combinations of primary and residual 

disinfectants. Brief paragraphs then follow the table, which describe noteworthy issues related to 

different disinfectant combinations. 

 Some systems have used chlorine dioxide as a disinfectant residual. Monitoring 

requirements, the MRDL for chlorine dioxide, the MCL for chlorite, and public notification 

requirements (some violations are considered acute and require immediate notification) make 

this a difficult option to implement to meet SWTR residual disinfection requirements. Thus, 

chlorine dioxide is not included as a residual disinfectant option in Exhibit 5.6. 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-42 For the Long Term 2 and Stage 2 DBP Rules 

Exhibit 5.6 Summary of Potential Benefits and Adverse Effects Associated with Different Co

Primary and Residual Disinfectants 

Disinfection Switch 

(primary/residual, 

 from oto)

Potential Benefits Potential Adverse Effects 

1 

Chlorine/Chlorine oChlorine/Chloramines 

• improved ability to maintain a 

disinfectant residual 

• lower TTHM and HAA5 • possible improved biofilm 

control 

• improved taste and odor 

• excess ammonia can cause nitrification • possible elevated nitrite/nitrate levels • possible corrosion concerns • concerns for dialysis patients, fish owners, and 

other industrial customers 

• • • • • • • 

Chlorine/Chlorine o

Ozone/Chlorine 

• Lower TTHM and HAA5 • Cryptosporidium inactivation • better taste and odor control 

• Bromate MCL concerns • additional bromate monitoring required • may increase brominated DBPs • increased AOC may enhance biofilm growth 

• • • • 

Chlorine/Chlorine o

Ozone/Chloramines 

• Lower TTHM and HAA5 • Cryptosporidium inactivation • improved ability to maintain 

disinfectant residual 

• may improve taste and odor 

• nitrification may increase • possible elevated nitrite/nitrate levels • possible corrosion concerns • bromate MCL concerns • additional bromate monitoring required • increased AOC may enhance biofilm growth • concerns for dialysis patients, fish owners, and 

other industrial customers 

• • • • • • 

Chlorine/Chloramines o

Chlorine Dioxide/ Chloramines 

• Lower TTHM and HAA5 • Cryptosporidium inactivation • Giardia and virus inactivation • can control iron and manganese 

• chlorite from chlorine dioxide 

may control nitrification 

• additional chlorine dioxide and chlorite 

monitoring required 

• chlorite MCL concerns • chlorine dioxide MRDL concerns 

• • • • 

Chlorine/Chloramines o

Ozone/Chloramines 

• Lower TTHM and HAA5 • Cryptosporidium inactivation • improved taste and odor control • Giardia and virus inactivation 

• increased AOC can encourage nitrification and 

biofilm growth 

• additional bromate monitoring required • ozone taste and odor issues • may create brominated DBPs • bromate MCL concerns 

• • • • • 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-43 For the Long Term 2 and Stage 2 DBP Rules 

Ozone/Chlorineo



Ozone/Chloramines 

• Lower TTHM and HAA5 • improved ability to maintain a 

disinfectant residual 

• improved taste and odor control  Giardia and virus inactivation 

• AOC may encourage nitrification • concerns for dialysis patients, fish owners, and 

other industrial customers 

• possible corrosion concerns 

• • • • 

Chlorine/Chlorine or Chlorine/Chloramines o

 UV/Chlorine or 

UV/Chloramines 

• Lower TTHM and HAA5 • Cryptosporidium inactivation • Giardia and virus inactivation 

•

• UV less effective than chlorine at inactivating 

viruses 

• UV is not a pre-oxidant • less taste and odor control 

• • • 

Ozone/ Chlorine o

Ozone/ UV/Chlorine 

• additional Cryptosporidium

inactivation 

• good taste and odor control • Giardia and virus inactivation 

• ozone can lower UV transmittance • 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-44 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

5.5.1 Noteworthy Issues About Disinfectant Combinations 

Potential Drawback of Switching from Chlorine/ Chloramines to Ozone/ Chloramines

 Changing to ozone as a primary disinfectant while maintaining chloramines as a 

secondary disinfectant may impact TCR compliance due to the reaction of ozone with natural 

organic matter to form AOC. Having already established distribution system practices for 

biofilm growth in chloraminated distribution water, public water systems making this 

disinfection practice modification should focus on the biological stability of their distribution 

system water. 

 In cases where the use of ozone as the primary disinfectant increases levels of AOC, 

biological stability in the distribution system could be disrupted. AOC provides nutrient value 

for cell metabolism. In a previously chloraminated system, control of nitrification may be 

achieved using one or more of the techniques described in Section 5.1.2. However, the 

additional nutrition provided by the increased AOC may require modification to the practices. 

Alternatively, biological filtration can be used to effectively reduce nutrient levels. Biological 

filtration can also reduce dissolved oxygen, which can lead to changes in redox chemistry in the 

system and potentially change scale chemistry, affecting corrosion control treatment. 

Potential Benefit of Switching from Chlorine/ Chloramines or Ozone/ Chloramines to Chlorine 

Dioxide/ Chloramines

 McGuire et al. (2006) provided field and laboratory evidence that the chlorite ion may be 

effective at controlling nitrification in distribution systems. The study showed that even low 

dosages of chlorite (0.1 mg/L) were effective at inactivating 3 to 4 logs of ammonia-oxidizing 

bacteria over several hours. Field investigations at five water systems in Texas showed that the 

presence of chlorite in the distribution systems resulted in less loss of chloramines and ammonianitrogen. 

5.5.2 Recommendations for Gathering More Information 

Read Case Studies 

Case Study #13 - Chlorine Dioxide for Primary Disinfection and Chloramines for 

Secondary Disinfection on page B-75 describes a surface water treatment plant in a wholesale 

system serving seven municipalities and approximately 92,000 people. The treatment plant 

switched from chlorine to chlorine dioxide as its primary disinfectant and from chlorine to 

chloramines for residual disinfection. In addition, the system uses chlorine dioxide intermittently 

as a pre-oxidant in its raw water. Among the challenges the system has encountered is being 

able to achieve sufficient Cryptosporidium inactivation to be granted LT2ESWTR credit and still 

comply with the Stage 1 DBPR’s chlorite MRDL. 

Case Study #14 - Chlorine Dioxide for Primary Disinfection and Chloramines 

for Residual Disinfection on page B-81 in Appendix B provides an example of a small surface 

water system that switched from chlorine for primary and residual disinfection to chlorine 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-45 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

dioxide for primary disinfection and chloramines for residual disinfection. The system pays 

close attention to the potential for nitrification in its distribution system as a result of the 

chloramines, and has developed a monitoring program and guidelines for action to prevent 

nitrification episodes. Chlorite is one of the parameters tracked closely in the distribution 

system. The system tries to take advantage of the possibility that chlorite may be toxic to 

nitrifying bacteria. 

See Additional References

 Readers can refer to Chapter 7 for more references on this topic. Section 7.1.1 contains 

references on general water treatment, section 7.1.2 contains references on controlling DBP 

formation, Section 7.1.12 contains references on chloramines, Section 7.1.13 contains references 

on ozone, Section 7.1.14 contains references on UV disinfection, and Section 7.1.15 contain 

references on chlorine dioxide. 

Consider Tools 

 There are additional tools available to help systems evaluate and improve their current 

water system in relation to the compliance issues they may face when modifying their treatment 

operations. Readers are encouraged to read through Chapter 6 before making any final 

compliance decision. 
5. Alternative Disinfection Strategies 

Simultaneous Compliance Guidance Manual 5-46 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Simultaneous Compliance Guidance Manual 6-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules

This Chapter covers: 

 6.1 Introduction 

 6.2 Issues to Consider When Making a Compliance Decision 

 6.3 Tools for Gathering Information 

 6.4 Basic Approach for Implementing Regulatory Compliance Projects 

 The information provided in this chapter is meant to help water system managers and 

their regulators identify what issues should be considered before a change in treatment or 

operations is made. It also describes tools available to help systems collect information and a 

methodology for using information generated by these tools to make a compliance decision. 

6.1 Introduction 

 To comply with the Stage 2 DBPR and LT2ESWTR, water systems will be making 

changes to their treatment and operations ranging from relatively small adjustments in how they 

run existing systems to major capital improvements. Systems should weigh the impacts of any 

modifications they are considering, including impacts related to the issues described in Chapter 2 

and Section 6.2. They should identify what information they need to help them decide whether 

and how they can adjust their treatment to comply. If they do not have that information, they 

should identify what monitoring and/or studies are necessary to obtain it. Subsection 6.3.1 

provides resources system managers can use as guidance for collecting data about their systems 

to help them make these decisions. 

 Subsection 6.3.3 describes available desktop studies that can be useful tools for decisionmaking. Subsection 6.3.4 lists resources available about bench-scale tests, including those 

describing proper jar testing applications and procedures. These are all relatively inexpensive 

ways for a system to determine whether it can comply by optimizing its existing treatment. 

 If a system opts to install new treatment, managers should proceed carefully and in an 

informed way. They too should consider the issues described in Chapter 2 and Section 6.2 and 

how those issues affect what treatment should be installed. 

 Some water systems will have more resources available than others for evaluating the 

potential impacts of a treatment change. The references provided in Section 6.3 give readers 

perspective on how involved and expensive different evaluation tools can be. Water system 

managers, particularly those with limited resources, are encouraged to take the time to make 

informed decisions about what evaluations should be performed before new treatment is 

installed. 

 Water system managers should examine the issues listed in Section 6.2 and determine 

which are most important to their system. Failing to consider the appropriate issues can cause 

unforeseen problems. For example, a system with historic low levels of arsenic in their water 

6 Making Compliance Decisions 
6. Making Compliance Decisions 

Simultaneous Compliance Guidance Manual 6-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

may decide to switch from chlorine to chloramines based on factors such as cost, compatibility 

with the existing process, and operator knowledge of the process; however, the change in 

oxidation reduction potential in the distribution system may cause arsenic adsorbed in 

distribution system scale to be released. In making determinations, it is important not only to 

evaluate the number of positives or negatives for a given compliance response but also to 

analyze the magnitude of each advantage or disadvantage. 

 Finally, simultaneous compliance is a necessary consideration when deciding how to 

proceed. System managers should use the information and references available throughout this 

and other guidance manuals to make Stage 2 DBPR and LT2ESWTR compliance decisions with 

confidence that all regulations will be met. 

6.2 Issues to Consider When Making a Compliance Decision 

 As the previous chapters have indicated, numerous considerations should be taken into 

account when deciding on the best strategy for complying with a new regulation. Factors should 

be considered and balanced when coming to a conclusion that will satisfy all parties: system 

owners; regulatory agencies; customers; and other stakeholders. The earlier sections of this 

manual have laid out considerations for specific technologies. This section identifies issues to 

consider whenever any change is made to a water system, including changes that may not be 

discussed previously, such as novel technologies or seemingly minor operational changes. 

 Exhibit 6.1 summarizes the types of considerations that should be made before making 

changes, along with some direction as to what kind of information would help decision-makers 

during their review of those considerations. 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-3 For the Long Term 2 and Stage 2 DBP Rules  

Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or 

Issue Description of the Issue

Information to Help 

the Iss

Production Capability • Quantity and quality of water may be an issue in arid or highly developed areas. 

• Systems operating at or near peak production capabilities are 

likely to be affected by decreases in production. 

• Some treatment technologies (e.g., enhanced filtration and 

anion exchange, membrane technologies) may lower production capacity. 

• Methods of lowering disinfection byproduct (DBP) production 

(e.g., changing storage tank fill/drain cycles, removing storage tanks) can affect the amount of storage available for droughts and fire fighting. 

• Chapter 4 discusses issue

technologies in more det

• The amount of storage ne

droughts and fire fighting account when making chsystem storage. HydraulSection 6.3.2 can aid in mdeterminations. 

Compatibility with Existing Treatment Facilities 

• A public water system (PWS) is a series of linked and interrelated processes that affect one another. Systems should 

consider the effects that changes or additions to any process in the system may have on other processes within the system. 

• Any modification that changes the chemical properties of the 

water such as pH, alkalinity, metals concentrations, or organic matter concentration will likely affect the coagulation and sedimentation process. 

• Adding new chemicals may cause corrosion of plant materials. 

• Case studies #1-5, #7, an

provide examples of systa result of changing exist

• Many known effects of te

in the preceding chaptersspecific to a particular wspecific variables, or to a discussed in this guidanc

• Tools discussed in Sectio

studies, pilot testing) are determining potential eff

Production of Residuals and Disposal Issues 

• Some process changes can affect the composition or cause the 

production of residuals or other wastes. Disposal of additional waste should be taken into account when determining costs and in other considerations. 

• Systems should consider whether waste streams can be 

disposed of through sanitary sewer lines or if separate disposal means are required. Pretreatment requirements and requirements by the wastewater treatment plant should be investigated if sewer disposal is an option. 

• Process changes and changes in water quality (e.g., pH, 

alkalinity, metals concentrations, and organic matter) may affect the properties of residuals (e.g., the residual’s density and its ability to be dewatered). 

• Sections 3.6.2 and 3.7.2 p

on disposal of additional 

• Combinations of jar tests 

determine changes that mto deal with them, as desand 6.3.5, respectively. 

• Case studies #3 and #6 in 

examples of residuals dis
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-4 For the Long Term 2 and Stage 2 DBP Rules  

Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or 

Issue Description of the Issue

Information to Help 

the Iss

Site-Specific Issues • System size and available resources vary widely and can impact 

compliance strategies. 

• Systems need to consider the number and skill of operators 

when making treatment decisions. 

• Systems need sufficient space for new technologies to be easily 

accessed for service and maintenance. 

• A system should consider how the addition of any new 

processes will affect the hydraulic gradient in the plant. 

• Location can be an important factor (e.g., price and availability 

of chemicals, delivery charges for equipment and chemicals, effect of the local climate on treatment processes). 

• System-specific studies a

how various issues will aissues can be sufficiently literature reviews and dismanufacturer representatbe investigated more thotechniques discussed in S

• The case studies in Appe

system-specific issues afdecision-making. 

Compatibility with Distribution System Materials 

• Changes to water quality, especially to pH, alkalinity, or redox 

potential, can affect corrosion both in the plant and in the distribution system. 

• Some types of distribution system surfaces (e.g., highly scaled 

iron pipes) lend themselves to easily releasing scale materials into the water if changes are made to water quality. 

• Any treatment change should be analyzed to determine if it will 

change the corrosion rate of system materials. 

• Section 6.3 discusses des

bench and pilot methods studies, which can be usein corrosion rates associa

• Section 6.3.1 discusses w

which can provide warnichange unexpectedly aftemodification. 

• Case studies #2 and #5 in 

relevant examples. 

• Appendix D also include

can be used to determine rates. 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-5 For the Long Term 2 and Stage 2 DBP Rules  

Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or 

Issue Description of the Issue

Information to Help 

the Iss

Compatibility with Distribution System Operations 

• Treatment changes that alter the chemical make-up of the water 

can affect the distribution system and may require changes in its operation. 

• Systems should consider corrosion issues and microbial 

stability of the system (some chemicals added to the water may promote microbial growth in the distribution system). Systems using chloramines may have an increased risk of nitrification problems. 

• Systems may need to make distribution system changes (e.g., 

more frequent flushing, reducing residence times) to counter increased microbial activity. 

• Section 5.1.2 describes th

with chloramines. 

• Section 6.3 describes mo

predict and circumvent pnitrification. 

• Case studies #1, 2, 5, 9, 1

distribution system issueresult of treatment chang

Environmental Issues • Changes to treatment or system operations may present 

environmental issues (e.g., change to flushing procedures to remove chloramines, which are toxic to fish, before water is discharged to natural waters). 

• Constituents added to drinking water may raise issues at the 

wastewater treatment plant (WWTP) (e.g., metals such as zinc, used in some corrosion inhibitors, may inhibit the denitrification process at the WWTP) because some treated water eventually ends up in the sewer system. WWTPs may also have discharge permit limits for water quality parameters like pH, metals, and phosphorus. 

• If a system needs to purchase new land for a treatment process 

or wants to change sources, environmental issues may arise such as the presence of wetlands or endangered species; discharges to a stream or surface water body (e.g. filter backwash water, well development water) 

• Systems should review en

and WWTP requirementmajor changes. Related regulations may include Assessment Program and Program (State primacy aon wetland protection anlocal zoning ordinances. 

• Case study #6 in Append

radiation exposure issue radioactive water treatme
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-6 For the Long Term 2 and Stage 2 DBP Rules  

Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or 

Issue Description of the Issue

Information to Help 

the Iss

Consumer Driven Issues • Changes may result in consumer complaints about tastes, odors, or colored water, which can arise from many different factors. 

Changes in water chemistry can cause corrosion, causing colored water at the tap. Tastes and odors can result from high disinfectant doses or from microbial activity encouraged by water chemistry changes. 

• Changes in water rates require good communication • Good public education is important for public health protection 

and can head off consumer complaints. 

• Section 5.1.2 discusses is

understand about use of c

• Sections 6.3.4 and 6.3.5 d

pilot testing which help pcause undesired outcome

• Section 6.3.8 provides so

planning, such as public 

• Case studies #5, 8, 11, an

discuss relevant example

Preference of Operations Staff 

• Operator preferences for selecting a compliance option may be 

based on manpower and training requirements, safety concerns, monitoring requirements, chemical feed methods, the amount of automation, and equipment positioning. 

• Systems should solicit inp

since they are responsiblimplementation of any chconcerns that others have the planning process, and implications for training. 

• Case studies #10-12 in A

operational needs and imUV treatment. 

Consecutive System Requirements 

• Systems selling some or all of their water to other systems will 

have to take into account the needs of the purchasing systems, which may not have treatment themselves. 

• Consecutive (purchasing) systems may have large distribution 

systems with long residence times. Water that is delivered may meet total trihalomethane (TTHM) maximum contaminant levels (MCLs) at delivery but may exceed them nearer the end of the distribution system. 

• Mixing different types of disinfectant residuals can cause 

problems if not done very carefully. 

• EPA’s Consecutive Syste

the Stage 2 DBPR (USEPhelpful information that gfor consecutive systems. 

Cost • Cost can be a driving force behind selection of compliance 

strategies 

• Section 6.3.7 describes se

that can help with costing 
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Simultaneous Compliance Guidance Manual 6-7 March 2007 

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6.3 Tools for Gathering Information 

 The objective of this section is to provide examples of tools that can assist utilities to 

evaluate and improve their current water system in relation to compliance with Total Coliform 

Rule (TCR), Lead and Copper Rule (LCR), LT2ESWTR, and Stage 2 DBPR. These tools 

include computer software, models, technical publications, and research reports that can be 

acquired through public domains, non-profit organizations, or private companies. While some of 

the tools can be obtained freely from government agencies or the internet (such as reports and 

guidance manuals from EPA), the acquisition of some tools may either require member 

subscription (such as reports from AwwaRF) and/or fees (such as AWWA publications and 

proprietary software). 

 These tools are organized into the following eight categories: 

• Water quality monitoring 

• Hydraulic and water quality modeling for distribution systems 

• Desktop evaluations 

• Bench-scale testing 

• Pilot testing 

• Full-scale applications 

• Cost estimation 

• Community preferences 

A subsection is dedicated to each of these categories and a brief introduction is included to 

describe the purpose of tools in that category and how they relate to other subsections. 

 This document does not intend to provide a comprehensive list of tools that may be used 

to assist with simultaneous compliance, but rather to provide examples of available tools. 

Readers of this document should consult with regulatory agencies and professional organizations 

for other similar tools and updated information. 

6.3.1 Water Quality Monitoring 

 Tools included in this section provide guidance and methodologies for monitoring water 

quality in water supplies, water treatment facilities, and transmission and distribution systems. 

The first five tools are EPA documents that describe water quality sampling requirements for 

various regulations. Utilities should consult with these documents to meet the minimum 

regulatory monitoring requirements. 

• Total Coliform Rule: A Quick Reference Guide (USEPA 2001f). This EPA 

document provides updated information on water quality monitoring requirements for 

the TCR. This document is included in Appendix A and can also be obtained from 

the following EPA Web site: 

http://www.epa.gov/safewater/disinfection/tcr/pdfs/qrg_tcr_v10.pdf 
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• A Small System Guide to the Total Coliform Rule (USEPA 2001g). This EPA 

document provides guidance on monitoring requirements for small systems that serve 

3,300 or fewer people. This document can be obtained from the following EPA Web 

site: http://www.epa.gov/safewater/smallsys/small-tcr.pdf. 

• Drinking Water Regulations: National Primary Drinking Water Regulations for

Lead and Copper Rule (USEPA 2000b) & Lead and Copper Rule Minor 

Revision Fact Sheet (USEPA 1999i). Lead and Copper Rule: A Quick Reference 

Guide (USEPA 2004g). These documents summarize the monitoring requirement of 

the LCR and can be found on the following EPA web site: 

http://www.epa.gov/safewater/lcrmr/index.html . The LCR quick reference guide is 

also included in Appendix A. In addition, EPA proposed minor revisions to the LCR 

in 2006 that affect monitoring requirements. The proposed changes are summarized 

in a fact sheet available at the EPA Web site listed above. 

• Source Water Monitoring Guidance Manual for Public Water Systems (USEPA 

2006f). This EPA guidance manual for PWSs affected by the rule provides 

information on laboratory contracting, sample collection procedures and data 

evaluation, and interpretation. This guidance manual also provides information on 

grandfathering requirements for Cryptosporidium and E. coli data under the 

LT2ESWTR. The guidance manual is available at the following EPA web site: 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_swmonitoringguidance.

pdf 

• The Stage 2 DBPR Initial Distribution System Evaluation Guidance Manual 

(USEPA 2006a). This EPA document provides distribution system water quality 

monitoring requirements for the Stage 2 DBPR. This guidance manual describes the 

monitoring frequency, number of sampling locations, and the methodologies for 

selecting appropriate sampling locations for TTHM and HAA5. The guidance 

manual is available at the following EPA web site: 

http://www.epa.gov/safewater/disinfection/stage2/compliance_idse.html 

• Initial Distribution System Evaluation Guide for Systems Serving < 10,000 

People (USEPA 2006g). This EPA document provides distribution system water 

quality monitoring requirements for the Stage 2 DBPR for small systems. This 

guidance manual describes the monitoring frequency, number of sampling locations, 

and the methodologies for selecting appropriate sampling locations for TTHM and 

HAA5. It is available at the following web site: 

http://www.epa.gov/safewater/disinfection/stage2/compliance_idse.html.

• Design of Early Warning and Predictive Source-Water Monitoring Systems 

(AwwaRF Report 90878, Grayman, Deininger and Males 2001). This research 

report provides guidance on the development of early warning systems for real-time 

source water contaminant monitoring. These systems will allow utilities to predict 

water quality events in the source water that may require subsequent treatment 

adjustment in the water treatment facilities. 
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• Guidance Manual for Monitoring Distribution System Water Quality (AwwaRF 

Report 90882, Kirmeyer et al. 2002). This document provides water utilities with 

guidance on how to design and implement a distribution system water quality data 

collection and analysis program. This document features a comprehensive approach 

for collecting and analyzing water quality information, providing important input to 

costly infrastructure improvements, documenting benefits of operational procedures, 

and addressing consumer complaints. 

• Methods for Real-Time Measurement of THMs and HAAs in Distribution 

Systems (AwwaRF Report 91003F, Emmert et al. 2004). This document 

summarizes existing technologies and methods that can be used to quantify 

concentrations of total THMs and the sum of the five regulated HAA5 in near-real 

time. Some of the methods are also capable of quantifying individual THM and HAA 

species. 

• Optimizing Corrosion Control in Water Distribution Systems (AwwaRF Report 

90983, Duranceau, Townley and Bell 2004). This report demonstrates the use of a 

multi-element sensor electrochemical technique for instantaneously monitoring 

corrosion and optimizing corrosion control in water distribution systems. This 

document also describes the uses of real-time corrosion sensors to screen various 

corrosion inhibitors. 

• You may go to the following documents for national occurrence information to 

determine how your source water compares with source waters of other systems, and 

to get a sense of the technologies being commonly used by water systems with source 

water quality similar to yours. 

- USEPA. 2005e. Stage 2 Occurrence Assessment for Disinfectants and 

Disinfection Byproducts. EPA 815-R-05-011 

- USEPA. 2005a. Occurrence Assessment for the Final Stage 2 Disinfectants and 

Disinfection Byproducts Rule. Prepared by The Cadmus Group, Inc. Contract 68-

C-99-206. EPA 815-R-06-002. 

- McGuire, M.J., J.L. McLain, and A. Obolensky. 2002. Information Collection 

Rule Data Analysis. AwwaRF Report 90947. Project #2799. Denver: AwwaRF. 

6.3.2 Hydraulic and Water Quality Modeling for Distribution System 

 While documents listed in the previous section provide guidance on monitoring water 

quality, tools described in this section provide means to predict and model water quality changes 

in the distribution system based on the calculation of hydraulic retention time (water age), 

kinetics of water chemistry, and parameters that could affect water chemistry (e.g., temperature, 

pipe material, etc.). In addition to water quality modeling, most of these tools are also capable of 

hydraulic modeling. Results from these modeling exercises can assist utilities in projecting 

distribution system water quality and planning for simultaneous compliance. 
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• EPANET (USEPA 2002b). Developed by EPA, EPANET 2.0 is a Windows-based 

computer program that performs extended period simulation of hydraulic and water 

quality behavior within pressurized pipe networks. It is available at the following 

EPA Web site: http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html. Several 

software companies (including DHI, MWH Soft, Haestad Methods, and Wallingford 

Software) use EPANET as the foundation to develop their proprietary versions of 

hydraulic and water quality modeling tools. These commercial programs provide 

similar functions to that by EPANET, but may be more flexible, and user-friendly. 

• SynerGEE® Water. Developed by Advantica, SynerGEE Water is a simulation 

software package for modeling and analyzing water distribution systems. It is 

capable of conducting steady state analysis, dynamic analysis, and the analyses of 

water age, source contribution, water quality, fire flow, and pump operating costs. 

• Advanced Water Distribution Modeling and Management (Walski et al. 2003). 

Written by industry experts, it provides practical resources for engineers and 

modelers. Walks through the modeling process from start to finish - from data 

collection and field-testing to using a model for system design and complex 

operational tasks. Explores transient analysis, GIS technology applications, and 

water system vulnerability and security. 

• Water Quality Modeling of Distribution System Storage Facilities (AwwaRF 

Report 90774, Grayman et al. 2000). This document describes procedures that can 

be used to characterize water quality conditions and changes in water storage 

reservoirs. This report also provides a hydraulic model with a water quality model 

that can be used to determine the effects of daily fill and draw cycles. Optimum 

design and operation of distribution system tanks and reservoirs is also addressed. 

• Predictive Models for Water Quality in Distribution Systems (AwwaRF Report 

91023F, Clement et al. 2005). This research report provides a comprehensive 

review of the current state of predictive water quality modeling covering water 

quality processes models for corrosion and metal release, discoloration, disinfectant 

decay, DBPs, and microbial water quality. This review also describes how these 

models can be applied to distribution networks, including water quality network 

models, storage tank models, and zone level models. 

• Computer Modeling of Water Distribution Systems Second Edition (AWWA 

Manual M32) (AWWA 2004a). This manual provides step-by-step instructions for 

the design and use of computer modeling for water distribution systems. Distribution 

system operators can build an accurate and detailed “virtual” model of the system 

using computer software. Computer models can help the operators to uncover 

problems and explore different scenarios to solve the problems without actually 

entering or changing the physical distribution system. This manual also includes 

results from a survey of U.S. and Canadian water utilities on future trends of water 

distribution and water quality modeling. 
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6.3.3 Desktop Evaluations 

 Desktop evaluation tools included in this section can be used to assist utilities in 

evaluating and optimizing treatment strategies to comply with LT2ESWTR and Stage 2 DBPR. 

These tools are particularly helpful in identifying the best combination of treatment components 

for simultaneous regulatory compliance. 

• Water Treatment Plant Model for MS Windows 3.1: Version 1.55 (USEPA 

1994b). The Water Treatment Plant Model (WTP) was originally developed in support 

of the Stage 1 Disinfectant/Disinfection Byproducts Rule. It was prepared with the 

understanding that the predictions should reflect the central tendency for treatment. It 

is not to be construed that the results from the model will necessarily be applicable to 

individual raw water quality and treatment effects at unique municipalities. The 

model does not replace sound engineering judgment based on site-specific treatability 

data to evaluate the best manner in which to address the requirements of the SWTR or 

D/DBP rules. 

Originally developed by EPA in 1992 to support the Stage 1 D/DBP Rule, the Water 

Treatment Plant Model was updated in 1994 to include more data and alternative 

treatment processes to assist utilities in achieving total system optimization (TSO), 

i.e., a method by which treatment processes can be implemented such that a utility 

meets the required levels of disinfection while maintaining compliance with 

requirements of Stage 1 and, potentially, Stage 2 DBPR. Available on EPA’s website: 

http://yosemite.epa.gov/water/owrccatalog.nsf/e673c95b11602f2385256ae1007279fe/

80acea46c3412a1185256b06007259ee!OpenDocument The model was further 

updated in 1999 to include new data and to update treatment processes. The latest 

version of the model (USEPA 2001i) is available by calling 1-800-426-4791.

• Operational Evaluation Guidance Manual (USEPA N.d.f). The purpose of this 

guidance manual is to provide technical information and guidance for water systems 

and states to use for identifying and reducing significant excursions of DBP levels. 

• Self-Assessment for Treatment Plant Optimization, International Edition. 

(Lauer 2001). Optimize conventional treatment processes without investing in major 

capital improvements with this detailed guidebook. The guide provides procedures 

for optimizing particulate removal and disinfection through improvements in 

administration, maintenance, design, and operations.

• Partnership for Safe Water Information Center. The Partnership for Safe Water 

is a voluntary program organized collaboratively among EPA, AWWA, and other 

drinking water organizations to optimize water treatment plant performance above 

and beyond regulatory requirements. The Information Center, found at the following 

Web site, http://www.awwa.org/science/partnership/InfoCenter/, includes selfassessment checklists, sample reports, and fact sheets to help a water system get 

started. 

• The Rothberg, Tamburini & Winsor Blending Application Package 4.0 (AWWA 

2001a). This new RTW program is the successor of Model for Water Process and 
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Corrosion Chemistry 4.0. This computer program is developed to simplify the task of 

evaluating water chemistry associated with precipitation/coagulation and corrosion 

potential of water. The model provides prediction on the change of water quality 

(such as pH, hardness, alkalinity, and Langelier Saturation Index) in response to the 

changes in operating conditions. The new version can handle more than one water 

source under multiple blending scenarios. Although the RTW model adequately 

predicts the changes in water quality, any intent of correlating these information to 

actual corrosion potential should also include more detail and direct corrosion 

assessment as described in other sections of this document. 

• Metals Solubility Prediction Tools. Additional models have been developed to 

evaluate the solubility of metals in the distribution system. The AwwaRF report, A 

General Framework for Corrosion Control Based on Utility Experience and Control 

of Pb and Cu Corrosion By-Products Using CORRODE Software. (Edwards and 

Reiber 1997a, b) includes chemical equilibrium software that can be used to identify 

causes of corrosion problems and test the validity of different corrosion control 

strategies. The USGS PHREEQC is a computer program designed to perform a wide 

variety of low-temperature aqueous geochemical calculations. Information on 

PHREEQC is available on the USGS website at 

http://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/ 

6.3.4 Bench-Scale Testing 

 This section includes bench-scale testing procedures and methods for acquiring technical 

information on water quality, treatment efficacy, and internal corrosion potential. This 

information is critical to water quality modeling and system evaluation and optimization. Five 

categories of bench-scale testing methods are presented in this section, including: 

• Disinfectant Demand and Decay 

• DBP Growth and Decay 

• Taste and Odor Profiles 

• Jar/Column Testing Procedures 

• Internal Corrosion Assessment 

Each of these bench-scale testing tools is described below. 

Disinfectant Demand and Decay 

• Standard Method 2350, Oxidant Demand/Requirement (American Public Heath 

Association (APHA), AWWA, and Water Environment Federation (WEF)

1998). Information on chlorine demand in the transmission and distribution system is 

critical to the assurance of public health as well as an effective internal control 

practice. Increasing chlorine dosage to compensate excessive chlorine demand may 

also result in high DBP formation. This standard method provides step-by-step 

instruction on four methods for the determination of oxidant demands: one method 

each for chlorine and chlorine dioxide and two methods for ozone (batch and semibatch methods). 
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DBP Formation and Decay 

• Field and material-specific simulated distribution system testing as aids to 

understanding trihalomethane formation in distribution systems (Brereton and 

Mavinic 2002). This paper presents results from a comprehensive study using an 

extensive field monitoring program and an improved simulated distribution system 

(SDS) bench-scale test. The SDS bench test includes the potential increased chlorine 

demand caused by internal pipe walls in the evaluation of DBP formation. During 

field testing, this study compared both pre-formed THM and THM formation 

potential among several distribution system locations to reduce inherent uncertainties 

associated with the complexities of network hydraulics, leaving exposure to the 

internal pipe environment as the primary factor of interest. Findings in this paper 

suggest the reliability of using the material-specific SDS (MS-SDS) test is a better 

representation of DBP evolution in a real distribution system. The MS-SDS test is 

readily adaptable for pilot-plant studies where real distribution system conditions are 

inaccessible. This article can be acquired from the following internet Web site: 

http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_abst_e?cjce_l01-074_29_ns_nf_cjce.

• Simulated Distribution System DBP development procedure 

- Predicting the formation of DBPs by the simulated distribution system (Koch et 

al. 1991). This study developed a simulated distribution system (SDS) method 

that can be used to predict the amounts of DBPs that would form in a distribution 

system. Key parameters (including chlorine dosage, incubation temperature, and 

incubation holding time) are chosen to simulate the conditions of the treatment 

plant and the distribution. Results from this study show good correlation between 

the SDS samples and the samples collected from the distribution systems. 

- Assessing DBP yield: uniform formation conditions (Summers et al. 1996). This 

paper presents a new chlorination approach, the uniform formation conditions 

(UFC) test. The UFC test can be used to assess disinfection DBP formation under 

constant, yet representative conditions. Results from this study suggest that UFC 

test can be used for a direct comparison of DBP formation among different waters 

and allows the evaluation of how treatment changes affect DBP formation in a 

specific water. 

Taste and Odor Profiles 

• Practical Taste-and-Odor Methods for Routine Operations: Decision Tree 

(AwwaRF Report 91019, Burlingame et al. 2004). This report describes the 

existing and newly developed sensory methods for monitoring the taste-and-odor 

quality of drinking water, as well as the odor quality of source or partially-treated 

water, in order to understand the reasons for customers’ attitudes and complaints, to 

make decisions for treatment, to track problems to their sources, and to provide early 

warning of problems that are expected to recur. The new methods are described in 

detail in this report while existing methods are already described in Standard Methods 

for the Examination of Water and Wastewater (APHA 1998). The new methods 
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provide early warning to geosmin and 2-MIB, information about treatment, 

information for the approval of new installations in distribution, and the confirmation 

of customer complaints. 

• Water Utility Self-Assessment for the Management of Aesthetic Issues (AwwaRF 

Report 90978F, McGuire et al. 2004). This report provides guidance for utility to 

conduct self-assessment on its T&O control strategies. This self-assessment tool 

improves a utility’s ability to quickly identify the source of problems, implement 

control strategies, and communicate with its stakeholders. 

Jar/Column Testing Procedures 

• Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual, 

Section 3: The Step 2 Procedure and Jar Testing (USEPA 1999h). This document 

provides procedures for conducting jar testing to determine the optimum coagulation 

conditions for achieving desirable total organic carbon (TOC) removal and 

coagulated/settled water turbidity. This document can be found at the following EPA 

Web site: http://www.epa.gov/safewater/mdbp/coaguide.pdf.

• Procedures Manual for Polymer Selection in Water Treatment Plants (AwwaRF 

Report 90553, Dentel et al. 1989). This manual describes the bench-scale testing 

protocols for the selection of coagulants as well as the appropriate types of polymer 

for coagulant aids, filter aids, and sludge dewatering aids. 

• Operational Control of Coagulation and Filtration Processes (AWWA Manual 

M37, AWWA 2000). This manual provides information on standard jar testing 

procedure for bench-scale coagulation testing. 

• Enhanced and Optimized Coagulation for Particulate and Microbial Removal 

(AwwaRF Project #155, Bell et al. 2001). This research project evaluated the effect 

of enhanced and optimized coagulation on particulate and microbial removal. This 

study demonstrates the use of bench-scale studies on 18 waters corresponding to the 

EPA TOC – alkalinity matrix and removal of protozoan cysts and oocysts, viruses, 

enteric bacteria, spores, and bacteriophage. The bench-scale jar testing protocol 

described in this report can be used to determine the optimum coagulant type, 

coagulant dose, and coagulation pH for the compliance of Stage 2 DBPR, as well as 

LT2ESWTR and TCR. 

• Design of Rapid Small-Scale Adsorption Test for a Constant Diffusivity 

(Crittenden et al. 1986) This paper describes the fundamental theory and bench 

scale testing procedure for using a small adsorptive media column to quickly predict 

effective GAC adsorption capacity for specific organic compounds in full-scale 

operation. This technique, known as RSSCT, has been widely accepted by the 

chemical engineering industry and has also been used to estimate useful GAC life 

time when used for the removal of aquatic organic contaminants. 

• Prediction of GAC Performance Using Rapid-Small Scale Column Tests 

(AwwaRF Project #230, Crittendon 1989). This document describes the use of 
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RSSCT techniques to predict full-scale GAC useful life time when it is used to 

remove dissolved organic matter in drinking water source. This report also 

demonstrates how to use pilot-scale testing data to further refine the RSSCT 

prediction. 

Internal Corrosion Assessment 

• Internal Corrosion of Water Distribution Systems (AwwaRF Report 90508, 

AwwaRF and DVGW-Technologiezentrum Wasser 1996). This report covers a 

wide range of topics related to internal corrosion, such as corrosion principles, 

corrosion of various materials including copper alloys and solder, mitigation of 

corrosion impacts, assessment technologies, and approaches to corrosion control 

studies. This document also describes a bench-scale testing protocol of using various 

techniques (such as electrochemical techniques and coupon techniques) to evaluate 

corrosion potential. Other useful topics covered by this report include types of 

chemicals used for corrosion control, corrosion assessment options for metal 

plumbing materials, water quality conditions that affect corrosion of various types of 

materials, and benefits and drawbacks of bench testing versus flow-through pipe 

loops. 

6.3.5 Pilot Testing 

 

 Prior to implementing a new technology, some systems may conduct pilot testing to 

evaluate technology performance under different design and operating conditions. Tools 

described in this section provide guidelines on how to conduct pilot testing. Since technology 

development proceeds at a very fast pace in the water industry, to ensure a successful project, 

utilities are strongly encouraged to consult with experienced engineers, reputable equipment 

providers, and regulatory agencies when planning a pilot testing program. 

• Membrane Filtration Guidance Manual (USEPA 2005b). The purpose of this 

guidance manual is to provide technical information on the use of membrane filtration 

and application of the technology for compliance with the LT2ESWTR, which would 

require certain systems to provide additional treatment for Cryptosporidium. Section 

6 of this guidance manual provides general guidelines for membrane pilot testing. 

Utilities who are considering using membrane technology to comply with 

LT2ESWTR should consult with this document before conducting on-site pilot 

testing and membrane selection. This document can be found at the following EPA 

Web site: http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

• Long Term 2 Enhanced Surface Water Treatment Rule: Microbial Toolbox 

Guidance Manual (USEPA N.d.e). While there is no specific standardized pilot 

testing protocol developed for each of the treatment processes identified in the 

LT2ESWTR Toolbox, with the exception of UV and membranes, this Toolbox 

Guidance Manual provides general guidance on the Demonstration of Performance 

(DOP) protocol that can be used to develop a specific pilot testing protocol for each 

treatment technology of interest. The final version of the document will be posted on 

EPA’s Web site: http://www.epa.gov/safewater/disinfection/lt2/compliance.html
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• Internal Corrosion of Water Distribution Systems (AwwaRF Report 90508, 

AwwaRF and DVGW-Technologiezentrum Wasser 1996). As described in the 

Bench-Scale Testing section, this report provides a wide range of useful information 

on internal corrosion, including the description of an on-site pilot testing protocol for 

using a single-pass pipe loop tester to evaluate corrosion potential. 

6.3.6 Full-Scale Applications 

 This section provides useful guidelines and tools for utilities to conduct treatment plant 

assessment and optimization. The goals for these exercises are to improve treatment 

performance and to comply with multiple regulations without major capital expenditure. 

Treatment enhancement through these practices is usually achieved by optimizing operating 

conditions and minor equipment updates or additions. Major capital improvement, such as the 

construction of a new membrane facility, is not within the scope of these plant optimization 

protocols, but may be needed after other options are exhausted. 

• Comprehensive Performance Evaluations (CPE). Optimizing Water Treatment 

Plant Performance Using the Composite Correction Program (USEPA 1998a). 

This handbook consists of two components: the Comprehensive Performance 

Evaluations (CPE) and Comprehensive Technical Assistance (CTA). The CPE 

provides a set of tools that assist a utility to review and analyze its performance-based 

capabilities and associated administrative, operations, and maintenance practices. 

The goal of CPE is to help a utility to identify factors that might adversely impact a 

plant’s ability to achieve permit compliance without major capital improvements. 

The CTA provides guidance for the performance improvement phase once the CPE 

identifies performance improvement potential. Information on this EPA manual can 

be found at the following EPA Web site: 

http://www.epa.gov/ORD/NRMRL/pubs/625691027/625691027.htm.

• Partnership for Safe Water Information Center. The Partnership for Safe Water 

is a voluntary program organized collaboratively among EPA, AWWA, and other 

drinking water organizations to optimize water treatment plant performance above 

and beyond regulatory requirements. The Information Center, found at the following 

Web site, http://www.awwa.org/science/partnership/InfoCenter/ includes selfassessment checklists, sample reports, and fact sheets to help a water system get 

started. 

• Texas Optimization Program (TNRCC 2005). The Texas Optimization Program 

(TOP) is a voluntary, non-regulatory program designed to improve the performance 

of existing surface water treatment plants without major capital improvements. 

Information on TOP can be found at the following Web site: 

http://www.tceq.state.tx.us/permitting/water_supply/pdw/swmor/top/. 

• Self-Assessment for Treatment Plant Optimization (Lauer 2001). This guidebook 

presents protocols on how to optimize conventional treatment plants without 

investing in major capital improvements. This document provides procedures for 
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optimizing particulate removal and disinfection through improvements in 

administration, maintenance, design, and operations. 

• Ultraviolet Disinfection Guidance Manual (USEPA 2006b). Similar to the 

Membrane Filtration Guidance Manual, this manual provides guidance on the 

validation, selection, design, and operation of ultraviolet (UV) disinfection to comply 

with treatment requirements under the LT2ESWTR. The key to the manual is EPA’s 

recommended protocol for validation of UV reactors. The document is posted on 

EPA’s web site: 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_uvguidance.pdf 

• Full Scale Implementation of UV in Groundwater Disinfection Systems 

(AwwaRF Report No. 90860, Malley et al. 2002). This document identifies key 

issues related to full-scale UV implementation, including the importance of UV 

reactor hydraulic design, water quality evaluation, sensor calibration, and proper 

cleaning techniques to insure optimal UV performance. The report provides specific 

guidance for the selection, design, and operation of UV systems.

• Integrating UV Disinfection Into Existing Water Treatment Plants (AwwaRF 

Report No. 91086. Cotton et al. 2005.). This document provides user-friendly web 

tools that will assist utilities in assessing important disinfection decisions and UV 

implementation issues. This report also finds that electric power quality will most 

likely not cause a water utility to violate the regulatory requirements on UV 

application; however, power quality problems may reduce operational flexibility as 

well as UV lamp operations. The analysis protocol for the Cryptosporidium downtime 

and off-specification risk assessment could be used to assist regulators in developing 

criteria based on Cryptosporidium occurrence and risk. 

• Handbook of Public Water Systems, Second Edition (HDR Engineering Inc. 

2001). This handbook provides detailed engineering design information for various 

drinking water treatment processes, including granular activated carbon. 

• Integrated Membrane Systems (AwwaRF Report No. 90899, Schippers et al. 

2004). This document provides guidance on the selection, design, and operation of an 

integrated membrane system that can function as a synergistic system for removing 

microbiological contaminants and DBP precursors. The integrated system may 

include membranes (including RO, NF, UF, and MF) and any pre- or post-treatment. 

This document also provides procedures for bench and pilot testing for membrane 

elements. 

• Integrating Membrane Treatment in Large Water Utilities (AwwaRF Report 

91045F, Brown and Hugaboom 2004). This study addresses issues related to the 

integration of low pressure membranes into existing or planned water treatment 

facilities. Results from this study can be used as guidance for membrane layout, 

piping, cost comparison, and operations and maintenance. 

• NOM Rejection by, and Fouling of, NF and UF Membranes (AwwaRF Report 

90837, Amy, Clark and Pellegrino 2001). NF membranes can effectively remove 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-18 March 2007 

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natural organic matter (NOM) from a water supply, while ultrafiltration provides very 

limited NOM removal capability. This report provides information on the selection 

of appropriate membranes to achieve high NOM rejection, and also presents 

information on how water quality (such as the presence of calcium and pH) and 

operational conditions might affect NOM rejection by NF membranes. 

• Evaluation of Riverbank Filtration as a Drinking Water Treatment Process 

(AwwaRF Report No. 90922, Wang, Hubbs and Song 2002). This report describes 

the effectiveness of using river bank filtration for the removal of DBP precursors and 

microbial contaminants as a function of design and operation variables. This 

document also provides general information for riverbank system design and 

operation. 

6.3.7 Cost Estimation 

 Accurate cost estimation for facility upgrades requires a comprehensive database that 

consists of updated equipment and construction cost information. While engineering consultants 

and construction companies usually keep their proprietary cost estimation tools refined and 

updated with major cost indices, very few cost estimation tools for the drinking water industry 

are available to the general public. The cost estimation tools listed in this section represent the 

starting points for budgetary planning. Utility budgetary planning personnel should consult with 

the authors of these tools and the additional information sources listed at the end of this section 

for a more accurate and updated cost estimation. 

• Drinking Water Infrastructure Needs Survey: Modeling the Cost of 

Infrastructure (USEPA 2006c). This document provides cost models for water 

sources (such as surface water intake, well development, and aquifer storage and 

recovery wells), various treatment processes, storage, transmission/distribution 

systems, pumping, and other (i.e., SCADA). The cost of rehabilitation is also 

provided along with new installation in some cases. These cost models were designed 

for estimating national infrastructure needs and are not applicable to estimating the 

costs of specific projects at individual water systems. The document is available at 

the following EPA web site: 

http://www.epa.gov/ogwdw/needssurvey/pdfs/2003/report_needssurvey_2003_costm

odeling.pdf . 

• Water/Wastewater Costs, Windows Version 3.0, (Wesner 2000). This computer 

software provides detailed capital and O&M costs of any combination of treatment 

processes based on the treatment processes and design criteria selected by the users. 

It should be noted that not all of the cost information of every treatment component 

were updated during the 2000 revision. 

• WTCost©, 2003. This computer program is developed by the U.S. Bureau of 

Reclamation and I. Moch & Associates (sponsored by the American Membrane 

Technology Association, AMTA) for estimating membrane treatment plant costs. It 

allows the evaluation and comparison of water treatment processes that employ 

reverse osmosis/nanofiltration, electrodialysis, microfiltration/ultrafiltration, and ion 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-19 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

exchange. Using flexible cost indices and adjustable inputs, WTCost includes costs 

equations for estimating different pre- and post-treatment unit operations such as 

gravity media filtration; coagulation and flocculation with powered activated carbon 

(PAC), granulated activated carbon (GAC), alum, ferric chloride, ferrous sulfate, or 

polyelectrolyte; disinfection by chlorine, monochloramine, ozone and UV; lime/soda 

softening; electrical, including energy recovery, and chemical consumption; and 

various intake and outfall infrastructures. Labor and supervision, membrane 

replacements, amortization rates, and tanks, piping, and instrumentation are also 

included in the cost model, permitting calculation of plant capital requirements, and 

operating and maintenance costs. Information on purchasing this tool can be found at 

the following Web site: http://www.membranes-amta.org/publications.html . 

• WaterCAD (Haestad Methods). This commercial software can be used to design 

and analyze distribution systems, including pipelines, and pump stations. With the 

Cost Manager component, this program is capable of assessing the capital costs 

associated with the water distribution network including pumps, valves, and storage 

facilities, and recommends future improvements based on both hydraulic and 

financial impacts. Another cost function provided by this program is to estimate 

energy costs for constant speed and variable-speed pumps. This program can further 

examine the tradeoffs between energy costs and the capital costs required to improve 

pump efficiency. 

• Technologies and Costs for the Final Long Term 2 Enhanced Surface Water 

Treatment Rule and Final Stage 2 Disinfectants and Disinfection Byproducts 

Rule (USEPA 2005d). While this publication does not provide system-specific cost 

information, systems may use it to determine approximate and relative costs. The 

document is available at the following EPA website: 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/costs_lt2-stage2_technologies.pdf

• Technology and Cost Document for the Final Ground Water Rule. (USEPA 

2006d). Like the technologies and costs document for the final LT2ESWTR and 

Stage 2 DBPR, this cost document does not provide system-specific cost information. 

It can, however, be used to evaluate relative costs of different compliance 

technologies. The document is available at the following EPA website: 

http://www.epa.gov/safewater/disinfection/gwr/pdfs/support_gwr_costtechnologies.pdf. 

• Additional Resources for Cost Information 

- Most recent cost information or cost curves of a specific technology are published 

in professional journals or conference proceedings; 

- Utilities from the same region that have conducted similar projects at similar scale 

in recent years; 

- Reputable equipment suppliers; and 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-20 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

- Reputable engineering consultants. 

6.3.8 Community Preferences 

 This section includes recently published AwwaRF research reports that provide utility 

survey data and practical guidance to assist water utilities in improving their customer 

communications, public perception, and public involvement of the water quality issues, 

regulatory compliance issues, and potential capital improvement projects. 

• Consumer Attitude Survey Update (AwwaRF Report No. 394, AwwaRF 2000). 

This report discusses trends in public confidence and expectations, perceptions, and 

satisfaction. Also identified in this report are the driving factors behind these 

attitudes and trends and the impact of media on public confidence and customer 

satisfaction. The implications of these findings for measuring customer attitudes at 

the local utility level are also discussed. 

• Tools and Methods to Effectively Measure Customer Perceptions (AwwaRF 

Report No. 90856, Colbourne 2001). This report evaluates available assessment 

tools and methods that measure customer perceptions and changes in their opinions 

toward drinking water utilities and utility services. 

• Best Practices for a Continually Improving Customer Responsive Organization 

(AwwaRF Report 90868, Olstein 2001). This report provides case studies of five 

successful customer-driven water utilities that have used different approaches to 

achieving a continually improving customer-responsive organization. This document 

presents public input to the best practices, and a toolkit for utilities that includes a 

self-assessment questionnaire, a technology identification matrix, and benchmarking 

data. 

• Public Involvement . . . Making It Work (AwwaRF Report 90865, Nero et al. 

2001). In 1995, AwwaRF published the Public Involvement Strategies: A Manager's 

Handbook (AwwaRF 1995) to provide a framework for building consensus on 

difficult decisions. It presents a ten-step process to help water utility managers 

identify, understand, and plan public involvement and project implementation. This 

new report reduces the ten-step public involvement process to three essential steps, 

and provides a new handbook to guide utility managers through the public 

involvement process. 

• Public Involvement Strategies on the Web (AwwaRF 2003). This web-based 

interactive tool was provided by AwwaRF in 2003 to expand the AwwaRF Report 

90865 (Nero et al. 2001) by offering public involvement case studies and interactive 

features on the internet. This interactive tool can be found at the following AwwaRF 

Web site: 

http://www.awwarf.org/research/TopicsAndProjects/Resources/webTools/ch2m/defau

lt.html.

• Customer Attitudes, Behavior and the Impact of Communications Efforts 

(AwwaRF Report 90975, Tatham, Tatham and Mobley 2004). This report 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-21 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

provides guidelines on the following three areas that are critical to communication 

with customers: (1) determine whether or not communication can be used as a tool by 

water utilities to positively affect the attitudes and behaviors of residential water 

utility customers, (2) identify the types of information that should be communicated 

by water utilities to enhance customer satisfaction and the methods for 

communicating this information to customers, and (3) report on ways to inform 

customers about water quality issues and provide guidance on communication 

strategies. This report includes a CD-ROM that contains 18 Microsoft Word 

documents that illustrate the survey data for various demographic groups. 

• Effective Practices to Select, Acquire, and Implement a Utility CIS (AwwaRF 

Report 91071, Rettie et al. 2005). This report provides guidance to utilities as they 

select, acquire, and implement a customer information system (CIS). Guidelines 

provided in this document focus on four areas: (1) characterizing the current status of 

water utilities regarding CIS solutions, (2) identifying and documenting critical 

success factors (and barriers to success) related to CIS implementations, (3) 

documenting successful CIS implementations and associated practices, and (4) 

providing a CIS projects roadmap for utilities. 

• Strategic Communication Planning: A Guide for Water Utilities (AwwaRF 

Report 91106, Mobley et al. 2006). This report discusses the role of strategic 

communication planning in the overall performance and success of drinking water 

utilities. It establishes the link between high trust and credibility and the ability to 

communicate effectively. It provides a guidebook that integrates key findings from 

past research and this project to help drinking water utilities develop strategic 

communication plans. 

6.4 Basic Approach for Implementing Regulatory Compliance Projects 

 The implementation of a project to accomplish regulatory compliance involves several 

stages, including planning, design, implementation, and on-going evaluation. Exhibit 6.2 

illustrates how the tools discussed in this chapter can be used to accomplish these various project 

implementation stages. 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-22 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

In the planning stage, the project objective(s) should be defined and the data needs for 

meeting these objectives should be identified. In addition, the project team should seek input 

from all interested parties to confirm that the project has the correct focus and direction. The 

planning process typically includes an evaluation and comparison of various compliance options 

based on cost, treatment performance and other system-specific factors such as customer 

preferences. 

Once a compliance option has been selected, the design stage is initiated to develop 

specific design criteria such as chemical dosage rates, equipment sizing, and plans for integrating 

new treatment processes with existing facilities. Further testing may be warranted during the 

design stage to establish design and operating criteria under expected treatment conditions. 

Exhibit 6.2 Application of Information Gathering Tools at Various Project Implementation 

Stages 

 

Tool Type Planning Design Implementation On-going 

Evaluation 

Water quality monitoring X X X 

Hydraulic and water 

quality modeling for 

distribution systems 

X X 

 Desktop evaluations X 

Bench-scale testing X X X 

Pilot testing X X 

Full-scale applications X X X

Cost estimation X X

Community preferences X X X 

Planning 

Design 

Implementation 

On-going Evaluation 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-23 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

Project implementation is the process of carrying out the project as designed and may 

involve site and building construction, equipment installation, and start-up operations. Water 

quality monitoring activities during this stage may focus on possible construction impacts to 

finished water quality and the local environment. Additional testing may be needed to address 

issues raised during start-up operations. 

Once a project has been implemented, information should be gathered on an on-going 

basis to further optimize system operation, finished water quality, and O&M costs. Customer 

feedback is important at this stage to assure that the project has not caused unforeseen secondary 

impacts to water quality or customer service. Water quality monitoring may be intensive when 

new facilities are first put into service. 

The approach used by Owenton Water Works and Kentucky American Tri-Village in 

solving their simultaneous compliance issue (as described in Case Study # 1 in Appendix B) is 

summarized as an example. Rather than switching to a higher quality source of supply, the water 

systems decided to take a less expensive approach by changing chlorination practices at the 

existing treatment facility to reduce TTHM. The approach included the following specific steps: 

Planning 

• Identified primary objective (reducing TTHM); 

• Collected existing water quality data from both systems to define causative factors for 

elevated DBPs; and 

• Considered costs of different compliance options (developing new source vs. 

modifying existing treatment). 

Design 

• Collected profiles of TOC removal, TTHM formation, and disinfection through the 

plant and distribution system; 

• Conducted tracer studies to assess in-plant disinfection contact time; and 

• Developed design drawings and specifications for new chlorine feed equipment. 

Implementation 

• Initiated enhanced coagulation at lower pH; 

• Optimized potassium permanganate feed to raw water to control source water 

manganese; 

• Revised operational guidelines to increase hydraulic retention time in plant clearwell; 
6. Making Compliance Decisions 

 

Simultaneous Compliance Guidance Manual 6-24 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

• Moved chorination point; and 

• Optimized chlorine dosage rates at distribution system booster stations. 

On-going Evaluation 

• Evaluated results of enhanced coagulation process change; 

• Evaluated results of potassium permanganate feed changes; and 

• Continued to conduct special distribution system water quality monitoring. 
7. References 

Simultaneous Compliance Guidance Manual 7-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

The references in this chapter have been organized as follows under the following headings in 

Section 7.1, with a complete alphabetical list in Section 7.2: 

7.1 References Organized by Topic................................................................................... 7-1 

7.1.1 General................................................................................................................. 7-1 

7.1.2 Formation and Control of Chlorinated DBPs ......................................................7-9 

7.1.3 Corrosion............................................................................................................ 7-10

7.1.4 Source Management........................................................................................... 7-13 

7.1.5 Distribution System Management......................................................................7-14 

7.1.6 Problem Organisms in Water Treatment ...........................................................7-16 

7.1.7 Pre-sedimentation ..............................................................................................7-17 

7.1.8 Enhanced Coagulation and Enhanced Softening ............................................... 7-17 

7.1.9 GAC ................................................................................................................... 7-19 

7.1.10 Membranes.........................................................................................................7-20 

7.1.11 Riverbank Filtration...........................................................................................7-21 

7.1.12 Chloramines .......................................................................................................7-22 

7.1.13 Ozone ................................................................................................................. 7-25 

7.1.14 Ultraviolet Light.................................................................................................7-27 

7.1.15 Chlorine Dioxide................................................................................................ 7-28 

7.1.16 Tools for Gathering More Information..............................................................7-29 

7.1.17 Chlorination .......................................................................................................7-35 

7.2 Comprehensive List of References ............................................................................7-38 

7.1 References Organized by Topic 

7.1.1 General 

Angers, J. 2001. Question of the Month: Which Disinfectant Will Work Best for Us? 

Opflow. 27(5): 6-7, 22. 

AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: 

McGraw-Hill. 

AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water 

Supplies. 5th Edition. Letterman, R.D. (editor). New York: McGraw-Hill. 

AWWA. 1999d. Design and Construction of Small Water Systems. 2nd Edition. 228 pp. 

Denver: AWWA. 

AWWA. 1999e. Hydraulic Design Handbook. Mays, L.W.(editor). New York: McGrawHill. 

7 References 
7. References 

Simultaneous Compliance Guidance Manual 7-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd 

Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA. 

AWWA. 2004e. Recommended Practice for Backflow Prevention and Cross-Connection 

Control. 3rd Edition. AWWA Manual M14. Denver: AWWA. 

AWWA. 2005c. Disinfecting Water Mains. AWWA Standard C651-05. Denver: 

AWWA. 

AwwaRF and Lyonnaise des Eaux. 1995. Advances in Taste and Odor Treatment and 

Control. AwwaRF Report 90610. Project #629. Denver: AwwaRF. 

Becker, W.C., K. Au, C.R. O'Melia, and J.S. Young, Jr. 2004. Using Oxidants to 

Enhance Filter Performance. AwwaRF Report 90998. Project #2725. Denver: AwwaRF. 

Bevery, R. P. 2005. Filter Troubleshooting and Design Handbook. 425 pp. Denver: 

AWWA. 

Burlingame, G.A., A.M. Dietrich, T. Gittleman, and R.C. Hoehn. 2004. Practical Tasteand-Odor Methods for Routine Operations: Decision Tree. AwwaRF Report 91019. 

Project #467. Denver: AwwaRF. 

Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: 

AWWA. 

Culp, G.L. and R.L. Culp. 1974. New Concepts in Water Purification. New York: Van 

Norstrand Reinhold Co. 

DeMers, L.D. and R.C. Renner. 1993. Alternative Disinfection Technologies for Small 

Drinking Water Systems. AwwaRF Report 90619. Project #621. Denver: AwwaRF. 

Dewettinck T., E. Van Houtte, D. Geenens, K. Van Hege, and W. Verstraete. 2001. 

HACCP (Hazard Analysis and Critical Control Points) to Guarantee Safe Water Reuse 

and Drinking Water Production--a Case Study. Water Science and Technology. 43(12): 

31-8. 

DeWolfe, J., B. Dempsey, M. Taylor, and J. Potter. 2003. Guidance Manual for 

Coagulant Changeover. AwwaRF Report 90958. Project #2512. Denver: AwwaRF. 

Faust, S. and O. Aly. 1998. Chemistry of Water Treatment. 2nd Edition. New York: 

Lewis Publishers. 

Finch, G.R., D.W. Smith, and M. Belosevic. 2001. Sequential Disinfection Design 

Criteria for Inactivation of Cryptosporidium Oocysts in Drinking Water. AwwaRF 

Report 90831. Project #348. Denver: AwwaRF. 

Friedman, M. and G. Hamilton. 1997. Enhancing CTs, Coagulation, and Corrosion 

Control through Carbon Dioxide Injection. In Proceedings 1996 Water Quality 

Technology Conference, Part II. AWWA. 

Global Environment & Technology Foundation (GETF). 2000. Final Report: The US 

EPA Environmental Management System Pilot Program for Local Government. 

Annandale: GETF. 

Global Environment & Technology Foundation. 2002. Final Report: Second EMS 

Initiative for Government Entities (2000-2002). Annandale: GETF. 
7. References 

Simultaneous Compliance Guidance Manual 7-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Grant, G.B. Sc., CEA, EMS(LA), CEAS. 2004. ISO 14001 and Drinking Water Quality. 

Environmental Science and Engineering. January, 2004. 

http://www.esemag.com/0104/xcg.html 

HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd Edition. New 

York: John Wiley & Sons, Inc. 

Huck, P.M., B.M. Coffey, A. Amirtharajah, and E.J. Bouwer. 2000. Optimizing Filtration 

in Biological Filters. AwwaRF Report 90793. Project #252. Denver: AwwaRF. 

Hulsey, R.A., J.P. Malley, C.M. Spencer, A.J. Capuzzi, and S. Farabaugh. 2004. 

Evaluation of Ozone and Ultraviolet Light. AwwaRF Report 91046F. Project #2749. 

Denver: AwwaRF. 

Jacangelo, J.G., C. Gerba, and C.N. Haas. 2002. Inactivation of Waterborne Emerging 

Pathogens by Selected Disinfectants. AwwaRF Report 90886. Project #442. Denver: 

AwwaRF. 

Kawamura, S. 2000. Integrated Design and Operation of Water Treatment Facilities. 2nd 

Edition. New York: John Wiley & Sons, Inc. 

Kim, Y., Y. Lee, C.S. Gee, and E. Choi. 1997. Treatment of Taste and Odor Causing 

Substances in Drinking Water. Water Science and Technology. 35(8): 29-36. 

Lauer, W.C. 2004. Water Quality Complaint Investigator's Field Guide. 102pp. Denver: 

AWWA. 

LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988a. Factors Promoting Survival 

of Bacteria in Chlorinated Water Supplies. Applied and Environmental Microbiology. 

54(3): 649-654. 

LeChevallier, M.W., G. Di Giovanni, J.L. Clancy, Z. Bukhari, S. Bukhari, J.S. Rosen, J. 

Sobrinho, and M.M. Frey. 2002. Source Water Assessment: Variability of Pathogen 

Concentrations. AwwaRF Report 90906. Project #488. Denver: AwwaRF. 

Logsdon, G.S., A.F. Hess, M.J. Chipps, and A.J. Rachwal. 2002. Filter Maintenance and 

Operations Guidance Manual. AwwaRF Report 90908. Project #2511. Denver: 

AwwaRF. 

McGuire, M.J., J.L. McLain, and A. Obolensky. 2002. Information Collection Rule Data 

Analysis. AwwaRF Report 90947. Project #2799. Denver: AwwaRF. 

McMeen. 2001. Alternate Filtration: Placing New Technology in an Old Regulatory Box. 

In Proceedings of AWWA Membrane Conference. 

Mobley, J., E.L. Tatham, K. Reinhart, and C. Tatham. 2006. Strategic Communication 

Planning: A Guide for Water Utilities. AwwaRF Report 91106. Project #2955. Denver: 

AwwaRF. 

Mullenger, J., G. Ryan, and J. Hearn. 2002. A Water Authority's Experience with 

HACCP. Water Supply. 2(5-6): 149-155. 

Mysore, C., M. Prévost, B. Barbeau, G. Amy, M. Hernandez, D. Huffman, and B. 

Marinas. 2003. Impact of Water Quality on the Inactivation of Bacterial and Viral 

Pathogens. AwwaRF Report 90972F. Project #2592. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

NSF International. 1996. NSF International Environmental Management System 

Demonstration Project - Final Report. Ann Arbor: NSF International. 

Pennsylvania’s Multi State Working Group Pilot. The Effects of ISO 14001 

Environmental Management Systems on the Environmental and Economic Performance 

of Organizations. March 27, 1999. 

Prévost, M., P. Laurent, and J.C. Joret (editors). 2005. Biodegradable Organic Matter in 

Drinking Water Treatment and Distribution. Denver: AWWA. 

Redaud, J.L. 2005. ISO/TC 224 Service Activities Relating to Drinking Water Supply 

Systems and Wastewater Systems - Quality Criteria of the Service and Performance 

Indicators. ISO. March 31, 2005. 

Renner, R. 2004. Plumbing the Depths of D.C.’s Drinking Water Crisis. Environmental 

Science and Technology. 38(12): 224-227. 

Roig, R. and A. Saponara. 2003. ISO 14001 Environmental Management Systems: A 

Complete Implementation Guide. ISO. 

Smith, S.E., J.S. Colbourne, D.M. Holt, B.J. Lloyd, and A. Bisset. 1997. An Examination 

of the Nature and Occurrence of Deposits in a Distribution System and their effect on 

Water Quality. In Proceedings of AWWA Water Quality Technology Conference. 

Boston, November 17-21. Denver: AWWA. 

Sorg, T.J. 1988. Methods for Removing Uranium from Drinking Water. Journal of 

American Water Works Association. 80(7): 105-111. 

Texas Natural Resource Conservation Commission (TNRCC). 2005. Texas Optimization 

Program (TOP). http://www.tceq.state.tx.us/permitting/water_supply/pdw/swmor/top/ 

Tillman, G.M. 1996. Water Treatment: Troubleshooting and Problem Solving. 176 pp. 

Boca Raton: CRC Press LLC. 

Urfer, D., P.M. Huck, S.D.J. Booth, and B.M. Coffey. 1997. Biological Filtration for 

BOM and Particle Removal: A Critical Review. Journal of American Water Works 

Association. 89(12): 83-98. 

USEPA. 1989. National Primary Drinking Water Regulations; Giardia lamblia, Viruses, 

and Legionella, Maximum Contaminant Levels, and Turbidity, and Heterotrophic 

Bacteria. (Surface Water Treatment Rule), Final Rule. 43 FR 27486. June 29, 1989. 

USEPA. 1991. Guidance Manual for Compliance with the Filtration and Disinfection 

Requirements for Public Water Systems Using Surface Water Sources. Developed by 

Malcolm Pirnie and HDR. 568 pp. Washington D.C.: USEPA. 

USEPA. 1994a. National Primary Drinking Water Regulations: Disinfection and 

Disinfection Byproducts; Proposed Rule. 59 FR 38668. July 29, 1994. 

USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the 

Composite Correction Program. EPA 625/6-91/027. 

USEPA. 1998b. National Primary Drinking Water Regulations: Interim Enhanced 

Surface Water Treatment Rule; Final Rule. 63 FR 69477. December 16, 1998. 

http://www.epa.gov/safewater/mdbp/ieswtrfr.html 
7. References 

Simultaneous Compliance Guidance Manual 7-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 1998c. National Primary Drinking Water Regulations: Disinfectants and 

Disinfection By Products; Final Rule. 63 FR 69389. December 16, 1998. 

http://www.epa.gov/safewater/mdbp/dbpfr.html 

USEPA. 1999a. Disinfection Profiling and Benchmarking Guidance Manual. EPA 815-

R-99-013. 

USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R99-014. 

USEPA. 1999c. Uncovered Finished Water Reservoirs Guidance Manual. EPA 815-R99-011. http://www.epa.gov/safewater/mdbp/pdf/uncover/ufw8p.pdf 

USEPA. 1999d. Guidance Manual for Compliance with the Interim Enhanced Surface 

Water Treatment Rule: Turbidity Provisions. EPA 815-R-99-010. 

USEPA. 1999e. Unfiltered Water Supply Systems Guidance Manual. Office of Ground 

Water and Drinking Water. 

USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance 

Guidance Manual. EPA 815-R-99-011. August 1999. 

USEPA. 1999g. Guidance Manual for Conducting Sanitary Surveys of Public Water 

Systems; Surface Water and Ground Water Under the Direct Influence (GWUDI). EPA 

815-R-99-016. 

USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening Guidance 

Manual. EPA 815-R-99-012. 

USEPA. 1999i. Lead and Copper Rule Minor Revision Fact Sheet. EPA 815-F-99-010. 

USEPA. 1999j. M/DBP Stage 2 Federal Advisory Committee (FACA2) Distribution 

Systems & ICR Data Analysis (12 months). 

http://www.epa.gov/safewater/mdbp/st2oct99.html 

USEPA. 2000a. National Primary Drinking Water Regulations: Radionuclides Rule; 

Final Rule. 65 FR 76707. December 7, 2000. http://www.epa.gov/fedrgstr/EPAWATER/2000/December/Day-07/w30421.htm 

USEPA. 2000b. National Primary Drinking Water Regulations for Lead and Copper. 65 

FR 1949. January 12, 2000. http://www.epa.gov/fedrgstr/EPAWATER/2000/January/Day-12/w3.htm 

USEPA. 2000c. Lead and Copper Rule: Summary of Revisions. Office of Water. EPA 

815-R-99-020. 

USEPA. 2001a. Implementation Guidance for the Stage 1 Disinfectants/Disinfection 

Byproducts Rule. Office of Water. EPA 816-R-01-012. 

USEPA. 2001b. State Implementation Guidance for the Lead and Copper Rule Minor 

Revisions. Office of Water. EPA 816-R-01-021. 

USEPA. 2001c. Controlling Disinfection By-Products and Microbial Contaminants in 

Drinking Water. Office of Research and Development. EPA/600/R-01/110. 
7. References 

Simultaneous Compliance Guidance Manual 7-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 2001d. National Primary Drinking Water Regulations: Filter Backwash 

Recycling Rule; Final Rule. 66 FR 31085. June 8, 2001. 

http://www.epa.gov/safewater/mdbp/fr-fbr.html 

USEPA. 2001e. National Primary Drinking Water Regulations: Arsenic and 

Clarifications to Compliance and New Source Contaminants Monitoring . 66 FR 6975. 

January 22, 2001. http://www.epa.gov/fedrgstr/EPA-WATER/2001/January/Day22/w1668.htm 

USEPA. 2001f. Total Coliform Rule: A Quick Reference Guide. EPA 816-F-01-035. 

November, 2001. http://www.epa.gov/safewater/disinfection/tcr/pdfs/qrg_tcr_v10.pdf 

USEPA. 2001g. A Small System Guide to the Total Coliform Rule. Office of Water. EPA 

816-R-01-017A. http://www.epa.gov/safewater/smallsys/small-tcr.pdf 

USEPA. 2001h. Low-Pressure Membrane Filtration for Pathogen Removal: Application, 

Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001. 

http://www.epa.gov/OGWDW/disinfection/lt2/pdfs/report_lt2_membranefiltration.pdf 

USEPA. 2001k. Stage 1 Disinfectants and Disinfection Byproducts Rule: A Quick 

Reference Guide. Office of Water. EPA 816-F-01-010. May, 2001. 

http://www.epa.gov/safewater/mdbp/qrg_st1.pdf 

USEPA. 2001l. Interim Enhanced Surface Water Treatment Rule: A Quick Reference 

Guide. Office of Water. EPA 816-F-01-011. May, 2001. 

http://www.epa.gov/safewater/mdbp/qrg_ieswtr.pdf 

USEPA. 2001m. Filter Backwash Recycling Rule: A Quick Reference Guide. Office of 

Water. EPA 816-F-01-019. June 2001. http://www.epa.gov/safewater/mdbp/fbrr_qrg.pdf 

USEPA. 2001n. Arsenic and Clarifications to Compliance and New Source Monitoring 

Rule: A Quick Reference Guide. Office of Water. EPA 816-F-01-004. January, 2001. 

http://www.epa.gov/safewater/arsenic/pdfs/quickguide.pdf 

USEPA. 2002a. National Primary Drinking Water Regulations: Long Term 1 Enhanced 

Surface Water Treatment Rule. 67 FR 1811. January 14, 2002. 

http://www.epa.gov/fedrgstr/EPA-WATER/2002/January/Day-14/w409.htm 

USEPA. 2002d. Long Term 1 Enhanced Surface Water Treatment Rule: A Quick 

Reference Guide. Office of Water. EPA 816-F-02-001. January, 2002. 

http://www.epa.gov/safewater/mdbp/lt1eswtr-quick-ref.pdf 

USEPA. 2002e. Health Risks from Microbial Growth and Biofilms in Drinking Water 

Distribution Systems. Office of Ground Water and Drinking Water. 

USEPA. 2003d. Technologies and Costs for Control of Microbial Contaminants and 

Disinfection Byproducts. Office of Ground Water and Drinking Water. Washington, D.C. 

USEPA. 2004d. National Primary Drinking Water Regulations; Minor Corrections and 

Clarification to Drinking Water Regulations; National Primary Drinking Water 

Regulations for Lead and Copper. 69 FR 38850. June 29, 2004. 

http://www.epa.gov/fedrgstr/EPA-WATER/2004/June/Day-29/w14604.htm 

USEPA. 2004e. Guidance Manual for Compliance with the Long Term 1 Enhanced 

Surface Water Treatment Rule: Turbidity Provisions. EPA 816-F-02-001. 
7. References 

Simultaneous Compliance Guidance Manual 7-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 2004f. The Long Term 1 Enhanced Surface Water Treatment Rule 

Implementation Guidance. EPA 816-R-04-008. 

USEPA. 2004g. Lead and Copper Rule: A Quick Reference Guide. Office of Water. EPA 

816-F-04-009. March, 2004. 

USEPA. 2004h. Long Term 1 Enhanced Surface Water Treatment Rule Turbitity 

Provisions Technical Guidance Manual. Office of Water. EPA 816-R-04-007. August, 

2004. 

USEPA. 2004i. Lead and Copper Rule – Clarification of Requirements for Collecting 

Samples and Calculating Compliance. EPA 810-F-04-001. 

http://www.epa.gov/ogwdw/lcrmr/pdfs/memo_lcmr_samplingrequirements_1104.pdf 

USEPA. 2005a. Occurrence Assessment for the Final Stage 2 Disinfectants and 

Disinfection Byproducts Rule. Prepared by The Cadmus Group, Inc. Contract 68-C-99-

206. EPA 815-R-06-002. 

USEPA. 2005b. Membrane Filtration Guidance Manual. Office of Water. EPA 815-R-06-

009. November, 2005. 

http://www.epa.gov/ogwdw/disinfection/lt2/pdfs/guide_lt2_membranefiltration_final.pdf 

USEPA. 2005d. Technologies and Costs for the Final Long Term 2 Enhanced Surface 

Water Treatment Rule and Final Stage 2 Disinfectants and Disinfection Byproducts Rule. 

EPA 815-R-05-013. 

USEPA. 2005e. Stage 2 Occurrence Assessment for Disinfectants and Disinfection 

Byproducts. EPA 815-R-05-011. 

USEPA. 2005f. Fact Sheet - Long Term 2 Enhanced Surface Water Treatment Rule. 

Office of Water. EPA 815-F-05-009. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/fs_lt2_finalrule.pdf 

USEPA. 2005g. Fact Sheet: Stage 2 Disinfectants and Disinfection Byproducts Rule. 

Office of Water. EPA 815-F-05-003. 

http://www.epa.gov/safewater/disinfection/stage2/pdfs/fs_st2_finalrule.pdf 

USEPA. 2006a. Initial Distribution System Evaluation Guidance Manual for the Final 

Stage 2 DBPR. Office of Water. EPA 815-B-06-002. 

USEPA. 2006b. Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 

Enhanced Surface Water Treatment Rule. Office of Water. EPA 815-R-06-007. 

November, 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_uvguidance.pdf 

USEPA. 2006d. Technology and Cost Document for the Final Ground Water Rule. EPA 

815-R-06-015. 

USEPA. 2006e. Final Ground Water Rule: A Fact Sheet. Office of Water. EPA 815-F06-003. http://www.epa.gov/safewater/disinfection/gwr/pdfs/fs_gwr_finalrule.pdf 

USEPA. 2006f. Source Water Monitoring Guidance Manual for Public Water Systems 

for the Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA 

815-R-06-005. February 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_swmonitoringguidance.pdf 
7. References 

Simultaneous Compliance Guidance Manual 7-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 2006g. Initial Distribution System Evaluation Guide for Systems Serving Fewer 

than 10,000 People. Office of Water. EPA 815-B-06-001. January 2006. 

USEPA. 2007a. Small Entity Compliance Guidance for the LT2ESWTR. Office of 

Water. 

USEPA. 2007b. Small Systems Guidance Manual for the Stage 2 DBPR. Office of 

Water. 

USEPA. N.d.a. Consecutive Systems Guidance Manual for the GWR. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.b. Consecutive Systems Guidance Manual for the Stage 2 DBPR. Office of 

Water. Forthcoming. http://www.epa.gov/safewater/disinfection/stage2/compliance.html 

USEPA. N.d.c. Corrective Actions Guidance manual. GWR. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.f. Operational Evaluation Guidance Manual. Stage 2 DBPR. Office of 

Water. Forthcoming. http://www.epa.gov/safewater/disinfection/stage2/compliance.html 

USEPA. N.d.g. Sanitary Survey Guidance Manual. GWR. Office of Water. Forthcoming. 

http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.h. Complying with the GWR: Small Entity Compliance Guide. Office of 

Water. Forthcoming. 

http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.k. Source Water Monitoring Guidance Manual. GWR. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.l. The GWR Implementation Guidance. Office of Water. Forthcoming. 

http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.m. The LT2ESWTR State Implementation Guidance. Office of Water. EPA 

816-R-06-006. Forthcoming. 

http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

USEPA. N.d.n. The Stage 2 DBPR Implementation Guidance. Office of Water. EPA 816-

R-06-002. Forthcoming. 

http://www.epa.gov/safewater/disinfection/stage2/compliance.html 

Volk, C.J. and M.W. LeChevallier. 2002a. Effects of Conventional Treatment on AOC 

and BDOC Levels. Journal of American Water Works Association. 94(6): 112-123. 

Westerhoff, G.P., D. Gale, P.D. Reiter, S.A. Haskins, J.B. Gilbert, and J.B. Mannion. 

1998a. The Changing Water Utility: Creative Approaches to Effectiveness and Efficiency.

Denver: AWWA. 

White, G.C. 1992. Handbook of Chlorination and Alternative Disinfectants. 3rd Edition. 

New York: Van Nostrand Reinhold Co. 

White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. 

New York: Van Nostrand Reinhold Co. 

World Health Organization. 2004a. Guidelines for Drinking Water Quality. 3rd Edition. 

Geneva, Switzerland: World Health Organization. 
7. References 

Simultaneous Compliance Guidance Manual 7-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

World Health Organization. 2004b. Water Treatment and Pathogen Control: Process 

Efficiency in Achieving Safe Drinking Water. M.W. LeChevallier and K.K. Au (editors). 

ISBN: 1 84339 069 8. London: IWA Publishing. 

Wubbena, R.L. 2002. Strategic Business Planning as a Water Resource Management 

Tool. AwwaRF Report 90905. Project # 2698. Denver: AwwaRF. 

7.1.2 Formation and Control of Chlorinated DBPs 

Choi, J. and R. Valentine. 2002. Formation of N-nitrosodimethylamine (NDMA) from 

reaction of monochloramine: a new disinfection by-product. Water Research. 36(4): 817-

824. 

Cowman, G.A., and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid 

Speciation Resulting from Chlorination and Chloramination of Humic Extracts. In 

Proceedings of AWWA Annual Conference. New York, NY. 

George, D.B., V.D. Adams, S.A. Huddleston, K.L. Roberts, and M.B. Borup. 1990. Case 

Studies of Modified Disinfection Practices for Trihalomethane Control. AwwaRF Report 

90574. Project #201. Denver: AwwaRF. 

Krasner, S.W., S.R. Rajachandran, J.E. Cromwell III, D.M. Owen, and Z.K. Chowdhury. 

2003. Case Studies of Modified Treatment Practices for Disinfection By-Product Control. 

AwwaRF Report 90946F. Project #369. Denver: AwwaRF. 

Krasner, S.W., K.M. Reagan, J.G. Jacangelo, N.L. Patania, E.M. Aieta, and K.M. 

Gramith. 1990. Relationships Between Disinfection By-products and Water Quality 

Parameters: Implications for Formation and Control. In Proceedings, AWWA Annual 

Conference. Denver: AWWA. 

Mitch, W.A. and D.L. Sedlak. 2002. Factors Controlling Nitrosoamine Formation During 

Wastewater Chlorination. Water Supply. 2(3): 191-198. 

Najm, I. and R. Rhodes Trussell. 2001. NDMA formation in water and wastewater. 

Journal of American Water Works Association. 93(2): 92-99. 

Reckhow, D.A. and P.C. Singer. 1985. Mechanisms of Organic Halide Formation During 

Fulvic Acid Chlorination and Implications with Respect to Pre-ozonation. In Water 

Chlorination: Environmental Impact and Health Effects. Volume 5. pp. 1229-1257. 

Chelsea: Lewis Publishers, Inc. 

Routt, J.C. 2004. Lowering DBPs in Combined Systems. Opflow. 30(4): 1-7. 

Routt, J.C. and N.G. Pizzi 2000. Kentucky-American Water’s Cooperative, Step-wise 

Process of Assisting Two Small Contiguous Systems in Complying with Pending D/DBP 

Requirements. In Proceedings of AWWA Water Quality Technology Conference. 

Singer, P.C. 1992. Formation and Characterization of Disinfection Byproducts. Presented 

at the First International Conference on the Safety of Water Disinfection: Balancing 

Chemical and Microbial Risks. Washington, D.C. 

Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in 

Drinking Water. 424 pp. Denver: AWWA. 
7. References 

Simultaneous Compliance Guidance Manual 7-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Singer, P.C. and S.D. Chang. 1989. Correlations between trihalomethanes and total 

organic halides formed during water treatment. Journal of American Water Works 

Association. 81(8): 61-65. 

Singer, P.C., H.S. Weinberg, S. Krasner, H. Arora, and I. Najm. 2002. Relative 

Dominance of HAAs and THMs in Treated Drinking Water. AwwaRF Report 90844. 

Project #339. Denver: AwwaRF. 

Speitel, G.E. Jr. and J.M. Symons. 1998. Advanced Oxidation/Biodegradation Processes 

for the Destruction of TOC and Disinfection By-Product Precursors. AwwaRF Report 

#90758. Project #289. Denver: AwwaRF. 

Stevens, A.A., L.A. Moore, and R.J. Miltner. 1989. Formation and Control of NonTrihalomethane Byproducts. Journal of American Water Works Association. 81(8): 54. 

Stevens, A.A., C.J. Slocum, D.R. Seeger, and G.G. Robeck. 1976. Chlorination of 

Organics in Drinking Water. Journal of American Water Works Association. 68(11): 615. 

Summers, R.S., S.M. Hooper, H.M. Shukairy, G. Solarik, and D. Owen. 1996. Assessing 

DBP yield: uniform formation conditions. Journal of American Water Works Association. 

88(6): 80–93. 

USEPA. 2001c. Controlling Disinfection By-Products and Microbial Contaminants in 

Drinking Water. Office of Research and Development. EPA/600/R-01/110. 

7.1.3 Corrosion 

AWWA. 1993. Initial Monitoring Experiences of Large Water Utilities Under USEPA’s 

Lead and Copper Rule. Denver: WITAF. 

AWWA. 2004d. Proceedings of Workshop - Getting the Lead Out: Analysis & Treatment 

of Elevated Lead Levels in DC’s Drinking Water. San Antonio: WQTC. 

AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

Rule Corrosion Control Treatment. Denver: AWWA. 

AwwaRF. 1999. Distribution System Water Quality Changes Following Corrosion 

Control Strategies. Denver: AwwaRF. 

AwwaRF. 2007. Distribution System Corrosion and the Lead and Copper Rule: An 

Overview of AwwaRF Research. AwwaRF Special Report. Denver: AwwaRF. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Boyd, G.R., G.J. Pierson, G.J. Kirmeyer, M. Britton, and R.J. English. 2006. Pb release 

from end-use plumbing components. In Proceedings of Water Quality Technology 

Conference. November 5-9. Denver: AWWA. 

Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data. 

Opflow. 30(6):16-19. 

Butler, J.N. with a Chapter by David Cogley. 1998. Ionic Equilibrium. Solubility and pH 

Calculations. New York: Wiley-Interscience. 
7. References 

Simultaneous Compliance Guidance Manual 7-11 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Cantor, A., J.K. Park, and P. Vaiyavatjamai. 2003. Effect of Chlorine on Corrosion in 

Drinking Water Systems. Journal of American Water Works Association. 95(5): 112-

123. 

Clement, J., A. Sandvig, V. Snoeyink, W. Kriven, and P. Sarin. 1998. Analyses and 

Interpretation of the Physical, Chemical, and Biological Characteristics of Distribution 

System Pipe Scales. In Proceedings of Water Quality Technology Conference. Denver: 

AWWA. 

Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy: 

Electrochemical Impedance and Noise. Houston: National Association of Corrosion 

Engineers. 

Douglas, B.D., and D.T. Merrill. 1991. Control of Water Quality Deterioration Caused 

by Corrosion of Cement-Mortar Pipe Linings. Denver: AwwaRF. 

Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in 

Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Economic and Engineering Services, Inc. and Illinois State Water Survey. 1990. Lead 

Control Strategies. Denver: AwwaRF and AWWA. 

Edwards, M., J.F. Ferguson, and S. Reiber. 1994. The Pitting Corrosion of Copper. 

Journal of American Water Works Association. 86(7): 74-91. 

Edwards, M. and T. Holm. 2001. Role of Phosphate Inhibitors in Mitigating Lead and 

Copper Corrosion. AwwaRF Report 90823 Project #2587. Denver: AwwaRF. 

Edwards, M., S. Jacobs, and D. Dodrill 1999. Desktop Guidance for Mitigating Pb and 

Cu Corrosion Byproducts. Journal of American Water Works Association. 91(5): 66-77. 

Edwards, M., T.E. Meyer, J. Rehring, J. Ferguson, G. Korshin, and S. Perry. 1996. Role 

of Inorganic Anions, NOM, and Water Treatment Process in Copper Corrosion. 

AwwaRF Project 90687 Project #831. Denver: AwwaRF. 

Edwards, M. and S. Reiber. 1997a. A General Framework for Corrosion Control Based 

on Utility Experience. AwwaRF Report 90712A. Project #910. Denver: AwwaRF. 

Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole 

leaks in residential plumbing. Water Science and Technology. 49(2): 83-90. 

Estes-Smargiassi, S., and A. Cantor. 2006. Lead Service Line Contributions to Lead at 

the Tap. In Proceedings AWWA Water Quality Technology Conference. Denver: 

AWWA. November 2006. 

Estes-Smargiassi, S., J. Steinkrauss, A. Sandvig, and T. Young. 2006. Impact of Lead 

Service Line Replacement on Lead Levels at the Tap. In Proceedings AWWA Annual 

Conference and Exposition. San Antonio: AWWA. June, 2006. 

Kirmeyer, G.J., J. Clement, and A. Sandvig. 2000a. Distribution System Water Quality 

Changes Following Implementation of Corrosion Control Strategies. AwwaRF Report 

90764. Project #157. Denver: AwwaRF. 

Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G. 

Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring 

Strategies. AwwaRF Report 90996F Project #2679. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-12 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Kirmeyer, G.J., A.M. Sandvig, G.L. Pierson, and C.H. Neff. 1994. Development of a 

Pipe Loop Protocol for Lead Control. AwwaRF Report 90650 Project #604. Denver: 

AwwaRF. 

Korshin, G.V. and J.F. Ferguson. 1999. Corrosion and Metal Release for Lead 

Containing Materials: Influence of NOM. AwwaRF Report 90759 Project #182. 

Denver: AwwaRF. 

Lytle, D.A. and M.R. Schock. 2005. The Formation of Pb(IV) Oxides in Chlorinated 

Water. Journal of American Water Works Association. 97(11):102. 

Maas, R.P., J.C. Pitch, and A.M. Smith. 2005. Effects of Fluorides and Chloramines on 

Lead Leaching from Leaded-Brass Surfaces. Asheville Environmental Quality Institute 

Technical Report #04-137 

Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids 

and chlorine in copper pitting corrosion. In Proceedings of AWWA Annual Conference. 

Denver: AWWA. 

Rego, C.A. and M.R. Schock. 2007. Case Studies in the Integrated Use of Scale Analyses 

to Solve Lead Problems. In Proceedings of Distribution System Research Symposium. 

Denver: AWWA. 

Rushing, J.C., and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold 

water pitting of copper. In Proceedings of AWWA Water Quality Technology Conference.

Sarin, P., J.A. Clement, V.L. Snoeyink, and W.M. Waltraud. 2003. Iron Release from 

Corroded, Unlined Cast-Iron Pipes. Journal of American Water Works Association. 

95(11): 85-96. 

Sarin, P., V.L. Snoeyink, J. Bebee, K.K. Jim, M.A. Beckett, W.M. Kriven, and J.A. 

Clement. 2004. Iron Release from Corroded Iron Pipes in Drinking Water Distribution 

Systems: Effect of Dissolved Oxygen. Water Research. 38: 1259-1269. 

Schock, M. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment: 

Conforming to the Lead and Copper Rule. Presented at NACE Corrosion 1996 

Conference.

Schock, M.R., 2001. Tetravalent Lead: A Hitherto Unrecognized Control of Tap Water 

Lead Contamination. In Proceedings of AWWA Water Quality Technology Conference. 

Denver: AWWA. 

Schock, M.R. and J.C. Fox. 2001. Solving Copper Corrosion Problems while Maintaining 

Lead Control in a High Alkalinity Water using Orthophosphate. Presented at the Ohio 

AWWA Annual Conference. August 30, 2001. Cleveland: AWWA. 

Schock, M.R. and R. Giani. 2004. Oxidant/Disinfectant Chemistry and Impacts on Lead 

Corrosion. In Proceedings of AWWA Water Quality Technology Conference. Denver: 

AWWA. 

Schock, M.R., K.G. Scheckel, M. DeSantis, and T.L. Gerke. 2005. Mode of Occurrence, 

Treatment and Monitoring Significance of Tetravalent Lead. In Proceedings of AWWA 

Water Quality Technology Conference. Denver: AWWA. 
7. References 

Simultaneous Compliance Guidance Manual 7-13 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Schock, M.R., I. Wagner, and R. Oliphant. 1996. The Corrosion and Solubility of Lead in 

Drinking Water. In Internal Corrosion of Water Distribution Systems. 2nd edition. 

AwwaRF and DVGW TZW Cooperative Research Report. AwwaRF Report 90508. 

Project #725. Denver: AwwaRF. 

USEPA. 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water 

Systems. Office of Water. EPA 816-R-02-009. 

USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control 

Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 

Valentine, R. 2001. Mechanisms and Kinetics of Chloramine Loss and By-Product 

Formation in the Presence of Reactive Drinking Water Distribution System Constituents. 

Washington, D.C.: USEPA 

Veazey, M.V. 2004. New Research May Explain Pinholes in Copper Tubing. Materials 

Performance. 43(5): 18-22. 

7.1.4 Source Management 

Cooke, G.D. and R.E. Carlson. 1989. Reservoir Management for Water Quality and THM 

Precursor Control. AwwaRF Report 90569. Project #308. Denver: AwwaRF. 

Cooke, G.D. and R.H. Kennedy. 2001. Managing drinking water supplies. Lake and 

Reservoir Management. 17(3): 157-174. 

Effler, S.W., D.A. Matthews, M. T. Auer, M. Xiao, B.E. Forrer, and E.M. Owens. 2005. 

Origins, Behavior, and Modeling of THM Precursors in Lakes and Reservoirs. AwwaRF 

Report 91057F. Project #557. Denver: AwwaRF. 

Faust, S. and O. Aly. 1998. Chemistry of Water Treatment. 2nd Edition. New York: 

Lewis Publishers. 

Grayman, W.M., R.A. Deininger, and R.M. Males. 2001. Design of Early Warning and 

Predictive Source-Water Monitoring Systems. AwwaRF Report 90878. Project #2527. 

Denver: AwwaRF. 

Knappe, D.R.U., R.D. Belk, D.S. Briley, S.R. Gandy, N. Rastogi, A.H. Rike, H. 

Glasgow, E. Hannon, W.D. Frazier, P. Kohl, and S. Pugsley. 2004. Algae Detection and 

Removal Strategies for Drinking Water Treatment Plants. AwwaRF Report 90971. 

Project #360. Denver: AwwaRF. 

Kornegay, B.H. 2000. Natural Organic Matter in Drinking Water: Recommendations to 

Water Utilities. AwwaRF Report 90802. Project #2543. Denver: AwwaRF. 

USEPA. 2006f. Source Water Monitoring Guidance Manual for Public Water Systems 

for the Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA 

815-R-06-005. February 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_swmonitoringguidance.pdf 
7. References 

Simultaneous Compliance Guidance Manual 7-14 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

7.1.5 Distribution System Management 

AWWA. 1996. Water Transmission and Distribution. 2nd Edition. Denver: AWWA. 

AWWA. 1998. Distribution System Requirements for Fire Protection. 3rd Edition. 

AWWA Manual M31. 63 pp. Denver: AWWA. 

AWWA. 2001b. Elevated Water Storage Tanks: Maintenance. VHS Video. Denver: 

AWWA. 

AWWA. 2002. Unidirectional Flushing. DVD. Denver: AWWA. 

AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

AWWA. 2003b. Sizing Water Service Lines and Meters. 2nd Edition. AWWA Manual 

M22. 112 pp. Denver: AWWA. 

AWWA. 2004a. Computer Modeling of Water Distribution Systems. AWWA Manual 

M32. 160 pp. Denver: AWWA. 

AWWA. 2004c. G200-04: Distribution Systems Operation and Management. 16 pp. 

Denver: AWWA. 

AWWA. 2005b. Distribution System Water Quality Challenges in the 21st Century – A 

Strategic Guide. MacPhee, M.J. (Editor). 190 pp. Denver: AWWA. 

AWWA. 2005c. Disinfecting Water Mains. AWWA Standard C651-05. Denver: 

AWWA. 

AWWA and AwwaRF. 1992. Water Industry Database: Utility Profiles. Denver: 

AWWA. 

Brandt, M.J., J. Clement, J. Powell, R. Casey, D. Holt, N. Harris, and C.T. Ta. 2004. 

Managing Distribution System Retention Time to Improve Water Quality. Denver: 

AwwaRF. 

Camper, A.K. and W.L. Jones. 2000. Factors Affecting Microbial Growth in Model 

Distribution Systems. AwwaRF Report 90785. Project #183. Denver: AwwaRF. 

Cesario, A. L. 1995. Modeling, Analysis, and Design of Water Distribution Systems. 

Denver: AWWA. 

Clark, R.M., and W.M. Grayman. 1998. Modeling Water Quality in Drinking Water 

Distribution Systems. 231 pp. Denver: AWWA. 

Clement, J., Powell, M. Brandt, R. Casey, D. Holt, W. Grayman, and M. LeChevallier. 

2005. Predictive Models for Water Quality in Distribution Systems. AwwaRF Report 

91023F. Project #2865. Denver: AwwaRF. 

DeNadai, A.J., H.M. Gorrill, Y.J. Hasit, S.B. McCammon, R.S. Raucher, and J. 

Whitcomb. 2004. Cost and Benefit Analysis of Flushing. Denver: AWWA and AwwaRF. 

Escobar, I.C., A.A. Randall, and J. S. Taylor. 2001. Bacterial Growth in Distribution 

Systems: Effect of Assimilable Organic Carbon and Biodegradable Dissolved Organic 

Carbon. Environmental Science and Technology. 35(17): 3442-3447. 
7. References 

Simultaneous Compliance Guidance Manual 7-15 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Friedman, M.J., G. Kirmeyer, G. Pierson, S. Harrison, K. Martel, A. Sandvig, and A. 

Hanson. 2005. Development of Distribution System Water Quality Optimization Plans. 

Denver: AwwaRF. 

Friedman, M., K. Martel, A. Hill, D. Holt, S. Smith, T. Ta, C. Sherwin, D. Hiltebrand, P. 

Pommerenk, Z. Hinedi, and A. Camper. 2003. Establishing Site-Specific Flushing 

Velocities. Denver: AwwaRF. 

Grayman, W.M., L.A. Rossman, C. Arnold, R.A. Deininger, C. Smith, J.F. Smith, and R. 

Schnipke. 2000. Water Quality Modeling of Distribution System Storage Facilities. 

AwwaRF Report 90774. Projct #260. Denver: AwwaRF. 

Haestad Methods. WaterCAD. Water Distribution Modeling & Management Software. 

Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. 

Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesen, and R. Cushing. 

2000b. Guidance Manual for Maintaining Distribution System Water Quality. AwwaRF 

Report 90798. Project #357. Denver: AwwaRF. 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA. 

Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988b. Inactivation of Biofilm 

Bacteria. Applied and Environmental Microbiology. 54(10): 2492-2499. 

LeChevallier, M.W., C.D. Lowry, and R.G. Lee. 1990. Disinfection of Biofilms in a 

Model Distribution System. Journal of American Water Works Association. 82(7): 87-99. 

LeChevallier, M.W., C.D. Lowry, R.G. Lee, and D.L. Gibbon. 1993. Examining the 

Relationship Between Iron Corrosion and the Disinfection of Biofilm Bacteria. Journal 

of American Water Works Association. 85(7): 111-123. 

LeChevallier, M.W., N.J. Welch, and D.B. Smith. 1996. Full scale studies of factors 

related to coliform regrowth in drinking water. Applied and Environmental Microbiology.

62(7): 2201-2211. 

Liu, W., H. Wu, Z. Wang, S.L. Ong, J.Y. Hu and W.J. Ng. 2002. Investigation of 

Assimilable Organic Carbon (AOC) and Bacterial Regrowth in Drinking Water 

Distribution System. Water Research. 36(4): 891-898. 

Lowther, E.D. and R.H. Mosher. 1984. Detecting and Eliminating Coliform Regrowth. In 

Proceedings of AWWA Water Quality Technology Conference. Denver: AWWA. 

Martel, K., G. Kirmeyer, A. Hanson, M. Stevens, J. Mullenger, and D. Deere. 2006. 

Application of HACCP for Distribution System Protection. AwwaRF Report 91131. 

Project #2856. Denver: AwwaRF. 

Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

Najm, I. 2000. Case Studies of the Impacts of Treatment Changes on Biostability in FullScale Distribution Systems. AwwaRF Report 90816. Project #361. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-16 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

National Research Council. 2006. Drinking Water Distribution Systems: Assessing and 

Reducing Risks. Washington, D.C.: The National Academies Press. 

Pierson, G., K. Martel, A. Hill, G. Burlingame, and A. Godfree. 2001. Practices to 

Prevent Microbiological Contamination of Water Mains. Denver: AwwaRF and AWWA. 

Roberts, P.J.W., X. Tian, F. Sotiropoulos, and M. Duer. 2006. Physical Modeling of 

Mixing in Water Storage Tanks. Denver: AWWA. 

Schock, M.R. 2005. Chapter 6: Distribution Systems as Reservoirs and Reactors for 

Inorganic Contaminants. In Distribution System Water Quality Challenges in the 21st 

Century. Denver: AWWA. 

Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. 

Denver: AWWA. 

Snyder, J.K. and AK. Deb. 2002. Impacts of Fireflow on Distribution System Water 

Quality, Design, and Operation. AwwaRF Report 90913. Project #2554. Denver: 

AwwaRF. 

Tikkanen, M., J.H. Schroeter, L.Y.C. Leong, and R. Ganesh. 2001. Guidance Manual for 

Disposal of Chlorinated Water. AwwaRF Report 90863. Project #2513. Denver: 

AwwaRF. 

USEPA. 1992a. Control of Biofilm Growth in Drinking Water Distribution Systems. 

Office of Research and Development. EPA 625/R-92/001. 

USEPA. 2006a. Initial Distribution System Evaluation Guidance Manual for the Final 

Stage 2 DBPR. Office of Water. EPA 815-B-06-002. 

Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 

pp. Denver: AWWA. 

White, G.C. 1992. Handbook of Chlorination and Alternative Disinfectants. 3rd Edition. 

New York: Van Nostrand Reinhold Co. 

 

7.1.6 Problem Organisms in Water Treatment 

AWWA. 2003c. Problem Organisms in Water: Identification and Treatment (M7). 3rd 

edition. 155 pp. Denver: AWWA. 

Belanger, Scott E., D.S. Cherry, J.L. Farris, K.G. Sappington, and J. Cairns, Jr. 1991. 

Sensitivity of the Asiatic Clam to Various Biocidal Control Agents. Journal of American 

Water Works Association. 83(10): 79-87. 

Britton, J.C. and B. Morton. 1982. A dissection guide, field and laboratory manual for the 

introduced bivalve Corbicula fluminea. Malacological Review Supplement. 3:1-82. 

Cameron, G.N., J.M. Symons, S.R. Spencer, and J.Y. Ma. 1989. Minimizing THM 

Formation During Control of the Asiatic Clam: A Comparison of Biocides. Journal of 

American Water Works Association. 81(10):53-62. 

Counts, C. L., III. 1986. The zoogeography and history of the invasion of the United 

States by Corbicula fluminea (Bivalvia: Corbiculidae). American Malacological Bulletin, 
7. References 

Simultaneous Compliance Guidance Manual 7-17 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Special Edition No. 2. In Proceedings of the Second International Corbicula Symposium.

pp. 7-39. 

Lange, C. L., T. M. Short, and E. Blake. 1994. Development of Zebra Mussel Control 

Strategies for a Coalition of Vermont Water Suppliers on Lake Champlain. In 

Proceedings of the Fourth International Zebra Mussel Conference. Madison, WI. 

Stevenson, B. 1997. Controlling Zebra Mussels at Water Treatment Plant Intakes.

AwwaRF Report 90612. Project #614. Denver: AwwaRF. 

Stevenson, B. 1999. Controlling Zebra Mussels at Water Treatment Plant Intakes Part II. 

AwwaRF Report. Project #821. Denver: AwwaRF. 

7.1.7 Pre-sedimentation 

AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd 

Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA. 

Kawamura, S. 2000. Integrated Design and Operation of Water Treatment Facilities. 2nd 

Edition. New York: John Wiley & Sons, Inc. 

USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the 

Composite Correction Program. EPA 625/6-91/027. 

USEPA. N.d.e. LT2ESWTR Microbial Toolbox Guidance Manual. Office of Water. 

7.1.8 Enhanced Coagulation and Enhanced Softening 

Gates, D. 1997. The Chlorine Dioxide Handbook. 177pp. Denver: AWWA. 

Hering, J.G., P.Y. Chen, J.A. Wilkie, M. Elimelech, and S. Liang. 1996. Arsenic removal 

by ferric chloride. Journal of American Water Works Association. 88(4): 155-167. 

Hoehn, R.C. 1993. Chlorine Dioxide Use in Water Treatment. Key Issues Proceedings, 

2nd International Symposium, Chlorine Dioxide and Drinking Water Issues. pp. 1-14. 

Houston, TX. 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA. 

Krasner, S.W. and G. Amy, 1995. Jar-test evaluations of enhanced coagulation. Journal 

of American Water Works Association. 87(10): 93-107. 

Logsdon, G., A. Hess, P. Moorman, and M. Chipps. 2000. Turbidity Monitoring and 

Compliance for the Interim Enhanced Surface Water Treatment Rule. Denver: AWWA. 

Lovins, W.A., III, S.J. Duranceau, R.M. Gonzalez, and J.S. Taylor. 2003. Optimized 

Coagulation Assessment for a Highly Organic Surface Water Supply. Journal of 

American Water Works Association. 95(10): 94-108. 

Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids 

and chlorine in copper pitting corrosion. In Proceedings of AWWA Annual Conference. 

Denver: AWWA. 
7. References 

Simultaneous Compliance Guidance Manual 7-18 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water 

Treatment Plant No. 3. Membrane Softening Facility Operations Manual Final Report. 

pp. 4-19 to 4-20. 

Randtke, S.J., and R.C. Hoehn. 1999. Removal of DBP precursors by Enhanced 

Coagulation and Lime Softening. AwwaRF Report 90783. Project #814. Denver: 

AwwaRF. 

Randtke, S.J., C.E. Thiel, M.Y. Liao, and C.N. Yamaya. 1982. Removing Soluble 

Organic Contaminants by Lime-Softening. Journal of American Water Works 

Association. 74(4): 192. 

Reckhow, D.A. 1999. Control of Disinfection Byproduct Formation Using Ozone. In 

Formation and Control of Disinfection By-Products in Drinking Water. Singer, P.C. 

(editor). pp. 179-204. Denver: AWWA. 

Rushing, J.C., and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold 

water pitting of copper. In Proceedings of AWWA Water Quality Technology Conference.

Scott, K.N., J.F. Green, H.D. Do, and S.J. McLean. 1995. Arsenic Removal by 

Enhanced Coagulation. Journal of American Water Works Association. 87(4): 114-126. 

Schock, M. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment: 

Conforming to the Lead and Copper Rule. Presented at NACE Corrosion 1996 

Conference.

Shorney, H.L., and S.J. Randtke. 1994. Enhanced Lime Softening for the Removal of 

Disinfection By-Product Precursors. In Proceedings of 1994 Annual AWWA Conference. 

Denver: AWWA. 

Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in 

Drinking Water. 424 pp. Denver: AWWA. 

Sorg, T.J. 1988. Methods for Removing Uranium from Drinking Water. Journal of 

American Water Works Association. 80(7): 105-111. 

States, S., R. Tomko, M. Scheuring, and L. Casson. 2002. Enhanced coagulation and 

removal of Cryptosporidium. Journal of American Water Works Association. 94(11): 67-

77. 

Thompson, P.L., and W.L. Paulson 1998. Dewaterability of Alum and Ferric Coagulation 

Sludges. Journal of American Water Works Association. 90(4): 164-170. 

USEPA. 1991. Guidance Manual for Compliance with the Filtration and Disinfection 

Requirements for Public Water Systems Using Surface Water Sources. Developed by 

Malcolm Pirnie and HDR. 568 pp. Washington D.C.: USEPA. 

USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening Guidance 

Manual. EPA 815-R-99-012. 

USEPA. 2001h. Low-Pressure Membrane Filtration for Pathogen Removal: Application, 

Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001. 

http://www.epa.gov/OGWDW/disinfection/lt2/pdfs/report_lt2_membranefiltration.pdf 

USEPA. 2005c. A Regulator’s Guide to the Management of Radioactive Residuals from 

Drinking Water Treatment Technologies. USEPA 816-R-05-004. 
7. References 

Simultaneous Compliance Guidance Manual 7-19 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. N.d.e. LT2ESWTR Microbial Toolbox Guidance Manual. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia 

for Controlling Bromate During Cryptosporidium Disinfection. Journal of American 

Water Works Association. 95(10): 82-93. 

7.1.9 GAC 

American Chemical Society. 1983. Treatment of Water by Granular Activated Carbon. 

Advances in Chemistry Series Number 202. M.J. McGuire and I.H. Suffet (editors). 

Washington, D.C.: American Chemical Society. 

Crittenden, J.C. 1989. Prediction of GAC Performance Using Rapid Small-Scale Column 

Tests. AwwaRF Report 90549. Project #230. Denver: AwwaRF. 

Klotz, M., P. Werner, and R. Schweisfurth. 1976. Investigations concerning the 

microbiology of activated carbon filters. pp. 312-330. H. Sontheimer (editor). Translation 

of Reports on Special Problems of Water Technology. Volume 9 Adsorption. Conference 

held in Karlsruhe, Federal Republic of Germany. USEPA, Municipal Environmental 

Research Laboratory, Cincinnati, OH. Report No. EPA 600/9-76-030. 

Leung, K.S. and R.L. Segar. 2000. Adsorption Interactions of S-Triazine Herbicide with 

Trace Organics in a GAC Filter-Absorber. Presented at the AWWA Conference. Denver: 

AWWA. 

McTigue, N. and D. Cornwell. 1994. The Hazardous Potential of Activated Carbons 

Used in Water Treatment. AwwaRF Report 90640. Project #620. Denver: AwwaRF. 

Najm, I., M. Kennedy, and W. Naylor. 2005. Lignite versus Bituminous GAC for 

Biofiltration - A Case Study. Journal of American Water Works Association. 97(1): 94-

101. 

Owen, D.M. 1998. Removal of DBP Precursors by GAC Adsorption. AwwaRF Report 

90744. Project #816. Denver: AwwaRF. 

USEPA. 2003d. Technologies and Costs for Control of Microbial Contaminants and 

Disinfection Byproducts. Office of Ground Water and Drinking Water. Washington, D.C. 

Xie, Y., H. Wu, and H. Tung. 2004. Haloacetic Acid Removal Using Granular Activated 

Carbon. AwwaRF Report 91041F. Project #2825. Denver: AwwaRF. 

Youngsug, K., L. Yeongho, C.S. Gee, and C. Euiso. 1997. Treatment of Taste and Odor 

Causing Substances in Drinking Water. Water Science and Technology. 35(8): 29-36. 

Parson, F., P.R. Wood, and J. DeMarco. 1980. Bacteria associated with granular activated 

carbon columns. In Proceedings of AWWA Technology Conference. p.271-296. Denver: 

AWWA. 

Krasner, S.W., S.R. Rajachandran, J.E. Cromwell III, D.M. Owen, and Z.K. Chowdhury. 

2003. Case Studies of Modified Treatment Practices for Disinfection By-Product Control. 

AwwaRF Report 90946F. Project #369. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-20 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd Edition. New 

York: John Wiley & Sons, Inc. 

USEPA. 2001h. Low-Pressure Membrane Filtration for Pathogen Removal: Application, 

Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001. 

http://www.epa.gov/OGWDW/disinfection/lt2/pdfs/report_lt2_membranefiltration.pdf 

7.1.10 Membranes 

Adham, S., K. Chiu, K. Gramith, and J. Oppenheimer. 2005. Development of a 

Microfiltration and Ultrafiltration Knowledge Base. AwwaRF Report 91059. Project 

#2763. Denver: AwwaRF. 

Amy, G., M. Clark, and J. Pellegrino. 2001. NOM Rejection by, and Fouling of, NF and 

UF Membranes. AwwaRF Report 90837. Project #390. Denver: AwwaRF. 

Amy, G.L., M. Edwards, M. Benjamin, K. Carlson, J. Chwirka, P. Brandhuber, L. 

McNeill, and F. Vagliasindi. 2000. Arsenic Treatability Options and Evaluation of 

Residuals Management Issues. AwwaRF Report 90771. Project #153. Denver: AwwaRF. 

AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. Denver: 

AWWA. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Brown, J. and and D. Hugaboom. 2004. Integrating Membrane Treatment in Large Water 

Utilities. AwwaRF Report 91045F. Project #2876. Denver: AwwaRF. 

Chang, S.D., W.D. Bellamy, and H. Ruiz. 1994. Removal of Arsenic by Enhanced 

Coagulation and Membrane Technology. In Proceedings AWWA Annual Conference. 

New York: AWWA. 

Duranceau, S.J. 2001. Membrane Practices for Water Treatment. Denver: AWWA. 

Glucina, K., A. Alvarez, and J.M. Laine. 2000. Assessment of an integrated membrane 

system for surface water treatment. In Proceeding of the conference in drinking and 

industrial water production. Italy. 2:113-122. 

HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd Edition. New 

York: John Wiley & Sons, Inc. 

Laine, J.M., J.G. Jacangelo, E.W. Cummings, K.E. Carns, and J. Mallevialle. 1993. 

Influence of Bromide on Low Pressure Membrane Filtration for Controlling DBPs in 

Surface Waters. Journal of American Water Works Association. 85(6): 87-99. 

Malcom Pirnie, Inc. 1992. Arsenic Removal Pilot-Studies. Prepared for EPA Office of 

Ground Water and Drinking Water. 

Mallevialle, J., , P.E. Odendaal, and M.R. Wiesner. 1996. Water Treatment Membrane 

Processes. AwwaRF Report 90716. Project #826. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-21 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water 

Treatment Plant No. 3. Membrane Softening Facility Operations Manual Final Report. 

pp. 4-19 to 4-20. 

Panayides, N. 1999. Operational Procedures of a New 27 MGD Nanofiltration Membrane 

Water Treatment Plant (WTP No. 9) in South Florida. Palm Beach County Water 

Utilities Department. 

Parson, F., P.R. Wood, and J. DeMarco. 1980. Bacteria associated with granular activated 

carbon columns. In Proceedings of AWWA Technology Conference. p.271-296. Denver: 

AWWA. 

Schippers, J.C., J.C. Kruithof, M.M. Nederlof, J.A.M.H. Hofman, and J. Taylor. 2004. 

Integrated Membrane Systems. AwwaRF Report 90899. Project #264. Denver: AwwaRF. 

U.S. Bureau of Reclamation. 1998. The Desalting and Water Treatment Membrane 

Manual: A Guide to Membranes for Municipal Water Treatment. 2nd Edition. Technical 

Service Center, Water Treatment Engineering and Research, Denver, CO. 

USEPA. 2001h. Low-Pressure Membrane Filtration for Pathogen Removal: Application, 

Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001. 

http://www.epa.gov/OGWDW/disinfection/lt2/pdfs/report_lt2_membranefiltration.pdf 

USEPA. 2005b. Membrane Filtration Guidance Manual. Office of Water. EPA 815-R-06-

009. November, 2005. 

http://www.epa.gov/ogwdw/disinfection/lt2/pdfs/guide_lt2_membranefiltration_final.pdf 

USEPA. N.d.e. LT2ESWTR Microbial Toolbox Guidance Manual. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

7.1.11 Riverbank Filtration 

Gollnitz, W.D., J.L.Clancy, J. B. McEwen, and S. C. Garner. 2005. Riverbank Filtration 

for IESWTR Compliance. Journal of American Water Works Association. 97(12):64-76. 

Julich, W. and J. Schubert (editors). Proceedings of International Riverbank Filtration 

Conference, Nov. 2-4, Duesseldorf. International Arbeitgemeinschaft der Wasserwerke 

im Rheineinzugsgebiet, Amsterdam. 

Ray, C. (editor). 2001. Riverbank Filtration: Understanding Contaminant 

Biogeochemistry and Pathogen Removal. NATO Science Series IV. Earth and 

Environmental Sciences, Vol. 14. Norwell: Kluwer Academic Publishers. 

USEPA. 2001h. Low-Pressure Membrane Filtration for Pathogen Removal: Application, 

Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001. 

http://www.epa.gov/OGWDW/disinfection/lt2/pdfs/report_lt2_membranefiltration.pdf 

Wang, J., S. Hubbs, and R. Song. 2002. Evaluation of Riverbank Filtration as a Drinking 

Water Treatment Process. AwwaRF Report 90922. Project #2622. Denver: AwwaRF. 

Weiss, W.J., E.J. Bouwer, W.P. Ball, C.R. O’Melia, M.W. LeChevallier, H. Arora, and 

T.F. Speth. 2003. Riverbank Filtration – fate of DBP presursors and selected 

microorganisms. Journal of American Water Works Association. 95(10): 68-81. 
7. References 

Simultaneous Compliance Guidance Manual 7-22 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

7.1.12 Chloramines 

Arber, R., M.A. Speed, and F. Scully. 1985. Significant Findings Related to Formation of 

Chlrinated Organics, in the Presence of Chloramines. In Water Chlorination: 

Environmental Impact and Health Effects, Vol. 7. Edited by R.L. Jolley, R.J. Bull, W.P. 

Davis, S. Katz, M.H. Roberts, and V.A. Jacobs. Chelsea: Lewis Publishers. 

AWWA. 2004b. Converting Distribution Systems from Chlorine to Chloramines. DVD. 

Denver: AWWA. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Bonds, R.W. 2004. Effect of Chloramines on Ductile-Iron Pipe Gaskets of Various 

Elastomer Compounds. Journal of American Water Works Association. 96(4): 153-160. 

Boyd, G.R., K.M. Dewis, A.M. Sandvig, G.J. Kirmeyer, S.H. Reiber, and G.V. Korshin. 

2006. Effect of Changing Disinfectants on Distribution System Lead and Copper Release, 

Part 1—Literature Review. AwwaRF Report 91152. Project # 3107. Denver: AwwaRF. 

Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions. 

AwwaRF Report 90856. Project #466. Denver: AwwaRF. 

Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in 

Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole 

leaks in residential plumbing. Water Science and Technology. 49(2): 83-90. 

Flannery, B., L.B. Gelling, D.J. Vugia, J.M. Weintraub, J.J. Salemo, and M.J. Conroy. 

2006. Reducing Legionella colonization of water systems with monochloramine. 

Emerging Infectious Diseases.12(4): 588-596. 

Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage 

Disinfection By-Products. New York State Section AWWA. New York: O’Brien and 

Gere. 

Gianatasio, J.M. 1985. Experience at Tampa, Florida, Using Combined Chlorine to 

Control THM Production. Presented at the North Carolina AWWA/WPLC Joint Technical 

Conference. Charlotte, NC. 

Harms, L.L. and C. Owen. 2004. A Guide for the Implementation and Use of 

Chloramines. AwwaRF Report 91018F. Project #2847. Denver: AwwaRF. 

Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan, 

and D. Van Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution 

System Nitrification. AwwaRF Report 90949. Project #553. Denver: AwwaRF. 

Hoehn, R.C., A.M. Dietrich, W.S., Farmer, M.P. Orr, R.G. Lee, E.M. Aieta, D.W. Wood 

III, and G. Gordon. 1990. Household Odors Associated with the Use of Chlorine Dioxide. 

Journal of American Water Works Association. 82(4): 166-172. 

Jacangelo, J.G., V.P. Olivieri, and K. Kawata. 1987. Mechanism of Inactivation of 

Microorganisms by Combined Chlorine. Denver: AWWA. 
7. References 

Simultaneous Compliance Guidance Manual 7-23 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA. 

Kirmeyer, G.J., M. LeChevallier, H. Barbeau, K. Martel, G. Thompson, L. Radder, W. 

Klement, and A. Flores. 2004a. Optimizing Chloramine Treatment. AwwaRF Report 

90993. Project #2760. Denver: AwwaRF and AWWA. 

Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, and R. Wolfe. 1995. Nitrification 

Occurrence and Control in Chloraminated Water Systems. AwwaRF Report 90669. 

Project #710. Denver: AwwaRF. 

Krasner, S.W., and S.E. Barrett. 1985. Aroma and Flavor Characteristics of Free Chlorine 

and Chloramines. In Proceedings of Twelfth Annual AWWA Water Quality Technology 

Conference. Denver: AWWA. 

Krasner, S.W., S.R. Rajachandran, J.E. Cromwell III, D.M. Owen, and Z.K. Chowdhury. 

2003. Case Studies of Modified Treatment Practices for Disinfection By-Product Control. 

AwwaRF Report 90946F. Project #369. Denver: AwwaRF. 

LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988a. Factors Promoting Survival 

of Bacteria in Chlorinated Water Supplies. Applied and Environmental Microbiology. 

54(3): 649-654. 

LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988b. Inactivation of Biofilm 

Bacteria. Applied and Environmental Microbiology. 54(10): 2492-2499. 

LeChevallier, M.W., C.D. Lowry, and R.G. Lee. 1990. Disinfection of Biofilms in a 

Model Distribution System. Journal of American Water Works Association. 82(7): 87-99. 

Lytle, D.A. and M.R. Schock. 2005. The Formation of Pb(IV) Oxides in Chlorinated 

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Maas, R.P., J.C. Pitch, and A.M. Smith. 2005. Effects of Fluorides and Chloramines on 

Lead Leaching from Leaded-Brass Surfaces. Asheville Environmental Quality Institute 

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McGuire, M.J., N.I. Lieu, and M.S. Pearthree. 1999. Using chlorite ion to control 

nitrification. Journal of American Water Works Association. 91(10): 52-61. 

McGuire, M.J., M.S. Pearthree, N.K. Blute, K.F. Arnold, and T. Hoogerwerf. 2006. 

Nitrification Control by Chlorite Ion at Pilot Scale. Journal of American Water Works 

Association. 98(1): 95-105. 

Means, E.G., K.N. Scott, M.L. Lee, and R.W. Wolfe. 1986. Effects of Chlorine and 

Ammonia Application Points on Bactericidal Efficiency. Journal of American Water 

Works Association. 78(1): 62-69. 

Ollos, P.J., P.M. Huck, and R.M. Slawson. 2003. Factors Affecting Biofilm 

Accumulation in Model Distribution Systems. Journal of American Water Works 

Association. 94(1): 87-97. 

Reiber, S. 1991. Corrosion Effects by Chloramines. Denver: AwwaRF. 

Reiber, S. 1993. Chloramine Effects on Distribution System Materials. AwwaRF Report 

90624. Project #508. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-24 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Schock, M.R., 2001. Tetravalent Lead: A Hitherto Unrecognized Control of Tap Water 

Lead Contamination. In Proceedings of AWWA Water Quality Technology Conference. 

Denver: AWWA. 

Schock, M.R. 2005. Chapter 6: Distribution Systems as Reservoirs and Reactors for 

Inorganic Contaminants. In Distribution System Water Quality Challenges in the 21st 

Century. Denver: AWWA. 

Schock, M.R. and R. Giani. 2004. Oxidant/Disinfectant Chemistry and Impacts on Lead 

Corrosion. In Proceedings of AWWA Water Quality Technology Conference. Denver: 

AWWA. 

Schock, M.R., I. Wagner, and R. Oliphant. 1996. The Corrosion and Solubility of Lead in 

Drinking Water. In Internal Corrosion of Water Distribution Systems. 2nd edition. 

AwwaRF and DVGW TZW Cooperative Research Report. AwwaRF Report 90508. 

Project #725. Denver: AwwaRF. 

Skadsen, J. 1993. Nitrification in a Distribution System. Journal of American Water 

Works Association. 85(7): 95-103. 

Speitel, G.E. Jr., P.G. Pope, M.R. Collins, and M. Martin-Doole. 2004. Disinfection ByProduct Formation and Control During Chloramination. AwwaRF Report 91040F. 

Project #2677. Denver: AwwaRF. 

Symons, J.M., G.E. Speitel, Jr., C. Hwang, S.W. Krasner, and S.E. Barrett. 1998. Factors 

Affecting DBP Formation During Chloramination. AwwaRF Report 90728. Project #803. 

Denver: AwwaRF. 

Tokuno, S. 1999. Granulated Activated Carbon Filtration and Chloramine. Water 

Engineering Management. 146(1): 16-21. 

Uchida, M. and A. Okuwaki. 1999. Dissolution Behavior of Lead Plates in Aqueous 

Nitrate Solutions. Corrosion Science. 41(10): 1977-1986. 

USEPA. 1992a. Control of Biofilm Growth in Drinking Water Distribution Systems. 

Office of Research and Development. EPA 625/R-92/001. 

USEPA. 1992b. Lead and Copper Rule Guidance Manual, Vol. II: Corrosion Control 

Treatment. Prepared by Malcolm Pirnie, Inc. & Black & Veatch. September 1992. 

Valentine, R.L. 1998. Chloramine Decomposition in Distribution System and Model 

Waters. AwwaRF Report 90721. Project #937. Denver: AwwaRF. 

Vikesland, P.J., N.G. Love, K. Chandran, E.M. Fiss, R. Rebodos, A.E. Zaklikowski, F.A. 

DiGiano, and B. Ferguson. 2006. Seasonal Chlorimation Practices and Impacts to 

Chloraminating Utilties. Denver: AwwaRF. 

Wilczak, A. L. Hoover, and H.H. Lai. 2003. Effects of Treatment Changes on 

Chloramine Demand and Decay. Journal of American Water Works Association. 95(7): 

94-107. 

Wilczak, A., J.G. Jacangelo, J.P. Marcinko, L.H. Odell, G.J. Kirmeyer, and R.L. Wolfe. 

1996. Occurrence of Nitrification in Chloraminated Distribution Systems. Journal of 

American Water Works Association. 88(7): 74-85. 
7. References 

Simultaneous Compliance Guidance Manual 7-25 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Wolfe, R.L, N.I. Lieu, G. Izagiurre, and E.G. Means. 1990. Ammonia-Oxidizing Bacteria 

in a Chloraminated Distribution System: Seasonal Occurrence, Distribution, and 

Disinfection Resistance. Applied and Environmental Microbiology. 56(2): 451-462. 

Wolfe. R.L., E.G. Means, M.K. Davis, and S.E. Barrett. 1988. Biological Nitrification in 

Covered Reservoirs Containing Chloraminated Water. Journal of American Water Works 

Association. 80(9): 109-114. 

7.1.13 Ozone 

Angara, G., L. Cummings, W.R. Knocke, and G.C. Budd. 2004. Intermediate and LongTerm Manganese Control Strategies During the Upgrade of the Little Falls Water 

Treatment Plant. In Proceedings AWWA WQTC. Denver: AWWA. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

AwwaRF and Compagnie Generale des Eaux. 1992. Ozone in Water Treatment: 

Application and Engineering. AwwaRF Report. Project #421. Denver: AwwaRF. 

Becker, W.C., O'Brien and Gere Engineers, C.R. O'Melia, and Department of Geography 

and Environmental Engineering, The Johns Hopkins University. 1996. Optimizing 

Ozonation for Turbidity and Organics (TOC) Removal by Coagulation and Filtration. 

AwwaRF Report 90703. Project #934. Denver: AwwaRF. 

Carlson, K.H. and G.L. Amy. 2001. Ozone and biofiltration optimization for multiple 

objectives. Journal of American Water Works Association. 93(1): 88-98. 

Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions. 

AwwaRF Report 90856. Project #466. Denver: AwwaRF. 

Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in 

Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Escobar, I.C. and A.A. Randall. 2001. Case study: Ozonation and distribution system 

biostability. Journal of American Water Works Association. 93(10): 77-89. 

Gabelich, C.J., W.R. Knocke, B.M. Coffey, R. Johnston, H. Do, and A.A. Mofidi. 2005. 

Manganese Desorption from filter media: experiences with biological filtration. AWWA 

Annual Conference and Exposition. San Francisco: AWWA. 

Galey, C., V. Mary-Dile, D. Gatel, G. Amy, and J. Cavard. 2001. Controlling bromate 

formation. Journal of American Water Works Association. 93(8): 105-115. 

Huck, P.M., B.M. Coffey, A. Amirtharajah, and E.J. Bouwer. 2000. Optimizing Filtration 

in Biological Filters. AwwaRF Report 90793. Project #252. Denver: AwwaRF. 

Kennedy, R.M. and M.E. Richardson. 2004. Ozone and Biofiltration, An Improved Water 

Quality at Wilmington. PowerPoint Presentation. 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA. 
7. References 

Simultaneous Compliance Guidance Manual 7-26 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

LeChevallier, M.W., W.C. Becker, P. Schorr, and R.G. Lee. 1992. Evaluating the 

Performance of Biologically Active Rapid Sand Filters. Journal of American Water 

Works Association. 84(4): 136. 

McGuire, M., R. Hund, G. Burlingame, N. Graziano, and L. Sullivan. 2004. Water Utility 

Self-Assessment for the Management of Aesthetic Issues. AwwaRF Report 90978F. 

Project #2777. Denver: AwwaRF. 

National Research Council. 2000. Identifying Future Drinking Water Contaminants. 

Washington, D.C.: National Academy Press. 

Price, M.L., CH2M Hill, in association with East Bay Municipal Utility District and City 

of Tampa (FL) Water Department. 1994. Ozone and Biological Treatment for DBP 

Control and Biological Stability. AwwaRF Report 90649. Project #504. Denver: 

AwwaRF. 

Reckhow, D.A. 1999. Control of Disinfection Byproduct Formation Using Ozone. In 

Formation and Control of Disinfection By-Products in Drinking Water. Singer, P.C. 

(editor). pp. 179-204. Denver: AWWA. 

Reckhow, D.A. J.K. Edzwald, and J.E. Tobiason. 1993. Ozone as an Aid to Coagulation 

and Filtration. AwwaRF Report 90643. Project #403. Denver: AwwaRF. 

Stolarik, G. and J.D. Christie. 1997. A Decade of Ozonation in Los Angeles. In 

Proceedings, IOA Pan American Group Annual Conference. Lake Tahoe, NV. 

Urfer, D., P.M. Huck, S.D.J. Booth, and B.M. Coffey. 1997. Biological Filtration for 

BOM and Particle Removal: A Critical Review. Journal of American Water Works 

Association. 89(12): 83-98. 

Urfer, D., P.M. Huck, G.A. Gagnon, D. Mutti, and F. Smith. 1999. Modeling enhanced 

coagulation to improve ozone disinfection. Journal of American Water Works 

Association. 91(3): 59-73. 

USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the 

Composite Correction Program. EPA 625/6-91/027. 

USEPA. 1999a. Disinfection Profiling and Benchmarking Guidance Manual. EPA 815-

R-99-013. 

USEPA. 1999j. M/DBP Stage 2 Federal Advisory Committee (FACA2) Distribution 

Systems & ICR Data Analysis (12 months). 

http://www.epa.gov/safewater/mdbp/st2oct99.html 

Van der Kooij, D. 1997. Bacterial Nutrients and Biofilm Formation Potential within 

Drinking Water Distribution Systems. In Proceedings, AWWA Water Quality Technology 

Conference.

Wert, E.C., D.J. Rexing, and R.E. Zegers. 2005. Mangenese release from filter media 

during the conversion to biological filtration. AWWA Annual Conference and Exposition.

San Francisco: AWWA. 

Westerhoff, G.P., R. Song, G. Amy, and R. Minear. 1998b. NOM's role in bromine and 

bromate formation during ozonation. Journal of American Water Works Association. 

90(2): 82-94. 
7. References 

Simultaneous Compliance Guidance Manual 7-27 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Westerhoff, P., R.S. Summers, Z. Chowdhury, and S. Kommineni. 2005. OzoneEnhanced Biofiltration for Geosmin and MIB Removal. AwwaRF Report 91075. Project 

#2775. Denver: AwwaRF. 

Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia 

for Controlling Bromate During Cryptosporidium Disinfection. Journal of American 

Water Works Association. 95(10): 82-93. 

Zhou, P. and J. Neemann. 2005. Use of Chlorine Dioxide and Ozone for Control of 

Disinfection By-Products. AwwaRF Report 90981F. Project #2742. Denver: AwwaRF. 

7.1.14 Ultraviolet Light 

Ballester, N.A. and J.P. Malley, Jr. 2004. Sequential Disinfection of Adenovirus Type 2 

with UV-Chlorine-Chloramine. Journal of American Water Works Association. 

96(10):97-103. 

Brodkorb, T. and D. Richards. 2004. UV disinfection design to avoid chlorine destruction 

in high UVT waters. Presented at Ontario Water Works Association. Niagara Falls, 

Ontario, Canada. May, 2004. 

Bukhari, Z., T.M. Hargy, J.R. Bolton, B. Dussert, and J.L. Clancy. 1999. MediumPressure UV for Oocyst Inactivation. Journal of American Water Works Association. 

91(3): 86-94. 

Clancy, J.L., Z. Bukhari, T.M. Hargy, J.R. Bolton, B.W. Dussert, and M.M. Marshall. 

2000. Using UV to inactivate Cryptosporidium. Journal of American Water Works 

Association. 92(9): 97-104. 

Cotton, C.A., D.M. Owen, G.C. Cline, and T.P. Brodeur. 2001. UV disinfection costs for 

inactivating Cryptosporidium. Journal of American Water Works Association. 93(6): 82-

94. 

Cotton, C.A., L. Passantino, D.M. Owen, M. Bishop, M. Valade, W. Becker, R. Joshi, J. 

Young, M. LeChevallier, and R. Hubel. 2005. Integrating UV Disinfection Into Existing 

Water Treatment Plants. AwwaRF Report 91086. Project #2861. Denver: AwwaRF. 

Crozes, G. 2001. Practical Aspects of UV Disinfection. AwwaRF Report 90875. Project 

#2623. Denver: AwwaRF. 

Gagnon, G.A., T.S. Dykstra, K.C. O’Leary, R.C. Andrews, C. Chauret and C. Volk. 

2004. Impact of UV Disinfection on Biological Stability. AwwaRF Report 90999F. 

Project #2723. Denver: AwwaRF. 

Mackey, E.D., J. Malley, Jr., R.S. Cushing, M. Janex-Habibi, N. Picard, and J. Laine. 

2001. Bridging Pilot-Scale Testing to Full-Scale Design of UV Disinfection Systems. 

AwwaRF Report 90991. Project #2593. Denver: AwwaRF. 

Malley, J. 2000. The state of the art in using UV disinfection for waters and wastewater 

in North America. In Proceedings of ENVIRO 2000. April 9-13. Sydney: Australian 

Water Association. 
7. References 

Simultaneous Compliance Guidance Manual 7-28 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Malley, J., Jr., E.D. Mackey, R.S. Cushing, M. Janex-Habibi, N. Picard, and J. Laîné. 

2004. Inactivation of Pathogens with Innovative UV Technologies. AwwaRF Report 

91024. Project #2593. Denver: AwwaRF. 

Malley, J.P., Jr., B.A. Petri, G.V. Hunter, D. Moran, M. Nadeau, and J. Leach. 2002. Full 

Scale Implimentation of UV in Groundwater Disinfection Systems. AwwaRF Report 

90860. Project #474. Denver: AwwaRF. 

Mofidi, A.A., H. Baribeau, P.A. Rochelle, R. De Leon, B.M. Coffey, and J.F. Green. 

2001. Disinfection of Cryptosporidium parvum with polychromatic UV light. Journal of 

American Water Works Association. 93(6): 95-109. 

National Research Council. 2000. Identifying Future Drinking Water Contaminants. 

Washington, D.C.: National Academy Press. 

NWRI and AwwaRF. 2000. Ultraviolet Disinfection Guidelines for Drinking Water and 

Water Reuse. AwwaRF Report. Project #2674. Denver: AwwaRF. 

Shaw, J.P., J.P. Malley Jr., and S. Willoughby. 2000. Effects of UV irradiation on organic 

matter. Journal of American Water Works Association. 92(4): 157-167. 

USEPA. 2006b. Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 

Enhanced Surface Water Treatment Rule. Office of Water. EPA 815-R-06-007. 

November, 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_uvguidance.pdf 

Wilczak, A. and H. Lai. 2006. Preliminary bench and pilot evaluation of UV-irradiation 

for nitrification control. In Proceedings of the American Water Works Association Annual 

Conference. June 11 – 16. San Antonio: AWWA. 

7.1.15 Chlorine Dioxide 

American Public Heath Association (APHA), AWWA, and Water Environment 

Federation (WEF). 1998. Standard Methods for the Examination of Water and 

Wastewater. 20th Edition. 220 pp. Washington, D.C.: APHA, AWWA, and WEF. 

Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, 

G.A. Ganon, J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on 

Transmission, Treatment, and Distribution System Performance. AwwaRF Report 91082. 

Project #2843. Denver: AwwaRF. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions. 

AwwaRF Report 90856. Project #466. Denver: AwwaRF. 

Dietrich, A.M. and R.C. Hoehn. 1991. Taste-and-Odor Problems Associated with 

Chlorine Dioxide. AwwaRF Report 90589. Project #405. Denver: AwwaRF. 

Gallagher, D.L., R.C. Hoehn, and A.M. Dietrich. 1994. Sources, Occurrence, and 

Control of Chlorine Dioxide By-Product Residuals in Drinking Water. AwwaRF Report 

90656. Project #611. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-29 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Gates, D. 1997. The Chlorine Dioxide Handbook. 177pp. Denver: AWWA. 

Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage 

Disinfection By-Products. New York State Section AWWA. New York: O’Brien and 

Gere. 

Gordon, G. 2001. Is all chlorine dioxide created equal? Journal of American Water 

Works Association. 93(4): 163-174. 

Hoehn, R.C. 1993. Chlorine Dioxide Use in Water Treatment. Key Issues Proceedings, 

2nd International Symposium, Chlorine Dioxide and Drinking Water Issues. pp. 1-14. 

Houston, TX. 

Hoehn, R.C., A.M. Dietrich, W.S., Farmer, M.P. Orr, R.G. Lee, E.M. Aieta, D.W. Wood 

III, and G. Gordon. 1990. Household Odors Associated with the Use of Chlorine Dioxide. 

Journal of American Water Works Association. 82(4): 166-172. 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA. 

Krasner, S.W., S.R. Rajachandran, J.E. Cromwell III, D.M. Owen, and Z.K. Chowdhury. 

2003. Case Studies of Modified Treatment Practices for Disinfection By-Product Control. 

AwwaRF Report 90946F. Project #369. Denver: AwwaRF. 

McGuire, M., R. Hund, G. Burlingame, N. Graziano, and L. Sullivan. 2004. Water Utility 

Self-Assessment for the Management of Aesthetic Issues. AwwaRF Report 90978F. 

Project #2777. Denver: AwwaRF. 

Volk, C.J., R. Hofmann, C. Chauret, G.A. Gagnon, G. Ranger, and R.C. Andrews. 2002b. 

Implementation of chlorine dioxide disinfection: Effects of the treatment change on 

drinking water quality in a full-scale distribution system. Journal of Environmental 

Engineering and Science. 1(5): 323-330. 

Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia 

for Controlling Bromate During Cryptosporidium Disinfection. Journal of American 

Water Works Association. 95(10): 82-93. 

Zhou, P. and J. Neemann. 2005. Use of Chlorine Dioxide and Ozone for Control of 

Disinfection By-Products. AwwaRF Report 90981F. Project #2742. Denver: AwwaRF. 

7.1.16 Tools for Gathering More Information 

Advantica. SynerGEE Water. Advanced water distribution analysis. 

http://www.advantica.biz/Default.aspx?page=321 

American Public Heath Association (APHA), AWWA, and Water Environment 

Federation (WEF). 1998. Standard Methods for the Examination of Water and 

Wastewater. 20th Edition. 220 pp. Washington, D.C.: APHA, AWWA, and WEF. 

ASTM D2688-83 Method B. 1983a. Standard Test Methods for the Corrosivity of 

Water in the Absence of Heat Transfer (Weight Loss Protocol). Philadelphia: American 

Society for Testing and Materials. 
7. References 

Simultaneous Compliance Guidance Manual 7-30 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ASTM D2688-83 Method C. 1983b. Standard Test Methods for the Corrosivity of 

Water in the Absence of Heat Transfer (Machined Nipple Test). Philadelphia: American 

Society for Testing and Materials. 

ASTM D934-80. 2003. Standard Practices for Identification of Crystalline Compounds in 

Water Formed Deposits by X-Ray Diffraction. Philadelphia: American Society for 

Testing and Materials. 

ASTM G1-81. 1981. Recommended Practise for Preparing, Cleaning and Evaluating 

Corrosion Test Specimens. Philadelphia: American Society for Testing and Materials. 

ASTM G46-76. 1976. Recommended Practise for the Examination and Evaluation of 

Pitting Type Corrosion. Philadelphia: American Society for Testing and Materials. 

AWWA. 1993. Initial Monitoring Experiences of Large Water Utilities Under USEPA’s 

Lead and Copper Rule. Denver: WITAF. 

AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd 

Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA. 

AWWA. 2001a. The Rothberg, Tamburini & Winsor Blending Application Package 4.0. 

AWWA Catalog Number 53042. 

AWWA. 2004a. Computer Modeling of Water Distribution Systems. AWWA Manual 

M32. 160 pp. Denver: AWWA. 

AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

Rule Corrosion Control Treatment. Denver: AWWA. 

AwwaRF. 1999. Distribution System Water Quality Changes Following Corrosion 

Control Strategies. Denver: AwwaRF. 

AwwaRF. 2000. Consumer Attitude Survey Update. AwwaRF Report 394. Project #394. 

Denver: AwwaRF. 

AwwaRF. 2003. Public Involvement Strategies on the Web. Interactive tool that builds 

on AwwaRF Report. 

http://www.awwarf.org/research/TopicsAndProjects/Resources/webTools/ch2m/default.h

tml 

AwwaRF. 2007. Distribution System Corrosion and the Lead and Copper Rule: An 

Overview of AwwaRF Research. AwwaRF Special Report. Denver: AwwaRF. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Boyd, G.R., G.J. Pierson, G.J. Kirmeyer, M. Britton, and R.J. English. 2006. Pb release 

from end-use plumbing components. In Proceedings of Water Quality Technology 

Conference. November 5-9. Denver: AWWA. 

Brereton, J.A. and D.S. Mavinic. 2002. Field and material-specific simulated distribution 

system testing as aids to understanding trihalomethane formation in distribution systems. 

Canadian Journal of Civil Engineering. 29(1): 17-26. 
7. References 

Simultaneous Compliance Guidance Manual 7-31 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Burlingame, G.A., A.M. Dietrich, T. Gittleman, and R.C. Hoehn. 2004. Practical Tasteand-Odor Methods for Routine Operations: Decision Tree. AwwaRF Report 91019. 

Project #467. Denver: AwwaRF. 

Burlingame, G.A., J.J. Muldowney, R.E. Maddrey. 1992. Cucumber Flavor in 

Philadelphia’s Drinking Water. Journal of American Water Works Association. 84(8): 92-

97. 

Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data. 

Opflow. 30(6):16-19. 

Butler, J.N. with a Chapter by David Cogley. 1998. Ionic Equilibrium. Solubility and pH 

Calculations. New York: Wiley-Interscience. 

CH2M Hill. 1995. Public Involvement Strategies: A Manager’s Handbook. AwwaRF 

Report 90694. Project #918. Denver: AwwaRF. 

Clement, J., Powell, M. Brandt, R. Casey, D. Holt, W. Grayman, and M. LeChevallier. 

2005. Predictive Models for Water Quality in Distribution Systems. AwwaRF Report 

91023F. Project #2865. Denver: AwwaRF. 

Clement, J., A. Sandvig, V. Snoeyink, W. Kriven, and P. Sarin. 1998. Analyses and 

Interpretation of the Physical, Chemical, and Biological Characteristics of Distribution 

System Pipe Scales. In Proceedings of Water Quality Technology Conference. Denver: 

AWWA. 

Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions. 

AwwaRF Report 90856. Project #466. Denver: AwwaRF. 

Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy: 

Electrochemical Impedance and Noise. Houston: National Association of Corrosion 

Engineers. 

Crittenden, J.C., J.K. Berrigan, and D.W. Hand. 1986. Design of Rapid Small-Scale 

Adsorption Tests for a Constant Diffusivity. Journal Water Pollution Control Federation. 

58(4):312-319. 

Dentel, S.K., B.M. Gucciardi, T.A. Bober, P.V. Shetty, and J.J. Resta. 1989. Procedures 

Manual for Polymer Selection in Water Treatment Plants. AwwaRF Report 90553. 

Project #209. Denver: AwwaRF. 

Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in 

Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Economic and Engineering Services, Inc. and Illinois State Water Survey. 1990. Lead 

Control Strategies. Denver: AwwaRF and AWWA. 

Edwards, M. and S. Reiber. 1997a. A General Framework for Corrosion Control Based 

on Utility Experience. AwwaRF Report 90712A. Project #910. Denver: AwwaRF. 

Edwards, M. and S.H. Reiber. 1997b. Predicting Pb and Cu corrosion by-product release 

using CORRODE software. AwwaRF Report 90712B. Project #910. Denver: AwwaRF. 

Emmert, G., G. Cao, G. Geme, N. Joshi, and M. Rahman. 2004. Methods for Real-Time 

Measurement of THMs and HAAs in Distribution Systems. AwwaRF Report 91003F. 

Project #2873. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-32 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Estes-Smargiassi, S., and A. Cantor. 2006. Lead Service Line Contributions to Lead at 

the Tap. In Proceedings AWWA Water Quality Technology Conference. Denver: 

AWWA. November 2006. 

Estes-Smargiassi, S., J. Steinkrauss, A. Sandvig, and T. Young. 2006. Impact of Lead 

Service Line Replacement on Lead Levels at the Tap. In Proceedings AWWA Annual 

Conference and Exposition. San Antonio: AWWA. June, 2006. 

Friedman, M.J., G. Kirmeyer, G. Pierson, S. Harrison, K. Martel, A. Sandvig, and A. 

Hanson. 2005. Development of Distribution System Water Quality Optimization Plans. 

Denver: AwwaRF. 

Giani, R., M. Edwards, C. Chung, and J. Wujek. 2004. Lead Profiling Methodologies 

and Results. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

Levels in DC’s Drinking Water at the 2004 AWWA WQTC. San Antonio, TX. 

Proceedings of AWWA Water Technology Conference. Denver: AWWA. 

Grayman, W.M., R.A. Deininger, and R.M. Males. 2001. Design of Early Warning and 

Predictive Source-Water Monitoring Systems. AwwaRF Report 90878. Project #2527. 

Denver: AwwaRF. 

Grayman, W.M., L.A. Rossman, C. Arnold, R.A. Deininger, C. Smith, J.F. Smith, and R. 

Schnipke. 2000. Water Quality Modeling of Distribution System Storage Facilities. 

AwwaRF Report 90774. Projct #260. Denver: AwwaRF. 

Hecht, P.M., and E.A. Turner. 2004. Washington Aqueduct Desktop & Flow-Through 

Study. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead Levels 

in DC’s Drinking Water at the 2004 AWWA WQTC. 

Khiari, D., S. Barrett, R. Chinn, A. Bruchet, P. Piriou, L. Matia, F. Ventura, I. Suffet, T. 

Gittelman, and P. Luitweiler. 2002. Distribution Generated Taste-and-Odor Phenomena. 

AwwaRF Report 90897. Project # 365. Denver: AwwaRF. 

Kirmeyer, G.J., J. Clement, and A. Sandvig. 2000a. Distribution System Water Quality 

Changes Following Implementation of Corrosion Control Strategies. AwwaRF Report 

90764. Project #157. Denver: AwwaRF. 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA. 

Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G. 

Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring 

Strategies. AwwaRF Report 90996F Project #2679. Denver: AwwaRF. 

Kirmeyer, G.J., A.M. Sandvig, G.L. Pierson, and C.H. Neff. 1994. Development of a 

Pipe Loop Protocol for Lead Control. AwwaRF Report 90650 Project #604. Denver: 

AwwaRF. 

Koch, B., S.W. Krasner, M.J. Sclimenti, and W.K. Schimpff. 1991. Predicting the 

formation of DBPs by the simulated distribution system. Journal of American Water 

Works Association. 83(10): 62–70. 

Lauer, B. 2001. Self-Assessment for Treatment Plant Optimization, International Edition. 

256 pp. Denver: AWWA. 
7. References 

Simultaneous Compliance Guidance Manual 7-33 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

McGuire, M., R. Hund, G. Burlingame, N. Graziano, and L. Sullivan. 2004. Water Utility 

Self-Assessment for the Management of Aesthetic Issues. AwwaRF Report 90978F. 

Project #2777. Denver: AwwaRF. 

McGuire, M.J., J.L. McLain, and A. Obolensky. 2002. Information Collection Rule Data 

Analysis. AwwaRF Report 90947. Project #2799. Denver: AwwaRF. 

Mobley, J., E.L. Tatham, K. Reinhart, and C. Tatham. 2006. Strategic Communication 

Planning: A Guide for Water Utilities. AwwaRF Report 91106. Project #2955. Denver: 

AwwaRF. 

Nero, W., J. Campbell, B. Beaudet, H. Kunz, T. Esqueda, J. Rogers, S. Katz, and P. 

Tennyson. 2001. Public Involvement . . . Making It Work. AwwaRF Report 90865. 

Project #2526. Denver: AwwaRF. 

Olstein, M.A. 2001. Best Practices for a Continually Improving Customer Responsive 

Organization. AwwaRF Report 90868. Project #2525. Denver: AwwaRF. 

Parkhurst, D.L. and C.A.J. Appelo. 1999. User’s guide to PHREEQC (Version2)—A 

computer program for speciation, batch-reaction, one-dimensional transport, and inverse 

geochemical calculations. 310 pp. Water Resources Investigations Report 99-4259. U.S. 

Geological Survey. 

Raucher, R., D. Chapman, J. Henderson, M.L. Hagenstad, J. Rice, J. Goldstein, A. 

Huber-Lee, W. DeOreo, P. Mayer, R. Linsky, E. Means, and M. Renwick. 2005. The 

Value of Water: Concepts, Estimates, and Applications for Water Managers. AwwaRF 

Report 91068F. Project #2855. Denver: AwwaRF. 

Reiber, S., W. Keefer, L. Dufresne, and R. Giani. 2004. Circulation Loop Testing 

Provides Rapid Assessment of Corrosion Control Strategies. Presented at Getting the 

Lead Out: Analysis & Treatment of Elevated Lead Levels in DC’s Drinking Water at the 

2004 AWWA WQTC. San Antonio, TX. In Proceedings of AWWA Water Quality 

Technology Conference. Denver: AWWA. 

Renner, R.C. and B.A. Hegg. 1997. Self-Assessment Guide for Surface Water Treatment 

Plant Optimization. AwwaRF Report 90736. Project #274. 

Rettie, M., G. Haupt, M. Isbell, B. McClung, and R. Grantham. 2005. Effective Practices 

to Select, Acquire, and Implement a Utility CIS. AwwaRF Report 91071. Project # 3007. 

Denver: AwwaRF. 

Schock, M. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment: 

Conforming to the Lead and Copper Rule. Presented at NACE Corrosion 1996 

Conference.

Smith, S.E., J.S. Colbourne, D.M. Holt, B.J. Lloyd, and A. Bisset. 1997. An Examination 

of the Nature and Occurrence of Deposits in a Distribution System and their effect on 

Water Quality. In Proceedings of AWWA Water Quality Technology Conference. Boston, 

November 17-21. Denver: AWWA. 

Summers, R.S., S.M. Hooper, H.M. Shukairy, G. Solarik, and D. Owen. 1996. Assessing 

DBP yield: uniform formation conditions. Journal of American Water Works Association. 

88(6): 80–93. 
7. References 

Simultaneous Compliance Guidance Manual 7-34 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Tatham, C., E. Tatham, and J. Mobley. 2004. Customer Attitudes, Behavior and the 

Impact of Communications Efforts. AwwaRF Report 90975. Project #2613. Denver: 

AwwaRF. 

Taylor, J.S., J.D. Dietz, A.A. Randall, S.K. Hong, C.D. Norris, L.A. Mulford, J.M. 

Arevalo, S. Imran, M. Le Puil, S. Liu, I. Mutoti, J. Tang, W. Xiao, C. Cullen, R. 

Heaviside, A. Mehta, M. Patel, F. Vasquez, and D. Webb. 2005. Effects of Blending on 

Distribution System Water Quality. AwwaRF Report 91065F. Project #2702. Denver: 

AwwaRF. 

Texas Natural Resource Conservation Commission (TNRCC). 2005. Texas Optimization 

Program (TOP). http://www.tceq.state.tx.us/permitting/water_supply/pdw/swmor/top/ 

U.S. Bureau of Reclamation and I. Moch & Associates. 2003. WTCost©. Development 

of program sponsored by the American Membrane Technology Association. 

USEPA. 1992b. Lead and Copper Rule Guidance Manual, Vol. II: Corrosion Control 

Treatment. Prepared by Malcolm Pirnie, Inc. & Black & Veatch. September 1992. 

USEPA. 1994b. Water Treatment Plant Model (Version 3.1). 

http://yosemite.epa.gov/water/owrccatalog.nsf/e673c95b11602f2385256ae1007279fe/80a

cea46c3412a1185256b06007259ee!OpenDocument 

USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the 

Composite Correction Program. EPA 625/6-91/027. 

USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening Guidance 

Manual. EPA 815-R-99-012. 

USEPA. 1999i. Lead and Copper Rule Minor Revision Fact Sheet. EPA 815-F-99-010. 

USEPA. 2000b. National Primary Drinking Water Regulations for Lead and Copper. 65 

FR 1949. January 12, 2000. http://www.epa.gov/fedrgstr/EPAWATER/2000/January/Day-12/w3.htm 

USEPA. 2001f. Total Coliform Rule: A Quick Reference Guide. EPA 816-F-01-035. 

November, 2001. http://www.epa.gov/safewater/disinfection/tcr/pdfs/qrg_tcr_v10.pdf 

USEPA. 2001g. A Small System Guide to the Total Coliform Rule. Office of Water. EPA 

816-R-01-017A. http://www.epa.gov/safewater/smallsys/small-tcr.pdf 

USEPA. 2001i. Water Treatment Plant Model. Version 2.0. Developed by the Center for 

Drinking Water Optimization, University of Colorado - Boulder and Malcom Pirnie, Inc. 

May, 2001. 

USEPA. 2002b. EPANET 2.0. http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html 

USEPA. 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water 

Systems. Office of Water. EPA 816-R-02-009. 

USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control 

Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 

USEPA. 2004g. Lead and Copper Rule: A Quick Reference Guide. Office of Water. EPA 

816-F-04-009. March, 2004. 
7. References 

Simultaneous Compliance Guidance Manual 7-35 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 2005a. Occurrence Assessment for the Final Stage 2 Disinfectants and 

Disinfection Byproducts Rule. Prepared by The Cadmus Group, Inc. Contract 68-C-99-

206. EPA 815-R-06-002. 

USEPA. 2005b. Membrane Filtration Guidance Manual. Office of Water. EPA 815-R-06-

009. November, 2005. 

http://www.epa.gov/ogwdw/disinfection/lt2/pdfs/guide_lt2_membranefiltration_final.pdf 

USEPA. 2005e. Stage 2 Occurrence Assessment for Disinfectants and Disinfection 

Byproducts. EPA 815-R-05-011. 

USEPA. 2006a. Initial Distribution System Evaluation Guidance Manual for the Final 

Stage 2 DBPR. Office of Water. EPA 815-B-06-002. 

USEPA. 2006c. 2003 Drinking Water Infrastructure Needs Survey: Modeling the Cost of 

Infrastructure. Office of Water. EPA 816-R-06-007. 

USEPA. 2006f. Source Water Monitoring Guidance Manual for Public Water Systems 

for the Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA 

815-R-06-005. February 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_swmonitoringguidance.pdf 

USEPA. 2006g. Initial Distribution System Evaluation Guide for Systems Serving Fewer 

than 10,000 People. Office of Water. EPA 815-B-06-001. January 2006. 

USEPA. N.d.e. LT2ESWTR Microbial Toolbox Guidance Manual. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

USEPA. N.d.f. Operational Evaluation Guidance Manual. Stage 2 DBPR. Office of 

Water. Forthcoming. http://www.epa.gov/safewater/disinfection/stage2/compliance.html 

Walski, T., D.V. Chase, D. Savic, W.M. Grayman, S. Beckwith, and E. Koelle. 2003. 

Advanced Water Distribution Modeling and Management. Waterbury: Haestad Press. 

Wesner, G.M. Copyright 2000. Water/Wastewater Costs, Windows Version 3.0. 

7.1.17 Chlorination

American Public Heath Association (APHA), AWWA, and Water Environment 

Federation (WEF). 1998. Standard Methods for the Examination of Water and 

Wastewater. 20th Edition. 220 pp. Washington, D.C.: APHA, AWWA, and WEF. 

Angara, G., L. Cummings, W.R. Knocke, and G.C. Budd. 2004. Intermediate and LongTerm Manganese Control Strategies During the Upgrade of the Little Falls Water 

Treatment Plant. In Proceedings AWWA WQTC. Denver: AWWA. 

AWWA. 2003c. Problem Organisms in Water: Identification and Treatment (M7). 3rd 

Edition. 155 pp. Denver: AWWA. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Becker, W.C., K. Au, C.R. O'Melia, and J.S. Young, Jr. 2004. Using Oxidants to 

Enhance Filter Performance. AwwaRF Report 90998. Project #2725. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-36 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Belanger, Scott E., D.S. Cherry, J.L. Farris, K.G. Sappington, and J. Cairns, Jr. 1991. 

Sensitivity of the Asiatic Clam to Various Biocidal Control Agents. Journal of American 

Water Works Association. 83(10): 79-87. 

Brereton, J.A. and D.S. Mavinic. 2002. Field and material-specific simulated distribution 

system testing as aids to understanding trihalomethane formation in distribution systems. 

Canadian Journal of Civil Engineering. 29(1): 17-26. 

Britton, J.C. and B. Morton. 1982. A dissection guide, field and laboratory manual for the 

introduced bivalve Corbicula fluminea. Malacological Review Supplement. 3:1-82. 

Cameron, G.N., J.M. Symons, S.R. Spencer, and J.Y. Ma. 1989. Minimizing THM 

Formation During Control of the Asiatic Clam: A Comparison of Biocides. Journal of 

American Water Works Association. 81(10): 53-62. 

Cantor, A., J.K. Park, and P. Vaiyavatjamai. 2003. Effect of Chlorine on Corrosion in 

Drinking Water Systems. Journal of American Water Works Association. 95(5): 112-

123. 

Counts, C. L., III. 1986. The zoogeography and history of the invasion of the United 

States by Corbicula fluminea (Bivalvia: Corbiculidae). American Malacological Bulletin, 

Special Edition No. 2. In Proceedings of Second International Corbicula Symposium. pp. 

7-39. 

Culp, G.L. and R.L. Culp. 1974. New Concepts in Water Purification. New York: Van 

Norstrand Reinhold Co. 

Edwards, M. and S. Reiber. 1997a. A General Framework for Corrosion Control Based 

on Utility Experience. AwwaRF Report 90712A. Project #910. Denver: AwwaRF. 

Edwards, M. and S.H. Reiber. 1997b. Predicting Pb and Cu corrosion by-product release 

using CORRODE software. AwwaRF Report 90712B. Project #910. Denver: AwwaRF. 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

AwwaRF Report 90882. Project #2522. Denver: AwwaRF and AWWA. 

Koch, B., S.W. Krasner, M.J. Sclimenti, and W.K. Schimpff. 1991. Predicting the 

formation of DBPs by the simulated distribution system. Journal of American Water 

Works Association. 83(10): 62–70. 

Krasner, S.W., K.M. Reagan, J.G. Jacangelo, N.L. Patania, E.M. Aieta, and K.M. 

Gramith. 1990. Relationships Between Disinfection By-products and Water Quality 

Parameters: Implications for Formation and Control. In Proceedings, AWWA Annual 

Conference. Denver: AWWA. 

Lange, C. L., T. M. Short, E. Blake. 1994. Development of Zebra Mussel Control 

Strategies for a Coalition of Vermont Water Suppliers on Lake Champlain. In 

Proceedings of Fourth International Zebra Mussel Conference. Madison, WI. 

LeChevallier, M.W., N.J. Welch, and D.B. Smith. 1996. Full scale studies of factors 

related to coliform regrowth in drinking water. Applied and Environmental Microbiology.

62(7): 2201-2211. 
7. References 

Simultaneous Compliance Guidance Manual 7-37 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Lytle, D.A. and M.R. Schock. 2005. The Formation of Pb(IV) Oxides in Chlorinated 

Water. Journal of American Water Works Association. 97(11):102. 

Reckhow, D.A. and P.C. Singer. 1985. Mechanisms of Organic Halide Formation During 

Fulvic Acid Chlorination and Implications with Respect to Pre-ozonation. In Water 

Chlorination: Environmental Impact and Health Effects. Volume 5. pp. 1229-1257. 

Chelsea: Lewis Publishers, Inc. 

Schock, M.R. 2005. Chapter 6: Distribution Systems as Reservoirs and Reactors for 

Inorganic Contaminants. In Distribution System Water Quality Challenges in the 21st 

Century. Denver: AWWA. 

Schock, M.R. and J.C. Fox. 2001. Solving Copper Corrosion Problems while Maintaining 

Lead Control in a High Alkalinity Water using Orthophosphate. Presented at the Ohio 

AWWA Annual Conference. August 30, 2001. Cleveland: AWWA. 

Schock, M.R. and R. Giani. 2004. Oxidant/Disinfectant Chemistry and Impacts on Lead 

Corrosion. In Proceedings of AWWA Water Quality Technology Conference. Denver: 

AWWA.

Singer, P.C. and S.D. Chang. 1989. Correlations between trihalomethanes and total 

organic halides formed during water treatment. Journal of American Water Works 

Association. 81(8): 61-65. 

Stevens, A.A., L.A. Moore, and R.J. Miltner. 1989. Formation and Control of NonTrihalomethane Byproducts. Journal of American Water Works Association. 81(8): 54. 

Summers, R.S., S.M. Hooper, H.M. Shukairy, G. Solarik, and D. Owen. 1996. Assessing 

DBP yield: uniform formation conditions. Journal of American Water Works Association. 

88(6): 80–93. 

USEPA. 1999a. Disinfection Profiling and Benchmarking Guidance Manual. EPA 815-

R-99-013. 

USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R99-014. 

USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening Guidance 

Manual. EPA 815-R-99-012. 

USEPA. 2001h. Low-Pressure Membrane Filtration for Pathogen Removal: Application, 

Implementation, and Regulatory Issues. Office of Water. EPA 815-C-01-001. 

http://www.epa.gov/OGWDW/disinfection/lt2/pdfs/report_lt2_membranefiltration.pdf 

USEPA. 2002e. Health Risks from Microbial Growth and Biofilms in Drinking Water 

Distribution Systems. Office of Ground Water and Drinking Water. 

USEPA. 2003a. LT1ESWTR Disinfection Profiling and Benchmarking: Technical 

Guidance Manual. Office of Water. EPA 816-R-03-004. May, 2003. 

http://www.epa.gov/safewater/mdbp/pdf/profile/lt1profiling.pdf 

USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control 

Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 
7. References 

Simultaneous Compliance Guidance Manual 7-38 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Wert, E.C., D.J. Rexing, and R.E. Zegers. 2005. Mangenese release from filter media 

during the conversion to biological filtration. AWWA Annual Conference and Exposition.

San Francisco: AWWA. 

White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. 

New York: Van Nostrand Reinhold Co. 

7.2 Comprehensive List of References 

Adham, S., K. Chiu, K. Gramith, and J. Oppenheimer. 2005. Development of a 

Microfiltration and Ultrafiltration Knowledge Base. AwwaRF Report 91059. Project 

#2763. Denver: AwwaRF. 

Advantica. SynerGEE Water. Advanced water distribution analysis. 

http://www.advantica.biz/Default.aspx?page=321 

American Chemical Society. 1983. Treatment of Water by Granular Activated Carbon. 

Advances in Chemistry Series Number 202. M.J. McGuire and I.H. Suffet (editors). 

Washington, D.C.: American Chemical Society. 

American Public Heath Association (APHA), AWWA, and Water Environment 

Federation (WEF). 1998. Standard Methods for the Examination of Water and 

Wastewater. 20th Edition. 220 pp. Washington, D.C.: APHA, AWWA, and WEF. 

Amy, G., M. Clark, and J. Pellegrino. 2001. NOM Rejection by, and Fouling of, NF and 

UF Membranes. AwwaRF Report 90837. Project #390. Denver: AwwaRF. 

Amy, G.L., M. Edwards, M. Benjamin, K. Carlson, J. Chwirka, P. Brandhuber, L. 

McNeill, and F. Vagliasindi. 2000. Arsenic Treatability Options and Evaluation of 

Residuals Management Issues. AwwaRF Report 90771. Project #153. Denver: AwwaRF. 

Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, 

G.A. Ganon, J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on 

Transmission, Treatment, and Distribution System Performance. AwwaRF Report 91082. 

Project #2843. Denver: AwwaRF. 

Angara, G., L. Cummings, W.R. Knocke, and G.C. Budd. 2004. Intermediate and LongTerm Manganese Control Strategies During the Upgrade of the Little Falls Water 

Treatment Plant. In Proceedings AWWA WQTC. Denver: AWWA. 

Angers, J. 2001. Question of the Month: Which Disinfectant Will Work Best for Us? 

Opflow. 27(5): 6-7, 22. 

Arber, R., M.A. Speed, and F. Scully. 1985. Significant Findings Related to Formation of 

Chlrinated Organics, in the Presence of Chloramines. In Water Chlorination: 

Environmental Impact and Health Effects, Vol. 7. Edited by R.L. Jolley, R.J. Bull, W.P. 

Davis, S. Katz, M.H. Roberts, and V.A. Jacobs. Chelsea: Lewis Publishers. 

ASTM D2688-83 Method B. 1983a. Standard Test Methods for the Corrosivity of Water 

in the Absence of Heat Transfer (Weight Loss Protocol). Philadelphia: American Society 

for Testing and Materials. 
7. References 

Simultaneous Compliance Guidance Manual 7-39 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ASTM D2688-83 Method C. 1983b. Standard Test Methods for the Corrosivity of 

Water in the Absence of Heat Transfer (Machined Nipple Test). Philadelphia: American 

Society for Testing and Materials. 

ASTM D934-80. 2003. Standard Practices for Identification of Crystalline Compounds in 

Water Formed Deposits by X-Ray Diffraction. Philadelphia: American Society for 

Testing and Materials. 

ASTM G1-81. 1981. Recommended Practise for Preparing, Cleaning and Evaluating 

Corrosion Test Specimens. Philadelphia: American Society for Testing and Materials. 

ASTM G46-76. 1976. Recommended Practise for the Examination and Evaluation of 

Pitting Type Corrosion. Philadelphia: American Society for Testing and Materials. 

AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: 

McGraw-Hill. 

AWWA. 1993. Initial Monitoring Experiences of Large Water Utilities Under USEPA’s 

Lead and Copper Rule. Denver: WITAF. 

AWWA. 1996. Water Transmission and Distribution. 2nd Edition. Denver: AWWA. 

AWWA. 1998. Distribution System Requirements for Fire Protection. 3rd Edition. 

AWWA Manual M31. 63 pp. Denver: AWWA. 

AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. Denver: 

AWWA. 

AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water 

Supplies. 5th Edition. Letterman, R.D. (editor). New York: McGraw-Hill. 

AWWA. 1999d. Design and Construction of Small Water Systems. 2nd Edition. 228 pp. 

Denver: AWWA. 

AWWA. 1999e. Hydraulic Design Handbook. Mays, L.W.(editor). New York: McGrawHill. 

AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd 

Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA. 

AWWA. 2001a. The Rothberg, Tamburini & Winsor Blending Application Package 4.0. 

AWWA Catalog Number 53042. 

AWWA. 2001b. Elevated Water Storage Tanks: Maintenance. VHS Video. Denver: 

AWWA. 

AWWA. 2002. Unidirectional Flushing. DVD. Denver: AWWA. 

AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

AWWA. 2003b. Sizing Water Service Lines and Meters. 2nd Edition. AWWA Manual 

M22. 112 pp. Denver: AWWA. 

AWWA. 2003c. Problem Organisms in Water: Identification and Treatment (M7). 3rd 

Edition. 155 pp. Denver: AWWA. 
7. References 

Simultaneous Compliance Guidance Manual 7-40 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

AWWA. 2004a. Computer Modeling of Water Distribution Systems. AWWA Manual 

M32. 160 pp. Denver: AWWA. 

AWWA. 2004b. Converting Distribution Systems from Chlorine to Chloramines. DVD. 

Denver: AWWA. 

AWWA. 2004c. G200-04: Distribution Systems Operation and Management. 16 pp. 

Denver: AWWA. 

AWWA. 2004d. Proceedings of Workshop - Getting the Lead Out: Analysis & Treatment 

of Elevated Lead Levels in DC’s Drinking Water. San Antonio: WQTC. 

AWWA. 2004e. Recommended Practice for Backflow Prevention and Cross-Connection 

Control. 3rd Edition. AWWA Manual M14. Denver: AWWA. 

AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

Rule Corrosion Control Treatment. Denver: AWWA. 

AWWA. 2005b. Distribution System Water Quality Challenges in the 21st Century – A 

Strategic Guide. MacPhee, M.J. (Editor). 190 pp. Denver: AWWA. 

AWWA. 2005c. Disinfecting Water Mains. AWWA Standard C651-05. Denver: 

AWWA. 

AWWA and AwwaRF. 1992. Water Industry Database: Utility Profiles. Denver: 

AWWA. 

AwwaRF. 1999. Distribution System Water Quality Changes Following Corrosion 

Control Strategies. Denver: AwwaRF. 

AwwaRF. 2000. Consumer Attitude Survey Update. AwwaRF Report 394. Project #394. 

Denver: AwwaRF. 

AwwaRF. 2003. Public Involvement Strategies on the Web. Interactive tool that builds 

on AwwaRF Report. 

http://www.awwarf.org/research/TopicsAndProjects/Resources/webTools/ch2m/default.h

tml 

AwwaRF. 2007. Distribution System Corrosion and the Lead and Copper Rule: An 

Overview of AwwaRF Research. AwwaRF Special Report. Denver: AwwaRF. 

AwwaRF and Compagnie Generale des Eaux. 1992. Ozone in Water Treatment: 

Application and Engineering. AwwaRF Report. Project #421. Denver: AwwaRF. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

AwwaRF and Lyonnaise des Eaux. 1995. Advances in Taste and Odor Treatment and 

Control. AwwaRF Report 90610. Project #629. Denver: AwwaRF. 

Ballester, N.A. and J.P. Malley, Jr. 2004. Sequential Disinfection of Adenovirus Type 2 

with UV-Chlorine-Chloramine. Journal of American Water Works Association. 

96(10):97-103. 

Becker, W.C., K. Au, C.R. O'Melia, and J.S. Young, Jr. 2004. Using Oxidants to 

Enhance Filter Performance. AwwaRF Report 90998. Project #2725. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-41 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Becker, W.C., O'Brien and Gere Engineers, C.R. O'Melia, and Department of Geography 

and Environmental Engineering, The Johns Hopkins University. 1996. Optimizing 

Ozonation for Turbidity and Organics (TOC) Removal by Coagulation and Filtration.

AwwaRF Report 90703. Project #934. Denver: AwwaRF. 

Belanger, Scott E., D.S. Cherry, J.L. Farris, K.G. Sappington, and J. Cairns, Jr. 1991. 

Sensitivity of the Asiatic Clam to Various Biocidal Control Agents. Journal of American 

Water Works Association. 83(10): 79-87. 

Bell, K., M. LeChevallier, M. Abbaszadegan, G. Amy, S. Sinha, M. Benjamin, and E. 

Ibrahim. 2001. Enhanced and Optimized Coagulation for Particulate and Microbial 

Removal. AwwaRF Report. Project #155. Denver: AwwaRF. 

Bevery, R. P. 2005. Filter Troubleshooting and Design Handbook. 425 pp. Denver: 

AWWA. 

Bonds, R.W. 2004. Effect of Chloramines on Ductile-Iron Pipe Gaskets of Various 

Elastomer Compounds. Journal of American Water Works Association. 96(4): 153-160. 

Boyd, G.R., G.J. Pierson, G.J. Kirmeyer, M. Britton, and R.J. English. 2006. Pb release 

from end-use plumbing components. In Proceedings of Water Quality Technology 

Conference. November 5-9. Denver: AWWA. 

Boyd, G.R., K.M. Dewis, A.M. Sandvig, G.J. Kirmeyer, S.H. Reiber, and G.V. Korshin. 

2006. Effect of Changing Disinfectants on Distribution System Lead and Copper Release, 

Part 1—Literature Review. AwwaRF Report 91152. Project # 3107. Denver: AwwaRF. 

Brandt, M.J., J. Clement, J. Powell, R. Casey, D. Holt, N. Harris, and C.T. Ta. 2004. 

Managing Distribution System Retention Time to Improve Water Quality. Denver: 

AwwaRF. 

Brereton, J.A. and D.S. Mavinic. 2002. Field and material-specific simulated distribution 

system testing as aids to understanding trihalomethane formation in distribution systems. 

Canadian Journal of Civil Engineering. 29(1): 17-26. 

Britton, J.C. and B. Morton. 1982. A dissection guide, field and laboratory manual for the 

introduced bivalve Corbicula fluminea. Malacological Review Supplement. 3:1-82. 

Brodkorb, T.,and D. Richards. 2004. UV disinfection design to avoid chlorine destruction 

in high UVT waters. Presented at Ontario Water Works Association. Niagara Falls, 

Ontario, Canada. May, 2004. 

Brown, J. and and D. Hugaboom. 2004. Integrating Membrane Treatment in Large Water 

Utilities. AwwaRF Report 91045F. Project #2876. Denver: AwwaRF. 

Bukhari, Z., T.M. Hargy, J.R. Bolton, B. Dussert, and J.L. Clancy. 1999. MediumPressure UV for Oocyst Inactivation. Journal of American Water Works Association. 

91(3): 86-94. 

Burlingame, G.A., A.M. Dietrich, T. Gittleman, and R.C. Hoehn. 2004. Practical Tasteand-Odor Methods for Routine Operations: Decision Tree. AwwaRF Report 91019. 

Project #467. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-42 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Burlingame, G.A., J.J. Muldowney, R.E. Maddrey. 1992. Cucumber Flavor in 

Philadelphia’s Drinking Water. Journal of American Water Works Association. 84(8): 92-

97. 

Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data. 

Opflow. 30(6):16-19. 

Butler, J.N. with a Chapter by David Cogley. 1998. Ionic Equilibrium. Solubility and pH 

Calculations. New York: Wiley-Interscience. 

Cameron, G.N., J.M. Symons, S.R. Spencer, and J.Y. Ma. 1989. Minimizing THM 

Formation During Control of the Asiatic Clam: A Comparison of Biocides. Journal of 

American Water Works Association. 81(10): 53-62. 

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Carlson, K.H. and G.L. Amy. 2001. Ozone and biofiltration optimization for multiple 

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7. References 

Simultaneous Compliance Guidance Manual 7-43 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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7. References 

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For the Long Term 2 and Stage 2 DBP Rules 

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7. References 

Simultaneous Compliance Guidance Manual 7-46 March 2007 

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7. References 

Simultaneous Compliance Guidance Manual 7-47 March 2007 

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Grayman, W.M., L.A. Rossman, C. Arnold, R.A. Deininger, C. Smith, J.F. Smith, and R. 

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7. References 

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7. References 

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7. References 

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7. References 

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7. References 

Simultaneous Compliance Guidance Manual 7-57 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Tillman, G.M. 1996. Water Treatment: Troubleshooting and Problem Solving. 176 pp. 

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BOM and Particle Removal: A Critical Review. Journal of American Water Works 

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Urfer, D., P.M. Huck, G.A. Gagnon, D. Mutti, and F. Smith. 1999. Modeling enhanced 

coagulation to improve ozone disinfection. Journal of American Water Works 

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Bacteria. (Surface Water Treatment Rule), Final Rule. 43 FR 27486. June 29, 1989. 

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7. References 

Simultaneous Compliance Guidance Manual 7-58 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 1999a. Disinfection Profiling and Benchmarking Guidance Manual. EPA 815-

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USEPA. 1999c. Uncovered Finished Water Reservoirs Guidance Manual. EPA 815-R99-011. http://www.epa.gov/safewater/mdbp/pdf/uncover/ufw8p.pdf 

USEPA. 1999d. Guidance Manual for Compliance with the Interim Enhanced Surface 

Water Treatment Rule: Turbidity Provisions. EPA 815-R-99-010. 

USEPA. 1999e. Unfiltered Water Supply Systems Guidance Manual. Office of Ground 

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Systems; Surface Water and Ground Water Under the Direct Influence (GWUDI). EPA 

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7. References 

Simultaneous Compliance Guidance Manual 7-59 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Water. EPA 816-F-01-019. June 2001. http://www.epa.gov/safewater/mdbp/fbrr_qrg.pdf 

USEPA. 2001n. Arsenic and Clarifications to Compliance and New Source Monitoring 

Rule: A Quick Reference Guide. Office of Water. EPA 816-F-01-004. January, 2001. 

http://www.epa.gov/safewater/arsenic/pdfs/quickguide.pdf 

USEPA. 2002a. National Primary Drinking Water Regulations: Long Term 1 Enhanced 

Surface Water Treatment Rule. 67 FR 1811. January 14, 2002. 

http://www.epa.gov/fedrgstr/EPA-WATER/2002/January/Day-14/w409.htm 

USEPA. 2002b. EPANET 2.0. http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html 

USEPA. 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water 

Systems. Office of Water. EPA 816-R-02-009. 

USEPA. 2002d. Long Term 1 Enhanced Surface Water Treatment Rule: A Quick 

Reference Guide. Office of Water. EPA 816-F-02-001. January, 2002. 

http://www.epa.gov/safewater/mdbp/lt1eswtr-quick-ref.pdf 

USEPA. 2002e. Health Risks from Microbial Growth and Biofilms in Drinking Water 

Distribution Systems. Office of Ground Water and Drinking Water. 

USEPA. 2003a. LT1ESWTR Disinfection Profiling and Benchmarking: Technical 

Guidance Manual. Office of Water. EPA 816-R-03-004. May, 2003. 

http://www.epa.gov/safewater/mdbp/pdf/profile/lt1profiling.pdf 

USEPA. 2003d. Technologies and Costs for Control of Microbial Contaminants and 

Disinfection Byproducts. Office of Ground Water and Drinking Water. Washington, D.C. 
7. References 

Simultaneous Compliance Guidance Manual 7-60 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control 

Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 

USEPA. 2004d. National Primary Drinking Water Regulations; Minor Corrections and 

Clarification to Drinking Water Regulations; National Primary Drinking Water 

Regulations for Lead and Copper. 69 FR 38850. June 29, 2004. 

http://www.epa.gov/fedrgstr/EPA-WATER/2004/June/Day-29/w14604.htm 

USEPA. 2004e. Guidance Manual for Compliance with the Long Term 1 Enhanced 

Surface Water Treatment Rule: Turbidity Provisions. EPA 816-F-02-001. 

USEPA. 2004f. The Long Term 1 Enhanced Surface Water Treatment Rule 

Implementation Guidance. EPA 816-R-04-008. 

USEPA. 2004g. Lead and Copper Rule: A Quick Reference Guide. Office of Water. EPA 

816-F-04-009. March, 2004. 

USEPA. 2004h. Long Term 1 Enhanced Surface Water Treatment Rule Turbitity 

Provisions Technical Guidance Manual. Office of Water. EPA 816-R-04-007. August, 

2004. 

USEPA. 2004i. Lead and Copper Rule – Clarification of Requirements for Collecting 

Samples and Calculating Compliance. EPA 810-F-04-001. 

http://www.epa.gov/ogwdw/lcrmr/pdfs/memo_lcmr_samplingrequirements_1104.pdf 

USEPA. 2005a. Occurrence Assessment for the Final Stage 2 Disinfectants and 

Disinfection Byproducts Rule. Prepared by The Cadmus Group, Inc. Contract 68-C-99-

206. EPA 815-R-06-002. 

USEPA. 2005b. Membrane Filtration Guidance Manual. Office of Water. EPA 815-R-06-

009. November, 2005. 

http://www.epa.gov/ogwdw/disinfection/lt2/pdfs/guide_lt2_membranefiltration_final.pdf 

USEPA. 2005c. A Regulator’s Guide to the Management of Radioactive Residuals from 

Drinking Water Treatment Technologies. USEPA 816-R-05-004. 

USEPA. 2005d. Technologies and Costs for the Final Long Term 2 Enhanced Surface 

Water Treatment Rule and Final Stage 2 Disinfectants and Disinfection Byproducts Rule. 

EPA 815-R-05-013. 

USEPA. 2005e. Stage 2 Occurrence Assessment for Disinfectants and Disinfection 

Byproducts. EPA 815-R-05-011. 

USEPA. 2005f. Fact Sheet - Long Term 2 Enhanced Surface Water Treatment Rule. 

Office of Water. EPA 815-F-05-009. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/fs_lt2_finalrule.pdf 

USEPA. 2005g. Fact Sheet: Stage 2 Disinfectants and Disinfection Byproducts Rule. 

Office of Water. EPA 815-F-05-003. 

http://www.epa.gov/safewater/disinfection/stage2/pdfs/fs_st2_finalrule.pdf 

USEPA. 2006a. Initial Distribution System Evaluation Guidance Manual for the Final 

Stage 2 DBPR. Office of Water. EPA 815-B-06-002. 

USEPA. 2006b. Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 

Enhanced Surface Water Treatment Rule. Office of Water. EPA 815-R-06-007. 
7. References 

Simultaneous Compliance Guidance Manual 7-61 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

November, 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_uvguidance.pdf 

USEPA. 2006c. 2003 Drinking Water Infrastructure Needs Survey: Modeling the Cost of 

Infrastructure. Office of Water. EPA 816-R-06-007. 

USEPA. 2006d. Technology and Cost Document for the Final Ground Water Rule. EPA 

815-R-06-015. 

USEPA. 2006e. Final Ground Water Rule: A Fact Sheet. Office of Water. EPA 815-F06-003. http://www.epa.gov/safewater/disinfection/gwr/pdfs/fs_gwr_finalrule.pdf 

USEPA. 2006f. Source Water Monitoring Guidance Manual for Public Water Systems 

for the Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA 

815-R-06-005. February 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_swmonitoringguidance.pdf 

USEPA. 2006g. Initial Distribution System Evaluation Guide for Systems Serving Fewer 

than 10,000 People. Office of Water. EPA 815-B-06-001. January 2006. 

USEPA. 2007a. Small Entity Compliance Guidance for the LT2ESWTR. Office of 

Water. 

USEPA. 2007b. Small Systems Guidance Manual for the Stage 2 DBPR. Office of 

Water. 

USEPA. N.d.a. Consecutive Systems Guidance Manual for the GWR. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.b. Consecutive Systems Guidance Manual for the Stage 2 DBPR. Office of 

Water. Forthcoming. http://www.epa.gov/safewater/disinfection/stage2/compliance.html 

USEPA. N.d.c. Corrective Actions Guidance manual. GWR. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.e. LT2ESWTR Microbial Toolbox Guidance Manual. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

USEPA. N.d.f. Operational Evaluation Guidance Manual. Stage 2 DBPR. Office of 

Water. Forthcoming. http://www.epa.gov/safewater/disinfection/stage2/compliance.html 

USEPA. N.d.g. Sanitary Survey Guidance Manual. GWR. Office of Water. Forthcoming. 

http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.h. Complying with the GWR: Small Entity Compliance Guide. Office of 

Water. Forthcoming. 

http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.k. Source Water Monitoring Guidance Manual. GWR. Office of Water. 

Forthcoming. http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.l. The GWR Implementation Guidance. Office of Water. Forthcoming. 

http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html 

USEPA. N.d.m. The LT2ESWTR State Implementation Guidance. Office of Water. EPA 

816-R-06-006. Forthcoming. 

http://www.epa.gov/safewater/disinfection/lt2/compliance.html 
7. References 

Simultaneous Compliance Guidance Manual 7-62 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. N.d.n. The Stage 2 DBPR Implementation Guidance. Office of Water. EPA 816-

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Valentine, R.L. 1998. Chloramine Decomposition in Distribution System and Model 

Waters. AwwaRF Report 90721. Project #937. Denver: AwwaRF. 

Valentine, R. 2001. Mechanisms and Kinetics of Chloramine Loss and By-Product 

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Van der Kooij, D. 1997. Bacterial Nutrients and Biofilm Formation Potential within 

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Veazey, M.V. 2004. New Research May Explain Pinholes in Copper Tubing. Materials 

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Vikesland, P.J., N.G. Love, K. Chandran, E.M. Fiss, R. Rebodos, A.E. Zaklikowski, F.A. 

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Volk, C.J., R. Hofmann, C. Chauret, G.A. Gagnon, G. Ranger, and R.C. Andrews. 2002b. 

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drinking water quality in a full-scale distribution system. Journal of Environmental 

Engineering and Science. 1(5): 323-330. 

Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 

pp. Denver: AWWA. 

Walski, T., D.V. Chase, D. Savic, W.M. Grayman, S. Beckwith, and E. Koelle. 2003. 

Advanced Water Distribution Modeling and Management. Waterbury: Haestad Press. 

Wang, J., S. Hubbs, and R. Song. 2002. Evaluation of Riverbank Filtration as a Drinking 

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7. References 

Simultaneous Compliance Guidance Manual 7-63 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Westerhoff, P., R.S. Summers, Z. Chowdhury, and S. Kommineni. 2005. OzoneEnhanced Biofiltration for Geosmin and MIB Removal. AwwaRF Report 91075. Project 

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1996. Occurrence of Nitrification in Chloraminated Distribution Systems. Journal of 

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Wilczak, A. and H. Lai. 2006. Preliminary bench and pilot evaluation of UV-irradiation 

for nitrification control. In Proceedings of the American Water Works Association Annual 

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Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia 

for Controlling Bromate During Cryptosporidium Disinfection. Journal of American 

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Wolfe, R.L, N.I. Lieu, G. Izagiurre, and E.G. Means. 1990. Ammonia-Oxidizing Bacteria 

in a Chloraminated Distribution System: Seasonal Occurrence, Distribution, and 

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Covered Reservoirs Containing Chloraminated Water. Journal of American Water Works 

Association. 80(9): 109-114. 

World Health Organization. 2004a. Guidelines for Drinking Water Quality. 3rd Edition. 

Geneva, Switzerland: World Health Organization. 

World Health Organization. 2004b. Water Treatment and Pathogen Control: Process 

Efficiency in Achieving Safe Drinking Water. M.W. LeChevallier and K.K. Au (editors). 

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Tool. AwwaRF Report 90905. Project # 2698. Denver: AwwaRF. 

Xie, Y., H. Wu, and H. Tung. 2004. Haloacetic Acid Removal Using Granular Activated 

Carbon. AwwaRF Report 91041F. Project #2825. Denver: AwwaRF. 

Youngsug, K., L. Yeongho, C.S. Gee, and C. Euiso. 1997. Treatment of Taste and Odor 

Causing Substances in Drinking Water. Water Science and Technology. 35(8): 29-36. 

Zhou, P. and J. Neemann. 2005. Use of Chlorine Dioxide and Ozone for Control of 

Disinfection By-Products. AwwaRF Report 90981F. Project #2742. Denver: AwwaRF. 
7. References 

Simultaneous Compliance Guidance Manual 7-64 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix A 

Summary of Pertinent Drinking Water Regulations
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Appendix A. Summary of Pertinent Drinking Water Regulations 

Simultaneous Compliance Guidance Manual A-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Appendix A 

Summary of Pertinent Drinking Water Regulations

 This appendix contains fact sheets and quick reference guides for the major rules 

discussed in this guidance manual. The fact sheets and quick reference guides are brief 

summaries of the major requirements of the rules. More detailed information on rule 

requirements and guidance can be found on EPA’s Web site at http://www.epa.gov/safewater.

The following is a list of fact sheets and quick reference guides that are included in this appendix 

and the order in which they appear: 

Rule Date of 

Promulgation

Contaminant of 

Concern

Rule Summary 

Information

Available from EPA

Ground Water Rule (GWR) November 

2006

Source Water Microbial 

Pathogens

Fact Sheet 

Long Term 2 Enhanced Surface 

Water Treatment Rule (LT2ESWTR) 

January 2006 Source Water Microbial 

Pathogens

Fact Sheet 

Stage 2 Disinfectants and Disinfection 

Byproducts Rule (Stage 2 DBPR) 

January 2006 Disinfection Byproducts Fact Sheet 

Arsenic and Clarifications to 

Compliance and New Source 

Monitoring Rule 

January 2001 Arsenic Quick Reference 

Guide

Lead and Copper Rule (LCR) June 1991 Lead and Copper Quick Reference 

Guide

LCR Clarification of Requirements 

for Collecting Samples and 

Calculating Compliance 

March 2004 Lead and Copper Fact Sheet 

Total Coliform Rule (TCR) June 1989 Distribution System 

Microbial Pathogens

Quick Reference 

Guide

Stage 1 Disinfectants and Disinfection 

Byproducts Rule (Stage 1 D/DBPR) 

December 

1998

Disinfectants and 

Disinfection Byproducts 

Quick Reference 

Guide

Interim Enhanced Surface Water 

Treatment Rule (IESWTR) 

December 

1998

Source Water Microbial 

Pathogens

Quick Reference 

Guide

Long Term 1 Enhanced Surface 

Water Treatment Rule (LT1ESWTR) 

January 2002 Source Water Microbial 

Pathogens

Quick Reference 

Guide

Filter Backwash Recycling Rule 

(FBRR)

June 2001 Filter Backwash 

(Microbial Pathogens) 

Quick Reference 

Guide
Appendix A. Summary of Pertinent Drinking Water Regulations 

Simultaneous Compliance Guidance Manual A-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Final Ground Water Rule 

Summary 

The Environmental Protection Agency (EPA) promulgated the final Ground Water Rule (GWR) in 

October 2006 to reduce the risk of exposure to fecal contamination that may be present in public water 

systems that use ground water sources. EPA proposed the GWR on May 10, 2000 (65 Federal Register

30194). The rule establishes a risk-targeted strategy to identify ground water systems that are at high 

risk for fecal contamination. The GWR also specifies when corrective action (which may include 

disinfection) is required to protect consumers who receive water from ground water systems from 

bacteria and viruses.

Background

The 1996 Amendments to the Safe Drinking Water Act required EPA to develop regulations that 

require disinfection of ground water systems “as necessary” to protect the public health (section 

1412(b)(8)). 

Ground water occurrence studies and recent outbreak data show that pathogenic viruses and bacteria 

can occur in public water systems that use ground water and that people may become ill due to 

exposure to contaminated ground water. 

Most cases of waterborne disease are characterized by gastrointestinal symptoms (e.g., diarrhea, 

vomiting, etc.) that are frequently self-limiting in healthy individuals and rarely require medical 

treatment. However, these same symptoms are much more serious and can be fatal for persons in 

sensitive subpopulations (such as young children, the elderly, and persons with compromised immune 

systems). 

Viral and bacterial pathogens are present in human and animal feces, which can, in turn, contaminate 

drinking water. Fecal contamination can reach ground water sources, including drinking water wells, 

from failed septic systems, leaking sewer lines, and by passing through the soil and large cracks in the 

ground. Fecal contamination from the surface may also get into a drinking water well along its casing or 

through cracks if the well is not properly constructed, protected, or maintained. 

EPA does not believe all ground water systems are fecally contaminated; data indicate that only a small 

percentage of ground water systems are fecally contaminated. However, the severity of health impacts 

and the number of people potentially exposed to microbial pathogens in ground water indicate that a 

regulatory response is warranted. 

About this Regulation

The GWR applies to more than 147, 000 public water systems that use ground water (as of 2003). The 

rule also applies to any system that mixes surface and ground water if the ground water is added 

directly to the distribution system and provided to consumers without treatment equivalent to surface 

water treatment. In total, these systems provide drinking water to more than 100 million consumers. 
Final Requirements: The rule addresses risks through a risk-targeting approach that relies on four 

major components: 

1. Periodic sanitary surveys of ground water systems that require the evaluation of eight critical 

elements and the identification of significant deficiencies (e.g., a well located near a leaking 

septic system). States must complete the initial survey by December 31, 2012 for most 

community water systems (CWSs) and by December 31, 2014 for CWSs with outstanding 

performance and for all non-community water systems. 

2. Source water monitoring to test for the presence of E. coli, enterococci, or coliphage in the 

sample. There are two monitoring provisions: 

-Triggered monitoring for systems that do not already provide treatment that achieves at 

least 99.99 percent (4-log) inactivation or removal of viruses and that have a total coliformpositive routine sample under Total Coliform Rule sampling in the distribution system. 

-Assessment monitoring- As a complement to triggered monitoring, a State has the option 

to require systems, at any time, to conduct source water assessment monitoring to help 

identify high risk systems. 

3. Corrective actions required for any system with a significant deficiency or source water fecal 

contamination. The system must implement one or more of the following correction action 

options:

 -correct all significant deficiencies, 

-eliminate the source of contamination, 

-provide an alternate source of water, or 

-provide treatment which reliably achieves 99.99 percent (4-log) inactivation or removal of 

viruses.

4. Compliance monitoring to ensure that treatment technology installed to treat drinking water 

reliably achieves at least 99.99 percent (4-log) inactivation or removal of viruses. 

Environmental and Public Health Benefits

The GWR will reduce public health risk from contaminated ground water drinking water sources, 

especially in high-risk or high-priority systems. The GWR is estimated to reduce the average number 

of waterborne viral (rotovirus and echovirus) illnesses by nearly 42,000 illnesses each year from the 

current baseline estimate of approximately 185,000 (a 23 percent reduction in total illnesses). In 

addition, nonquantified benefits from the rule resulting in illness reduction from other viruses and 

bacteria are expected to be significant. 

Cost of the Regulation

The GWR will result in increased costs to public water systems and States. The mean annualized 

present value national compliance costs of the final GWR are estimated to be approximately $62 

million (using three percent discount rate). Public water systems will bear the majority of costs. The 

annual household costs for community water systems (including those that do not add treatment) range 

from $0.21 to $16.54. Annual household costs for the subset of systems that undertake corrective 

actions range from $0.45 to $52.38, with 90 percent having household cost increases of no more than 

$3.20. 

How to Get Additional Information

For general information on the GWR, please contact the Safe Drinking Water Hotline, at (800) 426-

4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding Federal holidays, 

from 10 a.m. to 4 p.m., Eastern time. For copies of the Federal Register notice of the final regulation, 

visit the EPA Safewater Web site, http://www.epa.gov/safewater/disinfection/gwr.

Office of Water (4607M) EPA 815-F-06-003 October 2006 www.epa.gov/safewater
Fact Sheet - Long Term 2 Enhanced Surface 

Water Treatment Rule 

In the past 30 years, the Safe Drinking Water Act (SDWA) has been highly effective in protecting 

public health and has also evolved to respond to new and emerging threats to safe drinking water. 

Disinfection of drinking water is one of the major public health advances in the 20th century. One 

hundred years ago, typhoid and cholera epidemics were common through American cities; 

disinfection was a major factor in reducing these epidemics. 

In the past 15 years, we have learned that there are specific microbial pathogens, such as 

Cryptosporidium, which can cause illness, and are highly resistant to traditional disinfection 

practices. We also know that the disinfectants themselves can react with naturally-occurring 

materials in the water to form byproducts, which may pose health risks. 

Amendments to the SDWA in 1996 require EPA to develop rules to balance the risks between 

microbial pathogens and disinfection byproducts (DBPs). The Stage 1 Disinfectants and 

Disinfection Byproducts Rule and Interim Enhanced Surface Water Treatment Rule, promulgated in 

December 1998, were the first phase in a rulemaking strategy required by Congress as part of the 

1996 Amendments to the Safe Drinking Water Act. 

The Long Term 2 Enhanced Surface Water Treatment Rule builds upon earlier rules to address 

higher risk public water systems for protection measures beyond those required for existing 

regulations.

The Long Term 2 Enhanced Surface Water Treatment Rule and the Stage 2 Disinfection Byproduct 

Rule are the second phase of rules required by Congress. These rules strengthen protection against 

microbial contaminants, especially Cryptosporidium, and at the same time, reduce potential health 

risks of DBPs. 

Questions and Answers 

What is the LT2ESWTR? 

The purpose of Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) is to reduce 

illness linked with the contaminant Cryptosporidium and other pathogenic microorganisms in 

drinking water. The LT2ESWTR will supplement existing regulations by targeting additional 

Cryptosporidium treatment requirements to higher risk systems. This rule also contains provisions to 

reduce risks from uncovered finished water reservoirs and provisions to ensure that systems maintain 

microbial protection when they take steps to decrease the formation of disinfection byproducts that 

result from chemical water treatment. 

Current regulations require filtered water systems to reduce source water Cryptosporidium levels by 

2-log (99 percent). Recent data on Cryptosporidium infectivity and occurrence indicate that this 

treatment requirement is sufficient for most systems, but additional treatment is necessary for certain 
higher risk systems. These higher risk systems include filtered water systems with high levels of 

Cryptosporidium in their water sources and all unfiltered water systems, which do not treat for 

Cryptosporidium.

The LT2ESWTR is being promulgated simultaneously with the Stage 2 Disinfection Byproduct 

Rule to address concerns about risk tradeoffs between pathogens and DBPs.

What are the health risks of Cryptosporidium? 

Cryptosporidium is a significant concern in drinking water because it contaminates most surface 

waters used as drinking water sources, it is resistant to chlorine and other disinfectants, and it has 

caused waterborne disease outbreaks. Consuming water with Cryptosporidium can cause 

gastrointestinal illness, which may be severe and sometimes fatal for people with weakened immune 

systems (which may include infants, the elderly, and people who have AIDS). 

Who must comply with this rule?

This regulation will apply to all public water systems that use surface water or ground water under 

the direct influence of surface water. 

What does the rule require? 

Monitoring: Under the LT2ESWTR, systems will monitor their water sources to determine treatment 

requirements. This monitoring includes an initial two years of monthly sampling for Cryptosporidium.

To reduce monitoring costs, small filtered water systems will first monitor for E. coliCa bacterium which 

is less expensive to analyze than CryptosporidiumCand will monitor for Cryptosporidium only if their E.

 coli results exceed specified concentration levels.

Monitoring starting dates are staggered by system size, with smaller systems beginning monitoring after 

larger systems. Systems must conduct a second round of monitoring six years after completing the initial 

round to determine if source water conditions have changed significantly. Systems may use (grandfather) 

previously collected data in lieu of conducting new monitoring, and systems are not required to monitor 

if they provide the maximum level of treatment required under the rule. 

Cryptosporidium treatment: Filtered water systems will be classified in one of four treatment 

categories (bins) based on their monitoring results. The majority of systems will be classified in the 

lowest treatment bin, which carries no additional treatment requirements. Systems classified in 

higher treatment bins must provide 90 to 99.7 percent (1.0 to 2.5-log) additional treatment for 

Cryptosporidium. Systems will select from a wide range of treatment and management strategies in 

the Amicrobial toolbox@ to meet their additional treatment requirements. All unfiltered water systems 

must provide at least 99 or 99.9 percent (2 or 3-log) inactivation of Cryptosporidium, depending on 

the results of their monitoring. These Cryptosporidium treatment requirements reflect consensus 

recommendations of the Stage 2 Microbial and Disinfection Byproducts Federal Advisory 

Committee. 
Other requirements: Systems that store treated water in open reservoirs must either cover the 

reservoir or treat the reservoir discharge to inactivate 4-log virus, 3-log Giardia lamblia, and 2-log 

Cryptosporidium. These requirements are necessary to protect against the contamination of water 

that occurs in open reservoirs. In addition, systems must review their current level of microbial 

treatment before making a significant change in their disinfection practice. This review will assist 

systems in maintaining protection against microbial pathogens as they take steps to reduce the 

formation of disinfection byproducts under the Stage 2 Disinfection Byproducts Rule, which EPA is 

finalizing along with the LT2ESWTR. 

What are the benefits of the rule?

The LT2ESWTR will improve the control of Cryptosporidium and other microbiological pathogens 

in drinking water water systems with the highest risk levels. EPA estimates that full compliance with 

the LT2ESWTR will reduce the incidence of cryptosporidiosis - the gastrointestinal illness caused by 

ingestion of Cryptosporidium - by 89,000 to 1,459,000 cases per year, with an associated reduction 

of 20 to 314 premature deaths. The monetized benefits associated with these reductions ranges from 

$253 million to $1.445 billion per year. The additional Cryptosporidium treatment requirements of 

the LT2ESWTR will also reduce exposure to other microbial pathogens, such as Giardia, that cooccur with Cryptosporidium. Additional protection from microbial pathogens will come from 

provisions in this rule for reviewing disinfection practices and for covering or treating uncovered 

finished water reservoirs, though EPA has not quantified these benefits.

What are the costs of the rule?

The LT2ESWTR will result in increased costs to public water systems and states. The average 

annualized present value costs of the LT2ESWTR are estimated to range from $92 to $133 million 

(using a three percent discount rate). Public water systems will bear approximately 99 percent of this 

total cost, with states incurring the remaining 1 percent. The average annual household cost is 

estimated to be $1.67 to $2.59 per year, with 96 to 98 percent of households experiencing annual 

costs of less than $12 per year.

What technical information will be available on the rule? 

The following guidance documents will be available: 

x Source Water Monitoring Guidance

x Microbial Laboratory Guidance

x Small Entity Compliance Guidance

x Microbial Toolbox Guidance Manual

x Ultraviolet Disinfection Guidance Manual

x Membrane Filtration Guidance Manual

x Simultaneous Compliance Guidance Manual

x Low-pressure Membrane Filtration for Pathogen Removal: Application, Implementation, 

and Regulatory Issues
Where can I find more information about this notice and the LT2ESWTR? 

For general information on the LT2ESWTR, contact the Safe Drinking Water Hotline at (800) 

426-4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding legal 

holidays, from 10:00 a.m. to 4:00 p.m., Eastern time. For copies of the Federal Register notice of 

the regulation or technical fact sheets, visit the EPA Safewater website at 

http://www.epa.gov/safewater/disinfection/lt2. For technical inquiries, email 

stage2mdbp@epa.gov.

Office of Water (4607M) EPA 815-F-05-009 December 2005 www.epa.gov/safewater 
Fact Sheet: Stage 2 Disinfectants and 

Disinfection Byproducts Rule

In the past 30 years, the Safe Drinking Water Act (SDWA) has been highly effective in 

protecting public health and has also evolved to respond to new and emerging threats to safe 

drinking water. Disinfection of drinking water is one of the major public health advances in the 

20th century. One hundred years ago, typhoid and cholera epidemics were common through 

American cities; disinfection was a major factor in reducing these epidemics. 

However, the disinfectants themselves can react with naturally-occurring materials in the water 

to form byproducts, which may pose health risks. In addition, in the past 10 years, we have 

learned that there are specific microbial pathogens, such as Cryptosporidium, which can cause 

illness, and are highly resistant to traditional disinfection practices. 

Amendments to the SDWA in 1996 require EPA to develop rules to balance the risks between 

microbial pathogens and disinfection byproducts (DBPs). The Stage 1 Disinfectants and 

Disinfection Byproducts Rule and Interim Enhanced Surface Water Treatment Rule, 

promulgated in December 1998, were the first phase in a rulemaking strategy required by 

Congress as part of the 1996 Amendments to the Safe Drinking Water Act. 

The Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) builds upon the 

Stage 1 DBPR to address higher risk public water systems for protection measures beyond those 

required for existing regulations.

The Stage 2 DBPR and the Long Term 2 Enhanced Surface Water Treatment Rule are the second 

phase of rules required by Congress. These rules strengthen protection against microbial 

contaminants, especially Cryptosporidium, and at the same time, reduce potential health risks of 

DBPs.

Questions and Answers

What is the Stage 2 DBPR?

The Stage 2 Disinfection Byproducts Rule will reduce potential cancer and reproductive and 

developmental health risks from disinfection byproducts (DBPs) in drinking water, which form 

when disinfectants are used to control microbial pathogens. Over 260 million individuals are 

exposed to DBPs.

This final rule strengthens public health protection for customers by tightening compliance 

monitoring requirements for two groups of DBPs, trihalomethanes (TTHM) and haloacetic acids 

(HAA5). The rule targets systems with the greatest risk and builds incrementally on existing 

rules. This regulation will reduce DBP exposure and related potential health risks and provide 

more equitable public health protection. 
The Stage 2 DBPR is being promulgated simultaneously with the Long Term 2 Enhanced 

Surface Water Treatment Rule to address concerns about risk tradeoffs between pathogens and 

DBPs.

What does the rule require?

Under the Stage 2 DBPR, systems will conduct an evaluation of their distribution systems, 

known as an Initial Distribution System Evaluation (IDSE), to identify the locations with high 

disinfection byproduct concentrations. These locations will then be used by the systems as the 

sampling sites for Stage 2 DBPR compliance monitoring. 

Compliance with the maximum contaminant levels for two groups of disinfection byproducts 

(TTHM and HAA5) will be calculated for each monitoring location in the distribution system. 

This approach, referred to as the locational running annual average (LRAA), differs from current 

requirements, which determine compliance by calculating the running annual average of samples 

from all monitoring locations across the system. 

The Stage 2 DBPR also requires each system to determine if they have exceeded an operational 

evaluation level, which is identified using their compliance monitoring results. The operational 

evaluation level provides an early warning of possible future MCL violations, which allows the 

system to take proactive steps to remain in compliance. A system that exceeds an operational 

evaluation level is required to review their operational practices and submit a report to their state 

that identifies actions that may be taken to mitigate future high DBP levels, particularly those 

that may jeopardize their compliance with the DBP MCLs. 

Who must comply with the rule? 

Entities potentially regulated by the Stage 2 DBPR are community and nontransient 

noncommunity water systems that produce and/or deliver water that is treated with a primary or 

residual disinfectant other than ultraviolet light. 

A community water system (CWS) is a public water system that serves year-round residents of a 

community, subdivision, or mobile home park that has at least 15 service connections or an 

average of at least 25 residents. 

A nontransient noncommunity water system (NTNCWS) is a water system that serves at least 25 

of the same people more than six months of the year, but not as primary residence, such as 

schools, businesses, and day care facilities. 

What are disinfection byproducts (DBPs)?

Disinfectants are an essential element of drinking water treatment because of the barrier they 

provide against waterborne disease-causing microorganisms. Disinfection byproducts (DBPs) 

form when disinfectants used to treat drinking water react with naturally occurring materials in 

the water (e.g., decomposing plant material). 
Total trihalomethanes (TTHM - chloroform, bromoform, bromodichloromethane, and 

dibromochloromethane) and haloacetic acids (HAA5 - monochloro-, dichloro-, trichloro-, 

monobromo-, dibromo-) are widely occurring classes of DBPs formed during disinfection with 

chlorine and chloramine. The amount of trihalomethanes and haloacetic acids in drinking water 

can change from day to day, depending on the season, water temperature, amount of disinfectant 

added, the amount of plant material in the water, and a variety of other factors. 

Are THMs and HAAs the only disinfection byproducts? 

No. The four THMs (TTHM) and five HAAs (HAA5) measured and regulated in the Stage 2 

DBPR act as indicators for DBP occurrence. There are many other known DBPs, in addition to 

the possibility of unidentified DBPs present in disinfected water. THMs and HAAs typically 

occur at higher levels than other known and unknown DBPs. The presence of TTHM and HAA5 

is representative of the occurrence of many other chlorination DBPs; thus, a reduction in the 

TTHM and HAA5 generally indicates a reduction of DBPs from chlorination. 

What are the costs and benefits of the rule? 

Quantified benefits estimates for the Stage 2 DBPR are based on reductions in fatal and non-fatal 

bladder cancer cases. EPA has projected that the rule will prevent approximately 280 bladder 

cancer cases per year. Of these cases, 26% are estimated to be fatal. Based on bladder cancer 

alone, the rule is estimated to provide annualized monetized benefit of $763 million to $1.5 

billion.

The rule applies to approximately 75,000 systems; a small subset of these (about 4%) will be 

required to make treatment changes. The mean cost of the rule is $79 million annually. Annual 

household cost increases in the subset of plants adding treatment are estimated at an average of 

$5.53, with 95 percent paying less than $22.40. 

What are the compliance deadlines?

Compliance deadlines are based on the sizes of the public water systems (PWSs). Wholesale 

and consecutive systems of any size must comply with the requirements of the Stage 2 DBPR on 

the same schedule as required for the largest system in the combined distribution system (defined 

as the interconnected distribution system consisting of wholesale systems and consecutive 

systems that receive finished water). Compliance activities are outlined in the following table. 
 ACTIONS 

PUBLIC WATER 

SYSTEMS Submit IDSE 

monitoring plan, system 

specific study plan, or 

40/30 certification 

Complete an 

initial distribution 

system evaluation 

(IDSE)

Submit IDSE 

Report

Begin subpart 

V (Stage 2) 

compliance

monitoring

CWSs and NTNCWSs 

serving at least 100,000 

October 1, 2006 September 30, 

2008

January 1, 2009 April 1, 2012 

CWSs and NTNCWSs 

serving 50,000 - 99,999 

April 1, 2007 March 31, 2009 July 1, 2009 October 1, 2012 

CWSs and NTNCWSs 

serving 10,000 - 49,999 

October 1, 2007 September 30, 

2009

January 1, 2010 October 1, 2013 

CWSs serving fewer 

than 10,000 

April 1, 2008 March 31, 2010 July 1, 2010 October 1, 2013 

NTNCWSs serving 

fewer than 10,000 

NA NA NA October 1, 2013 

*States may grant up to an additional two years for systems making capital improvements. 

What technical information will be available on the rule?

The following Guidance Documents will be available: 

$ Initial Distribution System Evaluation (IDSE) Guidance Manual 

$ Operational Evaluation Guidance Manual 

$ Consecutive Systems Guidance Manual 

$ Small Systems (SBREFA) Guidance Manual 

$ Simultaneous Compliance Guidance Manual 

Where can I find more information about this notice and the Stage 2 DBPR?

For general information on the rule, please visit the EPA Safewater website at 

http://www.epa.gov/safewater/disinfection/stage2 or contact the Safe Drinking Water Hotline at 

1-800-426-4791. The Safe Drinking Water Hotline is open Monday through Friday, excluding 

legal holidays, from 10:00 a.m. to 4:00 p.m., Eastern Time. For technical inquiries, email 

stage2mdbp@epa.gov.

Office of Water (4607M) EPA 815-F-05-003 December 2005 www.epa.gov/safewater 
United States

Environmental Protection

Agency

Office of Water

(4606)

EPA 816-F-01-004

January 2001

Arsenic and Clarifications to Compliance and New

Source Monitoring Rule: A Quick Reference Guide

Overview of the Rule

Title Arsenic and Clarifications to Compliance and New Source Monitoring Rule

66 FR 6976 (January 22, 2001)

Purpose To improve public health by reducing exposure to arsenic in drinking water.

General

Description

Changes the arsenic MCL from 50 μg/L to 10 μg/L; Sets arsenic MCLG at 0; Requires

monitoring for new systems and new drinking water sources; Clarifies the procedures for

determining compliance with the MCLs for IOCs, SOCs, and VOCs.

Utilities

Covered

All community water systems (CWSs) and nontransient, noncommunity water systems

(NTNCWSs) must comply with the arsenic requirements. EPA estimates that 3,024 CWSs

and 1,080 NTNCWSs will have to install treatment to comply with the revised MCL.

Critical Deadlines & Requirements

Consumer Confidence Report Requirements *

Report Due Report Requirements

July 1, 2001 For the report covering calendar year 2000, systems that detect arsenic between 25 μg/L

and 50 μg/L must include an educational statement in the consumer confidence reports

(CCRs).

July 1, 2002

and beyond

For reports covering calendar years 2001 and beyond, systems that detect arsenic

between 5 μg/L and 10 μg/L must include an educational statement in the CCRs.

July 1, 2002 -

July 1, 2006

For reports covering calendar years 2001 to 2005, systems that detect arsenic between

10 μg/L and 50 μg/L must include a health effects statement in their CCRs.

July 1, 2007

and beyond

For reports covering calendar year 2006 and beyond, systems that are in violation of the

arsenic MLC (10 μg/L) must include a health effects statement in their CCRs.

For Drinking Water Systems

Jan. 22, 2004 All NEW systems/sources must collect initial monitoring samples for all IOCs, SOCs, and

VOCs within a period and frequency determined by the State.

Jan. 1, 2005 When allowed by the State, systems may grandfather data collected after this date.

Jan. 23, 2006 The new arsenic MCL of 10 μg/L becomes effective. All systems must begin monitoring or

when allowed by the State, submit data that meets grandfathering requirements.

Dec. 31, 2006 Surface water systems must complete initial monitoring or have a State approved waiver.

Dec. 31, 2007 Ground water systems must complete initial monitoring or have a State approved waiver.

For States

Spring 2001 EPA meets and works with States to explain new rules and requirements and to initiate

adoption and implementation activities.

Jan. 22, 2003 State primacy revision applications due.

Jan. 22, 2005 State primacy revision applications due from States that received 2-year extensions.

Public Health Benefits

Implementation of the Arsenic

Rule will result in . . .

• Avoidance of 16 to 26 non-fatal bladder and lung cancers per year.

• Avoidance of 21 to 30 fatal bladder and lung cancers per year.

• Reduction in the frequency of non-carcinogenic diseases.

* For required educational and health effects statements, please see 40 CFR 141.154.
Monitoring Requirements for Total Arsenic (1)

Initial Monitoring

One sample after the effective date of the MCL (January 23, 2006). Surface water systems must take

annual samples. Ground water systems must take one sample between 2005 and 2007.

Reduced Monitoring

If the initial monitoring result for

arsenic is less than the MCL . . .

Ground water systems must collect one sample every 3 years.

Surface water systems must collect annual samples.

Increased Monitoring

A system with a sampling point result above the MCL must collect quarterly samples at that sampling

point, until the system is reliably and consistently below the MCL.

(1) All samples must be collected at each entry point to the distribution system, unless otherwise specified by the

 State.

Compliance Determination (IOCs, VOCs, and SOCs)

1. Calculate compliance based on a running annual average at each sampling point.

2. Systems will not be in violation until 1 year of quarterly samples have been collected (unless

fewer samples would cause the running annual average to be exceeded.)

3. If a system does not collect all required samples, compliance will be based on the running

annual average of the samples collected.

FIRST COMPLIANCE CYCLE SECOND COMPLIANCE CYCLE

3rd Compliance Period 1st Compliance Period 2nd Compliance Period 3rd Compliance Period

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Below Trigger Level

GROUND WATER

No Waiver

Waiver*

SURFACE WATER

No Waiver

Waiver*

Final Rule

Jan. 23, 2001

Effective Date of Revised MCL

Jan. 23, 2006

Surface Water Systems:

Initial Samples Collected by

Dec. 31, 2006

Ground Water Systems:

Initial Samples Collected by

Dec. 31, 2007

Key

One sampling event.

*Waivers are not permitted under the current arsenic requirements. States may issue 9 year monitoring waivers under the

revised final arsenic rule. To be eligible for a waiver, surface water systems must have monitored annually for at least 3 years.

Ground water systems must conduct a minimum of 3 rounds of monitoring with detection limits below 10 μg/L.

Applicability of the Standardized Monitoring Framework to Arsenic

For additional

information on the

Arsenic Rule

Call the Safe Drinking Water

Hotline at 1-800-426-4791;

visit the EPA Web site at

www.epa.gov/safewater; or

contact your State drinking

water representative. EPA

will provide arsenic training

over the next year.
Lead and Copper Rule: A Quick Reference Guide

Ov erv iew o f the Ru le

T ) itle Lead and Copper Rule (LCR 1, 1 56 FR 26460 - 26564, June 7, 199

Purpose

Protect public health by minimizing lead (Pb) and copper (Cu) levels in drinking

water, primarily by reducing water corrosivity. Pb and Cu enter drinking water

mainly from corrosion of Pb and Cu containing plumbing materials.

General

Description

Establishes action level (AL) of 0.015 mg/L for Pb and 1.3 mg/L for Cu based on

90th percentile level of tap water samples. An AL exceedance is not a violation but

can trigger other requirements that include water quality parameter (WQP)

monitoring, corrosion control treatment (CCT), source water monitoring/treatment,

public education, and lead service line replacement (LSLR).

Utilities

Covered

All community water systems (CWSs) and non-transient, non-community water

systems (NTNCWSs) are subject to the LCR requirements.

P u bli c H ealth Benefits

Implementation

of the LCR has

resulted in . . .

Reduction in risk of exposure to Pb that can cause damage to brain, red

blood cells, and kidneys, especially for young children and pregnant women.

Reduction in risk of exposure to Cu that can cause stomach and

intestinal distress, liver or kidney damage, and complications of Wilson's

disease in genetically predisposed people.

Treatment Techniqu e and Sampling Requ i rements

CORROSION CONTROL TREATMENT INSTALLATION: All large systems (except systems that

meet the requirements of 40 CFR 141.81(b)(2) or (3)) must install CCT. Medium and small systems

that exceed either AL must install CCT.

WATER QUALITY PARAMETER MONITORING: All large systems are required to do WQP

monitoring. Medium and small systems that exceed either AL are required to do WQP

monitoring.

1The June 1991 LCR was

revised with the following

Technical Amendments:

56 FR 32112, July 15, 1991;

57 FR 28785, June 29, 1992;

59 FR 33860, June 30, 1994;

and the LCR Minor Revisions

65 FR 1950, January 12, 2000.

Lead and Co pper Tap Sam pling Requ i r em ents

First draw samples must be collected by all CWSs & NTNCWSs at cold water taps in

homes/buildings that are at high risk of Pb/Cu contamination as identified in 40 CFR 141.86(a).

Number of sample sites is based on system size (see Table 1).

Systems must conduct monitoring every 6 months unless they qualify for reduced monitoring

(see Table 2).

Table 1: Pb and Cu Tap and WQP Tap Monitoring

Size

Category System Size

Number of Pb/Cu Tap Sample Sites Number of WQP Tap Sampling Sites

Standard Reduced Standard Reduced

Large

> 100K 1 0 00 5 52 01

50,001-100K 6 0 0 3 01 7

Medium

10,001 - 50K 6 0 0 3 01 7

3,301 - 10K 4 0 0 2 33

Small

501 - 3,300 2 0 0 1 22

101 - 500 15 11 0

# 100 55 1 1

Table 2: Criteria for Reduced Pb/Cu Tap Monitoringa

Can Monitor . . . If the System . . .

Annually

1. Serves # 50,000 and is # both ALs for 2 consecutive 6-month monitoring periods; or

2. Meets Optimal Water Quality Parameter (OWQP) specifications for 2 consecutive 6-

month monitoring periods.

Triennially

1. Serves # 50,000 and is # both ALs for 3 consecutive years of monitoring; or

2. Meets OWQP specifications for 3 consecutive years of monitoring; or

3. Has 90th percentile Pb levels # 0.005 mg/L & 90th percentile Cu level # 0.65 mg/L for

2 consecutive 6-month periods (i.e, accelerated reduced Pb/Cu tap monitoring), or

4. Meets the 40 CFR 141.81(b)(3) criteria.

Once every 9

years Serves # 3,300 and meets monitoring waiver criteria found at 40 CFR 141.86(g).

a Samples are collected at reduced number of sites (see Table 1 above).
IOCs1

For additional information on

the LCR, call the Safe Drinking

Water Hotline at 1-800-426-

4791; visit the EPA web site at

www.epa.gov/safewater/lcrmr/

implement.html; or contact your

State drinking water

representative.

Office of Water (4606) EPA 816-F-04-009 www.epa.gov/safewater March 2004

Nitrate Nitrite Radionuclides nuclides Asbestos Asbestos

Tr eatm ent Techniqu e and Sam pling Requ i r em ents if

the AL is Exceeded

Water Quality Parameter (WQP) Monitoring

All systems serving > 50,000 people, and those systems serving # 50,000 people if 90th percentile tap

level > either AL, must take WQP samples during the same monitoring periods as Pb/Cu tap sample.

Used to determine water corrosivity, and if needed, to help identify type of CCT to be installed and how

CCT should be operated (i.e., establishes OWQP levels).

WQPs include: pH, alkalinity, calcium, conductivity (initial WQP monitoring only), orthophosphate (if

phosphate-based inhibitor is used); silica (if silicate-based inhibitor is used), and temperature (initial

WQP monitoring only).

Samples are collected within distribution system (i.e., WQP tap samples), with number of sites based

on system size (see Table 1), and at each entry point to distribution system (EPTDS).

Systems installing CCT, must conduct follow-up monitoring for 2 consecutive 6-month periods – WQP

tap monitoring is conducted semi-annually; EPTDS monitoring increases to every two weeks.

After follow-up monitoring, State sets ranges of values for the OWQPs.

Reduced WQP tap monitoring is available for systems in compliance with OWQPs; Reduced

monitoring does not apply to EPTDS monitoring.

For systems # 50,000, WQP monitoring is not required whenever 90th percentile tap levels are # both

ALs.

Public Education (PE)

Only required if Pb AL is exceeded (no public education is required if only Cu AL exceeded).

Informs Public Water System's (PWS) customers about health effects, sources, and what can be done

to reduce exposure.

Includes billing inserts sent directly to customers, pamphlets or brochures distributed to hospitals &

other locations that provide services to pregnant woman & children, and for some CWSs, newspaper

notices and public service announcements (PSAs) submitted to TV/radio stations.

System must begin delivering materials within 60 days of Pb AL exceedance and continue every 6

months for PSAs and annually for all other forms of delivery for as long as it exceeds Pb AL.

Different delivery methods and mandatory language for CWSs & NTNCWSs.

Can discontinue delivery whenever # Pb AL; but must recommence if Pb AL subsequently exceeded.

PE requirements are in addition to the Public Notification required in 40 CFR Subpart Q.

Source Water Monitoring and Treatment

All systems that exceed Pb or Cu AL must collect source water samples to determine contribution from

source water to total tap water Pb/Cu levels and make a source water treatment (SOWT)

recommendation within 6 months of the exceedance.

One set of samples at each EPTDS is due within 6 months of first AL exceedance.

If State requires SOWT; system has 24 months to install SOWT.

After follow-up Pb/Cu tap and EPTDS monitoring, State sets maximum permissible levels for Pb & Cu

in source.

Corrosion Control Treatment

Required for all large systems (except systems that meet the requirements of 40 CFR 141.81(b)(2) or

(b)(3)) and medium/small systems that exceed either AL. The system shall recommend optimal CCT

within 6 months.

Corrosion control study required for large systems.

If State requires study for medium or small systems, it must be completed within 18 months.

Once State determines type of CCT to be installed, PWS has 24 months to install CCT.

Systems installing CCT must conduct 2 consecutive 6-months of follow-up monitoring.

After follow-up Pb/Cu tap & WQP monitoring, State sets OWQPs.

Small & medium systems can stop CCT steps if # both ALs for 2 consecutive 6-month monitoring

periods.

If the system continues to exceed the AL after installing CCT and/or SOWT...

Lead Service Line (LSL) Monitoring

Two types of sampling associated with LSL replacement (LSLR):

- Optional - Monitoring from LSL to determine need to replace line. If all Pb samples from line

# 0.015 mg/L then LSL does not need to be replaced and counts as replaced line.

- Required - Monitoring if entire LSL is not replaced to determine impact from "partial" LSLR. Sample is collected that is representative of water in service line that is partially replaced.

Monitoring only applies to system subject to LSLR.

Lead Service Line Replacement

System must replace LSLs that contribute more than 0.015 mg/L to tap water levels.

Must replace 7% of LSL per year; State can require accelerated schedule.

If only a portion of a LSL is replaced, PWS must:

- Notify customers at least 45 days prior to replacement about the potential for increased Pb levels;

- Collect sample within 72 hours of replacement and mail/post results within 3 days of receipt of

results.

Systems can discontinue LSLR whenever # Pb AL in tap water for 2 consecutive monitoring periods.

n

o

p

q

r

s







Appendix A. Summary of Pertinent Drinking Water Regulations 

Simultaneous Compliance Guidance Manual A-24 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

This page intentionally left blank. 
United States

Environmental Protection

Agency

Office of Water

(4606)

EPA 816-F-01-035

November 2001

www.epa.gov/safewater

Total Coliform Rule:

A Quick Reference Guide

Overview of the Rule

Title Total Coliform Rule (TCR)

54 FR 27544-27568, June 29, 1989, Vol. 54, No. 1241

Purpose

Improve public health protection by reducing fecal pathogens to minimal levels

through control of total coliform bacteria, including fecal coliforms and Escherichia

coli (E. coli).

General

Description

Establishes a maximum contaminant level (MCL) based on the presence or absence

of total coliforms, modifies monitoring requirements including testing for fecal

coliforms or E. coli, requires use of a sample siting plan, and also requires sanitary

surveys for systems collecting fewer than five samples per month.

Utilities

Covered The TCR applies to all public water systems.

Public Health Benefits

Implementation

of the TCR has

resulted in . . .

4 Reduction in risk of illness from disease causing organisms associated with

 sewage or animal wastes. Disease symptoms may include diarrhea, cramps,

 nausea, and possibly jaundice, and associated headaches and fatigue.

 What are the Major Provisions?

 ROUTINE Sampling Requirements

4 Total coliform samples must be collected at sites which are representative of water quality

 throughout the distribution system according to a written sample siting plan subject to state

 review and revision.

4 Samples must be collected at regular time intervals throughout the month except groundwater

 systems serving 4,900 persons or fewer may collect them on the same day.

4 Monthly sampling requirements are based on population served (see table on next page for the

 minimum sampling frequency).

4 A reduced monitoring frequency may be available for systems serving 1,000 persons or fewer

 and using only ground water if a sanitary survey within the past 5 years shows the system is

 free of sanitary defects (the frequency may be no less than 1 sample/quarter for community

 and 1 sample/year for non-community systems).

4 Each total coliform-positive routine sample must be tested for the presence of fecal coliforms or

 E. coli.

4 If any routine sample is total coliform-positive, repeat samples are required.

 REPEAT Sampling Requirements

4 Within 24 hours of learning of a total coliform-positive ROUTINE sample result, at least 3 REPEAT

 samples must be collected and analyzed for total coliforms:

4 One REPEAT sample must be collected from the same tap as the original sample.

4 One REPEAT sample must be collected within five service connections upstream.

4 One REPEAT sample must be collected within five service connections downstream.

4 Systems that collect 1 ROUTINE sample per month or fewer must collect a 4th REPEAT sample.

4 If any REPEAT sample is total coliform-positive:

4 The system must analyze that total coliform-positive culture for fecal coliforms or E.coli.

4 The system must collect another set of REPEAT samples, as before, unless the MCL has been

 violated and the system has notified the state.

 Additional ROUTINE Sample Requirements

4 A positive ROUTINE or REPEAT total coliform result requires a minimum of five ROUTINE

 samples be collected the following month the system provides water to the public unless

 waived by the state.

1 The June 1989 Rule was

revised as follows: Corrections and

Technical Amendments, 6/19/90

and Partial Stay of Certain Provisions (Variance Criteria) 56 FR

1556-1557, Vol 56, No 10.

Note: The TCR is currently

undergoing the 6 year review

process and may be subject to

change.
For additional information on

the TCR

Call the Safe Drinking Water

Hotline at 1-800-426-4791; visit

the EPA web site at

www.epa.gov/safewater/mdbp/

mdbp.html; or contact your state

drinking water representative.

A Monthly MCL Violation is Triggered if:

A system collecting fewer than 40

samples per month . . .

Has greater than 1 ROUTINE/REPEAT sample per month which

is total coliform-positive.

A system collecting at least 40

samples per month . . .

Has greater than 5.0 percent of the ROUTINE/REPEAT samples

in a month total coliform-positive.

An Acute MCL Violation is Triggered if:

Any public water system . . . Has any fecal coliform- or E. coli-positive REPEAT sample or

has a fecal coliform- or E. coli-positive ROUTINE sample

followed by a total coliform-positive REPEAT sample.

What are the Other Provisions?

Systems collecting fewer than 5

ROUTINE samples per month . . .

Must have a sanitary survey every 5 years (or every 10

years if it is a non-community water system using

protected and disinfected ground water).**

Systems using surface water or ground

water under the direct influence of

surface water (GWUDI) and meeting

filtration avoidance criteria . . .

Must collect and have analyzed one coliform sample

each day the turbidity of the source water exceeds 1

NTU. This sample must be collected from a tap near the

first service connection.

** As per the IESWTR, states must conduct sanitary surveys for community surface water and GWUDI systems in this

category every 3 years (unless reduced by the state based on outstanding performance).

What are the Public Notification and Reporting Requirements?

For a Monthly MCL Violation 4 The violation must be reported to the state no later than the

 end of the next business day after the system learns of the

 violation.

4 The public must be notified within 14 days. 2

For an Acute MCL Violation 4 The violation must be reported to the state no later than the

 end of the next business day after the system learns of the

 violation.

4 The public must be notified within 72 hours. 2

Systems with ROUTINE or

REPEAT samples that are fecal

coliform- or E. coli-positive . . .

Must notify the state by the end of the day they are notified of the

result or by the end of the next business day if the state office is

already closed.

How is Compliance Determined?

4 Compliance is based on the presence or absence of total coliforms.

4 Compliance is determined each calendar month the system serves water to the public (or each

 calendar month that sampling occurs for systems on reduced monitoring).

4 The results of ROUTINE and REPEAT samples are used to calculate compliance.

2 The revised Public Notification

Rule will extend the period allowed

for public notice of monthly violations

to 30 days and shorten the period for

acute violations to 24 hours. These

revisions are effective for all systems

by May 6, 2002 and are detailed in

40 CFR Subpart Q.

Public Water System ROUTINE Monitoring Frequencies

Population Minimum

Samples/ Month Population MinimumSamples/ Month Population MinimumSamples/ Month

25-1,000* 1 21,501-25,000 25 450,001-600,000 210

1,001-2,500 2 25,001-33,000 30 600,001-780,000 240

2,501-3,300 3 33,001-41,000 40 780,001-970,000 270

3,301-4,100 4 41,001-50,000 50 970,001-1,230,000 300

4,101-4,900 5 50,001-59,000 60 1,230,001-1,520,000 330

4,901-5,800 6 59,001-70,000 70 1,520,001-1,850,000 360

5,801-6,700 7 70,001-83,000 80 1,850,001-2,270,000 390

6,701-7,600 8 83,001-96,000 90 2,270,001-3,020,000 420

7,601-8,500 9 96,001-130,000 100 3,020,001-3,960,000 450

8,501-12,900 10 130,001-220,000 120 ≥≥ 3,960,001 480

12,901-17,200 15 220,001-320,000 150

17,201-21,500 20 320,001-450,000 180

*Includes PWSs which have at least 15 service connections, but serve <25 people.
United States

Environmental Protection

Agency

Office of Water

(4606)

EPA 816-F-01-010

May 2001

www.epa.gov/safewater

Stage 1 Disinfectants and Disinfection

Byproducts Rule:

A Quick Reference Guide

Overview of the Rule

Title

Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR)

63 FR 69390 - 69476, December 16, 1998, Vol. 63, No. 241

Revisions to the Interim Enhanced Surface Water Treatment Rule (IESWTR), the Stage 1

Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR), and Revisions to State Primacy

Requirements to Implement the Safe Drinking Water Act (SDWA) Amendments

66 FR 3770, January 16, 2001, Vol 66, No. 29

Purpose

Improve public health protection by reducing exposure to disinfection byproducts. Some

disinfectants and disinfection byproducts (DBPs) have been shown to cause cancer and

reproductive effects in lab animals and suggested bladder cancer and reproductive effects in

humans.

General

Description

The Stage 1 DBPR is the first of a staged set of rules that will reduce the allowable levels of

DBPs in drinking water. The new rule establishes seven new standards and a treatment

technique of enhanced coagulation or enhanced softening to further reduce DBP exposure. The

rule is designed to limit capital investments and avoid major shifts in disinfection technologies

until additional information is available on the occurrence and health effects of DBPs.

Utilities

Covered

The Stage 1 DBPR applies to all sizes of community water systems and nontransient

noncommunity water systems that add a disinfectant to the drinking water during any part of the

treatment process and transient noncommunity water systems that use chlorine dioxide.

Public Health Benefits

Implementation of the

Stage 1 DBPR will

result in . . .

4 As many as 140 million people receiving increased protection from DBPs.

4 24 percent average reduction nationally in trihalomethane levels.

4 Reduction in exposure to the major DBPs from use of ozone (DBP = bromate) and

 chlorine dioxide (DBP = chlorite).

Estimated impacts of

the Stage 1 DBPR

include . . .

4 National capital costs: $2.3 billion

4 National total annualized costs to utilities: $684 million

4 95 percent of households will incur an increase of less than $1 per month.

4 4 percent of households will incur an increase of $1-10 per month.

4 <1 percent of households will incur an increase of $10-33 per month.

Critical Deadlines and Requirements

For Drinking Water Systems

January 1, 2002 Surface water systems and ground water systems under the direct

influence of surface water serving ≥≥ 10,000 people must comply with the

Stage 1 DBPR requirements.

January 1, 2004 Surface water systems and ground water systems under the direct

influence of surface water serving < 10,000, and all ground water systems

must comply with the Stage 1 DBPR requirements.

For States

December 16, 2000 States submit Stage 1 DBPR primacy revision applications to EPA

(triggers interim primacy).

December 16, 2002 Primacy extension deadline - all states with an extension must submit

primacy revision applications to EPA.
For additional information

on the Stage 1 DBPR

Call the Safe Drinking Water

Hotline at 1-800-426-4791;

visit the EPA web site at

www.epa.gov/safewater; or

contact your State drinking

water representative.

Additional material is

available at www.epa.gov/

safewater/mdbp/

implement.html.

Routine Monitoring Requirements

Coverage Monitoring

Frequency Compliance

TTHM/HAA5 Surface and ground water

under the direct influence of

surface water serving ≥≥ 10,000

4/plant/quarter Running annual average

Surface and ground water

under the direct influence of

surface water serving 500 -

9,999

1/plant/quarter Running annual average

Surface and ground water

under the direct influence of

surface water serving < 500

1/plant/year in month of

warmest water temperature**

Running annual average

of increased monitoring

Ground water serving ≥≥ 10,000 1/plant/quarter Running annual average

Ground water serving < 10,000 1/plant/year in month of

warmest water temperature**

Running annual average

of increased monitoring

Bromate Ozone plants Monthly Running annual average

Chlorite Chlorine dioxide plants

Daily at entrance to

distribution system; monthly

in distribution system

Daily/follow-up monitoring

Chlorine dioxide Chlorine dioxide plants Daily at entrance to

distribution system Daily/follow-up monitoring

Chlorine/Chloramines All systems Same location and frequency

as TCR sampling Running annual average

DBP precursors Conventional filtration Monthly for total organic

carbon and alkalinity Running annual average

Regulated Contaminants/Disinfectants

Regulated

Contaminants

MCL

(mg/L)

MCLG

(mg/L)

Regulated

Disinfectants

MRDL*

(mg/L)

MRDLG*

(mg/L)

Total Trihalomethanes (TTHM) 0.080

Chlorine 4.0 as Cl2

Chloroform 4

Bromodichloromethane

Dibromochloromethane

Bromoform

-

zero

0.06

zero

Five Haloacetic Acids (HAA5) 0.060 Chloramines 4.0 as Cl2 4

Monochloroacetic acid

Dichloroacetic acid

Trichloroacetic acid

Bromoacetic acid

Dibromoacetic acid

-

zero

0.3

-

-

Chlorine dioxide 0.8 0.8

Bromate (plants that use ozone) 0.010 zero *Stage 1 DBPR includes maximum residual

disinfectant levels (MRDLs) and maximum

residual disinfectant level goals (MRDLGs)

which are similar to MCLs and MCLGs, but for

disinfectants.

Chlorite (plants that use chlorine

dioxide) 1.0 0.8

Treatment Technique

Enhanced coagulation/enhanced softening to improve removal of DBP precursors (See Step 1 TOC Table) for

systems using conventional filtration treatment.

Step 1 TOC Table - Required % Removal of TOC

Source Water

TOC (mg/L)

Source Water Alkalinity, mg/L as CaCO3

 0-60 > 60-120 > 120

> 2.0 to 4.0 35.0% 25.0% 15.0%

> 4.0 to 8.0 45.0% 35.0% 25.0%

> 8.0 50.0% 40.0% 30.0%

1Systems meeting at least one of the alternative compliance criteria in the rule are not required to meet the

removals in this table.

2Systems practicing softening must meet the TOC removal requirements in the last column to the right

** System must increase monitoring to 1 sample per plant per quarter if an MCL is exceeded.
United States

Environmental Protection

Agency

Office of Water

(4606)

EPA 816-F-01-011

May 2001

www.epa.gov/safewater

Interim Enhanced Surface Water

Treatment Rule:

A Quick Reference Guide

Overview of the Rule

Title

Interim Enhanced Surface Water Treatment Rule (IESWTR)

63 FR 69478 - 69521, December 16, 1998, Vol. 63, No. 241

Revisions to the Interim Enhanced Surface Water Treatment Rule (IESWTR), the Stage 1

Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR), and Revisions to State

Primacy Requirements to Implement the Safe Drinking Water Act (SDWA) Amendments

66 FR 3770, January 16, 2001, Vol 66, No. 29

Purpose

Improve public health control of microbial contaminants, particularly Cryptosporidium.

Prevent significant increases in microbial risk that might otherwise occur when systems

implement the Stage 1 Disinfectants and Disinfection Byproducts Rule.

General

Description

Builds upon treatment technique approach and requirements of the 1989 Surface Water

Treatment Rule. Relies on existing technologies currently in use at water treatment plants.

Utilities

Covered

Sanitary survey requirements apply to all public water systems using surface water or

ground water under the direct influence of surface water, regardless of size. All remaining

requirements apply to public water systems that use surface water or ground water under

the direct influence of surface water and serve 10,000 or more people.

Major Provisions

Regulated Contaminants

Cryptosporidium 4 Maximum contaminant level goal (MCLG) of zero.

4 99 percent (2-log) physical removal for systems that filter.

4 Include in watershed control program for unfiltered systems.

Turbidity Performance

Standards

Conventional and direct filtration combined filter effluent:

4 ≤≤ 0.3 nephelometric turbidity units (NTU) in at least 95 percent of

 measurements taken each month.

4 Maximum level of 1 NTU.

Turbidity Monitoring Requirements

(Conventional and Direct Filtration)

Combined Filter Effluent 4 Performed every 4 hours to ensure compliance with turbidity

 performance standards.

Individual Filter Effluent 4 Performed continuously (every 15 minutes) to assist treatment plant

 operators in understanding and assessing filter performance.

Additional Requirements

4 Disinfection profiling and benchmarking.

4 Construction of new uncovered finished water storage facilities prohibited.

4 Sanitary surveys, conducted by the state, for all surface water and ground water under the

 direct influence of surface water systems regardless of size (every 3 years for community water systems

 and every 5 years for noncommunity water systems).
For additional information

on the IESWTR

Call the Safe Drinking Water

Hotline at 1-800-426-4791;

visit the EPA web site at

www.epa.gov/safewater; or

contact your State drinking

water representative.

Additional material is

available at www.epa.gov/

safewater/mdbp/

implement.html.

Critical Deadlines and Requirements

For Drinking Water Systems

February 16, 1999 Construction of uncovered finished water reservoirs is prohibited.

March 1999 Public water systems lacking ICR or other occurrence data begin 4 quarters of

applicability monitoring for TTHM and HAA5 to determine if disinfection

profiling is necessary.

April 16, 1999 Systems that have 4 consecutive quarters of HAA5 occurrence data that meet

the TTHM monitoring requirements must submit data to the state to determine

if disinfection profiling is necessary.

December 31, 1999 Public water systems with ICR data must submit it to states to determine if

disinfection profiling is necessary.

April 1, 2000 Public water systems must begin developing a disinfection profile if their annual

average (based on 4 quarters of data) for TTHM is greater than or equal to

0.064 mg/L or HAA5 is greater than or equal to 0.048 mg/L.

March 31, 2001 Disinfection profile must be complete.

January 1, 2002 Surface water systems or ground water under the direct influence of surface

water systems serving 10,000 or more people must comply with all IESWTR

provisions (e.g., turbidity standards, individual filter monitoring).

For States

December 16, 2000 States submit IESWTR primacy revision applications to EPA (triggers interim

primacy).

January 2002 States begin first round of sanitary surveys.

December 16, 2002 Primacy extension deadline - all states with an extension must submit primacy

revision applications to EPA.

December 2004 States must complete first round of sanitary surveys for community water

systems.

December 2006 States must complete first round of sanitary surveys for noncommunity water

systems.

Public Health Benefits

Implementation of

the IESWTR will

result in . . .

4 Increased protection against gastrointestinal illnesses from

 Cryptosporidium and other pathogens through improvements in filtration.

4 Reduced likelihood of endemic illness from Cryptosporidium by 110,000 to

 463,000 cases annually.

4 Reduced likelihood of outbreaks of cryptosporidiosis.

Estimated impacts of

the IESWTR

include . . .

4 National total annualized cost: $307 million

4 92 percent of households will incur an increase of less than $1 per month.

4 Less than 1 percent of households will incur an increase of more than $5 per

 month (about $8 per month).

Profiling and Benchmarking

Public water systems must evaluate impacts on microbial risk before changing

disinfection practices to ensure adequate protection is maintained. The three major steps

are:

4 Determine if a public water system needs to profile based on TTHM and HAA5 levels

 (applicability monitoring)

4 Develop a disinfection profile that reflects daily Giardia lamblia inactivation for at least a year

 (systems using ozone or chloramines must also calculate inactivation of viruses)

4 Calculate a disinfection benchmark (lowest monthly inactivation) based on the profile and

 consult with the state prior to making a significant change to disinfection practices
Overview of the Rule

Title Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR)

67 FR 1812, January 14, 2002, Vol. 67, No. 9

Purpose

Improve public health protection through the control of microbial contaminants,

particularly Cryptosporidium. Prevent significant increases in microbial risk that

might otherwise occur when systems implement the Stage 1 Disinfectants and

Disinfection Byproducts Rule.

General

Description

Builds upon the requirements of the 1989 Surface Water Treatment Rule (SWTR).

Smaller system counterpart of the Interim Enhanced Surface Water Treatment Rule

(IESWTR).

Utilities

Covered

Public water systems that use surface water or ground water under the direct

influence of surface water (GWUDI) and serve fewer than 10,000 people.

For additional information on

the LT1ESWTR

Call the Safe Drinking Water

Hotline at 1-800-426-4791; visit

the EPA web site at

www.epa.gov/safewater/mdbp/

lt1eswtr.html; or contact your

State drinking water

representative.

Major Provisions

Control of

Cryptosporidium

4 The maximum contaminant level goal (MCLG) is set at zero.

4 Filtered systems must physically remove 99% (2-log) of Cryptosporidium.

4 Unfiltered systems must update their watershed control programs to

 minimize the potential for contamination by Cryptosporidium oocysts.

4 Cryptosporidium is included as an indicator of GWUDI.

Combined Filter

Effluent (CFE)

Turbidity

Performance

Standards

Specific CFE turbidity requirements depend on the type of filtration

used by the system.

Conventional and direct filtration:

4 ≤≤ 0.3 nephelometric turbidity units (NTU) in at least 95% of measurements

 taken each month.

4 Maximum level of turbidity: 1 NTU.

Slow sand and diatomaceous earth (DE) filtration:

4 Continue to meet CFE turbidity limits specified in the SWTR:

• 1 NTU in at least 95% of measurements taken each month.

• Maximum level of turbidity: 5 NTU.

Alternative technologies (other than conventional, direct, slow sand, or DE):

4 Turbidity levels are established by the State based on filter

 demonstration data submitted by the system.

• State-set limits must not exceed 1 NTU (in at least 95% of

 measurements) or 5 NTU (maximum).

Turbidity Monitoring Requirements

Combined Filter

Effluent

4 Performed at least every 4 hours to ensure compliance with CFE

 turbidity performance standards. 1

Individual Filter

Effluent (IFE)

(for systems using

conventional and

direct filtration only)

Since the CFE may meet regulatory requirements even though one

filter is producing high turbidity water, the IFE is measured to assist

conventional and direct filtration treatment plant operators in

understanding and assessing individual filter performance.

4 Performed continuously (recorded at least every 15 minutes).

4 Systems with two or fewer filters may conduct continuous monitoring

 of CFE turbidity in place of individual filter effluent turbidity monitoring.

4 Certain follow-up actions are required if the IFE turbidity (or CFE for

 systems with two filters) exceeds 1.0 NTU in 2 consecutive readings or

 more (i.e., additional reporting, filter self-assessments, and/or

 comprehensive performance evaluations (CPEs)).

1

 This frequency may be reduced

by the State to once per day for

systems using slow sand/alternative

filtration or for systems serving 500

persons or fewer regardless of the

type of filtration used.

Long Term 1 Enhanced Surface

Water Treatment Rule:

A Quick Reference Guide

Filter

1

Filter

2

Filter

3

IFE IFE IFE

CFE
Additional Requirements

4 Construction of new uncovered finished water reservoirs is prohibited.

Public Health Benefits

Implementation of

the LT1ESWTR will

result in . . .

4 Increased protection against gastrointestinal illnesses from Cryptosporidium and other pathogens through

 improvements in filtration.

4 Reduced likelihood of endemic illness from Cryptosporidium by an estimated 12,000 to 41,000 cases annually.

4 Reduced likelihood of outbreaks of cryptosporidiosis.

Estimated impacts

of the LT1ESWTR

include . . .

4 National total annualized cost: $39.5 million.

4 90% of affected households will incur an increase of less than $1.25 per month.

4 One percent of affected households are likely to incur an increase of more than $10 per month.

Disinfection Profiling and Benchmarking Requirements

Community and non-transient non-community public water systems must evaluate impacts on microbial risk before changing disinfection

practices to ensure adequate microbial protection is maintained. This is accomplished through a process called disinfection profiling and

benchmarking.

What are the disinfection profiling and benchmarking requirements?

4 Systems must develop a disinfection profile, which is a graphical compilation of weekly inactivation of Giardia lamblia, taken on the

 same calendar day each week over 12 consecutive months. (Systems using chloramines, ozone, or chlorine dioxide for primary

 disinfection must also calculate inactivation of viruses). Results must be available for review by the State during sanitary surveys.

4 A State may deem a profile unnecessary if the system has sample data collected after January 1, 1998–during the month of warmest

 water temperature and at maximum residence time in the distribution system–indicating TTHM levels are below 0.064 mg/L and HAA5

 levels are below 0.048 mg/L.

4 Prior to making a significant change to disinfection practices, systems required to develop a profile must calculate a disinfection

 benchmark and consult with the State. The benchmark is the calculation of the lowest monthly average of inactivation based on the

 disinfection profile.

Critical Deadlines and Requirements

For Drinking Water Systems

March 15, 2002 Construction of uncovered finished reservoirs is prohibited.

July 1, 2003 No later than this date, systems serving between 500-9,999 persons must report to the State:

4 Results of optional monitoring which show levels of TTHM < 0.064 mg/L and HAA5 < 0.048 mg/L, OR

4 System has started profiling.

January 1, 2004 No later than this date, systems serving fewer than 500 persons must report to the State:

4 Results of optional monitoring which show levels of TTHM < 0.064 mg/L and HAA5 < 0.048 mg/L, OR

4 System has started profiling.

June 30, 2004 Systems serving between 500 and 9,999 persons must complete their disinfection profile unless the State has

determined it is unnecessary.

December 31, 2004 Systems serving fewer than 500 persons must complete their disinfection profile unless the State has determined it is

unnecessary.

January 14, 2005 Surface water systems or GWUDI systems serving fewer than 10,000 people must comply with the applicable

LT1ESWTR provisions (e.g., turbidity standards, individual filter monitoring, Cryptosporidium removal requirements,

updated watershed control requirements for unfiltered systems).

For States

January 2002 As per the IESWTR, States begin first round of sanitary surveys (at least every 3 years for community water systems

and every 5 years for non-community water systems).

October 14, 2003 States are encouraged to submit final primacy applications to EPA.

January 14, 2004 Final primacy applications must be submitted to EPA unless granted an extension.

December 2004 States must complete first round of sanitary surveys for community water systems (as per the IESWTR).

January 14, 2006 Final primacy revision applications from States with approved 2-year extension agreements must be submitted to EPA.

December 2006 States must complete first round of sanitary surveys for non-community water systems (as per the IESWTR).

Office of Water (4606) EPA 816-F-02-001 www.epa.gov/safewater January 2002
United States

Environmental Protection

Agency

Office of Water

(4606)

EPA 816-F-01-019

June 2001

www.epa.gov/safewater

Filter Backwash Recycling Rule:

A Quick Reference Guide

Overview of the Rule

Title Filter Backwash Recycling Rule (FBRR)

66 FR 31086, June 8, 2001, Vol. 66, No. 111

Purpose

Improve public health protection by assessing and changing, where

needed, recycle practices for improved contaminant control, particularly

microbial contaminants.

General

Description

The FBRR requires systems that recycle to return specific recycle flows

through all processes of the system's existing conventional or direct

filtration system or at an alternate location approved by the state.

Utilities

Covered

Applies to public water systems that use surface water or ground water

under the direct influence of surface water, practice conventional or

direct filtration, and recycle spent filter backwash, thickener supernatant,

or liquids from dewatering processes.

Public Health Benefits

Implementation of

FBRR will result in . . .

4 Reduction in risk of illness from microbial pathogens in

 drinking water, particularly Cryptosporidium.

Estimated impacts of

the FBRR include . . .

4 FBRR will apply to an estimated 4,650 systems serving

 35 million Americans.

4 Fewer than 400 systems are expected to require capital

 improvements.

4 Annualized capital costs incurred by public water systems

 associated with recycle modifications are estimated to be

 $5.8 million.

4 Mean annual cost per household is estimated to be less

 than $1.70 for 99 percent of the affected households and

 between $1.70 and $100 for the remaining one percent of

 affected households.

Conventional and Direct Filtration

4 Conventional filtration, as defined in 40 CFR 141.2, is a series of processes including

 coagulation, flocculation, sedimentation, and filtration resulting in substantial

 particulate removal. Conventional filtration is the most common type of filtration.

4 Direct filtration, as defined in 40 CFR 141.2, is a series of processes including

 coagulation and filtration, but excluding sedimentation, and resulting in substantial

 particulate removal. Typically, direct filtration can be used only with high-quality raw

 water that has low levels of turbidity and suspended solids.
For additional information on

the FBRR

Call the Safe Drinking Water

Hotline at 1-800-426-4791; visit

the EPA web site at

www.epa.gov/safewater; or

contact your state drinking water

representative.

Additional material is available at

www.epa.gov/safewater/

filterbackwash.html.

What recycle flow information does a system need

to collect and retain on file?

4 Copy of recycle notification and information submitted to the state.

4 List of all recycle flows and frequency with which they are returned.

4 Average and maximum backwash flow rates through filters, and average and

 maximum duration of filter backwash process (in minutes).

4 Typical filter run length and written summary of how filter run length is determined.

4 Type of treatment provided for recycle flows.

4 Data on the physical dimension of the equalization and/or treatment units, typical

 and maximum hydraulic loading rates, types of treatment chemicals used,

 average dose, frequency of use, and frequency at which solids are removed, if

 applicable.

What does a recycle notification include?

4 Plant schematic showing origin of recycle flows, how recycle flows are conveyed,

 and return location of recycle flows.

4 Typical recycle flows (gpm), highest observed plant flow experienced in the previous

 year (gpm), and design flow for the treatment plant (gpm).

4 State-approved plant operating capacity (if applicable).

Critical Deadlines and Requirements

For Drinking Water Systems

December 8, 2003 Submit recycle notification to the state.

June 8, 2004 Return recycle flows through the processes of a system's

existing conventional or direct filtration system or an alternate

recycle location approved by the state (a 2-year extension is

available for systems making capital improvements to modify

recycle location).

Collect recycle flow information and retain on file.

June 8, 2006 Complete all capital improvements associated with relocating

recycle return location (if necessary).

For States

June 8, 2003 States submit FBRR primacy revision application to EPA

(triggers interim primacy).

June 8, 2005 Primacy extension deadline - all states with an extension must

submit primacy revision applications to EPA.

Recycle Flows

4 Spent Filter Backwash Water - A stream containing particles that are dislodged from

 filter media when water is forced back through a filter (backwashed) to clean the filter.

4 Thickener Supernatant - A stream containing the decant from a sedimentation basin,

 clarifier or other unit that is used to treat water, solids, or semi-solids from the primary

 treatment processes.

4 Liquids From Dewatering Processes - A stream containing liquids generated from a

 unit used to concentrate solids for disposal.
Appendix B 

Case Studies 
This page intentionally left blank. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-1 March 2007 For the Long Term 2 and Stage 2 DBP Rules 

Case Studies in this Guidance Manual and Issues They Address 

Case

Study 

No.

Treatment/Issue

Addressed 

Utility Name Case Study 

Location

Population

Served

Average

Annual

Treatment

Plant (MGD) 

Production

Source

Water

Page Section 

Where It is 

Referenced 

in the 

Manual

1 Improving and 

Optimizing Current Operations 

Owenton Water Works and Kentucky American TriVillage 

Owenton, Kentucky <10,000 1 Surface Water 

(reservoir)

B-5 3.3

2 Decreasing pH Public Utility District 

#1

Skagit County, Washington 

70,000 12 Surface Water 

(reservoir)

B-11 3.4 

3 Pre-sedimentation Kansas City Water 

Services

Kansas City, Missouri >600,000 240 Surface Water 

(river, ground water under the direct influence of surface water) 

B-19 3.6

4 Switching Coagulants Hillsborough River 

Water Treatment Plant

Tampa, Florida >450,000 100 Surface Water 

(river)

B-23 3.7 

5 Enhanced 

Coagulation - Problems with Copper Pitting 

Washington Suburban Sanitary Commission

Montgomery and Prince Georges County, Maryland 

1,600,000 167 Surface Water 

(rivers)

B-29 3.7

6 Enhanced 

Coagulation - Managing Radioactive Residuals 

Allen Water Filtration Plant

Englewood, Colorado 48,000 8.5 Surface Water 

(river, creek, diversions) 

B-33 3.7 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-2 March 2007 For the Long Term 2 and Stage 2 DBP Rules 

Case

Study 

No.

Treatment/Issue

Addressed 

Utility Name Case Study 

Location

Population

Served

Average

Annual

Treatment

Plant (MGD) 

Production

Source

Water

Page Section 

Where It is 

Referenced 

in the 

Manual

7 GAC for TOC 

Removal 

Higginsville Water Treatment Plant 

Higginsville, Missouri <10,000 2 Surface Water 

(reservoir)

B-39 4.1

8 Nanofiltration 

MembraneTechnology for TOC Removal 

PBCWUD Water Treatment Plant #9 

West Palm Beach, Florida 

132,000 27 Ground Water 

(surficialaquifer) 

B-43 4.3

9 Modifying 

Chloramination Practices to Address Nitrification Issues 

Ann Arbor Utilities Ann Arbor, Michigan 115,000 20 Surface Water 

(river, wells) 

B-51 5.1

10 Ozonation Ann Arbor Utilities Ann Arbor, Michigan 115,000 20 Surface Water 

(river, wells) 

B-57 5.2 

11 Ozonation and 

Biological Filtration 

Sweeney Water Treatment Plant 

Wilmington, North Carolina 

75,000 25 Surface Water 

(river)

B-65 5.2

12 UV Disinfection Poughkeepsie Water 

Treatment Facility 

Poughkeepsie, New York

75,000 16 Surface Water 

(river)

B-71 5.3 

13 Chlorine Dioxide for 

Primary Disinfection and Chloramines for Secondary Disinfection 

Gulf Coast Water Authority 

Texas City, Texas 92,000 12 Surface Water 

(river)

B-75 5.4
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-3 March 2007 For the Long Term 2 and Stage 2 DBP Rules 

Case

Study 

No.

Treatment/Issue

Addressed 

Utility Name Case Study 

Location

Population

Served

Average

Annual

Treatment

Plant (MGD) 

Production

Source

Water

Page Section 

Where It is 

Referenced 

in the 

Manual

14 Chlorine Dioxide for 

Primary Disinfection and Chloramines for Residual Disinfection 

Village of Waterloo Water Treatment Plant

Waterloo, New York <10,000 2 Surface Water 

(lake)

B-81 5.5 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

This page intentionally left blank. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #1 

Improving and Optimizing Current Operations

Owenton Water Works and Kentucky American TriVillage 

Owenton, Kentucky

 This case study provides an example of how two small PWSs, both using water treated by 

the same conventional filtration plant, worked together to change chlorination practices to their 

existing treatment and operations to reduce TTHM. Reducing TTHM was the primary objective, 

due to the timing of this work beginning in late 1999 prior to regulatory limits for these systems 

serving a combined population under 10,000. 

 Changes described here took place primarily over the first 6 months of 2000 and were 

made in a series of carefully planned and monitored steps in close consultation with the state 

regulatory officials and with knowledge of available EPA regulations and guidance. This work 

has also been successful in reducing HAA5s as these systems completed the first year (2004) in 

compliance with the 80/60 THM/HAA limits. 

 Prior to moving the point of chlorination, the following steps were carried out: 

1) Enhanced coagulation was initiated at lower pH to improve TOC removal and sodium 

hydroxide (caustic soda) was added to maintain distribution corrosion control; 

2) Potassium permanganate feed to the raw water was optimized to control source water 

manganese and to provide reliable pre-oxidation in anticipation of moving the 

chlorine application point; and 

3) In-plant chlorine disinfection contact time was assessed and operations revised to 

increase chlorine retention time in the plant clearwell. This step included trending 12 

months of disinfection data in the plant and consultation with the state. The state 

provided a list of additional source monitoring (microbiological and other related 

water quality parameters from source through distribution) to be conducted prior to 

and following the change in chlorine application point. 

 The point of chlorination was then moved by turning off the chlorine feed to the rapid 

mix portion of plant treatment and increasing chlorine at the application points just before and 

after the filters to provide the required residuals in the plant clearwell and through distribution. 

 This case study is documented in Routt (2004) and Routt and Pizzi (2000). Readers may 

refer to those references for more details. Updates were also provided for this case study by J. 

Routt in January 2005. 

Introduction

 The Owenton City Water Works operates a conventional 1 million gallons per day 

treatment plant that uses water from an algae-rich reservoir. Approximately half of the water 

that is produced by the Owenton facility is sold to Kentucky American Water Northern Division 

(TriVillage), a privately owned water system. Owenton delivers the remainder of the water in its 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

own distribution network. Together, the two systems serve fewer than 10,000 people. However, 

for several years prior to this work (which began in late 1999), both systems had been regularly 

issuing state-required health-based public notices due to elevated TTHM. 

 To define the factors contributing to the elevated DBPs, Kentucky American Water, in 

cooperation with the City of Owenton, collected water quality data from both systems. These 

data showed that the most effective solution to the elevated DBPs would be to switch to a source 

water of higher quality. Switching source waters, however, was understood to be a long-term, 

expensive project that would require designing and building new intake and transmission 

facilities. In the meantime, the systems decided to make operational changes to improve water 

quality before the completion of the new intake and transmission lines. 

The Original Treatment Process at the Owenton WTP

 The system used a high TOC, high alkalinity source water prone to fluctuating 

manganese levels. Before treatment changes were made, chlorine was being added at the rapid 

mix and again at booster stations to provide required free chlorine residuals through the 

distribution system. The treatment plant was using alum-lime coagulation with a pH of 

approximately 7.8, and was achieving less than 28 percent TOC removal. This TOC removal 

efficiency would not meet the Step 1 requirements of the Stage 1 D/ DBPR for the system. In 

addition, monitoring showed that TTHM levels were elevated leaving the treatment plant and 

increased substantially with retention time and re- chlorination through the distribution network. 

Simultaneous Compliance Issues Faced by the Utilities

 The combined systems had high TTHM concentrations and were faced with the challenge 

of complying with upcoming Stage 1 D/DBPR and Stage 2 DBPR requirements. Priorities and 

plans had to be clearly set to help ensure ongoing compliance with other regulations that stood to 

be impacted by treatment changes to reduce DBPs–such as SWTR disinfection and filtered 

turbidity requirements, LCR corrosion control requirements and TCR microbiological control 

requirements. To that end, the systems embarked upon a cooperative effort to proceed through 

steps to improve DBPs for the short term–using existing source water and treatment and 

distribution facilities–while keeping the multiple regulatory requirements in mind. 

Steps Taken by the Utilities

 Profiles of TOC removal, TTHM formation, and disinfection were collected through the 

plant and distribution system. These process profiles showed that TOC was not being effectively 

removed, and that high levels of TTHM and HAA5 were being formed in the treatment plant. 

 Treatment changes, therefore, consisted of maximizing TOC removal and optimizing 

chlorine disinfectant application. Operational changes were made in a phased process over 

several months, with state approval granted for each step. The results of each step were 

evaluated before the systems proceeded to the next phase. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Enhancing Coagulation

 The removal of TOC was increased by making several relatively simple changes to the 

coagulation process in the Owenton treatment plant. Coagulation and TOC removal were 

enhanced by ceasing pre-lime application, and approximately doubling the alum dose to lower 

the treated water pH to 6.9. The change in coagulation chemicals required addition of a 

postfiltration caustic feed (sodium hydroxide) to adjust the finished water's pH to 7.6-7.8 for 

distribution system corrosion control. 

 In addition, a switch from alum to ferric chloride was made in order to improve the solids 

handling in the plant's solids-contact upflow clarifier. Ferric chloride was expected to produce 

good TOC removal with less chemical, and to produce a more stable floc, less prone to upset and 

carry-over onto filters. These expectations were met. 

 Changes to the coagulation process roughly doubled the TOC removal and decreased 

chlorine demand. Chlorine residuals persisted noticeably longer in the distribution system, 

which allowed the systems to reduce their re- chlorination doses at the master metering points in 

the distribution system. Levels of TTHM, however, were decreased by only 15 percent. The 

next step was to evaluate plant disinfection and seek state approval to move the point of 

chlorination to later in the treatment process. 

Converting to Top-of-Filter Chlorination

 Prior to moving the chlorination point, the Owenton plant was thoroughly assessed for 

adequate disinfection contact time. Tracer studies were conducted of the clearwell, which is 

well-baffled, and operational guidelines were changed to increase the minimum water level in 

the clearwell which effectively increased the chlorine disinfection contact time with filtered 

water. This was to offset contact time that would be lost when chlorine application was moved 

from rapid mix to the top of the filters. Potassium permanganate pretreatment procedures were 

revised to incorporate regular demand tests to improve dosing accuracy and to reduce chlorine 

oxidant demand. It was emphasized that, once the point of chlorination was moved to the top of 

the filter, permanganate would be the only pre-oxidant. Therefore, optimization would be 

critical to good coagulation of natural organics and to prevent manganese carryover when 

treating the fluctuating dissolved manganese in the source water. 

 The state approved the system's proposal to switch to ferric chloride coagulant, followed 

by post-caustic for corrosion control, and moving the point of chlorination to the top of the 

filters. The changes were made in sequence and with close supervision and monitoring. The 

change in point of chlorination was approved with the contingency that additional testing would 

be conducted before and after the change, in order to verify adequate disinfection and good 

overall water quality. This additional testing included TOC and organic nitrogen source water 

monitoring, as well as heterotrophic and total coliform bacteria monitoring through the treatment 

plant and distribution network. 

Optimization of Booster Chlorination

 In addition to the changes made at the Owenton treatment plant, both water systems have 

worked to optimize their distribution systems, and the purchaser, TriVillage, has optimized 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

chlorine doses at the booster stations. The reduction in finished water TOC leaving the Owenton 

plant has allowed for a reduction in the amount of booster chlorine needed to maintain a residual 

throughout the distribution system. Both systems have conducted additional flushing and have 

cleaned and inspected their storage tanks. Since the changes, lead and copper action levels and 

TCR standards have been met in both distribution systems. The systems continued to conduct 

extra testing for TOC, DBPs, chlorine residual, and HPCs to track distribution system water 

quality. In 2004, the TOC and DBP “compliance” testing has replaced the earlier special testing. 

Implementation and Operational Issues Faced by the Utilities 

 Overall, operational changes have gone smoothly. The greatest ongoing operational 

impacts have been related to enhanced coagulation: an increase in (approximate doubling of) 

chemical treatment costs, along with a need for increased attention to solids removal from the 

upflow clarifier and filter backwash settling basins.

 Post-filter caustic feed has necessitated cleaning of deposits from filtered water transfer 

pumps just downstream of the application point. This caustic buildup did not become 

problematic until 2004 - 4 years after the initiation of caustic feed. However, utilities are advised 

to watch for caustic clogging in mechanical devises located immediately downstream of caustic 

application points. 

 In the summer of 2001, source water dissolved manganese temporarily increased to levels 

that could not be treated by potassium permanganate alone. The resulting discolored water 

forced the system to return to minimal prechlorination and, then, to switch briefly to 

polyaluminum chloride as coagulant. The polyaluminum chloride coagulated well at a higher pH 

(8.0), which improved potassium permanganate removal of the dissolved manganese and 

eliminated the need for pre-chlorine. Within a few weeks, the source water manganese levels 

dropped, and the system returned to ferric chloride coagulation at lower pH. This scenario has 

not recurred since. 

Systems should be extremely careful when switching coagulants to ensure that they 

maintain consistent particle and pathogen removal. The dosage of new coagulant needed should 

be carefully calculated and confirmed with up-to-date jar testing using the water to be treated. 

Results of the Steps Taken

 Since changes were made in May 2000, filtered and distributed water quality compliance 

has been maintained. TTHM levels have dropped below the 0.080 mg/L standard. Testing has 

shown that HAA5 levels have been reduced by more than half as well. As of 2004, the first year 

of compliance TOC testing showed monthly removal ratios ranging from 1.96-2.35 and 

averaging 2.19 for the year, and the RAAs for THM and HAA5 levels were 74 and 47 ug/L, 

respectively. 

 Overall, customers have noticed that their water has improved in clarity and taste of their 

water, possibly due to the enhanced coagulation, and decreased chlorine demand combined with 

diligent attention to water quality throughout the system. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Lessons Learned From this Case Study

x Source water testing and the development of treatment plant and distribution system 

profiles helped the systems identify the factors that were causing DBP formation; 

x By adjusting coagulation methods and the point of chlorination, while optimizing 

distribution operations to optimize booster chlorine use, these small surface water 

systems succeeded at reducing TTHM and HAA5 in the combined system, even when 

using a challenging source water; 

x Compliance with TTHM and HAA5 standards can be achieved, without negatively 

impacting other regulatory programs, by implementing a combination of several 

carefully planned and monitored operational changes; and 

x Water quality improvements can be realized with short-term operational changes, and 

provide information useful in decision-making, pending completion of more costly, 

time-intensive, long-term modifications. 

Further Reading

Readers can find more information about this case study in the following publications: 

Routt, J.C. 2004. Lowering DBPs in Combined Systems. Opflow. 30(4): 1-7. 

Routt, J.C. and N.G. Pizzi 2000. Kentucky-American Water’s Cooperative, Step-wise 

Process of Assisting Two Small Contiguous Systems in Complying with Pending D/DBP 

Requirements. In Proceedings of AWWA Water Quality Technology Conference.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-11 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #2 

Modifying pH During Chlorination

Public Utility District #1 

Skagit County, Washington 

 This case study provides an example of how a PWS used pH depression to reduce DBPs. 

The depression of pH via carbon dioxide (CO2) injection ahead of the flocculation basins also 

produced the following results: 

1) Increased coagulation efficiency and removal of DBP precursors; 

2) Increased CT throughout the treatment plant, allowing for reduced chlorine injection; 

and

3) Increased and stabilized pH levels in the distribution system by increasing the 

buffering capacity following caustic soda addition. 

 The information for this case study came from Friedman and Hamilton (1997). Readers 

should refer to that reference for further information. 

Introduction

 Public Utility District #1 of Skagit County (the District) is located in the northwest sector 

of Washington State, approximately 70 miles south of the Canadian border and 70 miles north of 

Seattle. The District's source of supply is Judy Reservoir, which is fed by several streams 

originating in the Cultus Mountain watershed in Sedro-Woolley, WA. The District operates a 

water filtration plant (WFP) designed to provide an original nominal/hydraulic flow of 12/18 

million gallons per day (MGD) with an ultimate capacity of 21/36 MGD. Exhibit B.1 provides a 

summary of typical water quality parameters. 

Exhibit B.1 Summary of Historical Source Water Quality Data 

Parameter Units Range of Values

Conductivity mhos/cm 30-60 

Temperature °C 1-21 

pH standard units 6.9-7.5 

Alkalinity mg/L as CaCO3 14-16 

Hardness mg/L as CaCO3 8.6-21.6 

Dissolved Oxygen mg/L 9-13 

TOC mg/L 3.0-7.0 

Turbidity NTU 0.25-1.5 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-12 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 In the late 1980s, the District faced several source water quality issues. The TOC in the 

Judy Reservoir supply ranged from 3 to 7 mg/L, leading to high formation of DBPs upon 

chlorination. The District was having difficulty meeting CTs year-round, especially during the 

colder months. The Judy Reservoir supply is soft and poorly buffered, with alkalinity levels 

between 14-16 mg/L as CaCO3, and the District exceeded the lead action level under the LCR. 

The Original Treatment Process at Judy Reservoir

 Before changes were made, initial oxidation/ disinfection was provided by chlorine 

dioxide, primarily to oxidize manganese which is present in the 0.2-0.3 mg/L range. Coagulants 

consisting of hybrid aluminum salts and a polyquaternaryamine were used. Direct filtration was 

conducted with a slight addition of a mild anionic filter aid. The filter media consisted of one 

foot of silica sand and two feet of anthracite coal. Typical flows were 6000 gpm (8.6 mgd) in 

the winter and 11,800 gpm (17 mgd) in the summer with 2000 square feet of available filter 

surface area. Chloramination was used for secondary disinfection. 

Simultaneous Compliance Issues Faced by the Utility

 The District was having difficulty meeting CTs required by the SWTR. To address this 

problem, free chlorine was historically applied ahead of the flocculation basins to increase CTs. 

However, TOC levels in the Judy Reservoir led to high formation levels of DBPs upon 

chlorination. This situation created difficulty for the District in complying with the Stage 1 

D/DBPR. Exhibit B.2 shows the historical relationship between inactivation ratio (calculated CT 

divided by required CT) and TTHM formation. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-13 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.2 Inactivation Ratio vs. TTHM Plant Effluent 

 Using existing treatment methods, CTs could not be met consistently without 

significantly increasing DBPs. Thus, a method other than increasing chlorine and contact time 

was needed to achieve higher inactivation ratios. Methods of decreasing pH levels throughout 

the treatment train were therefore considered. Because the District used direct filtration (rather 

than conventional filtration), they were not required to meet TOC removal criteria under the 

Stage 1 D/DBPR. However, lowering the pH at the beginning of the treatment train would have 

the added benefit of enhancing coagulation, increasing the removal of DBP precursor materials. 

 Simultaneously, the District was having difficulty complying with the LCR; the 90th 

percentile lead level was 0.049 mg/L at a finished water pH of approximately 7.3. The pH was 

raised to 8.0 but the lead action level was still exceeded. Electrochemical corrosion testing was 

conducted to compare the corrosion control effectiveness of pH adjustment and orthophosphate 

addition for lead containing surfaces. The greatest reductions in corrosion rate were observed 

when the pH was raised to 8.5, or when the pH was raised to 8.0 and 4 mg/L (as PO4) were 

added. Due to a number of functional constraints, the District did not want to add phosphates to 

the water supply. Thus, the decision was made to increase pH to the range of 8.5 to 9.0. 

 Like most surface water supplies in the Pacific Northwest, the District's Judy Reservoir 

supply is very soft and poorly buffered. Alkalinity levels are between 14-16 mg/L as CaCO3.

To maintain the desired pH range of 8.5 to 9.0 throughout the distribution system, alkalinity 

increases would also be required. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-14 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Steps Taken by the Utility

 The District injected CO2 prior to the flocculation basins in addition to at the end of the 

treatment train where caustic soda is added. The advantages of adding carbon dioxide ahead of 

the flocculation basins were three-fold: 

1) The associated pH depression increased coagulation efficiency to remove DBP 

precursors; 

2) The associated pH depression increased CTs throughout the treatment plant, allowing 

chlorine injection to be reduced; and

3) Subsequent pH increases using caustic soda provided finished water with increased 

alkalinity levels and, increased buffering capacity. 

 The chemistry of CO2 is well understood and is used extensively throughout the water 

and wastewater industry. However, use of CO2 for WTP process control in the Pacific 

Northwest was fairly uncommon. The stoichiometry of CO2 addition in the pH range of 6.0 to 

10.0 is outlined below. 

CO2 + H2O —> H2CO3 (carbonic acid) 

H2CO3 —> H+

 + HCO3

-

 (bicarbonate) 

Over the pH range of 6.0-10.0, the dissociation of carbonic acid in water depresses the pH and 

adds bicarbonate, which is the primary contributor to alkalinity. 

 CO2 feed was set up at two locations within the District's treatment facility: 1) ahead of 

the flocculation basins and 2) at the plant effluent. CO2 injection began on a trial basis during 

March, 1995. 24-144 lb/d (2 mg/L) were injected ahead of the flocculation basins (depending on 

plant flow), and 192 lb/d (3 mg/L) were injected after filtration. The target pH level ahead of the 

flocculation basin was less than 6.5. Additional CO2 was required prior to caustic soda addition 

to raise the alkalinity of the finished water to 25 mg/L as CaCO3.

Results of the Steps Taken

Effects on DBP Formation

 With the depression of pH and resulting increased coagulation efficiency, the percent of 

TOC removal increased from an average of 25 percent to approximately 40 percent. The mass of 

TOC removed nearly tripled from 1 mg/L to 2.5-3 mg/L. The percent and mass of TOC 

removed before and after CO2 injection are shown in Exhibit B.3. Thus, even a small decrease in 

pH (from 6.9 to 6.6) during coagulation and flocculation has significantly enhanced coagulation. 

Exhibit B.3 shows the percent and max of TOC removed after CO2 injection was initiated 

in March 1995. During the first few months, CO2 was fed on a trial basis using a temporary feed 

system that restricted the amount of CO2 that could be added. Thus, initial decreases in TOC 

removal were observed until the system stabilized. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-15 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

TTHM formation within the treatment train was reduced by approximately 33 percent. 

Observed decreases in TTHM formation can be attributed to enhanced TOC removal, reduced 

chlorine levels, and to the fact that less TTHMs are formed at lower pH levels. Prior to CO2

addition, HAA5 levels in the plant effluent ranged between 40-60 μg/L when TOC levels were 

between 3-5 mg/L. After CO2 addition, HAA5 levels in the plant effluent decreased to the range 

of 35-45 μg/L even though raw water TOC levels were in the range of 5-7 mg/L. 

Exhibit B.3 TOC Removal vs. Time 

Effects on CT Compliance

 CT credit decreases as temperature, disinfectant concentration, and contact time decrease. 

CT credit using chlorine increases as pH decreases. Since DBP formation was a concern for the 

District, the best way to increase CT credit without forming additional DBPs was to lower the 

pH.

 It is difficult to show actual improvements in the District's CT compliance as a result of 

CO2 addition since disinfectant dosages, plant throughput (i.e., contact time) and temperature 

vary from month to month. However, the impacts of depressing the pH by 0.5 units are outlined 

in terms of required chlorine dose and required contact time in Exhibit B.4. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-16 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.4 Impacts of CO2 Injection on CTs 

Effect of pH on Required Free Chlorine Dosages

pH Contact Time (min) Required Free Cl2 (mg/L)

7.0 82.5 2.0 

6.5 82.5 1.67 

6.0 82.5 1.41 

Effect of pH on Required Contact Time

pH Contact Time (min) Required Free Cl2 (mg/L)

7.0 82.5 2.0 

6.5 69 2.0 

6.0 58 2.0 

Thus, the same CT can be achieved with less chlorine. Alternatively, higher flows can be 

accommodated without increasing chlorine dosages. It should be noted that in addition to 

considering impacts of reduced chlorine dosages on CT, utilities must consider other drivers for 

determining chlorine dose, such as the ability to maintain a disinfectant residual throughout the 

distribution system. Because Skagit PUD#1 chloraminates, they are able to maintain a stable 

residual despite fluctuations in chlorine dosage at the head of the treatment plant. 

Effects on Corrosion Control Treatment

 Distribution system water quality sampling suggested that pH and alkalinity levels are 

more uniform throughout the system. Alkalinity levels have nearly doubled (from 14 mg/L as 

CaCO3 to 25 mg/L as CaCO3), resulting in more stable water with respect to pH and corrosion 

control. Prior to CO2 injection, the District would raise the pH of the finished water to 8.0, but it 

would decrease to 7.4 at many locations within the distribution system. Follow-up LCR 

monitoring conducted by utilities across the U.S. has shown that providing consistent and stable 

pH/ alkalinity levels can be essential to controlling lead levels at the tap. The District found that 

nearly a year of CO2 injection has to pass before pH levels stabilized within the distribution 

system. 

 Lead levels at the tap decreased substantially at most of the "high lead" homes in the 

District. The 90th percentile lead level was 0.004 mg/L during the last round of monitoring 

conducted in 2003. It is likely that increased alkalinity helped to decrease lead levels by two 

different mechanisms: 1) providing stabilized pH levels at the tap; and 2) increasing carbonate 

levels to aid in the formation of more stable lead carbonate passivating films. 

 A study was undertaken by the District to determine whether elevated lead levels 

measured at the tap were in the soluble or particulate form. It was found the lead was primarily 

in the particulate form. When the pH was adjusted to 8.0 without alkalinity adjustment, elevated 

lead levels were mostly due to particulate lead (particulate being the difference between total and 

soluble lead), suggesting that stable lead carbonate films were not forming. After the pH was 

further increased and the alkalinity was doubled, total lead concentrations decreased as shown 

for three sampling locations in Exhibit B.5. Although lead solubility theoretically decreases as 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-17 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

pH increases to a maximum of 9.5, alkalinity adjustment may also be necessary to address the 

particulate lead fraction. 

Exhibit B.5 Total vs. Soluble Lead 

Implementation and Operational Issues Faced by the Utility

 CO2 does not solubilize instantaneously, and therefore a pressurized solution feed system 

was required. In this system, the CO2 is injected to a pressurized side stream forming carbonic 

acid. The carbonic acid solution is readily solubilized by the receiving water and is injected 

directly into the pipeline. 

 Chemical costs for caustic soda doubled once CO2 was injected since twice as much 

caustic was required to raise the pH to 8.5-9.0. Considering the multiple benefits the District is 

experiencing, a chemical cost increase of $30,000 per year or $10 per million gallons treated was 

relatively inexpensive. The capital cost of the permanent CO2 system was $15,000 (1996 

dollars). 

Lessons Learned From this Case Study

x It is possible to achieving both greater Ct and TOC removal by reducing pH during 

treatment; 

x pH reduction can in some cases be achieved through CO2 injection; and 

x CO2 injection at multiple locations during treatment may enhance benefits compared 

to injection at the end of treatment only for pH control purposes.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-18 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-19 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #3 

Pre-sedimentation

Kansas City Water Services 

Kansas City, Missouri

 This case study provides an example of how Kansas City’s existing pre-sedimentation 

basins may help to achieve compliance with the upcoming regulations. 

 Kansas City’s pre-sedimentation basins were constructed prior to development of the 

DBPRs and ESWTRs, but still provided a benefit with respect to regulatory compliance. These 

pre-sedimentation basins have the potential to assist in providing the following benefits:

x TOC reduction required under the Stage 1 D/DBPR due to coagulation in the basins; 

x Turbidity reduction necessary for compliance with the ESWTR; and 

x 0.5-log treatment credit for removal of Cryptosporidium (if needed to comply with 

the LT2ESWTR.

 Under the LT2ESWTR, systems are required to collect their source water samples prior 

to chemical treatment, such as coagulation, oxidation, and disinfection, for the purpose of 

determining their bin classification. Kansas City applies treatment chemicals (coagulants, 

potassium permanganate, lime) to the pre-sedimentation basins and must therefore collect 

samples for LT2ESWTR monitoring prior to the basins. However, Kansas City is eligible for a 

0.5-log Cryptosporidium treatment credit for the pre-sedimentation basins if the basins can 

achieve a monthly mean reduction of 0.5 log in turbidity. 

 Both the LT2ESWTR sampling location and the Stage 2 D/DBPR treatment plant pointof-entry are considered to be the influent to the pre-sedimentation basins. However, 

simultaneous compliance issues associated with pre-sedimentation basins include the potential 

for algae blooms, which can increase disinfection by-product formation at the plant effluent. 

 This case study was developed using information available from staff at Kansas City 

Water Services. 

Introduction

 The Kansas City, Missouri drinking WTP, which was originally constructed in the 1920s, 

is rated for 240 MGD. The source water comes from the Missouri River and wells under the 

influence of the Missouri River. The treatment process involves pre-sedimentation, excess lime 

softening, recarbonation, filtration, and stabilization. 

 Due to the turbidity levels of the Missouri River, the pre-sedimentation basins are a 

critical step in the City’s WTP processes. The turbidity of the untreated source water is quite 

variable, averaging 114 nephelometric turbidity units (NTU) in 2002, 185 NTU in 2003, and 318 

NTU in 2004. The untreated water turbidity can exceed 5,000 NTU. The turbidity of the 

untreated source water was even higher and more variable when the plant was built. However, 

the construction of several upstream dams during the 1960’s resulted in lower turbidity levels at 

the City’s intake. In addition, the pre-sedimentation basins serve to reduce the amount of solids 

entering the softening process.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-20 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 The plant was constructed well before the Safe Drinking Water Act (SDWA) and 

subsequent drinking water regulations came into effect. Therefore, the pre-sedimentation basins 

were not designed to meet compliance issues as much as they were needed as part of the water 

treatment process. However, as the treatment regulations evolved, the pre-sedimentation basins 

helped the plant meet new regulations. 

The Treatment Process at the Kansas City, Missouri WTP

 Today there are 6 pre-sedimentation basins, each with a detention time of about 4 hours 

at 40 MGD. Each pre-sedimentation basin is approximately 200 feet in diameter and has an 80-

foot diameter fiberglass ring installed that is approximately half the height of the basin. This 

fiberglass ring serves as a mixing area for the coagulation chemicals to react. There are four 

mixers in each pre-sedimentation basin. These mixers and the capability for chemical injection 

were added to the pre-sedimentation basins in the 1970s. Lower source water turbidity levels 

resulted in reduced solids loading to the pre-sedimentation basins and increased colloidal 

materials, impacting the efficiency of the pre-sedimentation basins for removing turbidity.

Therefore, the mixing areas and chemical feed capabilities were added. However, the solids 

removal capacity of the basins remained the same. 

Role of Pre-sedimentation Basins in Regulatory Compliance 

 Kansas City’s pre-sedimentation basins could be used to lower turbidity as part of 

compliance with the Surface Water Treatment Rules (SWTRs). Additionally, compliance with 

the Stage 1 D/DBPR requires removal of TOC from source water to reduce the formation of 

DBPs. Pre-sedimentation basins may serve to remove a portion of the TOC. Kansas City can 

receive a 0.5-log Cryptosporidium reduction credit for the pre-existing pre-sedimentation basins 

because the basins may assist in removing Cryptosporidium from the source water. Kansas City 

is required to monitor the influent of their pre-sedimentation basins to determine their 

Cryptosporidium bin classification.

Simultaneous Compliance Issues Faced by the Utility and Steps Taken

 Algae may grow in the pre-sedimentation basins, which could contribute additional NOM 

and result in the formation of DBPs, affecting compliance with the DBP Rules. Kansas City has 

managed to avoid this simultaneous compliance issue by minimizing algae blooms through 

potassium permanganate addition in the pre-sedimentation basins. Additionally, the velocity of 

the water in the pre-sedimentation basins is kept high by the mixers. In the rare instance that 

algae is observed, it is minimal and typically resides around the sides of the pre-sedimentation 

basins. Additionally, the pre-sedimentation basins are followed by an excess lime softening step, 

during which pH levels are raised above 10 units, reducing the potential for algae growth in this 

step.

Implementation and Operational Issues Faced by the Utility

 The pre-sedimentation basin improvements allow the plant to add a variety of treatment 

chemicals to control turbidity of the pre-sedimentation basin effluent. The water plant has the 

capability of feeding ferric sulfate, polymer, and potassium permanganate to these basins. The 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-21 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

turbidity of the pre-sedimentation basin effluent is controlled based on the economics of the 

treatment plant operations. By adding different coagulation chemical concentrations and 

combinations, the turbidity exiting the pre-sedimentation basis can be reduced to below 10 NTU.

The plant uses factors such as lime dose requirements to determine the optimal treatment in the 

pre-sedimentation basins. This is because higher turbidity water entering the softening basins 

usually has more colloidal material, which in turn requires more lime to provide the desired 

softening because of the competing reactions between the charges stabilizing the colloids and the 

calcium carbonate precipitation process. Thus, the cost of the coagulant dosage to obtain a 

certain turbidity from the basins is compared to the cost of the lime required to provide the 

desired softening and an economic balance is found. 

 The plant reports that 80-90 percent of the time, potassium permanganate is sufficient for 

addressing operational issues such as taste and odor control and turbidity control. The remainder 

of the time, ferric sulfate is able to maintain the plant’s operation. 

 To receive a treatment credit for Cryptosporidium removal under LT2ESWTR (if 

needed), Kansas City will need to evaluate the effectiveness of the dosages in reducing turbidity, 

and assure that a monthly mean reduction of 0.5-log turbidity is achieved to receive the 0.5-log 

Cryptosporidium treatment credit. 

Lessons Learned From this Case Study

The following lessons were learned from Kansas City’s experience with pre-sedimentation 

basins:

x The pre-sedimentation basins reduce the effects of large and variable turbidity 

episodes;

x Improving the pre-sedimentation basins to incorporate chemical treatment and mixing 

allowed the pre-sedimentation basins to become more useful in water treatment 

operations by allowing the plant to control turbidity entering the softening basins as 

well as assisting in removing TOC and DBP precursors; 

x The potential drawbacks of pre-sedimentation basins such as increased NOM from 

algae are minimized through operations; and 

x Utilities that apply treatment chemicals to their pre-sedimentation basins will need to 

designate a sampling location prior to the pre-sedimentation basins for 

Cryptosporidium monitoring under the LT2ESWTR. This location may be the same 

as the point of entry already used for compliance with other regulations.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-22 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

This page intentionally left blank. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-23 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #4 

Switching Coagulants

Hillsborough River Water Treatment Plant 

Tampa, Florida

 This case study describes how a system could simultaneously comply with the TOC 

removal requirements of the Stage 1 D/DBPR and the turbidity removal requirements of the 

IESWTR. Enhanced coagulation is a best available technology (BAT) for TTHM precursor 

removal for the Stage 1 D/DBPR. 

Introduction

 The City of Tampa, Florida, operates a 100 MGD conventional treatment plant (the 

Hillsborough River Water Treatment Plant, HRWTP). The HRWTP uses the Hillsborough River 

as its source water. The plant, built in 1924, currently serves over 450,000 people. In 1991, it 

switched from enhanced coagulation with alum to enhanced coagulation with ferric sulfate. The 

influent surface water has high TOC and is subject to large seasonal variations. By switching 

coagulant, the HRWTP’s operators expected to satisfy requirements of the Stage 1 D/DBPR. 

They had investigated the feasibility of enhanced coagulation with ferric sulfate before the Stage 

1 D/DBPR became a regulatory requirement. They found that enhanced coagulation with ferric 

sulfate not only increased TOC removal significantly, but also reduced turbidity levels in the 

finished water. 

 A summary of the influent water quality is provided in Exhibit B.6. 

Exhibit B.6 Influent Water Quality at HRWTP 

Water Quality Parameters Influent1

TOC (mg/L)

Minimum

Average

Maximum

4.3

13

26

Turbidity (NTU)

Minimum

Average

Maximum

1.2

2.1

40

pH

Minimum

Average

Maximum

6.8

7.6

8.5

Alkalinity (mg/L as CaCO3)

Minimum

Average

Maximum

42

93

143

Notes: 1. Data from an Information Collection Rule (ICR) sample collection from July 1997 - 

December 1998 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-24 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

The Original Treatment Process at HRWTP

 Exhibit B.7 shows a schematic of the treatment process at HRWTP prior to converting to 

ferric sulfate. Raw water was treated with potassium permanganate for taste and odor control. 

Enhanced coagulation was implemented using alum (range of alum dose = 50 - 200 mg/L, 

average dose = 120 mg/L), at an average pH of 5.7 (range 4.9 - 6.6). An organic polymer was 

added to enhance the flocculation process. Primary disinfection was attained by applying 

chlorine just prior to the filters. After filtration, more chlorine and ammonia were added to form 

chloramines for residual disinfection. The pH of the finished water was increased to around 7.6 

with caustic soda and soda ash in the blending chamber, to meet a Langelier Index goal of +/-0.2. 

Exhibit B.7 Treatment at the HRWTP Prior to Implementing Enhanced Coagulation 

Simultaneous Compliance Issues Faced by the Utility

 In order to reduce DBP precursors and TTHM and HAA5 concentrations, the City of 

Tampa decided to switch to enhanced coagulation with ferric sulfate, enhancing TOC removal 

and consequently lowering the DBP formation potential. 

 Successfully enhancing coagulation to improve TOC removal can affect particle and 

pathogen removal effectiveness. The system was concerned that, at lower pH, the higher 

coagulant dose conditions for enhanced coagulation could result in particle re-stabilization and 

an increase in settled water turbidity, leading to non-compliance with the IESWTR. Increased 

settled water turbidity could also impact the system’s ability to receive Cryptosporidium removal 

credit for enhanced filter performance. Variability in source water quality presented a further 

challenge to the operators who were attempting to optimize particle and TOC removal with a 

new coagulant. 

Coagulation Filtration

Blending

Finished

Water

Storage

Potassium

Permanganate

Alum +

Polymer

Lime

Raw River

Water

Chlorine

Chlorine +

Ammonia

Caustic Soda +

Soda Ash

Residuals Thickening

Residuals Processing

Distribution

System
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-25 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Steps Taken by the Utility

 Tampa implemented enhanced coagulation with ferric sulfate to improve TOC removal. 

At the same time, it applied BMPs to ensure that filter effluent turbidity would not be adversely 

affected. These included flow-pacing the coagulant feed and conducting additional jar tests to 

ensure that coagulant overdosing did not occur. 

 Exhibit B.8 shows a schematic of the treatment process at HRWTP after the system 

changed to enhanced coagulation with ferric sulfate. Raw water continues to be treated with 

potassium permanganate for taste and odor control. Enhanced coagulation uses ferric sulfate 

(range dose = 40 - 300 mg/L, average dose = 140 mg/L), at an average pH of 4.0 (range 3.5 - 

4.8). The low coagulation pH is attained by adding sulfuric acid. An organic polymer is added 

to enhance the flocculation process. The settled water is treated with lime for partial pH 

adjustment. The residuals are thickened and then pumped to a residuals processing facility for 

further dewatering, processing, and disposal. Primary disinfection is attained by adding chlorine 

to the settled water to produce a free residual of 1-2 mg/L just prior to the filters. After filtration, 

ammonia and chlorine are added to form chloramines. The finished water combined disinfectant 

residual ranges from 3 - 4.5 mg/L of monochloramine. The pH of the finished water is adjusted 

to around 7.6 with caustic soda and soda ash in the blending chamber, to meet a Langelier Index 

goal of +/-0.2. 

Exhibit B.8 Treatment at the HRWTP After Implementing Enhanced Coagulation 

 To ensure that excessive coagulant dosing doesn’t occur, the operators check the 

coagulant dose regularly with jar tests. The operators also ensure that coagulant feed is flow 

paced. These practices help ensure that turbidity requirements are not violated. 

Coagulation Filtration

Blending

Finished

Water

Storage

Potassium

Permanganate

Ferric Sulfate +

Polymer +

Sulfuric Acid

Lime

Raw River

Water

Chlorine

Chlorine +

Ammonia

Caustic Soda +

Soda Ash

Residuals Thickening

Residuals Processing

Distribution

System

Beneficial Re-use
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-26 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Results of the Steps Taken 

x TOC removal - Finished water TOC removal with enhanced alum coagulation ranged 

from 21 to 50 percent. For enhanced coagulation with ferric sulfate, TOC removal 

ranges from 70 to 88 percent, with an average of 81 percent. This is well beyond the 

minimum TOC removal requirements of the Stage 1 D/DBPR (based on the source 

water TOC and alkalinity concentrations). Influent and effluent water quality is 

shown in Exhibit B.9. Thus, enhanced coagulation with ferric sulfate is much more 

effective than enhanced coagulation with alum for removing DBP precursors; 

x TTHM reduction - Before the changes in the coagulation practice, the finished water 

TTHM ranged from 27 - 111 )g/L, with an average of 59 )g/L (Exhibit B.9). After 

the treatment modifications (from July 1997 through December 1998), the finished 

water TTHM ranged from 47 - 67 )g/L, with an average of 60 )g/L. Enhanced 

coagulation with ferric sulfate seems more effective than coagulation with alum at 

removing DBP precursors (i.e., TOC), when the raw water is high in TOC. This is 

reflected by the lower maximum level of TTHM measured after treatment 

modifications (i.e., the maximum trihalomethane (THM) concentration was reduced 

from 111 to 67 )g/L). The new treatment approach reduced THMs by increasing 

TOC removal and chlorinating at a lower pH. Implementing enhanced coagulation 

with ferric sulfate has enabled HRWTP to achieve compliance with the Stage 1 

TTHM MCL of 80 )g/L; and 

x Turbidity - As can be seen clearly from Exhibit B.9, enhanced coagulation with ferric 

sulfate was more effective than alum coagulation at reducing turbidity in the finished 

water. Enhanced coagulation with ferric sulfate was able to achieve the IESWTR 

turbidity requirements more easily and consistently. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-27 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.9 Finished Water Quality Before and After Implementing Enhanced 

Coagulation with Ferric Sulfate 

Water Quality 

Parameters

Influent1 Finished Water

Before implementing 

Enhanced 

Coagulation2

After implementing 

Enhanced 

Coagulation3

TOC (mg/L)

Minimum

Average

Maximum

4.3

13

26

1.8

6.2

8.9

1.6

2.9

5.1

Turbidity (NTU)

Minimum

Average

Maximum

1.2

2.1

40

0.04

0.32

1.13

0.04

0.11

0.28

pH

Minimum

Average

Maximum

6.8

7.6

8.5

7.1

7.6

8.2

7.2

7.6

7.7

Alkalinity (mg/L 

as CaCO3)

Minimum

Average

Maximum

42

93

143

80

122

187

48

92

125

TTHM ()g/L)

Minimum

Average

Maximum

NA 27

59

111

47

60

66

HAA5 ()g/L)

Minimum

Average

Maximum

NA NDC 32

47

66

Notes:

1. Data from ICR sample collection from July 1997 - December 1998 

2. Data collected for calendar year 1990. 

3. Data collected for calendar year 1997; ICR data from July 1997 - December 1998 was used for organic 

 analysis. 

4. NDC = No Data Collected 

5. NA = Not Applicable

Implementation and Operational Issues Faced by the Utility 

x Operator training and start-up - It took around 6 months for the operational staff to 

be comfortable with implementing enhanced coagulation, and nearly a year for the 

treatment plant to operate like an integral unit. The treatment strategy did not 

significantly change the operational needs of the plant and no additional staff were 

added;
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-28 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

x Controlling manganese - The only major problem experienced in implementing the 

treatment modification was the control of manganese. The lower pH required for 

enhanced coagulation with ferric sulfate, relative to alum coagulation, allowed 

dissolved manganese to pass through the filters. The issue was resolved by 

maintaining the pH on top of the filters at greater than 6.0; and 

x Corrosion due to acid addition - The addition of sulfuric acid promoted corrosion 

in the rapid-mix chamber at the feed diffuser. The problem was resolved when the 

utility found a suitable coating for their rapid-mix chamber. The coating used was 

a two-part commercial membrane applied at 60 wet mils, using an air-supplied 

mastic air gun. After application, the coating required a 7-day curing period 

before the basin could be put back into service. The settling basins were epoxycoated and did not experience any corrosion. 

Lessons Learned From this Case Study

x Enhanced coagulation with ferric sulfate can achieve the multiple objectives of 

increased TOC removal and improving reductions in finished water turbidity without 

significantly changing the operational needs of the plant; and 

x One key to successfully implementing enhanced coagulation is to ensure that 

excessive coagulant dosing does not occur. This results in turbidity breakthrough at 

the filters, resulting in potential non-compliance with the IESWTR. One way to 

achieve this is by conducting additional jar tests and flow-pacing the coagulant feed 

when plant water flows are variable. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-29 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #5 

Enhanced Coagulation - Problems with Copper Pitting

Washington Suburban Sanitary Commission 

Montgomery and Prince Georges County, Maryland

 This case study provides an example of negative effects that could possibly be caused by 

enhanced coagulation. Washington Suburban Sanitary Commission (WSSC) changed their 

coagulation process to reduce filtered water turbidity. This was implemented prior to 

development of the Stage 1 D/DBPR and, therefore, not optimized to meet associated 

requirements. However, WSSC's experience indicates that coagulation improvements might 

have had unintended results in the distribution system. After alterations were made to WSSC's 

coagulation process, WSSC customers began reporting pinhole leaks in their copper piping, 

possibly caused by a combination of factors. The utility has been unable to determine the exact 

cause of the pinhole leaks. In this case study, the primary concerns relate to compliance with: 

x LCR

x DBP Rules 

While this treatment was implemented prior to the DBP Rules, it does indicate a potential 

problem associated with implementing the Stage 1 D/DBPR's required treatment technique using 

enhanced coagulation. 

This case study was developed using information available from staff at the WSSC and from 

their customer care Web site detailing this issue 

(http://www.wsscwater.com/copperpipe/pinholescroll.cfm). The cause of pinhole leaks in 

WSSC’s system continues to be under investigation. 

Introduction

 The WSSC provides drinking water to 1.6 million people in suburban Maryland. WSSC 

relies on two rivers, the Potomac and Patuxent, to supply an average of 167 MG per day. Both 

river supplies are treated at separate filtration plants. The Potomac plant treats river supply while 

the Patuxent plant treats water from a reservoir system. In the mid-1990s, WSSC made 

treatment changes at the Potomac plant to enhance filtration performance, including changing 

filtration media and changing coagulant, from ferric chloride to polyaluminum chloride. During 

the 1990s, coagulant doses were increased slightly at the Patuxent plant, which used alum most 

of the time, occasionally switching to ferric chloride during the winter. 

 The primary reasons WSSC made these treatment changes were: 

$ Prevention of waterborne pathogen outbreaks - A large-scale cryptosporidiosis 

outbreak occurred in Milwaukee, Wisconsin in 1993. The outbreak coincided with 

elevated effluent turbidity levels. Studies of the causes and prevention methods 

indicated that coagulation and filtration performance are critical in preventing the 

entry of Cryptosporidium to the distribution system; and 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-30 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

$ Partnership for Safe Water - This is an industry program, supported by EPA and 

AWWA, that focuses on protecting drinking water customers from microbial 

contaminants. WSSC has participated in this program that includes meeting stringent 

criteria for turbidity in filtered drinking water. 

 While WSSC's coagulation changes were not optimized for compliance with the Stage 1 

D/DBPR, WSSC did observe lower TOC levels in effluent at the Potomac WTP. 

The Original Treatment Process at WSSC's WTPs

 Both the Potomac and Patuxent Treatment Plants include similar treatment processes: 

x Coagulation and flocculation 

x Sedimentation 

x Filtration 

x Fluoridation 

x Lime addition for corrosion control 

x Chlorination 

Simultaneous Compliance Issues Faced by the Utility

 In 1998, WSSC began receiving complaints from customers that pinhole leaks were 

developing in their copper piping. As of December 2004, almost 5,500 customers have reported 

this problem. Pinhole leaks have occurred in areas served by both drinking water supply 

sources. WSSC has collected data on pinhole leaks from customers and these trends have been 

apparent:

x Many pinhole leaks are in cold water horizontal copper piping 

x Many leaks are located in older portions of service area 

x Almost 80 percent of leaks have occurred in homes built before 1970 

 In 2000, WSSC formed a task force to study the pinhole leaks and possible causes. The 

task force included WSSC staff, copper and plumbing industry experts, and corrosion experts.

The researchers conducted bench-scale experiments with copper piping and simulated drinking 

water and determined that a combination of high pH, aluminum solids, and chlorine levels, and 

no remaining NOM caused significant pitting on copper piping in about one month (Marshall, 

Rushing and Edwards 2003).

 NOM present in drinking water supplies is a DBP precursor and is typically removed 

through filtration or coagulation. TOC levels usually correspond to the presence of NOM in 

drinking water. The presence of NOM in the distribution system was previously thought to 

prevent, to some extent, corrosion of piping materials, such as cement, iron, and copper. The 

research by Marshall, Rushing and Edwards (2003) contradicts previous understanding of 

NOM’s role in copper corrosion. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-31 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Water quality conditions in WSSC's distribution system that may have contributed to pinhole 

leaks in copper piping include: 

x Aluminum - Since 1995, both treatment plants have used an aluminum-based 

coagulant. Finished water aluminum levels are relatively low. The average Potomac 

WTP residual levels range from 0.046 mg/L to 0.060 mg/L, and at Patuxent WTP, 

which recently switched from alum to polyaluminum chloride, average effluent 

aluminum levels are 0.030 mg/L (Edwards et al. 2004). In comparison, the national 

average for effluent aluminum levels is 0.090 mg/L. Sampling in WSSC's 

distribution system indicated that aluminum levels increased after treatment to levels 

higher than 0.065 mg/L total aluminum. Researchers indicate that high aluminum 

samples were collected in areas near recently cleaned or re-lined piping (Edwards et 

al. 2004). A forensic analysis of WSSC failed copper piping showed that aluminum 

deposits were frequently present (Marshall, Rushing and Edwards 2003); 

x Chlorine - WSSC, like the majority of utilities, uses chlorine to provide a disinfectant 

residual in the distribution system; 

x pH - WSSC increases the pH of water entering their system during the treatment 

process for corrosion control. Water from the Potomac WTP has a pH of about 7.5 in 

the distribution system. Until recently, the Patuxent WTP had a pH of about 8.2 in 

the distribution system (now adjusted to about 7.5 since orthophosphate addition 

began); and 

x TOC - The Potomac WTP achieves approximately 40 percent TOC removal, which is 

a slight increase since the coagulant and filter media change. Patuxent reservoir 

water has a lower level of NOM, with treated water TOC levels below 2 mg/L. TOC 

removal at the Patuxent WTP has not changed. 

StepsTaken by the Utility

 In late 2003, WSSC implemented orthophosphate addition to both treatment plants. 

Addition was phased in slowly with the dose reaching a level of 1 mg/L (as PO4) after 4 to 5 

months. This gradual increase was recommended by WSSC's operations staff to limit the 

potential for discolored water problems caused by phosphates forming comples with iron, 

making it more soluble. In pilot-testing, orthophosphate effectively reduced pinhole leak 

activity. WSSC participated in a state-wide task force that surveyed utilities regarding pinhole 

leaks. WSSC also contacted the EPA regarding the pinhole leak issue and research findings that 

removal of NOM, as required in the DBP Rules, may promote pinhole leaks in certain waters. 

Finally, WSSC has worked to educate the public on this topic. 

Results of the Steps Taken

 Overall, the utility is receiving fewer pinhole leak reports from their customers and area 

plumbers have indicated that they are seeing fewer pinhole leaks. It will take more time before 

WSSC can conclusively determine whether orthophosphate has addressed the problem. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-32 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Implementation and Operational Issues Faced by the Utility

 WSSC experienced the following issues when implementing orthophosphate addition: 

x Increased wastewater phosphorus resulted in increasing cost for wastewater 

treatment; 

x WSSC investigated the potential for orthophosphate addition to increase discolored 

water complaints due to iron release from unlined cast iron mains; and 

x During summer conditions, turbidity of finished water (i.e., following post-filter lime 

addition) has increased occasionally after orthophosphate addition. WSSC is still 

investigating the cause. 

Lessons Learned From this Case Study

x Switching coagulant may have unintended consequences on water quality; 

x The role of NOM in copper corrosion control needs to be better understood by the 

drinking water industry; 

x The synergistic effects of chlorine and aluminum at pHs that have been optimized for 

corrosion control also need to be better understood by the drinking water industry.

These interactions can be exacerbated for utilities that use free chlorine; and 

x Pilot-scale and/or electro-chemical testing for determining the impacts of chemicals 

on corrosion control were useful in identifying an appropriate solution. 

References

Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole 

leaks in residential plumbing. Water Science and Technology. 49(2): 83-90.

Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids 

and chlorine in copper pitting corrosion. In Proceedings of AWWA Annual Conference.

Denver: AWWA.

Rushing, J.C. and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold 

water pitting of copper. In Proceedings of AWWA Water Quality Technology Conference.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-33 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #6 

Enhanced Coagulation - Managing Radioactive Residuals 

Allen Water Filtration Plant 

Englewood, CO 

 This case study presents a discussion of a system's options for disposing of 

radioactive residuals resulting from enhanced coagulation. Enhanced coagulation is 

practiced at the system to meet the requirements of the Stage 1 D/DBPR. Uranium is 

naturally occurring in the City's source water, but radionuclide levels in the raw water do 

not warrant treatment for removal. The radionuclides become concentrated in the residuals 

as a result of the enhanced coagulation process at levels that require special considerations 

for regulatory approval of sludge disposal. 

Introduction

 The City of Englewood Allen WFP is a conventional treatment plant with an average 

treated flow of 8.5 mgd (design flow of 28 mgd) to serve a population of 48,000 people. The 

primary raw water supply comes from surface sources, including the South Platte River, Bear 

Creek, and water sources diverted from the Western Slope of Colorado. The plant treatment 

processes include addition of potassium permanganate, coagulant, and coagulant aid to the 

pipeline ahead of the rapid mix. Mixing is followed by three-stage tapered flocculation and 

settling using lamella inclined plates. The water passes through GAC filters prior to chlorine 

addition. Chlorine contact time is obtained in the clearwell and ammonia is added after the 

clearwell for chloramine disinfectant residual in the distribution system. Sedimentation sludge 

and filter backwash water are dewatered by belt press and the filtrate is sent to the backwash 

settling lagoon along with the waste backwash water. Decant from the backwash settling lagoon 

is returned to the North Reservoir to be recycled to the head of the plant. Recycle goes into the 

washwater lagoon (aka backwash settling lagoon) which overflows to an 80 million gallon 

reservoir that is used sparingly as source water as it is blended with raw water drawn from other 

sources. The approximate recycle return flow is 1.5%. Treatment includes settling of solids in 

the lagoon and in the reservoir.

Exhibit B.10 presents source water and finished water quality details. A process 

schematic is shown in Exhibit B.11. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-34 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.10 Typical Water Quality Parameters at Allen WFP 

Water Quality Parameter Raw Water Treated Water

Turbidity (NTU) 1.0 - 12 0.10 - 0.24 

pH (SU) 7.9 - 8.7 7.6 - 8.4 

TOC (mg/L) 3.5 - 5.0 2.6 - 3.75 

Alkalinity (mg/L as CaCO3) 55 - 170 55 – 150 

Barium (mg/L) * 0.048 

Selenium (ug/L) * 0.0077 

Alpha Emitters (pCi/L) 34 + 5 7.8 + 3.3 

Beta/Photon Emitters (pCi/L) * 10 + 5 

TTHM (ug/L) * 34 – 55 

HAA5s (ug/L) * 3 – 21 

* If available, levels present in raw water will be added to next draft. 

 The Allen WFP practices enhanced coagulation to comply with the Stage 1 

D/DBPR by the addition of alum with typical doses of 40 - 60 mg/L of alum. Based on the 

average plant flow, the production rate of residuals would be expected to be 1632 lb/day or 

302 cy/yr. Recently (2002-2004), residuals production from the backwash pond is 

approximately 1600 cy/yr. The current large volume may be a result of catching up on 

previous years' storage. City employees are processing residuals from March to November 

to make sure the backwash pond does not exceed its capacity. 

Exhibit B.11 Allen Water Filtration Plant Schematic 

Coagulant and

Coagulant Aid

Settled Water

Plant Headworks Sludge

 Ammonia

Coagulant Sludge 

De-Watering System

( )

Finished Water

Water Treatment System

Pump Station

43 af

Backwash

Waste Backwash

Water Chlorine

North Reservoir

Zone II

Filter Backwash

Filtered Water

Zone I

Distribution System

Beltpress Filtrate

River

City Ditch Allen Water Treatment Plant

South Platte

Polymer

245 af

Settling Lagoon

Filter Backwash Water Recycle System

Discharge 002 A Discharge 001 A

To Big Dry Creek

Chlorine Contact 

Basin

Granular Activated 

Carbon Filters

Flocculation/Sedimentation

Basins

Pump

Station
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-35 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Residuals Management Prior to Enhanced Coagulation 

 The City of Englewood has historically disposed of water treatment residuals by 

land applying dried residuals at the City golf course. These residuals were mixed with fill 

dirt (2:1 ratio fill to residuals) for berm construction with grass cover. This procedure met 

the requirements of the Colorado Department of Health and Environment (CDPHE) with 

respect to the state's solid waste regulations and the hazardous/radioactive material 

regulations. Residuals disposal facilities in Colorado must comply with all Colorado 

health laws and with CDPHE regulations and standards. Acceptance criteria for solid 

waste disposal include: 

x WFP residuals containing any free liquid cannot be accepted for disposal; 

x WFP residuals with a pH less than 6.0 cannot be accepted for disposal; and 

x WFP residuals with a total alpha activity value exceeding 40 pCi/g of dry solids 

require additional CDPHE guidance prior to disposal. The residuals generator 

must contact the CDPHE's Radiation Control Division and the Solid Waste 

Division for guidance 

 Colorado drinking water utilities with residuals that have total alpha activity values 

exceeding 40 pCi/g have disposed of residuals using landfill disposal, sanitary sewer 

discharge, monofill disposal, and compost amendment with and without approval from 

CDPHE.

 Liquid residuals discharged to sanitary sewers are not regulated for water treatment 

residuals disposal by CDPHE. Acceptance of water treatment residuals is approved by the 

sanitary district authority based on impacts to the treatment process from additional flow 

and solids loading. 

Simultaneous Compliance Issue Faced by the Utility

 Since the inception of enhanced coagulation at the Allen WFP, analysis of the 

residuals has shown that the total alpha activity exceeds 40 pCi/g, resulting in the 

requirement that the City of Englewood must notify CDPHE of disposal plans for the 

residuals to comply with state regulations. The City can no longer dispose of residuals as 

has been done in the past because CDPHE no longer allows land application at the golf 

course. The concentrated residuals are considered technologically enhanced naturally 

occurring radioactive materials (TENORM). Regulation of TENORM in drinking water 

residuals is not clearly spelled out in Federal or state regulations.

Steps Taken by the Utility

 The City undertook a study to develop a long-term residuals disposal plan. Six 

disposal alternatives were evaluated using three criteria: compliance with residuals 

disposal regulations, cost of disposal, and ease of implementation. The six alternatives 

considered were as follows: 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-36 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

x Discharge to the sanitary sewer is not regulated by the state, however the waste 

water treatment plant (WWTP) has a limit of 30 pCi/g for biosolids. Because 

liquid residuals samples from the Allen WFP holding pond have an average 

gross alpha level of 5,880 pCi/L, the allowable discharge rate would be limited 

to a total flow well below the average daily production rate. This option is 

therefore not operationally sound; 

x Disposal at an approved landfill requires loading and trucking residuals to one 

of two landfills at a distances of 44 miles or 100 miles from the plant site. The 

landfills are approved for disposal of Resource Conservation and Recovery Act 

(RCRA) wastes by the State of Colorado and all material disposed is 

manifested and final disposal location within the landfill is documented. The 

minimum operating cost of this option is $66,000 per year; 

x Compost/topsoil amendment recycling requires the City to take responsibility 

for loading dry residuals onto City trucks to transport to the facility. The 

compost facility can mix residuals immediately upon delivery to avoid 

stockpiling of residuals only material. The expected annual operating cost for 

this option is $19,900; 

x Disposal at a new City monofill requires the development, operation, and 

eventual closing of a landfill operation used solely for Allen WFP residuals. In 

addition, trucking of the residuals to the landfill site would be required. This 

option requires a capital investment of approximately $1.4 million and annual 

operating costs of $233,000; 

x On-site mixing with fill material provides material ready for compost or topsoil 

application. A portion of residuals is mixed with fill material with low 

background gross alpha levels. City monitoring for gross alpha will be required 

to ensure levels below 40 pCi/g. Expected annual operating cost for this option 

is $68,100; and 

x Disposal at out-of-state approved landfill assumes transport of residuals by 

truck or rail cars to the nearest landfill (600 miles away) that accepts TENORM 

waste similar to the Allen WFP residuals. Material at this facility is manifested 

and final disposal location in the landfill is documented. The expected annual 

operational cost is a minimum of $202,500. 

 In addition to evaluating these six options, the City contracted for a human health 

risk assessment to be done to determine possible radiation exposure to City and landfill 

employees from managing the residuals, as well as the public exposure arising from 

possible future property uses. The risk assessment utilized RESRAD Version 6.21 

modeling software to assess the dose to workers and residents from contact with 

radioactive material in the treatment plant residuals, either directly or indirectly. Included 

were the possible radiation exposures for a landfill worker, a composting facility worker, 

and a hypothetical future resident farmer living and farming the area above a closed 

landfill. The risk assessment indicated that neither the landfill or compost worker would 

be subject to significant radiation exposure resulting from the residuals handling. In 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-37 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

addition, the hypothetical future farmer is unlikely to experience exposures above typical 

background levels in Colorado. Thus, the risk assessment supported the disposal of 

residuals in a local landfill and at the compost recycling facility. 

 As of March 2006, the sludge is being disposed of at a licensed industrial landfill 

within the state. 

 The City is assessing coagulation schemes that use less alum and produce less 

residuals. One such possibility is using a 15 mg/L dose of polyaluminum chloride (PACl) 

with a small supplemental dose of 8 mg/L of alum. Essential to making this change will be 

the ability to remove sufficient TOC to meet the Stage 1 D/DBPR. 

 Since there is currently no state or Federal guidance for disposal of radioactive 

water treatment residuals, the City has undertaken an effort with other local utilities to 

assist the State CDPHE in development of guidance for the disposal of TENORM in 

drinking water residuals. 

Results of the Steps Taken

 The long-term recommendation to the City is that residuals be transported to the 

compost/topsoil amendment recycling center. In addition the City is expected to obtain 

approval for both onsite mixing and in-state landfill disposal. Approval for all three 

disposal methods has been requested from CDPHE. 

 The State CDPHE has begun a stakeholder process that will ultimately result in 

guidance for utilities in disposing of TENORM.

Implementation and Operational Issues Faced by the Utility

 The fact that appropriate Federal and state guidance does not yet exist to provide utilities 

with an understanding of requirements has made managing residuals much more complex. 

Approval from CDPHE must be obtained as soon as possible as residuals are currently stockpiled 

on the plant site at near capacity. If residuals handling operations are impacted with respect to 

volume, the drinking water treatment process may also be impacted with respect to production. 

Lessons Learned From this Case Study

x The levels of radioactivity in sludge may be significantly higher than expected based 

on the background levels in the raw water when the treatment process produces 

residuals that concentrate contaminants. These residuals can be liquid and/or solid; 

x Disposal to the sanitary sewer is likely to be a problem for almost any concentrated 

contaminant that is regulated in biosolids; and 

x No regulatory guidance is available to utilities to assist in developing disposal options 

for residuals that qualify as TENORM.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-38 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

State regulatory agency groups that have responsibility for radioactive waste products are 

generally different from the group responsible for drinking water compliance. This can result in 

some complex interactions with regulators as the utility may find themselves in the role of 

initiating internal interactions within state agencies. In Colorado, the Hazardous Materials and 

Waste Management Division is the licensing group for disposal at hazardous waste disposal 

facilities or licensed radioactive waste facilities. Discharge permits, if the liquid waste meets 

water quality standards, are issued by the Water Quality Control Division's Colorado Discharge 

Permit System. Drinking water is regulated through the Water Quality Control Division 

Drinking Water Program. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-39 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #7 

Granular Activated Carbon Filtration for TOC Removal1

Higginsville Water Treatment Plant 

Higginsville, Missouri

Introduction

 This case study provides an example of how a utility used GAC to address high 

levels of atrazine in its source water and high TTHM levels in its finished water. Most of 

the information for this case study came from Leung and Segar (2000). Interested readers 

are referred to that reference for more information. 

 The Higginsville, Missouri Water Treatment Plant is a 2 million gallons per day 

(MGD) treatment plant that draws water from a small surface water impoundment in 

Missouri. The plant operates 12 hours a day and employs a two stage settling process with 

conventional filtration. In 1994, the plant experienced a violation of the atrazine maximum 

contaminant level (MCL). The system eventually switched to GAC caps on their filters to 

counter the problem. 

 The source for the Higginsville plant is an impoundment that collects surface 

runoff from nearby agricultural areas. It has high hardness and TOC. The average source 

water quality is described in Exhibit B.12. 

Exhibit B.12 Average Source Water Quality 

Parameter Average Value

pH 8.1 

Alkalinity 89 mg/L as CaCO3

Hardness 129 mg/L as CaCO3

Turbidity 18 NTU 

TOC 6 mg/L 

The Original Treatment Process at the Higginsville WTP 

Exhibit B.13 displays a schematic of the treatment scheme at the Higginsville plant. 

The plant adds chlorine dioxide to the raw water to control taste and odor problems. 

Copper sulfate is also added occasionally to control biological blooms that lead to taste and 

odor problems. The water is then pumped to a first set of coagulation and settling basins.

An average of approximately 40 mg/L of alum and 1.7 mg/L of cationic polymer are 

added. Lime and fluoride are added to a second flash mix prior to the water passing 

through a second set of coagulation and sedimentation basins. The water is then filtered 

1

 For an example of GAC used as a biological filter after ozonation, see Case Studies 9 and 10. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-40 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

through dual media filters. Chlorine is added both prior to the filters and to a 0.5 million 

gallon clearwell after the filters. 

 When the utility first experienced violations of the atrazine MCL in 1994, it added 

powdered activated carbon (PAC) in the first flash mixer to combat the problem. Although 

PAC did lower atrazine concentrations below the MCL, it was limited in removal 

capabilities because of the short contact time. 

Exhibit B.13 Higginsville Water Treatment Plant 

Simultaneous Compliance Issue Faced by the Utility

 The utility was in violation of the atrazine MCL. In addition, high TOC levels 

were contributing to total trihalomethane (TTHM) levels which averaged around 80 mg/L, 

which could cause problems with Stage 1 and Stage 2 DBPR compliance. Although PAC 

provided a temporary solution to the atrazine problem, it was not desirable as a long term 

treatment method because of high amounts of sludge. The system also faced periodic taste 

and odor episodes. 

Steps Taken by the Utility 

 The utility replaced the anthracite in its dual media filters with GAC in an attempt 

to reduce atrazine concentrations and lower TOC and DBPs. The pre-chlorination residual 

was also reduced to 0.1 mg/L to prevent degradation of the GAC. Twenty four inches of 

GAC were placed on top of the sand and gravel base of the filters. The total EBCT was 

7.5 minutes. 

Chlorine Dioxide

Alum

(Copper Sulfate

and/or PAC if 

needed)

Flash 

Mix #1

Coagulation 

Basin #1

Sedimentation 

Basin #1

Lime

Polymer

Fluoride

Flash 

Mix #2

Coagulation 

Basin #2

Sedimentation 

Basin #2

Chlorine Chlorine

Dual 

Media

Filters

0.5 MG 

Clearwell
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-41 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Results of the Steps Taken

 When the GAC caps were first installed, atrazine levels dropped to below detection 

and DBP precursors as measured by ultraviolet light adsorption at 254 nm (UV254) dropped 

by 50 percent. After about 3 months of operation the removal rates dropped. Removal 

rates eventually settled at 30 to 60 percent atrazine removal and 20 percent UV254 removal 

after about 6 months of operation. The atrazine concentrations were always below the 

MCL of 3 mg/L, averaging between 1 and 2 mg/L. The hydraulic performance of the filter 

was unaffected by the change to the GAC cap. Turbidity values leaving the filters were 

comparable to values produced previously with the anthracite filters. 

Implementation and Operational Issues Faced by the Utility

 Adsorption of atrazine and other organics onto the GAC gradually decreased 

removal rates over time. A build up of inorganic precipitates, largely calcium, was seen on 

the GAC, which also contributed to decreased removal rates. The removal rates can be 

restored by regenerating or replacing the GAC, though this can be expensive. 

 It is possible that initial removal was due to adsorption and biological activity was 

later established. If this were the case, subsequent removal resulted from a combination of 

adsorption and biological degradation. If biological activity is suspected, care should be 

taken not to change the operational characteristics (e.g., fluidized bed heights, backflow 

rates) since changes in these operational parameters might impact removal performance. 

 There was a trade-off between removal of atrazine and removal of UV254. Lower 

pH favored UV254 removal at the expense of atrazine removal, while high pH had the 

opposite effects. 

 The system still experiences occasional taste and odor episodes. This is most likely 

caused by taste and odor causing compounds passing through the filters because GAC 

contact time and design are not optimal for taste and odor control. These episodes have 

been dealt with by adding PAC prior to the filters. 

Lessons Learned From this Case Study

x GAC caps can be used effectively to reduce pesticide and TOC concentrations; 

x Adsorption of organic compounds by GAC is complicated and depends on the 

concentrations of other adsorbing compounds present in the source water. Bench 

scale tests should be done on the specific source water to determine if GAC itself, as 

well as different brands of GAC, will be effective with that water; and 

x The pH of the water can impact GAC removal rates for different organic compounds.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual 42 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

This page intentionally left blank. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-43 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study # 8 

Nanofiltration Membrane Technology for TOC Removal 

PBCWUD Water Treatment Plant #9 

West Palm Beach, Florida

 The Palm Beach County Water Utilities Department (PBCWUD) utilizes 

groundwater supplies that are treated at Water Treatment Plant # 9 (WTP #9) acquired by 

the County in 1983. The original plant, constructed in 1971 by private developers, utilized 

lime softening, rapid sand filtration, short-term free chlorination for biological growth 

control in the filters and chloramination for secondary disinfection. The facility had a 

maximum day flow capacity of 13.45 MGD, and was comprised of three treatment trains 

with capacities of 1 MGD, 3 MGD, and 10 MGD. 

 Initially, the plant provided water service to the local area, but it was later 

incorporated into the regional water distribution system to provide potable water for the 

southern portion of the PBCWUD Service Area. Recognizing the growing demands for 

water in the area and the implementation of new drinking water standards, PBCWUD 

administered a construction contract for a new 27 MGD nanofiltration plant that was 

awarded in 1999. Nanofiltration removes hardness, color, and TOC and its related 

chlorinated DBPs which are commonly found in South Florida ground water. The plant 

started operational testing in November 2001.

 This case study provides an example of several simultaneous compliance issues 

that can be associated with nanofiltration membrane technology. These issues were 

identified during initial start-up operations and have been resolved successfully. The 

issues include: 

x DBP Rules - ability to remove DBP precursors; 

x LCR - ability to provide a non-corrosive water in the PBCWUD distribution 

system; and 

x Secondary Drinking Water Standards - ability to provide an aesthetically 

pleasing water to PBCWUD customers. 

Introduction

 The mission of PBCWUD is to provide the highest quality drinking water service 

in a fiscally and environmentally sound manner. In the last decade, with the enforcement 

of the Secondary Drinking Water Standards and the Stage 1 D/DBPR in the State of 

Florida, PBCWUD's capital improvement strategy for new water treatment plants has been 

focused on nanofiltration membrane technology. Membrane water treatment technology is 

cost competitive with traditional conventional treatment methods while producing higher 

quality potable water; consequently, becoming the dominant water treatment technology in 

South Florida. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-44 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 In May of 2003, PBCWUD completed Phase I construction of a new, and one of 

the largest in the world, nanofiltration membrane treatment plant (WTP #9) with a 

maximum capacity of 27 million gallons per day (MGD) finished water, including 23 

MGD of membrane permeate and 4 MGD of raw blend water. As stated previously, the 

primary reason for the membrane softening is for removal of hardness, color, TOC, and its 

related chlorinated DBPs. 

 The raw water supply for WTP #9 is water from the local surficial Biscayne 

Aquifer. The surficial aquifer system provides the water source for most public water 

supply wellfields in southeastern Florida. The aquifer system is generally unconfined and 

extends from land surface to a depth of approximately 330 feet below land surface (bls). 

The ground water is generally colored due to organics, hard and alkaline with varying 

amounts of dissolved iron and hydrogen sulfide. Typical ranges of water quality found in 

the Biscayne Aquifer are shown in Exhibit B.14. 

Exhibit B.14 Typical ranges of raw water quality in the Biscayne Aquifer 

Water Quality Parameter Units Range of Values

pH Standard Units 7.0-7.5

Alkalinity Mg/L as CaCO3 200-240 

Chloride Mg/L <250 

Total Dissolved Solids Mg/L 250-600 

Hardness Mg/L as CaCO3 225-275

Sulfate Mg/L 15-25 

Total Organic Carbon Mg/L 10-12 

Color Color Units 360-400 

The New Treatment Process at Water Treatment Plant #9

 The treatment train for WTP #9 is shown in Exhibit B.15. The raw water supplied 

to WTP #9 is taken from the shallow surficial aquifer through a series of 24 wells.

Pretreatment includes a sand strainer which removes bulk sand from the raw water stream, 

acid injection to control pH to 5.0-5.9, and 5-micron cartridge filters to remove particulates 

greater than 5 microns. Six membrane feed pumps located after the micron filters boost 

the feed water pressure to 125-132 psi. The nanofiltration membrane building includes 

eight membrane treatment trains where each one has two stages with 47 and 22 pressure 

vessels, respectively. The degasifier/odor control system functions to remove hydrogen 

sulfide and carbon dioxide from the permeate water (product water from the membranes) 

and to prevent the emission of odors into the atmosphere. A sodium hypochlorite system 

supplies dilute liquid chlorine for disinfection. Six high service pumps supply water to the 

distribution system. Post-storage chemical injection points for ammonia, chlorine, and 

caustic soda are included in the system to allow final disinfection and/or pH adjustment 

before the finished water enters the distribution system. The water entering the 

distribution system is monitored for chlorine residual, pH, pressure, and flow. The 

impurities removed by the membrane softening trains are consolidated into a concentrate 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-45 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

stream and discharged through three-concentrate booster pumps into one deep injection 

well.

Treatment Steps Taken by Palm Beach County 

x Pretreatment of sand strainer, acid injection, cartridge filtering 

x Eight nanofiltration membrane treatment trains 

x Degasification and odor control 

x Dilute chlorine disinfection 

x Post-storage final disinfection and/or pH adjustment and control 

x Distribution system monitoring 

Simultaneous Compliance Issues Faced by the Utility

 Nanofiltration membranes remove organic compounds in a molecular weight range of 

200 to 20,000 Daltons and reject selected salts (typically divalent). Nanofiltration economically 

softens water without the use of salt-regenerated systems and provides unique organic removal 

capabilities. While effective in removing organic constituents or DBP precursors, the 

nanofiltration membrane rejects selected salts, producing treated water with low total dissolved 

solids (TDS). Low TDS water has poor buffering capacity and can lead to low pH water, which 

is corrosive to metal pipes. Generally, an alkalinity below 25 mg/L as CaCO3 (0.5 meq/l) can be 

problematic for corrosion of piping (AwwaRF and DVGW-Technologiezentrum Wasser 1996). 

This chemically unstable water can result in compliance issues with the Secondary Drinking 

Water Standards and the LCR.

.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-46 March 2007 For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.15 Water Treatment Plant #9 Treatment Train 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-47 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Steps Taken by the Utility

 Steps taken by the utility to overcome the potential simultaneous compliance issues 

discussed above occur primarily in the post-treatment process. The post-treatment process 

is mainly taking place in the clearwell complex area as shown in Exhibit B.15. The 

clearwell complex consists four major processes: 1) de-gasification process for degasification of hydrogen sulfide and carbon dioxide from the permeate solution, 2) odor 

control process to remove hydrogen sulfide from the air, 3) clearwell disinfection process 

to create free and combined chlorine, and 4) transfer pump process to discharge the posttreated water to the storage tanks. 

 Prior to the de-gasification process, approximately 4 MGD of raw water is 

introduced into the treatment train to blend with the 23 MGD of treated water. Blending of 

this raw water introduces some of the divalent salts back into the water that had been 

previously rejected by the membrane. This provides a more chemically-stable finished 

water.

 Permeate water from the nanofiltration trains contains excessive amounts of carbon 

dioxide and hydrogen sulfide; therefore, 4 identical de-gasifier towers with air blowers in 

the clearwell complex function to remove carbon dioxide (CO2) and hydrogen sulfide 

(H2S) from the permeate water with the air stripping process. Sodium hypochlorite is 

injected into the permeate water before entering into the de-gasifiers for disinfection. The 

towers are of the forced draft, randomly packed bed, counter flow type. 

 The de-gasifiers are designed for maximum influent pH of 6 std. units; influent H2S

with concentration of 1.3 mg/L and removal efficiency of 92 percent; and influent CO2

with concentration of 77 mg/L and with removal efficiency of 93.5 percent. 

 The stripped permeate is treated with a chlorine solution and ammonia for 

secondary disinfection and caustic soda for pH adjustment. 

Results of the Steps Taken

 The resulting finished water quality is listed in Exhibit B.16. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-48 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.16 Typical ranges of distribution system water quality 

Water Quality Parameter Units Range of Values

Total Trihalomethanes ppb ND-55.3

Haloacetic Acids ppb ND-51.4 

pH Standard Units 8.5-9.0

Alkalinity mg/L as CaCO3 30-50 

Chloride mg/L 17.2-110 

Total Dissolved Solids mg/L 90-300 

Hardness mg/L as CaCO3 40-60 

Sulfate mg/L 6.0-19.5 

Total Organic Carbon mg/L <0.5 

Color Color Units 1-7 

Lead ppb, 90th percentile 3

Copper ppm, 90th percentile 0.134 

 As shown in Exhibit B.16, all Secondary Drinking Water Standards, DBP Rule MCLs, 

and LCR Action Levels are met. 

Implementation and Operational Issues Faced by the Utility

 The utility experienced two serious problems in bringing the nanofiltration membrane 

treatment plant online. The most serious problem involved numerous leaks in the acid feed 

system. As a result of the leaks, the acid system had to be completely rebuilt during the first year 

of operation. 

 The other problem involved the micron cartridge filter housings and the string wound 

filter. The filter housings use a single open end cartridge with a stainless steel spring on the 

other end to keep tension on the cartridge, holding it in place. In this case, the filters sagged in 

the middle causing them to pull out of the socket. With the filter out of place, sand and debris 

accumulated on the membranes. This problem was eliminated by modifying the cartridge 

housings with a center bracket to support the filters. With these two modifications, the treatment 

plant has worked very well and continues to produce very high quality water. 

Lessons Learned From This Case Study 

x Nanofiltration economically softens water without the use of salt-regenerated systems 

and provides unique organic removal capabilities thereby removing disinfection 

byproduct precursors; 

x Blending a portion of the raw water with treated water and the de-gasification process 

significantly enhances the aesthetic qualities of the finished water and results in a 

more chemically stable water. This enables PBCWUD to provide their customers 

with water that complies with both the LCR and the Secondary Drinking Water 

Standards; and 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-49 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

x The nanofiltration membranes should be evaluated by monitoring conductivity in the 

permeate from the membrane train and from each membrane pressure vessel as 

necessary to isolate a problem. Monitoring TOC, particle count or HPC are not 

necessary.

References

 AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. Denver: 

AWWA. 

Glucina, K., A. Alvarez, and J.M. Laine. 2000. Assessment of an integrated membrane 

system for surface water treatment. In Proceeding of the conference in drinking and 

industrial water production. Italy. 2:113-122. 

HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd Edition. New 

York: John Wiley & Sons, Inc. 

Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water 

Treatment Plant No. 3. Membrane Softening Facility Operations Manual Final Report.

pp. 4-19 to 4-20.

Panayides, N. 1999. Operational Procedures of a New 27 MGD Nanofiltration Membrane 

Water Treatment Plant (WTP No. 9) in South Florida. Palm Beach County Water 

Utilities Department.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-50 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-51 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #9 

Modifying Chloramination Practices to Address Nitrification Issues

Ann Arbor Utilities2

Ann Arbor, Michigan 

 This case study demonstrates how a utility modified chloramination practices to address 

nitrification problems in the distribution system to be in compliance with the Stage 1 DBPR and 

the TCR. 

Introduction 

 The City of Ann Arbor operates a two-stage lime softening plant (50 million gallons per 

day (MGD) design flow) that treats a blend of surface water and ground water. It serves 

approximately 115,000 people. The influent to the plant consists of a blend of Huron River 

water (approximately 85 percent) and well water (approximately 15 percent). Typical water 

quality parameters for raw river water and well water, prior to any treatment modifications, are 

presented in Exhibit B.17. The water entering the plant has high alkalinity (average alkalinity of 

314 mg/L as CaCO3), with high TOC levels (average 6 mg/L). 

2

 This system is also used in Case Study #10 Ozonation. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-52 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.17 Summary of Relevant Water Quality Parameters at Ann Arbor Before 

Treatment Modifications 

Water Quality 

Parameters

Location1

River Well Blended Influent Effluent

TOC (mg/L)

Minimum

Average

Maximum

5.5

6.9

8.7

1.0

2.2

5.9

5.1

6.0

8.1

2.1

3.0

3.5 (3.7)2

pH

Minimum

Average

Maximum

7.9

8.1

8.2

 

9.3 (9.1)2

9.4

9.7

Alkalinity (mg/L as 

CaCO3)

Minimum

Average

Maximum

205

215

228

301

314

335

218

234

250

28

39

48

Total Coliforms (#/100 

ml)

Minimum

Average

Maximum

62

781

2,890

0

0

0

Cryptosporidium (# 

oocysts/100 gallons)

Minimum

Average

Maximum

ND

114

1,739

 

ND

ND

ND

Notes:

1. Data collected between July 1994 and June 1995; based on monthly (average) data. 

2. Minimum or maximum values (in parentheses) represent minimum or maximum of all measurements, not 

limited to monthly average data.

3. ND = Non Detectable

The Treatment Process at the Ann Arbor WTP 

 The treatment plant is a 50 MGD two-stage lime softening plant that uses chloramines for 

primary disinfection. The average operating flow is 20 MGD. Exhibit B.18 shows a schematic 

of the treatment plant. Raw river water is disinfected with chlorine, then chlorine is added again 

with ammonia after filtration to form chloramines. The free chlorine contact time is minimal. 

The water is softened with lime (average dose = 187 mg/L as CaCO3), at a pH slightly above 11.

From April through November well water is blended with softened water from the first stage 

clarifier effluent and recarbonated (i.e., addition of CO2) to bring the pH down to around 10. It 

then enters the second-stage clarifier. A cationic polymer is added at this point (average dose 

0.62 mg/L) to enhance settling. The water is then recarbonated (i.e., CO2 is added) down to a pH 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-53 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

slightly greater than 9, and sodium hexametaphosphate is added to facilitate corrosion control.

The water is then filtered (granular activated carbon (GAC)/sand dual-media filters). After 

filtration, sodium hypochlorite and ammonia are added to form chloramines and the finished 

water is distributed at an average pH of 9.4. 

 From December through March the chemical application points are similar to those 

during the summer months. However, the well water is blended with the river water prior to the 

first stage of the lime softening process to raise the water temperature and improve sludge 

dewatering.

 The chloramines dose ranged from 4.1-6.2 mg/L and Giardia log inactivation by 

chloramination ranged from 0.5 to1.0 logs. 

Exhibit B.18 Ann Arbor Water Treatment Plant

Simultaneous Compliance Issue Faced by the Utility

 The system switched to chloramines to reduce TTHM formation and to be in compliance 

with the Stage 1 Disinfectants/Disinfection Byproducts Rule (D/DBPR). However, the use of 

chloramines can result in the presence of ammonia in the distribution system if the proper 

chlorine to ammonia (as nitrogen) ratio is not maintained. This increases the potential for 

biological nitrification. Nitrification can result in a loss of combined chlorine residual, and result 

in sharp increases in HPC bacteria. This increases the chances of a TCR violation.

River Rapid Mix Flocculation

Primary Clarifier

Recarbonation

Flocculation Rapid Mix Secondary

Clarifier

Recarbonation Wet Well GAC/Sand

Filtration

Clearwell

Sodium Hexametaphosphate

Polymer

Well Water (During summer)

CO2

Chlorine and

Ammonia Lime

Well Water (during winter)

CO2

Covered Reservoir Distribution

System

Fluoride NaOCl and Ammonia
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-54 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Steps Taken by the Utility

 To cope with the nitrification problem, Ann Arbor expanded its monitoring program and 

made several operational and facility adjustments to improve ammonia feed rate control. The 

chlorine to ammonia (as nitrogen) ratio was maintained at 4.75:1, with a target level for free 

ammonia entering the distribution system of 0.15 mg/L. Warning and action levels for nitrite in 

the system were set at 0.025 and 0.050 mg/L, respectively. 

 As soon as the utility became aware of its nitrification problem, it attempted to control it 

by controlling the concentration of free ammonia reaching the filters. No changes were made to 

the existing treatment configuration. However, the system made several operational changes. 

Ammonia dosage at the headworks was reduced so that less than 0.15 mg/L of free ammonia 

remained in the water when it entered the filters. Along with this, distribution lines were flushed 

at low velocity until an average combined chlorine residual of approximately 3 mg/L was 

achieved. The Stage 1 DBPR specifies a running annual average maximum residual disinfectant 

level (MRDL) for chlorine of 4.0 mg/L (as Cl2). 

 During the summer months (i.e., June to September), the system switched back to 

chlorination. This was achieved by simply shutting down ammonia addition after filtration and 

adjusting the chlorine feed rate. This would ensure that nutrient levels (i.e., ammonia) in the 

distribution system were low during the warmer months, when the temperature was most 

conducive to the rapid growth of nitrifying organisms. This would decrease biological activity in 

the distribution system. 

Results of the Steps Taken

 As a result of these steps, nitrite concentrations in the distribution system were below 

detection level. Also, HPC levels dropped significantly in five of the six locations where 

nitrification had previously been found. The system did see an increase in TTHM formation 

during the summer months. However, careful monitoring, dosing, and complementary hydrant 

flushing (see next paragraph for details) resulted in compliance with the Stage 1 DBPR. The 

average and maximum TTHM in the finished water were 24 and 39 )g/L, respectively (based on 

the monthly TTHM data collected between July 1994 and June 1995). 

Implementation and Operational Issues Faced by the Utility

 Although switching to free chlorine during the summer was effective for controlling 

nitrification, it appeared to result in higher levels of heterotrophic and coliform bacteria than 

when the water was chloraminated. At the same time, increasing the chlorine dose during the 

summer months increased TTHM concentrations. As a result, the system decided to continue 

disinfecting with chloramines and pursue a more aggressive hydrant flushing program to control 

bacterial re-growth in the distribution system. 

 Analysis revealed that one of the prime causes of nitrification could have been the switch 

to a GAC/sand dual-media filter from a pure sand filter. The ammonia added before the water 

reached the filters could have provided a nutrient source sufficient for nitrifying bacteria to 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-55 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

attach, establish, and proliferate within the GAC media. Such a condition could have allowed 

the nitrifying organisms to pass through the filter and seed the distribution system if they 

survived the chloramine disinfection. 

Lessons Learned From this Case Study

x Controlling nitrification in the distribution can be a challenge for utilities switching to 

chloramines; 

x Carrying a chloramine residual through the treatment plant might increase distribution 

system problems with biological nitrification; 

x The most common strategies for controlling nitrification are listed below. 

- Improving ammonia feed rate control to limit the free ammonia levels entering the 

distribution system; 

- Implementing a comprehensive distribution system flushing and monitoring 

program; and 

- Having an alternative disinfection strategy for the warmer months of the year. 

x Systems adding ammonia prior to a GAC filter may be more likely to face 

nitrification in the distribution system. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-56 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

This page intentionally left blank. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-57 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #10 

Ozonation

Ann Arbor Utilities3

Ann Arbor, Michigan

 This case study demonstrates how a utility switched to ozonation to meet the Interim 

Enhanced Surface Water Treatment Rule (IESWTR) and the Stage 1 and 2 DBPR regulations, 

and simultaneously controlled microbial regrowth potential in the distribution system to be in 

compliance with the TCR. 

Introduction 

 The City of Ann Arbor serves approximately 115,000 people, and operates a two-stage 

lime softening plant (50 MGD design flow) that treats a blend of surface water and ground water. 

In 1990, for the reasons outlined below, the Ann Arbor plant decided to switch from chloramines 

to ozonation for primary disinfection. 

x Ozonation would meet IESWTR CT requirements for viruses at low temperatures; 

x In addition to complying with the IESWTR, ozonation was expected to allow the 

plant to comply with Stage 1 and 2 DBPRs; and

x Ozonation was also expected to improve taste and odor. 

 The influent to the plant consists of a blend of Huron River water (approximately 85 

percent) and well water (approximately 15 percent). Typical water quality parameters for raw 

river water and well water, prior to any treatment modifications, are presented below in Exhibit 

B.19. The water entering the plant has high alkalinity (average influent alkalinity of 314 mg/L as 

CaCO3), with high TOC levels (average 6 mg/L). 

3

 This system is also used in Case Study #9 Modifying Chloramination Practices to Address Nitrification Issues. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-58 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.19 Summary of Relevant Water Quality Parameters at Ann Arbor Before 

Treatment Modifications 

Water Quality 

Parameters

Location1

River Well Blended Influent Effluent

TOC (mg/L)

Minimum

Average

Maximum 

5.5

6.9

8.7

1.0

2.2

5.9

5.1

6.0

8.1

2.1

3.0

3.5 (3.7)2

pH

Minimum

Average

Maximum 

7.9

8.1

8.2

 

9.3 (9.1)2

9.4

9.7

Alkalinity (mg/L as 

CaCO3)

Minimum

Average

Maximum 

205

215

228

301

314

335

218

234

250

28

39

48

Total Coliforms 

(#/100 ml)

Minimum

Average

Maximum 

62

781

2,890

0

0

0

Cryptosporidium 

(# oocysts/ 100 

gallons)

Minimum

Average

Maximum 

ND

114

1,739

 

ND

ND

ND

TTHM ()g/L)

Minimum

Average

Maximum 

 

14

24

39

HAA54 ()g/L)

Minimum

Average

Maximum 

 

4.2

16

21

Notes:

Data collected between July 1994 and June 1995; based on monthly (average) data. 

Minimum or maximum values (in parentheses) represent minimum or maximum of all measurements, not limited 

to monthly average data.

ND = Non Detectable

Data collected quarterly between October 1995 and May 1996.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-59 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

The Original Treatment Process at the Ann Arbor WTP 

 The original treatment plant was a 50 MGD two-stage lime softening plant that used 

chloramines for primary and secondary disinfection. The average operating flow was 20 MGD. 

Exhibit B.20 shows a schematic of the treatment plant, prior to the modifications. Raw river 

water was disinfected with chlorine, followed by ammonia addition to form chloramines. The 

free chlorine contact time was minimal. The water was softened with lime (average dose = 187 

mg/L as CaCO3), at a pH slightly above 11. From April through November, well water was 

blended with softened water from the first stage clarifier effluent and recarbonated (i.e., addition 

of CO2) to bring the pH down to around 10. It then entered the second-stage clarifier. A cationic 

polymer was added at this point (average dose 0.62 mg/L) to enhance settling. The water was 

then recarbonated down to a pH slightly greater than 9 and sodium hexametaphosphate added, to 

facilitate corrosion control. It was then filtered (GAC/sand dual media filters). After filtration, 

sodium hypochlorite and ammonia were added to boost the level of chloramines. The finished 

water was distributed at an average pH of 9.4. 

 From December through March the chemical application points were similar to those 

during the summer months. However, the well water was blended with the river water prior to 

the first stage of the lime softening process to raise the water temperature and improve sludge 

dewatering.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-60 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.20 Ann Arbor Water Treatment Plant Before Treatment Modifications 

Simultaneous Compliance Issue Faced by the Utility

 Application of ozone would lower the formation of TTHM and HAA5s and enhance the 

ability to meet minimum virus and Giardia inactivation levels (to be in compliance with the 

IESWTR). However, ozonation could lead to an increase in the AOC levels in the finished water, 

resulting in potential microbial regrowth in the distribution system and non-compliance with the 

TCR.

Steps Taken by the Utility

 The utility switched to ozonation, followed by biofiltration, in order to address the 

simultaneous compliance issue. They no longer pre-chlorinate or pre-chloraminate. 

 Before switching to ozone, the operators of Ann Arbor’s system contacted known ozone 

facilities and talked with their engineers and operators to learn what features, in retrospect, they 

wish they had installed when they installed the ozone. Based on these discussions, some features 

missing from previous plant designs were incorporated into the Ann Arbor system’s design. One 

example of such as a feature is the addition of waterproof hatches for direct access to the contact 

chambers. This eliminated the need for roof entry, which is an important consideration for 

system operators. 

River Rapid Mix Flocculation

Primary Clarifier

Recarbonation

Flocculation Rapid Mix Secondary

Clarifier

Recarbonation Wet Well GAC/Sand

Filtration

Clearwell

Sodium Hexametaphosphate

Polymer

Well Water (During summer)

CO2

Chlorine and

Ammonia Lime

Well Water (during winter)

CO2

Covered Reservoir Distribution

System

Fluoride NaOCl and Ammonia
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-61 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Overall process – Exhibit B.21 shows a schematic of the treatment plant after the 

modifications. Changes made to the original treatment train are outlined below. 

x Ozonation is now the primary disinfection step. The pre-chlorination step was 

eliminated; 

x The first point of disinfectant addition (i.e., ozonation) is after the secondary clarifier, 

and recarbonation. The ozonation pH is 8.0; 

x After ozonation, sodium hydroxide is added to raise the pH of the water to 9.4 prior to 

adding sodium hexametaphosphate as a corrosion inhibitor; and 

x The original dual media (GAC/sand) filters are now operated as biofilters. To help 

inactivate HPC bacteria shed from the filters, filter effluent is disinfected with an 

average chloramine dose of 3.5 mg/L, and held for approximately 3 hours in the 

covered reservoir. 

Ozonation Details

 There are 8 ozone contact cells with an overall contact time of 16.8 minutes. The system 

is operated at a 6 to 10 percent gas concentration. An off-gas recycle system applies ozone to the 

first cell, which reduces demand in subsequent cells but does not produce an ozone residual. The 

goal is to achieve a residual of 0.1 mg/L or greater in the first cell, and to maintain sufficient 

residuals in subsequent cells, to meet the target CT.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-62 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.21 Ann Arbor Water Treatment Plant After Treatment Modifications 

River Rapid Mix Flocculation

Primary Clarifier

Recarbonation

Flocculation Rapid Mix Secondary 

Clarifier

Recarbonation Wet Well GAC/Sand 

Filtration

Clearwell

Sodium Hexametaphosphate

Polymer

Well Water (During summer)

CO2

Lime

Well Water (during winter)

CO2

Covered Reservoir Distribution 

System

Fluoride and 

Ammonia

NaOCl 

NaOH

Ozone

Biofiltration Operations

 The filter consists of 18 inches of GAC and 6 inches of sand. The filtration rate varies 

from 0.76 to 3.0 gpm/ft2

. The empty bed contact time (EBCT) of the GAC is 3.7 minutes at 

design flow and 7.4 minutes at typical flow. Filter backwash frequency is governed by: (a) 

effluent turbidity exceeding 0.2 nephelometric turbidity units (NTU), (b) number of hours in 

service (usually 80 hours is the cut-off point), and (c) acceptable headloss limits (which is 

usually not a controlling criterion). The backwash is performed using finished chloraminated 

water.

Results of the Steps Taken 

x DBP reductions - Exhibit B.22 shows the TTHM and HAA5 concentrations before 

and after the modifications at the Ann Arbor plant. Clearly, ozonation resulted in a 

significant drop in TTHM and HAA5 concentrations, resulting in no compliance 

problems with the Stage 1 and Stage 2 DBPRs; 

x Bromate formation - Ozonation can oxidize bromide to bromate, which is regulated 

by the Stage 1 DBPR at an MCL of 10 )g/L. Influent bromide concentrations at the 

ozonation plant ranged from 27 to 80 )g/L, with an average of 67 )g/L. The well 

contributes more to the bromide levels than the river water. The average bromide 

concentration in the ground water is 100 )g/L, and the Huron River water has an 

average bromide concentration of 59 )g/L. The bromate levels in the finished water 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-63 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ranged from 2 to 8 )g/L, with an average of 3 )g/L. At its current level of bromate 

formation, Ann Arbor meets the bromate MCL; and 

x TOC removal - The average influent TOC to the plant after the modifications was 5.5 

mg/L (with a range of 4.5-7.0 mg/L). The average effluent TOC was 2.7 mg/L (with 

a range of 2.1-3.4 mg/L). Therefore, TOC removal ranged from 40 to 59 percent with 

an average of 51 percent, which is quite similar to the TOC removals achieved before 

implementing ozonation. The Stage 1 D/DBPR TOC removal requirements for 

softening plants with an influent TOC >4.0-8.0 or >8.0 mg/L are 25 and 30 percent, 

respectively (USEPA 1998a). The Ann Arbor plant exceeds these requirements. 

Higher TOC removal has the advantage of lowering the ozone dose requirements 

because the ozone applied is not used up by reactions with TOC. 

Exhibit B.22 DBP Formation Before and After Ozonation at Ann Arbor 

DBPs Before Modification1 After Modifications2

TTHM ()g/L)

Minimum

Average

Maximum

14

24

39

1.4

7.2

13

HAA5 ()g/L)

Minimum

Average

Maximum

4.2

16

21

1.5

5.0

15

Bromate 

()g/L)

Minimum

Average

Maximum

2

3 or 43

8

Notes:

1. Monthly TTHM data collected between July 1994 and June 1995; other DBP data collected quarterly between 

October 1995 and May 1996. 

2. Data collected in calendar year 1997; based on monthly or quarterly data. 

3. Depending on whether the non-detects were set to zero or half the minimum detection level.

Implementation and Operational Issues Faced by the Utility 

x Operator training and start-up - It took about 2 to 3 months for the operational staff to 

be at ease with the new technology, and about 3 to 5 months for the plant to operate 

optimally and smoothly. The change in treatment also changed the operational needs 

of the plant; additional mechanics and instrumentation technicians were needed. 

Additional resources had to be allocated to treatment operation and maintenance; 

x Sludge accumulation over diffusers - This caused fluctuating ozone residuals, 

resulting in difficulty obtaining the required CT. The plant has been testing various 

chemicals to improve secondary settling to reduce the impact of the sludge on the 

ozone system; 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-64 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

x Liquid Oxygen (LOX) vaporizers did not defrost well in winters, causing the system 

to shut down due to low gas flow; and 

x Optimizing biofiltration during winters - Extremely large seasonal fluctuations in 

temperature have strongly governed treatment strategy at the Ann Arbor plant.

Average monthly river water temperature in 1997 ranged from 7.9 to 22oC, with an 

average of 14o

C. The lowest temperature in winter during the sampling period was 

3o

C. Well water temperatures are fairly constant at 14oC. After ozonation and 

biofiltration, AOC content ranged from 40 to 210 )g C/L (average = 129 )g C/L).

During the summer, approximately 40 percent of AOC produced by ozonation was 

removed during biofiltration, whereas in winter there was practically no removal.

This suggests poor biological activity on the filters in winter months. Ann Arbor 

raises the temperature of the influent water in winter by mixing in a larger proportion 

of ground water (24-29 percent versus 10-20 percent in the summer). It also 

introduces well water at the head of the plant in winter to increase the water 

temperature so that treatment processes like biofiltration are more effective. 

Lessons Learned From this Case Study

x Ozonation requires a high degree of operational expertise. The key to running a 

successful ozonation treatment unit depends greatly on the operator being 

comfortable with the new instrumentation and controls; 

x Ozonation may not be suitable for influent waters with high bromide concentrations; 

and

x Ozonation increases the AOC concentration in finished water. As a result, 

biofiltration is required downstream of ozonation to ensure AOC removal and reduce 

the opportunity for microbial regrowth in the distribution system. Failure to do so 

may result in TCR violations. Biofiltration needs careful monitoring and 

optimization, especially during winter when microbial activity is greatly reduced. 

One operational strategy is to increase the proportion of ground water in the influent 

surface/ground water blend during winter to ensure that treated water has a higher 

temperature. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-65 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #11

Ozonation and Biological Filtration

Sweeney Water Treatment Plant 

Wilmington, North Carolina

 This case study provides an example of a water system that upgraded its treatment plant 

by expanding its capacity from 15 MGD to 25 MGD and installing ozonation and biological 

filtration to improve compliance with IESWTR and LT2ESWTR regulations and to increase 

aesthetics and customer confidence. 

 The majority of the information for this case study was found in Najm et al., (2005). For 

more information on the Sweeney Water Treatment Plant, please refer to Kennedy et al. (2004).

Introduction

 Sweeney Water Treatment Plant (SWTP) is owned and operated by the City of 

Wilmington, NC. SWTP uses the Cape Fear River water as its source water, which has high 

organic content, high color, and low turbidity. The source water also contains iron and 

manganese that can cause aesthetic issues in the finished water. A summary of the source water 

quality as received at the SWTP is provided in Exhibit B.23. 

Exhibit B.23 Cape Fear River Water Quality 

(as received at the SWTP)

Water Quality Parameter (Unit) Average Minimum Maximum

TOC (mg/L) 5.6 4.8 8.3 

DOC (mg/L) 5.4 4.6 7.6 

Filtered UV-254 Abs. (cm-1) 0.218 0.123 0.337 

Specific ultraviolet absorbance (SUVA) 

(L/(mg-m)) 

4.0 2.7 4.4 

Color (PCU) 46 25 76 

Alkalinity (mg/L as CaCO3) 25 16 30 

pH 6.5 5.8 6.8 

Turbidity (NTU) 16 3.5 73 

Temperature (oC) 20 11 28 

Source: Adapted from Najm, et al., 2005 

Note: Data collected between Oct. 2001 - July 2002
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-66 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 The treatment train for the SWTP is shown schematically in Exhibit B.24 below. The 

capacity of the SWTP is 25 MGD, and consists of the following two treatment trains: 

South Plant (15 MGD) 

x Coagulation

x Flocculation 

x Sedimentation train 

x Intermediate ozonation 

x Dual-media GAC/sand filtration 

North Plant (10 MGD) 

x Coagulation

x High rate clarification (SuperPulsator) 

x Intermediate ozonation 

x Dual-media GAC/sand filtration 

 Source water first undergoes pre-ozonation and is then split between the North and South 

Plants, where the alkalinity is raised by adding caustic and/or lime. During the rapid mix step of 

each treatment train, alum and cationic polymer are added. Primary disinfection requirements of 

0.5-log Giardia removal and 2-log virus inactivation are satisfied via the intermediate ozonation 

step. After undergoing filtration, the treated waters from the South Plant and North Plant are 

joined and caustic and/or lime, chlorine, phosphate, and fluoride are added to the combined filter 

effluent (CFE) before the water enters the clearwell. Finally, the effluent of the SWTP’s 

clearwell receives additional chlorination prior to entering the distribution system. 

Exhibit B.24 Schematic of SWTP 

Source: Najm, et al., 2005 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-67 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Simultaneous Compliance Issue Faced by the Utility

 The City of Wilmington upgraded its facility for the following reasons: 

x To better accommodate future population growth; 

x To comply with LT2ESWTR regulations by providing Cryptosporidium inactivation; 

and

x To improve aesthetics and customer confidence. 

 Application of ozone also lowers the formation of TTHM and HAA5. However, 

ozonation could lead to an increase in the AOC levels in the finished water, resulting in potential 

microbial regrowth in the distribution system and non-compliance with the TCR. Biofiltration 

was used to remove AOC before the water entered the distribution system. 

Steps Taken by the Utility

 Changes made to the original treatment train of the SWTP are outlined below. 

x The North Plant (10 MGD facility) was constructed to be operated simultaneously 

with the existing South Plant (15 MGD); 

x An ozone generation and dissolution facility was constructed; 

x New pretreatment facilities were built for coagulation; 

x 12 sand/anthracite filters were converted to biofilters by the use of deep bed dual 

media with gravel support and GAC; and 

x A SCADA system to monitor/control all processes and equipment in the facility was 

installed. 

 Ozonation and biological filtration began at the SWTP in March, 1998. Details of the 

two processes are provided below. 

Ozonation Details

 SWTP has two application points for ozone. First, in pre-ozonation, ozone is applied 

prior to coagulation, at doses between 3-7 mg/L. In intermediate ozonation, ozone is applied 

again to settled water at doses between 0.75 - 4.0 mg/L before the water undergoes biological 

filtration. The ozonation system at the SWTP uses a maximum of 1380 lbs ozone/day. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-68 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Biofiltration Details

 Specifications for the four new biological filters in the North Plant are as follows: 

x Support Gravel - 3" 

x Silica Sand - 15" 

x GAC - 48" 

 Specifications for the 12 existing filters in the South Plant which were converted to 

biological filtration are as follows: 

x Support Gravel - 12" 

x Silica Sand - 6" 

x GAC - 21" 

 Finished water from the SWTP’s storage reservoir is used to backwash the biological 

filters at both the North and South Plants. At the North Plant, the filters undergo air scouring 

prior to backwash, and at the South Plant, the filters use surface sweeps prior to backwash. 

Results of the Steps Taken

 After the upgrades made at the SWTP, the following water quality improvements have 

been observed. 

x TOC reduction from raw water to settled water has been observed, and additional 

TOC reduction has been observed as result of the biological filtration. Finished water 

TOC levels have been reduced to 2.0 - 2.5 mg/L; 

x TTHM levels have decreased to 60 Pg/L (typical level); 

x HAA5 levels have decreased from 48.5 Pg/L (based on 1997 values) to 21.37 Pg/L

(based on 1999 values); 

x Iron levels have been reduced from 0.9 mg/L (maximum level in source water) to less 

than 0.020 mg/L (finished water); and 

x Manganese levels have been reduced from 0.06 - 4.0 mg/L (range of typical to 

maximum levels in source water) to less than 0.01 mg/L (finished water). 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-69 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Implementation and Operational Issues Faced by the Utility

 The SWTP switched from disinfection with chlorine/chlorine dioxide to ozone. Although 

no specific issues were described for the SWTP, the following general issues are relevant to 

switching to disinfection with ozone. 

x Increased costs (due to liquid oxygen, electricity, and higher O&M costs); 

x Use of ozone requires a higher level of technical skill from the operators; therefore, 

increased training may be required; and 

x Since ozonation could lead to an increase in the AOC levels in the finished water, 

biofiltration should be implemented to remove the additional AOC.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-70 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-71 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #12 

Ultraviolet Disinfection

Poughkeepsie Water Treatment Facility 

Poughkeepsie, New York 

 This case study provides an example of a water system that installed ultraviolet light 

(UV) to meet DBP requirements while maintaining compliance with SWTR and IESWTR 

requirements. By switching to UV, the system also facilitated compliance with the LT2ESWTR 

requirements for Cryptosporidium inactivation. 

 The information for this case study comes from interviews with water treatment plant 

staff (Alstadt 2005, Lill 2005) and from the plant’s Web site at http://www.pokwater.com.

Readers are also encouraged to refer to the Ultraviolet Disinfection Guidance Manual for the 

Final Long Term 2 Enhanced Surface Water Treatment Rule (USEPA 2006b) for information on 

UV sensor calibration procedures and practices. 

Introduction

 Poughkeepsie’s Water Treatment Facility (PWTF) is a surface water treatment plant 

located in Poughkeepsie, New York. The plant uses the Hudson River as a source and has a 

capacity of 16 MGD. In March 2002 the system began a series of improvements to the plant to 

increase its rated capacity, ensure continued compliance with existing regulations, and prepare 

for expected future regulations. In the second quarter of 2003 (May 1 through July 31) the 

PWTF incurred a violation for exceeding the MCL for HAA5. The system has been in 

compliance with the MCLs for both HAA5 and TTHM since that date and is completing 

modifications, including installing UV, to prevent another exceedance. 

 PWTF is a conventional surface water treatment plant with rapid mix, followed by three 

parallel trains, each with a solids contact tank and sedimentation followed by filtration. The 

plant has a total of six filters. An equalization basin succeeds the filters with orthophosphoric 

acid added in the first half and sodium hydroxide added in the second half. Chlorine is added in 

the sedimentation basins and again just before the water leaves the treatment plant to maintain a 

residual in the distribution system. 

Simultaneous Compliance Issues Faced by the Utility

 The primary issue faced by the system was the need to reduce DBPs. However, in doing 

so, the system needed to ensure that it could maintain a high enough CT to ensure compliance 

with the requirements for Giardia and viruses. In addition, the LT2ESWTR was expected to 

contain new requirements for Cryptosporidium inactivation. The system needed to consider how 

any modifications made to address DBPs could impact the system's ability to meet these other 

requirements.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-72 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Steps Taken by the Utility

 In order to reduce DBPs, the system proposed moving the point of disinfection from the 

sedimentation basins to just prior to the filters, after more DBP precursors have been removed. 

However, in doing so, the system would lose some disinfection contact time. In order to 

maintain the necessary CT, the system needed to add an additional contact basin after the filters. 

Due to space limitations, constructing a contact basin large enough to maintain CT was not 

feasible. Therefore, the system chose to install UV after each filter to provide additional CT and 

meet space requirements. In addition, UV does not produce any DBPs, so installing UV rather 

than additional chlorine contact time after the filters would further reduce the system's TTHM 

and HAA5 levels. The UV installation and all associated modifications have been completed. 

 An additional benefit of installing UV at the PWTF is that UV has been shown to be an 

effective technology for inactivating Cryptosporidium at a low dose. The use of UV at PWTF 

should enable the system to meet the Cryptosporidium inactivation requirements under the 

LT2ESWTR.

 PWTF is now planning to switch from chlorine to chloramines for secondary disinfection 

to further reduce DBPs in the distribution system. The system will continue to use chlorine and 

UV as primary disinfectants, but will begin adding ammonia after the equalization basin to form 

chloramines. The system expects to begin using chloramines in 2006 after a new flushing 

program has been implemented. 

Expected Results of the Steps Taken

 Bench-scale pilot testing indicated that installing UV would reduce TTHM and HAA5 by 

20 percent. Pilot testing also showed that addition of chloramines will reduce DBPs by another 

80 percent. The UV installation is expected to provide 3-log inactivation of Giardia and 

Cryptosporidium, which will ensure that the system maintains compliance with the Giardia 

inactivation requirements under the IESWTR. In addition, the system should be able to meet the 

requirements for Cryptosporidium under the LT2ESWTR. Because UV is less effective against 

some kinds of viruses, the system expects that it will need to achieve 1 log of virus inactivation 

through chlorination after the UV units. The system will meet this requirement with the existing 

equalization basin. 

Implementation and Operational Issues Faced by the Utility

 One of the biggest issues for the PWTF staff during the modifications was learning to 

operate and maintain the UV system. PWTF found that operating a UV system is very different 

from operating a chemical disinfection system. It is a fairly simple process to determine when a 

chemical disinfection system is operating properly because the residual can be easily measured 

with a grab sample. Determining how effectively a UV unit is working is much more complex 

because there is no measurable residual in the water. In order to determine the UV dose received 

by organisms in the water, the operator needs to know the intensity delivered by the UV bulbs 

and the transmittance of the water. The UV reactor contains an array of sensors that are used to 

determine the intensity and the readings among the sensors can vary significantly, making it 

difficult to determine which are correct. PWTF staff had problems with many of the intensity 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-73 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

sensors in their UV chambers and had to have them replaced. They also had problems with the 

transmittance meter. These problems had not been resolved as of Fall 2005. 

 Obtaining appropriate training was also an issue for the system. Although the 

manufacturer provided some training, the water treatment plant staff had not yet worked with the 

UV system and were unable to communicate specific training needs to the manufacturer. 

Therefore, the plant staff found that many operational and maintenance issues arose during 

installation and testing that were not addressed during training. 

 Programming the UV system and integrating it into plant controls was difficult. The 

water treatment plant would have to be shut down if the UV system failed and the control system 

would need to be programmed to do so. In addition, the UV units require 10 minutes to cool 

down before shutdown to avoid damage to the UV units. Therefore, PWTF had to install a UPS 

to hold the power for the UV units for 10 minutes in the event of a power failure. Trying to 

consider all possible scenarios and how to react to and program them was a complicated process. 

 Large UV systems require a significant amount of power, particularly at high doses. The 

UV units at PWTF have all been successfully started up and the system is receiving one (1) log 

inactivation credit for the UV although the primary disinfectant application point has not yet 

been moved. With all UV units running, PWTF observed a 20 percent increase in power 

utilization, which significantly increased the plant's power costs. The new UV system also led to 

increased maintenance time and costs. The UV system has many components, such as sensors 

and bulbs, which require periodic replacement. In addition, the monitoring equipment must be 

calibrated regularly. 

Lessons Learned From this Case Study

x UV disinfection is very different from chemical disinfection. It is important that 

operators undergo training and have continued access to knowledgeable 

representatives from the manufacturer during installation and start-up of this 

technology to allow them to become comfortable with the new instrumentation and 

controls; and 

x UV is an effective technology both for reducing DBPs and inactivating Giardia and 

Cryptosporidium. However, it also consumes much more electricity than chlorination 

or chloramination. Therefore, it is important to consider the availability of electricity 

and the financial impact of increased power usage before installing UV. 

References

 Alstadt, R. 2005. Personal Communication. 

 Lill, P. 2005. Personal Communication.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-74 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

This page intentionally left blank. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-75 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #13

Chlorine Dioxide for Primary Disinfection and Chloramines for Secondary 

Disinfection

Gulf Coast Water Authority 

Texas City, TX 

 This case study provides an example of a water treatment plant with high influent TOC, 

high bromide, warm water temperatures, and long residence times in the distribution system that 

converted to chlorine dioxide as a primary disinfectant and chloramines as a secondary 

disinfectant to reduce the formation of chlorinated DBPs. 

 The information for this case study was obtained primarily from Krasner et al. (2003).

Readers should refer to that text for more detailed information. 

Introduction

 The Gulf Coast Water Authority (GCWA), which has been operating since 1981, 

operates the Thomas S. Mackey WTP from which treated water is wholesaled to seven 

municipalities between Houston and Galveston, TX. All of the systems served by GCWA 

conduct their own distribution system monitoring for regulatory compliance. Approximately 

92,000 people are served by the GCWA in the seven municipalities. Additionally, raw water is 

pumped to industry and treated water is provided to the City of Houston via pipeline between 

Houston and Galveston. 

 The current rated capacity of the Thomas S. Mackey WTP is 25 MGD, with approximate 

average and maximum flows of 12 and 20 MGD, respectively. 

 GCWA uses the Brazos River as their source water, which has moderate to high levels of 

TOC, hardness, alkalinity, and bromide. 

 A summary of the influent water quality to the GCWA is provided in Exhibit B.25. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-76 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.25 Water Quality at GCWA 

Water Quality Parameter Influent Concentration

Turbidity (NTU) ~ 35 (median) 

Hardness (mg/L as CaCO3) 190 (median) 

pH 8.25 (median) 

Alkalinity (mg/L as CaCO3) 135 (median) 

TOC (mg/L) 4.7 (median) 

Bromide (mg/L) up to 0.3 

The Original Treatment Process at the Gulf Coast Water Authority

 Before treatment changes were made at the Thomas S. Mackey WTP, free chlorine was 

used as a primary disinfectant. The treatment train consisted of the following: 

x Raw water pumping 

x Chemical addition (including lime softening) 

x Upflow solids contact/clarification 

x Recarbonation

x Filtration 

x Disinfection (with free chlorine) 

x Finished water pumping 

 The Brazos River has moderate to high concentrations of TOC, as well as high bromide 

concentrations. The Thomas S. Mackey WTP was using chlorine as a disinfectant; therefore, 

GCWA was facing the challenge of controlling formation of chlorinated and brominated DBPs. 

Under these conditions, TTHM formation was ranging up to 350 Pg/L, and TTHM formation 

potential (TTHMFP) concentrations were ranging between 800 and 1000 Pg/L. These concerns 

were the main reasons that GCWA changed their disinfection strategy from chlorine to chlorine 

dioxide.

Simultaneous Compliance Issues Faced by the Utility

 Disinfection with chlorine dioxide raised the following compliance issues for GCWA: 

x Ensuring that the system was in compliance with SWTR and IESWTR under all 

operating conditions; 

x Ensuring that the Stage 1 DBPR TTHM MCL of 80 Pg/L and HAA5 MCL of 60 

Pg/L were not exceeded; and 

x Ensuring that the Stage 1 DBPR chlorine dioxide MRDL of 0.8 mg/L and the chlorite 

MCL of 1.0 mg/L were not exceeded. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-77 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 Note, at the time of the treatment train modifications, the plant was initially operating to 

comply with a TTHM MCL of 100 Pg/L and limiting the use of chlorine dioxide to make sure 

the sum of chlorine dioxide, chlorite, and chlorate did not exceed 1 mg/L. 

Steps Taken by the Utility

 GCWA conducted eight phases of research before a final decision was made to use 

chlorine dioxide as both a primary and secondary disinfectant. Exhibit B.26 show the various 

disinfection strategies implemented at GCWA during the eight phases. 

Exhibit B.26 Disinfection Strategies implemented at GCWA 

Phase Dates Primary Disinfectant Secondary Disinfectant

1 Prior to 11/83 Chlorine chlorine 

2 11/83 Chloramines chloramines 

3 12/83 - 4/84 Chloramines chlorine4

4 5/84 - 2/85 chlorine dioxide chlorine 

5 3/85 - 4/85 chlorine dioxide chlorine dioxide 

6 5/85 - 11/85 chlorine dioxide chlorine dioxide/chlorine 

7 12/85 - SWTR1 chlorine dioxide chlorine dioxide/ 

chloramines 

8 SWTR - 2003 chlorine dioxide2/chlorine 

dioxide3

chloramines 

Source: Adapted from Krasner et al., 2003. 

Notes:

1

 Disinfection scheme changed after SWTR promulgation 

2

 Chlorine dioxide used intermittently as a pre-oxidant in raw water 

3

 Chlorine dioxide used as primary disinfectant following filtration 

4

 Breakpoint chlorination used to achieve free chlorine residual in distribution system 

As shown in Exhibit B.26, the eight phases span more than 20 years. Following 

promulgation of SWTR, chlorine dioxide was used as a primary disinfectant, which was applied 

after filtration. Chloramines were used for secondary disinfection. Additionally, chlorine 

dioxide was also intermittently used as pre-oxidant, which was applied to the raw water. 

 A process schematic of the treatment train at the Thomas S. Mackey WTP after changes 

were made is provided in Exhibit B.27. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-78 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.27 Schematic of Thomas S. Mackey WTP Treatment TrainAfter Changes 

Were Made

Source: Krasner et al., 2003.

Results of the Steps Taken

 During the disinfection scheme used in phase 8, TTHM concentrations decreased 

significantly from above 300 Pg/L when free chlorine was used as the disinfectant. Disinfection 

with chlorine dioxide, followed by residual disinfection with chloramines, decreased TTHM 

concentrations in the GCWA system by approximately 80 percent, to 50 - 70 Pg/L.

 Stage 1 DBPR set a chlorine dioxide MRDL of 0.8 mg/L and a chlorite MCL of 1.0 

mg/L. GCWA is in compliance with these requirements. GCWA applies a chlorine dioxide 

dose of 0.75 mg/L and, as shown in Exhibit B.28, the chlorite concentration in the treated water 

is 0.5 mg/L. However, the chlorine dioxide dose applied is not high enough to obtain any CT log 

removal credit under LT2ESWTR. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-79 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 The GCWA treated water quality after modifications were made to disinfection is 

summarized in Exhibit B.28. 

Exhibit B.28 Treated Water Quality at GCWA 

Water Quality Parameter Concentration

Turbidity (NTU) 0.14 (median) 

Hardness (mg/L as CaCO3) 185 (median) 

pH 7.63 (median) 

Alkalinity (mg/L as CaCO3) 120 (median) 

TOC (mg/L) 2.9 (median) 

Bromide (mg/L) 0.11 (median) 

TTHM (mg/L)

Finished water (clearwell effluent) 

Customers’ distribution system 

36 - 58 

50 - 70, (RAA = 55) 

Chlorite (mg/L) 0.5 (median) 

Chlorate (mg/L) 0.18 (median) 

Note: Based on data collected between January 1996 - November 1997. Partial lime softening was 

discontinued in 1994.

Implementation and Operational Issues Faced by the Utility

 Because chlorine dioxide was a new technology at the time GCWA was considering 

switching disinfectants, they were faced with some technical questions and challenges in the 

implementation of chlorine dioxide as their primary disinfectant. Most of the technical issues 

concerned distribution system water quality, and therefore there was need for a full-scale plant 

study. The main technical issues faced by GCWA are summarized below: 

x Effectiveness of disinfection with chlorine dioxide 

x Microbial side effects in distribution system 

x Production of chlorite as a byproduct of chlorine dioxide generation 

x Taste and odor issues related to disinfection with chlorine dioxide 

Lessons Learned From this Case Study

x Use of chlorine dioxide can help a system comply with TTHM and HAA5 MCLs; and 

x Systems may have trouble providing sufficient Cryptosporidium inactivation to 

satisfy LT2ESWTR toolbox requirements and still meet the chlorine dioxide MRDL 

and chlorite MCL. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-80 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-81 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Case Study #14

Chlorine Dioxide for Primary Disinfection and Chloramines

for Residual Disinfection 

Village of Waterloo Water Treatment Plant 

Waterloo, New York

 This case study provides an example of a small surface water system that successfully 

converted from using chlorine as its primary and residual disinfectant to using chlorine dioxide 

for primary disinfection and chloramines for residual disinfection. By switching disinfectants, 

the Village of Waterloo improved its ability to comply with Stage 1 DBPR and Stage 2 DBPR 

requirements, added protection against Cryptosporidium, and improved the system’s ability to 

maintain a disinfectant residual throughout its distribution system. The narrative for this case 

study borrows from Gell and Bromka (2003). Readers should refer to this paper for more 

information about the changes made to Waterloo’s system. 

Introduction

 The Village of Waterloo operates a diatomaceous earth (DE) filtration plant that draws 

water from Seneca Lake in central New York. The original treatment plant design provides a 

nominal capacity of 2 million gallons per day (MGD), but the system plans to expand its service 

to neighboring areas. The system currently serves fewer than 10,000 people, but covers a large 

geographical area. 

 The DE filtration produces a low turbidity finished water (usually <0.2 NTU) but does 

not significantly reduce concentrations of DBP precursors. When chlorine was used, DBPs 

leaving the plant were generally low but increased to levels close to or above the TTHM MCL.

The high DBP levels resulted because the distribution system is sufficiently large and retention 

time sufficiently long that chlorine, NOM, and bromide in the water had several days to react 

with each other and form high TTHM concentrations. 

 A summary of Seneca Lake raw water quality is provided in Exhibit B.29. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-82 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit B.29 Seneca Lake Raw Water Quality 

Water Quality Parameter Average Observed Range

pH 8.1 7.7 - 8.3 

total alkalinity (mg/L as CaCO3) 84 69 - 119 

total hardness (mg/L as CaCO3) 145 107 - 158 

bromide (mg Br-/L) 0.32 0.28 - 0.50 

turbidity (NTU) 0.63 0.21 - 2.21 

TOC (mg C/L) 2.74 2.1 - 4.0 

DOC (mg C/L) 2.51 1.7 - 3.2 

SUVA (L/mg-m) 1.20 0.63 - 3.13 

chlorine demand1 (mg Cl2/L) 1.24 0.35 - 3.50 

Adapted from Gell, R. and Bromka, 2003.

1 Timeframe for the chlorine demand is 1.5 to 2 hours, depending on how much water is being pumped by the 

system.

 Moderate bromide concentrations in the raw water were causing predominantly 

brominated THMs to be formed in the finished water. A 1998 survey of distribution system 

samples showed an average TTHM concentration of 79 )g/L and an average HAA5 

concentration of 21 )g/L. TTHM concentrations ranged from 48 to 150 )g/L, with 

approximately 75 percent of the TTHM being brominated compounds. 

 At the same time when the Waterloo system was considering treatment modifications to 

improve water quality, the system was receiving requests from neighboring areas to expand its 

service area. As a result, modifications made at the treatment plant included upgrades to 

increase capacity as well as improve water quality. 

The Original Treatment Process at the Waterloo WTP

 The Village had added potassium permanganate consistently, and PAC/permanganate 

seasonally, to control zebra mussel growth and taste and odor problems. These were fairly 

effective at controlling seasonal taste and odor problems, but the Village operators were 

interested in improving taste and odor treatment for more consistent control. 

 Chlorine had previously been added after the DE filters and before water entered the 

clearwell in order to achieve sufficient Giardia and virus CT. Chlorine was added again at 

booster stations in order to maintain a sufficient disinfectant residual throughout

the distribution system. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-83 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Simultaneous Compliance Issues Faced by the Utility

 The Village of Waterloo faced problems complying with both the Stage 1 D/DBPR and 

the Stage 2 DBPR due to high TTHM concentrations in its distribution system. It was having 

trouble maintaining a disinfectant residual throughout the distribution system, which is a 

requirement of the SWTR. 

 At the same time that the Stage 1 DBPR requirements were introduced, the IESWTR and 

the LT1ESWTR introduced requirements for the removal of Cryptosporidium. Although DE 

filtration is not effective at removing DBP precursors, the Village of Waterloo wanted to keep its 

DE filters in use because of their simplicity and performance for Cryptosporidium removal. The 

Village has been monitoring their raw water for Cryptosporidium for several years, and no 

oocysts have been detected. 

Steps Taken by the Utility

 A pilot study helped the Village realize that installing treatment to remove DBP 

precursors would not be efficient, because of the low SUVA concentrations in Seneca Lake’s 

water. Since the system uses DE for its filtration step, enhanced coagulation would have 

required significant modifications to the current filtration process. Moreover, the Waterloo 

treatment plant’s lakefront location limited options for the disposal of waste streams that would 

have been generated by many of the DBP precursor removal options. 

 Simulated distribution system testing showed that TTHM and HAA5 concentrations 

could be lowered significantly if the system changed its residual disinfectant from chlorine to 

chloramines. This discovery enabled the system to keep its existing DE filtration process by 

opting for an alternative disinfection strategy. 

 In addition, by changing its primary disinfectant from chlorine to chlorine dioxide, the 

Village could simplify its operations by eliminating the use of potassium permanganate for zebra 

mussel and taste and odor control. Chlorine dioxide is now injected at the intake structure. 

Furthermore, changing primary disinfectant from chlorine to chlorine dioxide has enabled a 

smaller clearwell expansion, which has reduced the amount of expensive lakefront real estate 

needed by the treatment plant. 

 Chlorine dioxide is added to the intake and maintains a residual throughout the clearwell.

Anhydrous ammonia is added immediately after the clearwell into the discharge pipe before 

water is pumped into the distribution system. A few yards downstream of the ammonia addition 

point, chlorine gas is injected. Bench scale tests determined the optimum ammonia and chlorine 

dosages to maintain a total chlorine residual of 2.0 mg/L over several days. 

 Before converting from free chlorine to chloramines, the Village, with assistance from its 

consultants, conducted a thorough and successful public notification campaign to inform users of 

the potential adverse impact of chloramines consumption (primarily for dialysis patients and fish 

owners). The Village hosted public meetings, placed newspaper articles, and issued notifications 

that provided the important information. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-84 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Results of the Steps Taken

 The reductions in TTHM and HAA5 concentrations after the system switched to chlorine 

dioxide and chloramines exceeded the Water Manager’s expectations. In 2002, THM levels 

were mostly below their detection levels, with one TTHM measurement of 2.1 )g/L in August at 

the farthest sampling location. HAA5 concentrations in 2002 averaged 8 )g/L. The total 

chlorine residual has been maintained throughout the distribution system without the use of rechlorination stations. 

 The chlorine dioxide dosage ranges from 0.4 to 1.00 mg/L, depending on water 

temperature. Distribution system chlorite concentrations range from 0.25 to 0.45 mg/L. 

 The Village has not experienced any uncontrollable re-growth episodes, but uses a 

carefully monitored program to address the potential for nitrification and biological re-growth.

As part of this effort, the Village adheres to the following guidelines: 

x Maintain a high chlorine to ammonia weight ratio (5:1) at the time when the 

chloramines are formed; 

x Maintain a finished water total chlorine residual of 2 mg/L and a residual of at least 

1.0 mg/L throughout the distribution system; 

x Take advantage of the possibility that chlorite, a byproduct of chlorine dioxide 

disinfection, may be toxic to nitrifying bacteria; 

x Monitor monthly for HPC, nitrite, chlorite, free, and total ammonia at each storage 

tank and at key points in the distribution system; and 

x Routinely check the percentage of monochloramine in the total chlorine present. Aim 

to have at least 95 percent monochloramine leaving the treatment plant. 

 Since switching disinfectants, the Village has observed two occasions when HPC 

numbers increased, and traced the cause of these events to stagnation in a remote storage tank. 

Sodium hypochlorite was added to the tank and HPC levels returned to normal. Plans are being 

developed to improve mixing in the tanks. 

 The Water Director believes that previously bothersome taste and odor problems are 

being controlled more effectively by using chlorine dioxide. He also believes that the use of 

chloramines following chlorine dioxide has prevented the development of nuisance odors 

associated with chlorine dioxide in households (see Hoehn et al., 1990). 

Implementation and Operational Issues Faced by the Utility

 The Village encountered an operational problem when it first converted to chloramines. 

Ammonia reacts with calcium and magnesium hardness in the water and produces a scale, even 

when hardness values are as low as 35 mg/L as CaCO3. As a result, scaling was clogging the 

injector throat of the ammonia feed system. Since a water softening unit was installed to treat 

the water that is used for injection, the ammonia feed system has functioned reliably. 
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-85 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 The Village has a service contract with the company that provided the chlorine dioxide 

equipment to supply sodium chlorite and monitor and verify the performance of the generator.

This contract has provided the Village with sufficient time to educate its staff on proper 

equipment operation. 

Further Reading

Readers who are interested in learning more about the Village of Waterloo system should refer to 

the following paper: 

Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage 

Disinfection By-Products. New York State Section AWWA. New York: O’Brien and 

Gere.
Appendix B. Case Studies 

Simultaneous Compliance Guidance Manual B-86 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix C 

 Guidance for Evaluating Potential Impacts of Treatment Changes on 

Distribution Systems
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Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Appendix C 

 Guidance for Evaluating Potential Impacts of Treatment Changes on 

Distribution Systems

 This appendix is designed to accompany the guidance manual and provides a starting 

point for examining issues that might arise in the distribution system as a result of treatment 

changes. Water systems are encouraged to use this document to identify potential issues for their 

system and possible solutions to those issues. This guidance manual and its appendices, however, 

are not intended to provide comprehensive technical guidance for systems making regulatory 

compliance decisions and treatment modifications. Each state may have its own rules and 

regulations pertaining to treatment modifications. Systems should contact their state primacy 

agency or EPA regional office for more information. 

 The table below lists treatment changes that could potentially impact the distribution 

system and page numbers in this appendix where the potential impacts of particular treatment 

changes are discussed. A list of references is also included for each distribution system impact. 

Treatment Change See Appendix Page

Modifying pH C-2 

Change in finished water alkalinity C-7 

Change in finished water oxidation/reduction potential C-10 

Switching from chlorine to chloramines C-11 

Switching coagulant C-15 

Modifying chlorine dose with warmer water temperatures C-17 

Adding/discontinuing softening C-18 

Adding ozone C-22 

Adding chlorine dioxide C-25 

Enhanced coagulation C-28 

Installing nanofiltration C-30 

Installing granular activated carbon C-33 

Installing ozone without subsequent biological filtration C-34 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

MODIFYING pH 

 The following impacts to your distribution system may result from modifying pH: 

• Increased lead and copper in tap water 

• Change/disruption of scale 

• Colored water 

• High iron 

• Increased heterotrophic bacteria 

• Nitrite/nitrate formation 

• Change in DBP concentration/composition 

 References, along with brief descriptions of treatment impacts, are provided below. 

Refer to Section 3.4 for additional information on modifying pH during chlorination. 

Increased lead and copper in tap water

Description

As the pH of water decreases, the corrosion potential of the water increases. Therefore, a significant decrease in 

finished water pH may result in a significant increase in corrosion of distribution system pipes, resulting in 

increased concentrations of metals such as iron, copper, and lead in the water. In addition, if the pH of the water 

is too low, protective scales may be disrupted or unable to form on pipe surfaces. 

Further Reading

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• USEPA. 2000c. Lead and Copper Rule: Summary of Revisions. Office of Water. EPA 815-R-99-

020. 

• USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control Strategies. Office 

of Water. EPA 816-R-03-001. March, 2003.

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Change/disruption of scale

Description

When water is supersaturated with calcium carbonate, the calcium carbonate can precipitate in the distribution 

system and form a coating on pipes that protects against corrosion. The pH of the water plays a major role in the 

solubility of calcium carbonate. If the pH in the distribution system is too low, calcium carbonate becomes 

undersaturated, causing scales to change or become dislodged. Scales can also form in the distribution system 

from corrosion byproducts. Because corrosion (and subsequently formation of these scales) is partially dependent 

on pH, these scales can also be disrupted by changes in pH. 

Further Reading

• AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water Supplies. 5th

Edition. Letterman, R.D. (editor). 1,233 pp. New York: McGraw-Hill. 

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Colored water

Description

A decrease in pH can lead to increased corrosion and increased solubility of inorganics, which may result in 

increased iron and copper levels. A change in pH can also cause disruption of scales. Increased iron levels and 

disruption of scale containing iron corrosion byproducts can cause red water. Increased copper levels can cause 

blue or green water. 

Further Reading

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp. Denver: 

AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

High iron

Description

A decrease in pH can lead to increased corrosion and increased solubility of inorganics, which may result in 

increased iron levels when iron pipe is used. A change in pH can also cause disruption of scales. If the scales 

contain corrosion byproducts, the iron levels in the water can be further increased. 

Further Reading

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Increased heterotrophic bacteria

Description

Films and scales can build up on distribution system pipes and may contain microorganisms as well as inorganic 

contaminants and TOC. If the pH fluctuates below 7.0 in the distribution system, these scales may become 

dislodged. This would allow the release of the trapped microorganisms into the distribution system, thereby 

increasing their numbers in the water. 

Further Reading

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Nitrite/nitrate formation

Description

The optimum pH for nitrification to occur is between 7.5 and 8.5. If systems using chloramines make changes 

resulting in a finished water pH in this range, these systems may have problems with nitrification in the 

distribution system, causing increased levels of nitrite and nitrate. 

Further Reading

• Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan, and D. Van 

Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution System Nitrification.

AwwaRF Report 90949. Project #553. Denver: AwwaRF. 

• Kirmeyer, G.J., M. LeChevallier, H. Barbeau, K. Martel, G. Thompson, L. Radder, W. Klement, and 

A. Flores. 2004a. Optimizing Chloramine Treatment. 2nd Edition. AwwaRF Report 90993. Project 

#2760. Denver: AwwaRF. 

• Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, and R. Wolfe. 1995. Nitrification Occurrence 

and Control in Chloraminated Water Systems. AwwaRF Report 90669. Project #710. Denver: 

AwwaRF. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Cowman, G.A., and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation 

Resulting from Chlorination and Chloramination of Humic Extracts. In Proceedings of AWWA 

Annual Conference. New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp. Denver: 

AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Change in DBP concentration/composition

Description

Reducing the pH of the water may allow systems to use a lower chlorine concentration for disinfection, leading to 

less DBP formation. Since TTHMs generally show lower formation at lower pH, reducing the pH can also lead to 

lower TTHM levels. However, HAA5s generally show higher formation at lower pH, so the HAA5 levels may 

increase. 

Further Reading

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp. 

Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

CHANGE IN FINISHED WATER ALKALINITY

 The following impacts to your distribution system may result from changes in finished 

water alkalinity: 

• Increased lead and copper in tap water 

• Change/disruption of scale 

• Colored water 

• High iron 

• Pinhole leaks 

 The following reference can provide further information about how to address most of 

these impacts. Additional references and brief descriptions are listed by impact in the table 

below. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of 

Water Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. 

Denver: AwwaRF. 

 Refer to Sections 3.4 and 3.7 for additional information on changes in finished water 

alkalinity. 

Increased lead and copper in tap water

Description

When alkalinity is removed, the carbonate system must re-equilibrate, resulting in the production of the hydrogen 

ion. This in turn results in a lowering of the pH of the water. In addition, as alkalinity decreases, the buffering 

capacity of the water decreases, allowing the pH of the water to change more easily during treatment processes. 

However, when the alkalinity and pH are high, lead corrosion can also increase as a result of increased lead 

solubility and lead complexation with carbonate (AWWA 1999d). Therefore, both increases and decreases in 

finished water alkalinity can increase lead levels in tap water. Copper levels can also increase because 

bicarbonate is extremely aggressive toward copper (AWWA 1999d). 

Further Reading

• AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water Supplies. 5th

Edition. Letterman, R.D. (editor). New York: McGraw-Hill. 

• AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper Rule 

Corrosion Control Treatment. Denver: AWWA. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Change/disruption of scale

Description

Alkalinity is a measure of the carbonate and bicarbonate in water. When calcium ions combine with carbonate in 

water it can precipitate out to form a protective coating on pipes in the distribution system. If the alkalinity in the 

water is subsequently reduced, some of the calcium carbonate may re-dissolve in the water, disrupting the 

protective scale on the pipes, which can lead to increased corrosion or release of scales and corrosion by-products. 

Lowered alkalinity can also lead to increased leaching from cement/mortar lined pipes. In addition, when 

alkalinity is reduces, the pH in the water can fluctuate more easily. Fluctuations in pH can in turn disrupt scales 

in the distribution system. 

Further Reading

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill. 

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

• Douglas, B.D., and D.T. Merrill. 1991. Control of Water Quality Deterioration Caused by 

Corrosion of Cement-Mortar Pipe Linings. Denver: AwwaRF 

Colored water

Description

A decrease in alkalinity can result in a lowering of the pH of the water. The buffering capacity of the water also 

decreases, allowing the pH of the water to change more easily during treatment processes and in the distribution 

system. Decreased pH can lead to increased corrosion of iron pipe. In addition, decreased alkalinity can cause 

disruption of protective pipe scales, which can lead to further corrosion. Corrosion byproducts in the water can 

cause colored water problems. 

Further Reading

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition.278 pp. 

Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

High iron

Description

A decrease in alkalinity can result in a lowering of the pH of the water. The buffering capacity of the water also 

decreases, allowing the pH of the water to change more easily during treatment processes. Decreased pH can lead 

to increased corrosion of pipes. In addition, decreased alkalinity can cause disruption of protective pipe scales, 

which can lead to further corrosion. If iron pipe is present in the distribution system, increased corrosion can 

lead to higher iron levels in the water. 

Further Reading

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Pinhole leaks

Description

Changes in finished water alkalinity and resulting changes in pH can cause water to become more corrosive to 

copper piping, especially in the absence of corrosion inhibitors such as phosphate or NOM. 

Further Reading

• Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole leaks in 

residential plumbing. Water Science and Technology. 49(2): 83-90. 

• Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of American 

Water Works Association. 86(7): 74-91. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

CHANGE IN FINISHED WATER OXIDATION/REDUCTION POTENTIAL

 Oxidation/reduction potential (ORP) is the ability of the water to oxidize or reduce 

compounds it comes into contact with, and is measured electrochemically. If a treatment change 

causes a change in finished water ORP, you could possibly experience increased lead in tap 

water or a change or disruption of corrosion scales. 

 The following references can provide further information about how to address both of 

these impacts. Additional references and brief descriptions are listed by impact in the table 

below. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of 

Water Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. 

Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control 

in Distribution Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

 Refer to Section 5.1 for additional information on changes to finished water 

oxidation/reduction potential. 

Increased lead in tap water

Description 

Raising or lowering the ORP can affect the redox state of any corrosion products existing in passivating layers in 

the distribution system. As the solubility of lead changes with its redox state, this can lead to solublization of lead 

and its release into tap water. Ammonia and nitrate can increase leaching of lead from materials such as brass. 

Further Reading

• AWWA. 2004d. Proceedings of Workshop - Getting the Lead Out: Analysis & Treatment of 

Elevated Lead Levels in DC’s Drinking Water. San Antonio: WQTC. 

• Lytle, D.A. and M.R. Schock. 2005. The Formation of Pb(IV) Oxides in Chlorinated Water. 

Journal of American Water Works Association. 97(11):102. 

• Schock, M.R., K.G. Scheckel, M. DeSantis, and T.L. Gerke. 2005. Mode of Occurrence, Treatment 

and Monitoring Significance of Tetravalent Lead. In Proceedings of the AWWA Water Quality 

Technology Conference. Denver: AWWA. 

Change/disruption of scale

Description

Changing the ORP of the finished water will affect the oxidation/reduction equilibrium between the pipe surface 

and the water. Oxidation/reduction reactions may occur at the pipe surface to enable oxidation/reduction 

equilibrium to be achieved. If these reactions alter any passivating layers, dissolution and release of metals may 

occur. 

Further Reading

• AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper Rule 

Corrosion Control Treatment. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-11 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

SWITCHING FROM CHLORINE TO CHLORAMINES

 The following impacts to your distribution system may result from switching from 

chlorine to chloramines: 

• Increased lead in tap water 

• Change/disruption of scale 

• Taste and odor 

• Increased coliform bacteria 

• Increased heterotrophic bacteria 

• Nitrite/nitrate formation 

• Change in DBP concentration/composition 

 The following references can provide further information about how to address most of 

these impacts. Additional references and brief descriptions are listed by impact in the table 

below. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 

278 pp. Denver: AWWA. 

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-

R-99-014. 

 Refer to Section 5.1 for additional information on switching from chlorine to 

chloramines. 

Increased lead in tap water

Description

The use of chloramines can lead to nitrification in the distribution system. This in turn can lower the pH of the 

water and increase its corrosivity, causing increased levels of metals such as lead, copper, and iron in water in the 

distribution system. In addition, because chloramines have a lower oxidation potential than chlorine, switching 

from chlorine to chloramines is suspected to cause lead in pipes to change to a form that is more soluble. This can 

also increase the lead concentration in the water in the distribution system. 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-12 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Change/disruption of scale

Description

The use of chloramines can lead to nitrification in the distribution system. Nitrification can lower the pH of the 

water, causing disruption to scales formed from corrosion byproducts or protective scales, such as calcium 

carbonate. 

Further Reading

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Taste and odor

Description

Monochloramine is a preferred chlorine residual with regard to odor quality and customer perceptions. 

Dichloramine can add a more pungent, sharper chlorine-type odor to the water at lower levels such that some 

utilities have set a goal to keep the percentage dichloramine of the total combined chlorine residual below 20% 

(ref. Lines 11-12 page 7-6). Monochloramine is preferred over free chlorine as it takes a higher level to reach odor 

detection by customers, and changes in odor following changes in the residual are much less noticeable by 

customers. However, there have been reports of off-odors associated with nitrification, which could come from 

biological growth, loss of chloramine residual, and related conditions. 

Further Reading

• Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in Drinking Water. 

424 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-13 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Increased coliform bacteria

Description

The use of chloramines can lead to nitrification in the distribution system. The nitrite formed through nitrification 

exerts a high chlorine demand, which will rapidly deplete the disinfectant residual (Cowman and Singer 1994). 

When the disinfectant residual is low or depleted, microorganisms such as coliforms and heterotrophic bacteria 

can proliferate. 

Further Reading

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, and R. Wolfe. 1995. Nitrification Occurrence 

and Control in Chloraminated Water Systems. AwwaRF Report 90669. Project #710. Denver: 

AwwaRF. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Increased heterotrophic bacteria

Description

The use of chloramines can lead to nitrification in the distribution system. The nitrite formed through nitrification 

exerts a high chlorine demand, which will rapidly deplete the disinfectant residual (Cowman and Singer 1994). 

When the disinfectant residual is low or depleted, microorganisms such as coliforms and heterotrophic bacteria 

can proliferate. 

Further Reading

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Cowman, G.A. and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation 

Resulting from Chlorination and Chloramination of Humic Extracts. In Proceedings of AWWA 

Annual Conference. New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-14 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Nitrite/nitrate formation

Description

Nitrification can occur when chloramines are used to maintain a residual in the distribution system due to the 

presence of ammonia, which is used to form chloramines. Nitrifying bacteria convert the excess ammonia into 

nitrite and nitrate. Nitrification is not a problem when chlorine is used to maintain a residual, because no 

ammonia is used. 

Further Reading

• Kirmeyer, G.J., L.H. Odell, J. Jacangelo, A. Wilczak, and R. Wolfe. 1995. Nitrification Occurrence 

and Control in Chloraminated Water Systems. AwwaRF Report 90669. Project #710. Denver: 

AwwaRF. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Kirmeyer, G.J., M. LeChevallier, H. Barbeau, K. Martel, G. Thompson, L. Radder, W. Klement, and 

A. Flores. 2004a. Optimizing Chloramine Treatment. 2nd Edition. AwwaRF Report 90993. Project 

#2760. Denver: AwwaRF. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Cowman, G.A. and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation 

Resulting from Chlorination and Chloramination of Humic Extracts. In Proceedings, AWWA Annual 

Conference. New York, NY. 

• Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan, and D. Van 

Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution System Nitrification. 

AwwaRF Report 90949. Project #553. Denver: AwwaRF. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

Change in DBP concentration/composition

Description

Chloramines react more slowly with organic matter than free chlorine does. Therefore, switching from chlorine 

to chloramines can significantly reduce DBP formation. However, it will not completely eliminate DBP 

formation - TTHM and HAA5 will still be formed, though this formation may be undetectable, largely as a result 

of excess free chlorine or the hydrolysis of monochloramine to from free chlorine. 

Further Reading

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

• Valentine, R. 2001. Mechanisms and Kinetics of Chloramine Loss and By-Product Formation in 

the Presence of Reactive Drinking Water Distribution System Constituents. Washington, D.C.: 

USEPA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-15 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

SWITCHING COAGULANT

 The following impacts to your distribution system may result from switching your 

coagulant: 

• Change in finished water pH 

• Increased lead and copper in tap water 

• Change/disruption of scale 

• Change in finished water NOM 

• Change in chloride:sulfate ratio 

 The following references can provide further information about how to address most of 

these impacts. Additional references and brief descriptions are listed by impact in the table 

below. 

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

• USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening 

Guidance Manual. Office of Water. EPA 815-R-99-012. 

 Refer to Sections 3.3 and 3.7 for additional information on switching coagulants. 

Change in finished water pH

Description

Different coagulants have different optimum pH ranges. Therefore, when switching coagulants, it may be 

necessary to adjust the pH to achieve maximum contaminant removal. In addition, some coagulants consume 

alkalinity, which results in decreased buffering capacity and allows the pH to change more easily. 

Further Reading

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

Increased lead and copper in tap water

Description

The optimal pH range for coagulants varies by coagulant. Therefore, switching coagulants can require a pH 

change, and if the pH is significantly reduced, can lead to increased lead and copper corrosion in the distribution 

system. 

Further Reading

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-16 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Change/disruption of scale

Description

The optimal pH range for coagulants varies by coagulant. Therefore, switching coagulants can require a change 

in the operating pH, and consequently, in the distribution system. A higher pH can decrease the rate of corrosion, 

thereby decreasing the formation of scales from corrosion byproducts. A higher pH can also allow the formation 

of a protective calcium carbonate scale. A lower pH can cause disruption or dislodgement of scales formed from 

corrosion byproducts or protective scales, such as calcium carbonate. 

Further Reading

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Change in finished water NOM

Description

To accomplish enhanced coagulation, systems may switch coagulants to improve removal of TOC, which is a 

surrogate measure of NOM. Therefore, the NOM entering the distribution system is significantly reduced. Some 

NOM in the finished water can help inhibit corrosion. 

Further Reading

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

Change in chloride:sulfate ratio

Description

Some coagulants, such as aluminum sulfate (alum) and ferric sulfate add sulfate to the water. Other coagulants, 

such as ferric chloride add chloride to the water. Therefore, switching to or from any of these coagulants can 

affect the chloride to sulfate ratio. A shift in the sulfate to chloride ratio can cause increased lead and copper 

corrosion and can alter iron corrosion in the distribution system. 

Further Reading

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-17 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

MODIFYING CHLORINE DOSE WITH WARMER WATER TEMPERATURES

 The following impacts to your distribution system may result from reducing chlorine 

dose during warmer water temperatures in order to reduce DBP formation: 

• Increased coliform and heterotrophic bacteria 

• Increased loss of chlorine residual in the distribution system 

 The following references can provide further information about how to address this 

distribution system impact: 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th

Edition. New York: Van Nostrand Reinhold Co. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. 174 pp. Denver: 

AWWA. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 

278 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. 

Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesen, and R. 

Cushing. 2000b. Guidance Manual for Maintaining Distribution System Water 

Quality. AwwaRF Report 90798. Project #357. Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. 

Denver: AWWA. 

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-

R-99-014. 

Increased coliform and heterotrophic bacteria

Description

Chlorine is a more effective disinfectant at higher temperatures. However, because it reacts more quickly at 

warmer temperatures, the chlorine residual may dissipate more quickly in the distribution system, leaving low or 

no residual near the end of the distribution system. This can allow increased microbial growth in these areas. In 

addition, the growth rate of microorganisms is more rapid at higher temperatures, making them more difficult to 

control. These factors can lead to increased coliform and heterotrophic bacteria if the chlorine dose is lowered 

during warmer water temperatures. 

Increased loss of chlorine residual

Description

Lowering the chlorine dose will mean that there is less residual in the distribution system. Higher temperatures 

will also cause reactions of the residual with chlorine demand to proceed faster. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-18 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ADDING/DISCONTINUING SOFTENING

 The following impacts to your distribution system may result from adding or 

discontinuing softening: 

• Change in finished water pH 

• Increased lead and copper in tap water 

• Change/disruption of scale 

• Taste and color problems 

• Change in finished water NOM 

• High iron 

• Change in DBP concentration/composition 

• Pinhole leaks 

 The following reference can provide further information about how to address all of these 

impacts. Additional references and brief descriptions are listed by impact in the table below. 

• USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening 

Guidance Manual. Office of Water. EPA 815-R-99-012. 

 Refer to Section 3.8 for additional information on adding or discontinuing softening. 

Change in finished water pH

Description

In enhanced softening, the pH of the water is typically raised to a value above 10. However, most other water 

treatment processes are operated at much lower pHs. Therefore, when switching to enhanced softening, systems 

can expect to have a much higher finished water pH. Conversely, if a system switches from enhanced softening 

to another technology, the operating and finished water pH will be much lower. 

Further Reading

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

Increased lead and copper in tap water

Description

In enhanced softening, the pH of the water is typically raised to a value above 10. However, most other water 

treatment processes are operated at much lower pHs. Therefore, when discontinuing softening, systems can 

expect to have a much lower finished water pH. As the pH decreases, systems can expect an increase in corrosion 

of distribution system pipes, resulting in increased concentrations of metals such as iron, copper, and lead in the 

water. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-19 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Change/disruption of scale

Description

Installing softening requires an increase in operating pH, while discontinuing softening requires a reduction in pH. 

A higher pH can decrease the rate of corrosion, thereby decreasing the formation of scales from corrosion 

byproducts. A higher pH can also allow the formation of a protective calcium carbonate scale. A lower pH can 

cause disruption or dislodgement of scales formed from corrosion byproducts or protective scales, such as 

calcium carbonate. 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Taste and color problems

Description

Aluminum can be found in source water or introduced through coagulant use or as an impurity in lime. 

Aluminum is more soluble at high pH. Since enhanced softening is conducted at high pH, it allows more 

aluminum to pass through the treatment plant. In waters with high magnesium, enhanced softening can form 

lighter floc, which may not settle as well. This can also allow higher levels of aluminum to enter the distribution 

system. When aluminum precipitates out in the distribution system it can cause colored water and taste 

complaints. 

Further Reading

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-20 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Change in finished water NOM

Description

Enhanced softening preferentially removes high molecular weight organic molecules and organic molecules with 

oxygen-containing functional groups. NOM removal through enhanced softening varies widely depending on the 

nature and concentration of the NOM, water quality characteristics such as hardness, other plant treatment 

processes, and type and dose of the softening chemical. Some NOM in the finished water can help inhibit 

corrosion. 

Further Reading

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York : McGraw-Hill. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

High iron

Description

In enhanced softening, the pH of the water is typically raised to a value above 10. However, most other water 

treatment processes are operated at much lower pHs. Therefore, when discontinuing softening, systems can 

expect to have a much lower finished water pH. As the pH decreases, systems can expect an increase in corrosion 

of distribution system pipes, resulting in increased concentrations of metals such as iron, copper, and lead in the 

water. 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Change in DBP concentration/composition

Description

Softening removes DBP precursors, reducing the formation of DBPs. Therefore, by installing softening, systems 

can decrease TTHM and HAA5 levels in the plant and the distribution system. Systems installing softening will 

also see a shift in the balance of DBPs in the distribution system because TTHM formation is favored over HAA5 

formation at the high pH levels used in softening. In addition, prechlorination with softening can reduce the 

amount of DBP precursor removal (AWWA 1990) and should be avoided if possible. 

Further Reading

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: McGraw-Hill. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-21 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Pinhole leaks

Description

Adding softening raises pH and alkalinity of the finished water. Discontinuing softening lowers the pH and 

alkalinity. Lower pH can be corrosive to copper, but high pH in the absence of inhibitors such as NOM has also 

been shown to initiate pitting corrosion in copper. 

Further Reading 

• Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole leaks in 

residential plumbing. Water Science and Technology. 49(2): 83-90. 

• Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of American 

Water Works Association. 86(7): 74-91. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-22 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ADDING OZONE

 The following impacts to your distribution system may result from adding ozone: 

• Increased lead and copper in tap water 

• Taste and odor 

• Change in finished water NOM 

• Colored water 

• High iron 

• Change in DBP concentration/composition 

 The following references can provide further information about how to address most of 

these impacts. Additional references and brief descriptions are listed by impact in the table 

below. 

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-

R-99-014. 

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

 Refer to Section 5.2 for additional information on adding ozone. 

Increased lead and copper in tap water

Description

When ozone reacts in water it produces dissolved oxygen. Dissolved oxygen can cause increased growth of 

aerobic bacteria, which can lead to microbial-induced corrosion in the distribution system. Dissolved oxygen is 

also corrosive, and if not removed, it can directly cause lead and copper corrosion in the distribution system. 

Ozonation also breaks down organics into smaller molecules that are more readily used as a food source by 

microorganisms. If not removed, this can lead to increased microbial growth and microbial-induced corrosion in 

the distribution system. 

Further Reading

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-23 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Taste and odor

Description

Ozonation reacts with organics to break them down into smaller molecules, such as aldehydes and ketones. 

Aldehydes can impart tastes and odors to water. In addition, ozone itself can impart an “ozonous” or “oxidant” 

taste to the water even in the absence of a residual (AwwaRF and Lyonnaise des Eaux 1995). 

Further Reading

• AwwaRF and Lyonnaise des Eaux. 1995. Advances in Taste and Odor Treatment and Control. 

AwwaRF Report 90610. Project #629. Denver: AwwaRF. 

• Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in Drinking Water.

424 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

Change in finished water NOM

Description

Ozone reacts with NOM in water to destroys many DBP precursors. However, ozone breaks the NOM down into 

smaller organic molecules that are readily used as a food source by microorganisms, referred to as AOC. If ozone 

is followed by biological filtration, the AOC concentration can also be significantly reduced. 

Further Reading

• Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in Drinking Water.

424 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

Colored water

Description

Ozonation produces dissolved oxygen in water, which is corrosive. In addition, dissolved oxygen can cause 

increased microbial activity in the distribution system and microbial-induced corrosion. If iron pipe is present in 

the distribution system, increased corrosion can lead to colored water problems. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-24 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Further Reading

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

High iron

Description

Ozonation produces dissolved oxygen in water, which is corrosive. In addition, dissolved oxygen can cause 

increased microbial activity in the distribution system and microbial-induced corrosion. If iron pipe is present in 

the distribution system, increased corrosion can lead to higher iron levels in the water. 

Further Reading

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Change in DBP concentration/composition

Description

Ozone does not form chlorinated DBPs. Therefore, switching from chlorine or chlorine dioxide as a primary 

disinfectant to ozone will result in significantly lower levels of TTHM and HAA5. However, ozone reacts with 

bromide to form bromate, which is a regulated DBP. 

Further Reading

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-25 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ADDING CHLORINE DIOXIDE

 The following impacts to your distribution system may result from adding chlorine 

dioxide: 

• Increased lead and copper in tap water 

• Taste and odor 

• Change in finished water NOM 

• Colored water 

• High iron 

• Change in DBP concentration/composition 

 References, along with brief descriptions, that are specific to individual issues are listed 

by impact in the table below. Refer to Sections 5.4 and 5.5 for additional information on adding 

chlorine dioxide. 

Increased lead and copper in tap water

Description

Changing to chlorine dioxide from another oxidant can change the ORP of the tap water. Changes in ORP can 

alter the nature of passivating layers and could result in the release of lead and other metals into the distribution 

system. It is also possible that AOC formed by chlorine dioxide could encourage microbial-induced corrosion. 

Further Reading

• AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper Rule 

Corrosion Control Treatment. Denver: AwwaRF. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF 

Taste and odor

Description

Chlorine dioxide has a strong chlorinous odor. Even when chlorine dioxide is used only as a primary disinfectant, 

customers may still detect a strong chlorinous odor at the tap as chlorite can combine with free chlorine in the 

distribution system to form chlorine dioxide. If a customer has recently installed new carpeting, airborne organic 

compounds from the carpeting can react with the chlorine dioxide emanating from the customer’s tap to form 

offensive odors. These odors have been described as “cat-urine-like” and “kerosene-like” (Hoehn et al. 1990). 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-26 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Further Reading

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

Change in finished water NOM

Description

Chlorine dioxide reacts with organic matter in water. These reactions can form smaller organic molecules or 

AOC. Although AOC production is not as much of an issue with chlorine dioxide as it is with ozone, it is still 

possible AOC could increase and in turn increase microbial growth. 

Further Reading

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, G.A. Ganon, 

J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and 

Distribution System Performance. AwwaRF Report 91082. Project #2843. Denver: AwwaRF. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

Colored water

Description

Chlorine dioxide can react with organic chemicals to form AOC. AOC can act as a food source for microbes, 

which can in turn increase the corrosion rate causing corrosion products to be released into the distribution system. 

The change in ORP can also destabilize some already formed layers of corrosion products, leading to colored 

water. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-27 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Further Reading

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, G.A. Ganon, 

J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and 

Distribution System Performance. AwwaRF Report 91082. Project #2843. Denver: AwwaRF. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

High iron

Description

Chlorine dioxide can react with organic matter to form AOC which can cause microbial-induced corrosion. 

Changes in water ORP resulting from chlorine dioxide use may also allow dissolution of existing scales. 

Further Reading

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Andrews, R.C., Z. Alam, R. Hofmann, L. Lachuta, R. Cantwell, S. Andrews, E. Moffet, G.A. Ganon, 

J. Rand, and C. Chauret. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and 

Distribution System Performance. AwwaRF Report 91082. Project #2843. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Change in DBP concentration/composition

Description

Chlorine dioxide does not form significant amounts of TTHM or HAA5. Therefore, switching from chlorine or 

chloramines to chlorine dioxide will result in lower levels of these DBPs. However, chlorine dioxide generators 

produce some chlorine as a byproduct so some TTHM and HAA5 will be formed. In addition, chlorine dioxide 

can oxidize bromide ions to bromine, which can then react with organic matter in the water to produce brominated 

DBPs. Chlorine dioxide also reacts with NOM to produce chlorite, which is a regulated DBP. 

Further Reading

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. New York: 

Van Nostrand Reinhold Co. 

• Gates, D. 1997. The Chlorine Dioxide Handbook. 177pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-28 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ENHANCED COAGULATION

 The following impacts to your distribution system may result from using enhanced 

coagulation: 

• Reduction in finished water pH 

• Increased lead and copper in tap water 

• Change/disruption of scale 

• Change in finished water NOM 

• Change in DBP concentration/composition 

• Change in chloride:sulfate ratio 

 The following references can provide further information about how to address most of 

these impacts. Additional references and brief descriptions are listed by impact in the table 

below. 

• USEPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening 

Guidance Manual. Office of Water. EPA 815-R-99-012. 

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

 Refer to Section 3.7 for additional information on using enhanced coagulation. 

Change in finished water pH

Description

Enhanced coagulation tends to reduce the pH of the water. This can be accomplished by adding chemicals 

specifically to reduce the pH to as low as 5.5 or as a consequence of using heavy alum or ferric coagulant doses. 

Further Reading

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900pp. Denver: AWWA. 

Increased lead and copper in tap water

Description

Enhanced coagulation tends to reduce the pH of the water. This can be accomplished by adding chemicals 

specifically to reduce the pH to as low as 5.5 or as a consequence of using heavy alum or ferric coagulant doses. 

In addition, switching coagulants for enhanced coagulation can lead to reduced pH. A reduction in pH can cause 

increased lead and copper corrosion. 

Further Reading

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-29 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Change/disruption of scale

Description

Enhanced coagulation tends to reduce the pH of the water. This can be accomplished by adding chemicals 

specifically to reduce the pH to as low as 5.5 or as a consequence of using heavy alum or ferric coagulant doses. 

A lower pH can cause disruption or dislodgement of scales formed from corrosion byproducts or protective 

scales, such as calcium carbonate. 

Further Reading

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Change in finished water NOM

Description

Enhanced coagulation increases the removal of TOC, which is a surrogate measure of NOM. Therefore, the 

NOM entering the distribution system is significantly reduced. Some NOM in finished water can help inhibit 

corrosion. 

Further Reading

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

Change in DBP concentration/composition

Description

Enhanced coagulation improves the removal of DBP precursors in a conventional water treatment plant, reducing 

the formation of DBPs. Therefore, by practicing enhanced coagulation, systems can decrease TTHM and HAA5 

levels in the plant and the distribution system. 

Further Reading

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Change in chloride:sulfate ratio

Description

One option for systems initiating enhanced coagulation is to switch coagulants to increase TOC removal. Some 

coagulants, such as aluminum sulfate (alum) and ferric sulfate add sulfate to the water. Other coagulants, such as 

ferric chloride add chloride to the water. Therefore, switching to or from any of these coagulants can affect the 

chloride to sulfate ratio and, as a result, may cause increased lead and copper corrosion. 

Further Reading

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-30 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

INSTALLING NANOFILTRATION

 The following impacts to your distribution system may result from installing 

nanofiltration: 

• Change in finished water pH 

• Increased lead and copper in tap water 

• Change/disruption of scale 

• Change in finished water NOM 

• Colored water 

• High iron 

• Change in DBP concentration/composition 

• Pinhole leaks 

 The following reference can provide further information about how to address most of 

these impacts. Additional references and brief descriptions are listed by impact in the table 

below. 

• AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. 

 Refer to Section 4.3 for additional information on installing nanofiltration. 

Change in finished water pH

Description

Nanofiltration can remove virtually all particulate matter as well as larger dissolved compounds. However, it 

cannot remove dissolved gasses. Therefore, carbon dioxide in the feed water is not removed, while alkalinity, 

hardness, and other dissolved compounds are removed. Therefore, the carbonate system must re-equilibrate, 

resulting in the production of the hydrogen ion and loss of alkalinity. This in turn results in a lowering of the pH 

of the water. 

Further Reading

• Schippers, J.C., J.C. Kruithof, M.M. Nederlof, J.A.M.H. Hofman, and J. Taylor. 2004. Integrated 

Membrane Systems. AwwaRF Report 90899. Project #264. Denver: AwwaRF. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900 pp. Denver: AWWA. 

Increased lead and copper in tap water

Description

Nanofiltration can also result in a lowering of the pH of the water. The lower pH water will be more corrosive to 

lead and copper piping in the distribution system. As a result, both increased lead and copper levels can occur. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-31 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Change/disruption of scale

Description

Nanofiltration can also result in a lowering of the pH of the water. A lower pH can cause disruption or 

dislodgement of scales formed from corrosion byproducts or protective scales, such as calcium carbonate. 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Change in finished water NOM

Description

Nanofiltration is a physical process that removes molecules from water. Nanofiltration can remove both 

particulate matter and dissolved compounds, including NOM. Thus, the NOM concentration entering the 

distribution system is significantly reduced. Some NOM in finished water can help inhibit corrosion. 

Further Reading

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

Colored water

Description

Nanofiltration can also result in a lowering of the pH of the water. The lower pH water will be more corrosive to 

iron pipe in the distribution system. The corrosion will result in increased iron in the water, which can lead to 

colored water problems. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-32 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. Smith, M. 

LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. Cushing. 2000b. Guidance 

Manual for Maintaining Distribution System Water Quality. AwwaRF Report 90798. Project #357. 

Denver: AwwaRF and AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 900pp. Denver: AWWA. 

High iron

Description

Nanofiltration can also result in a lowering of the pH of the water. The lower pH water will be more corrosive to 

iron pipe in the distribution system. Corrosion of iron pipe will result in increased iron in the water. 

Further Reading

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AwwaRF Report 90983. Project #2648. Denver: AwwaRF. 

Change in DBP concentration/composition

Description

Nanofiltration physically removes DBP precursors, reducing the formation of DBPs. Therefore, by installing 

nanofiltration, systems can decrease TTHM and HAA5 levels in the plant and the distribution system. 

Further Reading

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 278 pp. Denver: 

AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Pinhole leaks

Description

Nanofiltration can remove most larger particles and many smaller ones. This includes NOM, which has been 

shown to inhibit pitting corrosion in copper piping. 

Further Reading

• Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole leaks in 

residential plumbing. Water Science and Technology. 49(2): 83-90. 

• Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of American 

Water Works Association. 86(7): 74-91. 

• AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: AwwaRF. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-33 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

INSTALLING GRANULAR ACTIVATED CARBON

 The following impacts to your distribution system may result from installing granulated 

activated carbon (GAC): 

• Increased coliform and heterotrophic bacteria 

 The following references can provide further information about how to address this 

impact. A brief description of the distribution system impact is provided in the table below. 

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). New York: 

McGraw-Hill. 

• American Chemical Society. 1983. Treatment of Water by Granular Activated 

Carbon. M.J. McGuire and I.H. Suffet (editors). Washington, D.C.: American 

Chemical Society. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 

278 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. 

Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. 

Cushing. 2000b. Guidance Manual for Maintaining Distribution System Water 

Quality. AwwaRF Report 90798. Project #357. Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 990 pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. 

Denver: AWWA. 

 Refer to Section 4.1 for additional information on installing GAC. 

Increased coliform and heterotrophic bacteria

Description

Heterotrophic bacteria can colonize GAC filters and can be shed in the filter effluent. The number of bacteria in 

the effluent of GAC systems is frequently higher than influent levels. This problem is compounded when GAC 

filters are operated in biologically active mode, where biological growth on the GAC filters is promoted. 
Appendix C. Guidance for Evaluating Impacts of Treatment Changes on Distribution Systems 

Simultaneous Compliance Guidance Manual C-34 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

INSTALLING OZONE WITHOUT SUBSEQUENT BIOLOGICAL FILTRATION

 The following impact to your distribution system may result from installing ozone 

without subsequent biological filtration: 

• Increased coliform and heterotrophic bacteria 

 The following references can provide information about how to address this impact. A 

brief description of the distribution system impact is provided in the table below. 

• Singer, P.C. (editor). 1999. Formation and Control of Disinfection By-Products in 

Drinking Water. 424 pp. Denver: AWWA. 

• USEPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-

R-99-014. 

• USEPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook. 2nd Edition. 

278 pp. Denver: AWWA. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

Transmission and Distribution. 3rd Edition. 553 pp. Denver: AWWA. 

• Kirmeyer, G.J., M. Friedman, J. Clement, A. Sandvig, P.F. Noran, K.D. Martel, D. 

Smith, M. LeChevallier, C. Volk, E. Antoun, D. Hiltebrand, J. Dykesan, and R. 

Cushing. 2000b. Guidance Manual for Maintaining Distribution System Water 

Quality. AwwaRF Report 90798. Project #357. Denver: AwwaRF and AWWA. 

• Lauer, W.C. 2005. Water Quality in the Distribution System. Denver: AWWA. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. 990pp. Denver: AWWA. 

• Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. 

Denver: AWWA. 

 Refer to Section 5.2 for additional information on installing ozone without subsequent 

biological filtration. 

Increased coliform and heterotrophic bacteria

Description

Ozone reacts with NOM in water to destroys many DBP precursors. However, ozone breaks the NOM down into 

smaller organic molecules that are readily used as a food source by microorganisms, referred to as assimilable 

organic carbon (AOC). If ozone is followed by biological filtration, the AOC concentration can be significantly 

reduced. However, if ozone is not followed by biological filtration, the AOC will pass into the distribution 

system where it can be readily used by microorganisms. This will result in increased heterotrophic bacterial 

growth and possibly higher coliform numbers and may cause nitrification in chloraminated systems. 
 

Appendix D 

Tools for Evaluating Impacts of Treatment Changes on 

Lead and Copper Rule Compliance 
 

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Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Appendix D 

Tools for Evaluating Impacts of Treatment Changes on Lead and 

Copper Rule Compliance 

Currently, water systems work with their primacy agencies (primarily state regulatory 

agencies) to ensure compliance with the LCR. The state establishes optimal water quality 

parameters that the system must monitor, in addition to regulatory lead and copper tap sampling, 

to evaluate compliance with the Rule. The system must maintain these water quality parameters 

at specified levels and/or ranges to maintain optimal corrosion control treatment (OCCT). Water 

systems must notify their primacy agency no later than 60 days after the addition of a new source 

or implementation of a treatment or source water change; however, systems are encouraged to 

provide notification to the State prior to any treatment change to minimize risks that the change 

will adversely impact OCCT (40 CFR 141.8(b)(3)). Proposed revisions to the LCR would

require water systems to provide advanced notification to their primacy agency and to get 

approval for intended changes in treatment or the addition of a new source that could increase 

release and uptake of lead. This proposed revision would allow states and water systems to take 

as much time as needed to consult about potential problems, allowing evaluations to be 

completed that would strive to avoid or minimize potential problems with corrosion control and 

ultimately ensure that OCCT is being maintained after the treatment change has been made. 

Conducting evaluations of the potential impact that a proposed treatment change may have on 

LCR compliance can provide information both parties can utilize in discussions of how best to 

maintain OCCT in the system. This appendix provides a summary of various corrosion 

assessment tools that can be used in these evaluations. 

Corrosion assessment tools should be used prior to a treatment change to predict the 

potential for causing metals release and uptake associated with the change. In cases where 

metals release has already become a problem, these assessment tools can also be used to 

determine where and why metals release is occurring and to test alternative corrosion control 

strategies. 

 There are many types of corrosion assessment tools ranging from relatively inexpensive 

data analyses to extensive pilot and partial system studies. For the purposes of this appendix, 

corrosion assessment tools have been organized into the following categories: 

• Desktop studies 

• Water Quality Monitoring 

– Expanded baseline monitoring 

– Supplemental tap water quality monitoring 

• Blending analysis 

• Solubility models 

• Laboratory and Field Testing 

– Treatment simulation 

– Pipe loop testing 

– Coupon studies 

– Electrochemical measurement techniques 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

– Scale and solids analysis 

– Partial system testing 

These tools can be used in a progressive manner to evaluate potential impacts of lead 

release and uptake by the water associated with a change in treatment or operations. For 

example, a desktop study, which is based on review and evaluation of readily available data and 

information, may be sufficient to understand the potential for metals release. However, in some 

cases there may be system-specific conditions (e.g., unlined cast iron pipe, changes in secondary 

disinfectant) that warrant additional study. In such cases, diagnostic tools such as pipe loop 

studies or scale analysis could be used to help establish optimum water quality and treatment 

conditions. In cases where the cause(s) of increased lead and/or copper release is not known, 

other diagnostic tools such as supplemental tap water quality monitoring could be useful. 

Ultimately, the system should select the appropriate corrosion assessment tool(s) for their 

applications. 

Exhibit D.1 provides a summary of the assessment tools, their usefulness in terms of 

assessing lead and copper release, and their relative costs. The sections that follow describe each 

tool and identify their uses and limitations. A list of references where the reader can find 

additional information is presented at the end of each section and in Chapter 7 of this guidance 

document. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit D.1 Summary of Corrosion Assessment Tools 

Tool Section Description Potential 

Uses*

Relative 

Cost 

Desktop studies D.1 Review of current and historical information 

such as literature, data, expert opinion, and 

analogous system experiences 

1, 2 Low 

Expanded 

baseline 

monitoring 

D.2.1 Increased monitoring in the distribution 

system for optimal water quality parameters 

(pH, alkalinity, calcium, conductivity, 

temperature, and corrosion inhibitors) and 

other parameters (e.g., ORP) that may provide 

useful information on metals release potential. 

1, 2, 3 Medium 

Supplemental 

tap water quality 

monitoring 

D.2.2 Includes LCR compliance sampling at more 

sites and/or more frequently and water line 

profiling at select sites 

1, 2, 3 Medium 

- High 

Blending 

analysis 

D.3 Predicting the water quality of multiple 

sources blended in a distribution system 

1, 2, 3 Low 

Solubility 

models 

D.4 Using models to predict the thermodynamic 

stability of a metal under specific water 

quality conditions and evaluate the 

mechanisms underlying scale development 

and passivation. 

1, 2, 3 Low 

Treatment 

Simulation 

D.5.1 Using models or conducting jar tests to 

simulate the effects of treatment changes 

1 High 

Pipe Loop 

Studies 

D.5.2 Studies that measure metals release under 

different water quality conditions. 

1, 3 High 

Coupon Studies D.5.3 Studies that utilize metal coupons to 

determine metal loss and corrosion rates in a 

given water quality. 

1, 3 High 

Electrochemical 

Measurement 

Techniques 

D.5.4 Using instruments to measure the potential or 

the current on the metal surface and determine 

the corrosion rate 

1, 3 High 

Scale and Solids 

Analysis 

D.5.5 Analytical methods used to examine the 

accumulated corrosion products on pipes. 

1, 2, 3 High 

Partial System 

Testing 

D.5.6 Testing a corrosion treatment method on a 

portion of the distribution system which has 

been hydraulically isolated from the rest of 

the system 

3 High 

* 1 = To predict the impact of a change in treatment or operations on metals release 

 2 = To diagnose the cause and location of metals release 

 3 = To test the effectiveness of corrosion control alternatives 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

D.1 Desktop Studies

Description of Method

 Desktop studies utilize current and historical information to document the extent, 

magnitude, and possible causes of potential problems. By referencing a variety of information 

sources, desktop studies can be used to 1) develop and assess treatment options and the 

corresponding water quality changes that potentially can occur, 2) identify the secondary impacts 

of those treatment and water quality changes, and 3) identify actions that will help to mitigate 

those potential problems. Information sources for desktop studies can include the following: 

• Literature reviews; 

• Reviews of historical water quality, treatment, and modeling data; 

• Review of standards and guidance documents; 

• Expert opinions; and 

• Consultation with, and analyses of data from other systems with similar water quality 

and distribution systems (analogous systems). 

 Literature reviews of field and laboratory studies may help reveal corrosion mechanisms 

and inter-relationships between lead and copper leaching and water quality conditions in the 

system, and also identify possible corrosion prevention strategies. The AWWA Research 

Foundation (AwwaRF) has published an overview of corrosion research (AwwaRF, 2007) and 

EPA includes references to several historical corrosion studies in drinking water regulations and 

guidance manuals. As part of a recent study, the American Water Works Association (AWWA, 

2005b) summarized unintended consequences associated with changes in source water, 

treatment, and operations and maintenance (O&M) practices on lead and copper release and 

uptake in the distribution system. These unintended consequences include changes in corrosionrelated water quality parameters, changes to existing scales, and other corrosion-related impacts. 

The study includes a checklist which can serve as a screening tool in identifying possible effects 

of changes on LCR compliance. 

 Historical data collected by utilities, including treatment data, finished and distribution 

system water quality and materials evaluations, existing LCR monitoring data, modeling results, 

and results from special studies, can all be utilized in a desktop evaluation to identify potential 

simultaneous compliance issues. Burlingame and Sandvig (2004) provide an example of how 

one system evaluated historical lead and copper data to determine if changes in operations, 

treatment, or source were impacting lead and copper levels. 

 Desktop studies can also incorporate a thorough review of regulatory standards and 

associated guidance documents. The EPA has developed a guidance manual for selecting lead 

and copper corrosion control strategies which incorporates information on secondary impacts of 

various corrosion treatment approaches (USEPA 2003h). 

Review of case studies of systems with similar water quality and treatment scenarios can 

provide insight into potential problems associated with implementation of corrosion control 

treatment and the ability to maintain compliance with regulations. Appendix B of this guidance 

manual provides numerous case studies showing how different water systems have addressed 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

simultaneous compliance and operational issues. AWWA’s Water Industry Technical Action 

Fund collected lead and copper data along with other water quality data such as, alkalinity, 

calcium, and the type of corrosion inhibitor used for 400 US water systems (AWWA, 1993). 

Systems could use this data to evaluate the effectiveness of corrosion inhibitors for systems with 

similar water quality. 

Uses and Limitations

 Desktop studies can be used by systems to characterize the potential for corrosion 

problems to occur when contemplating changes in water quality and/or treatment. Desktop 

studies are also a relatively inexpensive method for screening a number of potential solutions to 

a corrosion problem. Desktop studies provide a way for systems to learn from the experience of 

others and focus efforts on the most effective techniques. 

 In many cases, results from desktop studies can be sufficient for understanding potential 

compliance concerns associated with a change in treatment or operations. Desktop studies may 

be limited however, in situations where supply, treatment, and distribution system configurations 

and operations are complex and/or unusual. In these situations, desktop studies could be used in 

combination with other corrosion assessment tools. When evaluating corrosion control treatment 

options, systems should consider using desktop studies in combination with other tools to 

identify any system-specific treatment issues. 

 

References 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

AWWA. 1993. Initial Monitoring Experiences of Large Water Utilities Under EPA’s 

Lead and Copper Rule. Denver: WITAF. 

AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

Rule Corrosion Control Treatment. Denver: AWWA. 

AwwaRF. 2007. Distribution System Corrosion and the Lead and Copper: An Overview 

of AwwaRF Research. AwwaRF Special Report. Denver: AwwaRF. 

Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data. 

Opflow. 30(6):16-19. 

Economic and Engineering Services, Inc. and Illinois State Water Survey. 1990. Lead 

Control Strategies. Denver: AwwaRF and AWWA. 

Hecht, P.M., and E.A. Turner. 2004. Washington Aqueduct Desktop & Flow-Through 

Study. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead Levels 

in DC’s Drinking Water at the 2004 AWWA WQTC. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control 

Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 

D.2 Water Quality Monitoring

 This section describes two types of water quality monitoring tools, expanded baseline 

monitoring of the distribution system and supplemental monitoring of corrosion products at the 

tap. 

D.2.1 Expanded Baseline Monitoring 

Description of Method

 The LCR requires systems to monitor basic water quality parameters in the distribution 

system. Depending on the corrosion control treatment, some combination of the following 

parameters is typically required: pH, alkalinity, calcium, conductivity, temperature, and the 

corrosion inhibitor concentration. Results from this and other monitoring programs can provide 

useful information on the state of corrosion within the distribution system. For example, 

bacteriological data from compliance monitoring for the Total Coliform Rule (TCR) can help 

systems identify areas likely to suffer from microbial induced corrosion. Sampling for water 

quality parameters at more locations and performing it at more frequent intervals can provide 

better information on potential trouble spots in the systems. Also, systems can obtain a better 

spatial representation of the level of these parameters and be able to more accurately assess the 

potential for metals release in various parts of the system. 

Additional water quality and corrosion parameters may be incorporated into baseline 

monitoring such as measurements of oxidation reduction potential (ORP). ORP is the potential 

for transfer of electrons between chemical species and is measured in volts (V), millivolts (mV), 

or Eh (1Eh = 1mV). The ORP of the water can impact the metal oxidation rates and the nature 

of scales that form on the interior of piping and fittings, affecting metals release. 

Kirmeyer et al. (2002) present detailed corrosion control monitoring protocols including 

both proactive and reactive monitoring objectives. 

 

Usefulness and Limitations

 Expanded baseline monitoring can be used to identify areas of a distribution system that 

have potentially corrosive waters and find areas where a corrosion inhibitor is not performing 

effectively. An on-going distribution system expanded baseline water quality monitoring 

program can provide an ‘early-warning’ of potential system-wide problems that may occur after 

a treatment or operational change, as well as identify the occurrence of more localized water 

quality problems. Results from this type of monitoring program can also provide a more 

complete assessment of the system for evaluating the impact of future treatment changes. 

 

References 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

AWWA 2005a. Managing Change and Unintended Consequences: Lead and Copper 

Rule Corrosion Control Treatment. Denver: AWWA. 

Kirmeyer, G.J., J. Clement, and A. Sandvig. 2000a. Distribution System Water Quality 

Changes Following Implementation of Corrosion Control Strategies. AwwaRF Report 

90764. Project #157. Denver: AwwaRF. 

Kirmeyer, G.J., M. Friedman, K. Martel, G. Thompson, A. Sandvig, J. Clement, and M. 

Frey. 2002. Guidance Manual for Monitoring Distribution System Water Quality.

Denver: AwwaRF and AWWA. 

 

USEPA 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water 

Systems. Office of Water. EPA 816-R-02-009. 

D.2.2 Supplemental Tap Water Quality Monitoring 

Description of Method 

 Supplemental tap water sampling can provide a more complete picture of the occurrence 

of lead and copper levels at the tap, beyond the information available through regulatory 

monitoring required by the LCR. Supplemental tap water quality sampling includes collecting 

LCR samples at more sites and at a greater frequency than required. In addition to traditional 

LCR sampling, sequential samples can be collected from customer’s taps and analyzed to help 

determine the source of the lead (i.e., whether it is originating from faucets, meters, soldered 

joints, service lines, plumbing fittings, or other locations). This method is referred to as “water 

line profiling” or “sequential sampling.” Results from profiling can also provide useful 

information on the relationship of lead and copper corrosion products to other water quality 

parameters. Analyses of particulate versus dissolved lead can provide information on the 

possible mechanisms for lead release (e.g., soluble release from metals surfaces or particulate 

metals release from scales). 

 

Uses and Limitations

 Supplemental tap water quality monitoring can provide data that can be used to evaluate 

the potential impact of treatment and operational changes on lead and copper levels at the tap, 

and consequently, compliance with the LCR. Additional tap monitoring data on lead and copper 

levels can provide more confidence in the conclusions with respect to potential impacts systemwide. 

Water line profiling can provide diagnostic information on the location of metals release. 

Results from profiling can also provide useful information on the relationship of lead and copper 

corrosion products to other water quality parameters. Analyses of particulate versus dissolved 

lead can provide information on the possible mechanisms for lead release (e.g., soluble release 

from metals surfaces or particulate metals release from scales). 

Because samples are collected at the tap, supplemental monitoring programs require 

significant cooperation from customers. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 

References 

AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

Rule Corrosion Control Treatment. Denver: AWWA. 

 

Boyd, G.R., G.J. Pierson, G.J. Kirmeyer, M. Britton, and R.J. English. 2006. Pb release 

from end-use plumbing components. Proceedings of Water Quality Technology 

Conference. November 5-9. Denver: AWWA. 

Estes-Smargiassi, S., J. Steinkrauss, A. Sandvig, and T. Young. 2006. Impact of Lead 

Service Line Replacement on Lead Levels at the Tap. In Proceedings AWWA Annual 

Conference and Exposition. San Antonio: AWWA. June, 2006. 

Estes-Smargiassi, S., and A. Cantor. 2006. Lead Service Line Contributions to Lead at 

the Tap. In Proceedings AWWA Water Quality Technology Conference. Denver: 

AWWA. November 2006. 

Giani, R., M. Edwards, C. Chung, and J. Wujek. 2004. Lead Profiling Methodologies 

and Results. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

Levels in DC’s Drinking Water at the 2004 AWWA WQTC. Proceedings of AWWA Water 

Quality Technology Conference. Denver: AWWA. 

Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G. 

Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring 

Strategies. AwwaRF Report 90996F Project #2679. Denver: AwwaRF. 

D.3 Blending Analysis 

Description of Method

Blending analyses can predict the characteristics of the water when two sources are 

blended in the distribution system and help determine if corrosive conditions might result. While 

the prediction of some key corrosion parameters can be done using simple mass balance 

equations, evaluation of others could benefit from the use of computational software. One useful 

tool is the Rothberg, Tamburini & Winsor Blending Application Package 4.0 (AWWA 2001a). 

Uses and Limitations

 Blending analyses can be particularly useful if a water system is considering using an 

alternative source to comply with a regulation. As with any modeling exercise, the output of the 

model depends on the accuracy of the input parameters, and users will need a certain level of 

expertise and understanding of water chemistry and treatment. 

References 

AWWA. 2001a. The Rothberg, Tamburini & Winsor Blending Application Package 4.0. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

AWWA Catalog Number 53042.

Taylor, J.S., J.D. Dietz, A.A. Randall, S.K. Hong, C.D. Norris, L.A. Mulford, J.M. 

Arevalo, S. Imran, M. Le Puil, S. Liu, I. Mutoti, J. Tang, X. Xiao, C. Cullen, R. 

Heaviside, A. Mehta, M. Patel, F. Vasquez, and D. Webb. 2005. Effects of Blending on 

Distribution System Water Quality. AwwaRF Report 91065F. Project #2702. Denver: 

AwwaRF. 

D.4 Solubility Models 

Description of Method 

 Chemical solubility models can predict the thermodynamic stability of a given metal 

under specific water quality conditions and can be used to evaluate the mechanisms underlying 

scale development and passivation. These models can help in predicting potential corrosion 

problems and may be especially useful for lead corrosion. There are several non-proprietary and 

commercially available solubility models, including CORRODE (Edwards and Reiber 1997 a, b) 

and PHREEQCI (United States Geological Survey). 

Uses and Limitations 

 Solubility models are based on equilibrium kinetics, and may not take into account nonequilibrium conditions and variations in system conditions (particulate lead release, water usage, 

scale accumulation, etc.) that would impact metals release in the field. A certain level of 

expertise and understanding of equilibrium chemistry and solubility constants would be needed 

in order to effectively use these models and evaluate their results properly. 

References

Butler, J.N. with a Chapter by David Cogley. 1998. Ionic Equilibrium. Solubility and pH 

Calculations. New York: Wiley-Interscience. 

Edwards, M. and S. Reiber. 1997a. A General Framework for Corrosion Control Based 

on Utility Experience. AwwaRF Report 90712A. Project #910. Denver: AwwaRF. 

Edwards, M. and S.H. Reiber. 1997b. Predicting Pb and Cu corrosion by-product release 

using CORRODE software. AwwaRF Report 90712B. Project #910. Denver: AwwaRF.

Parkhurst, D.L. and C.A.J. Appelo. 1999. User’s guide to PHREEQC (Version2)—A 

computer program for speciation, batch-reaction, one-dimensional transport, and inverse 

geochemical calculations. 310 pp. Water Resources Investigations Report 99-4259. U.S. 

Geological Survey. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

D.5 Laboratory and Field Studies 

 Whereas desktop studies, modeling, and monitoring can provide useful tools for 

predicting the impact of treatment changes with respect to corrosion, laboratory and field studies 

can be used to address site-specific issues and in some cases, measure actual changes in 

corrosion parameters including metals release. This section builds on previous sections by 

providing information on the following corrosion assessment tools: 

• Treatment simulation 

• Pipe loop testing 

• Coupon studies 

• Electrochemical measurement techniques 

• Scale and solids analysis 

• Partial system testing 

D.5.1 Treatment Simulation 

Description of Method

 Treatment simulation models can used to evaluate the effect of certain treatment changes 

on corrosion parameters and can be useful in identifying the best combination of treatment 

scenarios to achieve simultaneous compliance. For example, the Water Treatment Plant Model

(USEPA 2001i) includes data and alternative treatment processes to assist utilities in achieving 

optimized conditions. In cases where models may not be sufficient, jar testing can show how 

treatment changes can alter finished water quality conditions as they relate to corrosion potential. 

Uses and Limitations 

 Jar tests and treatment simulation models are very useful in determining the impact of a 

treatment change on water quality at the treatment plant. They do not, however, take into account 

changes as water moves through the distribution system and site specific factors such as 

microbiological activity and interactions of the water with different pipe material. 

References 

AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd

Edition. AWWA Manual M37. pp. 1-34. Denver: AWWA. 

AwwaRF. 1999. Distribution System Water Quality Changes Following Corrosion 

Control Strategies. Denver: AwwaRF. 

USEPA. 2001i. Water Treatment Plant Model. Version 2.0. Developed by the Center for 

Drinking Water Optimization, University of Colorado - Boulder and Malcom Pirnie, Inc. 

May, 2001. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-11 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

D.5.2 Pipe Loop Studies 

Description of Method

 Pipe loop studies are intended to simulate corrosion in the consumer’s plumbing system 

and allow for direct measurement of metal release. Pipe loop material can include 1) pipes or 

pipe sections which reflect actual distribution system conditions with respect to corrosion scale 

(e.g., pipes extracted from the distribution system), 2) new lead, copper, and/or brass materials 

representative of new construction, and 3) lead pipes coupled with copper to represent areas 

where lead service line replacement has occurred. 

 Pipe loops are typically designed as flow-through or recirculating systems. In flow 

through pipe loops, water flows through the pipe a single time as in a real system and is 

discharged to waste. Recirculating pipe loops recirculate the same batch of water through the 

pipes. In both types, water can be stagnated for periods of time to represent water use patterns. 

Water from the pipe loops can be collected and analyzed for a variety of water quality 

parameters including lead, copper, and other corrosion products. Pipes should be conditioned 

prior to water quality changes to achieve a stable rate of metals leaching. 

Uses and Limitations 

 Pipe loops are well suited for determining how distribution or plumbing materials will 

respond to changes in water quality and to evaluate potential corrosion control strategies. One 

advantage is that pipe loops closely simulate actual distribution systems and the conditions under 

which corrosion occurs. One disadvantage is that these studies can require a relatively long time 

to conduct and the setups are more expensive than other corrosion assessment techniques. The 

AwwaRF report titled Internal Corrosion of Water Distribution Systems (AwwaRF and DVGWTechnologiezentrum Wasser 1996) contains a thorough description of assessment technologies 

for corrosion control studies, including a discussion of the benefits and drawbacks of pipe loop 

studies. AwwaRF reports (Economic and Engineering Services, Inc. and Illinois State Water 

Survey 1990; Kirmeyer et al. 1994) describe a standard protocol for a pipe loop system for 

evaluating corrosion control treatment options. 

 

References 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Economic and Engineering Services, Inc. and Illinois State Water Survey. 1990. Lead 

Control Strategies. Denver: AwwaRF and AWWA. 

Kirmeyer, G.J., A.M. Sandvig, G.L. Pierson, and C.H. Neff. 1994. Development of a Pipe 

Loop Protocol for Lead Control. AwwaRF Report 90650 Project #604. Denver: 

AwwaRF. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-12 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

D.5.3 Coupon Studies

Description of Method

 Coupon techniques are used to evaluate the corrosion of a given distribution system metal 

under specific conditions. Coupon techniques place a coupon in water either in a pilot testing 

apparatus or in the distribution system. The coupons are sacrificed periodically for total weight 

loss measurements. 

 Traditional coupon techniques have involved flat metal coupons mounted in a flow 

stream including methods ASTM D2688-83 method B, ASTM G1-81, ASTM G46-76, and the 

Water Research Center Coupon Rig. Other techniques have been developed that use actual pipe 

lengths including ASTM D2688-83 method C, Modified ISWS Coupon sleeve tester, Corps of 

Engineers Research Lab tester, Ringsaulen protocol, and the TZW Karlsruhe protocol. See 

Table 9-3 in the publication, Internal Corrosion of Water Distribution Systems (AwwaRF and 

DVGW-Technologiezentrum Wasser 1996), for a summary description of these techniques. 

Usefulness and Limitations

 Weight loss for lead coupons is generally very low, so interpretation of weight loss data 

using these methods may be challenging. Coupon techniques are best suited for determining 

likely corrosion rates that can be expected for given water quality conditions and a given metal, 

and can be useful in selecting new materials to be used for distribution system expansion or 

rehabilitation. Weight loss measurements have not always correlated well with measurements of 

lead release in water samples (Schock 1996). Therefore, the usefulness of this technique for 

evaluating LCR compliance issues related to lead may be limited, however, they may be of value 

in evaluating copper corrosion and copper release. 

References 

ASTM D2688-83 Method B. 1983a. Standard Test Methods for the Corrosivity of Water 

in the Absence of Heat Transfer (Weight Loss Protocol). Philadelphia: American Society 

for Testing and Materials. 

ASTM D2688-83 Method C. 1983b. Standard Test Methods for the Corrosivity of Water 

in the Absence of Heat Transfer (Machined Nipple Test). Philadelphia: American Society 

for Testing and Materials. 

ASTM G46-76. 1976. Recommended Practise for the Examination and Evaluation of 

Pitting Type Corrosion. Philadelphia: American Society for Testing and Materials. 

ASTM G1-81. 1981. Recommended Practise for Preparing, Cleaning and Evaluating 

Corrosion Test Specimens. Philadelphia: American Society for Testing and Materials. 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-13 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Schock, M. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment: 

Conforming to the Lead and Copper Rule. Presented at NACE Corrosion 1996 

Conference. 

D.5.4. Electrochemical Measurement Techniques

Description of Method

 Corrosion reactions are fundamentally electrochemical reactions which involve the 

transfer of electrons. Electrochemical methods use different tools and measurement techniques 

to measure this electron transfer and derive the underlying corrosion rate of a metal. For 

example, potentiodynamic scans rely on artificial perturbation of the corroding surface by 

impressing a current on it. Resulting changes in surface potential are measured and used to 

derive the corrosion rate. 

 Electrochemical impedance spectroscopy is a relatively new technique that is well suited 

for drinking water applications. It works similarly to other techniques in that an impressed 

current is applied to the surface and the resulting potential is measured. It differs from other 

techniques in that the current is an alternating current instead of a direct current. The results are 

analyzed to create a model of the corroded surface. This can give a picture of all the components 

of a corroding surface such as the polarization resistance of the surface and the presence of a 

passivating layer. 

Other electrochemical techniques that may be useful for online monitoring of corrosion 

include electrical resistance, linear polarization, and electrochemical noise. The 1996 report, 

Internal Corrosion of Water Distribution Systems (AwwaRF and DVGW-Technologiezentrum 

Wasser 1996), provides a summary of electrochemical corrosion assessment methodologies 

including their applications, precision, and equipment requirements. 

 

Uses and Limitations

 Unlike other evaluation tools which measure metals release, electrochemical techniques 

provide an instantaneous measurement of the underlying corrosion rate of the metal. They have 

been shown to be very useful for assessing uniform corrosion of metals such as lead, copper, 

zinc, and brass (AwwaRF and DVGW-Technologiezentrum Wasser 1996). Over the past decade, 

there has been substantial development of these techniques, making them more accessible to 

systems as an operational tool. Advantages of electrochemical techniques include their speed, 

ease of measurement using commercially available software, and the fact the analyses can be 

made without changing the test specimen. 

Electrochemical methods may be unsuitable for surfaces subject to heavy pitting (i.e. 

mild steel or iron). These techniques do not reproduce easily across different conditions and are 

thus more suitable for relative comparisons of corrosion rate rather than measurement of absolute 

values. 

 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-14 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

References 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

 Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy: 

Electrochemical Impedance and Noise. Houston: National Association of Corrosion 

Engineers. 

Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G. 

Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring 

Strategies. AwwaRF Report 90996F Project #2679. Denver: AwwaRF. 

D.5.5 Scale and Solids Analysis 

Description of Method

 Analysis of pipe scales and corrosion solids can reveal useful information on the 

corrosion process itself and effectiveness of various corrosion control strategies. Techniques 

such as X-ray emission spectroscopy, X-ray diffraction, X-ray fluorescence, and scanning 

electron microscopy can provide information on the elemental composition of the corrosion 

scales. Some analytical techniques give detailed information on chemical bonding and structure 

at the surface of the corrosion deposits which is helpful in estimating the probability of 

unintended adverse consequences of treatment or water quality changes (Rego and Schock 

2007). 

Uses and Limitations

 Pipe surface analyses using the techniques described above can be useful for determining 

the composition of corrosion scale and corrosion products, and the effectiveness of current 

treatment practices. Characterization of the corrosion scale can provide insight into the 

mechanisms behind metals release and how water quality changes may alter that existing scale, 

potentially resulting in increased metals release. These techniques can also give information on 

any passivating or barrier layers that can protect pipes from further corrosion. Currently, these 

methods are relatively expensive and the results can be difficult to interpret. As such, laboratory 

analyses of corrosion products are typically used for special studies. 

 

References 

ASTM D934-80. 2003. Standard Practices for Identification of Crystalline Compounds in 

Water Formed Deposits by X-Ray Diffraction. Philadelphia: American Society for 

Testing and Materials. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-15 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Clement, J., A. Sandvig, V. Snoeyink, W. Kriven, and P. Sarin.1998. Analyses and 

Interpretation of the Physical, Chemical, and Biological Characteristics of Distribution 

System Pipe Scales. In Proceedings of the Water Quality Technology Conference. 

Denver: AWWA. 

Rego, C.A. and M.R. Schock. 2007. Case Studies in the Integrated Use of Scale Analyses 

to Solve Lead Problems. In Proceedings of Distribution System Research Symposium. 

Denver: AWWA. 

Smith, S.E., J.S. Colbourne, D.M. Holt, B.J. Lloyd, and A. Bisset. 1997. An Examination 

of the Nature and Occurrence of Deposits in a Distribution System and their effect on 

Water Quality. In Proceedings of the AWWA Water Quality Technology Conference. 

Boston, 17-21 November 17-21. Denver: AWWA. 

D.5.6 Partial System Testing

Description of Method

 In partial system testing, a corrosion control treatment method is tested on a small part of 

the distribution system which has been hydraulically isolated from the rest of the system and 

where water quality conditions can be changed and the impact of that change evaluated. A 

variety of additional corrosion assessment tools can be used during partial system testing, 

including: 

• Supplemental water quality monitoring from residential taps to evaluate changes in 

metals release; 

• Increased baseline monitoring of key water quality parameters; 

• Inserting coupons into the distribution system that can be removed and analyzed; 

• Electrochemical monitoring using on-line devices; and 

• Removal of piping materials for evaluation of the corrosion scale. 

An outreach program should be in place to the customers in that section of the distribution 

system informing them of the test and any changes which they might experience. 

Uses and Limitations

 A partial system test can be very useful in examining system specific issues which might 

not be obvious from pipe loop tests or other laboratory techniques. For example, partial system 

tests can help determine whether a given water quality change might lead to red water incidents 

within the system. 

 A partial system test, however, does not guarantee that problems will not occur in the rest 

of the system as there can still be differences in piping material, water temperatures, soil 

conditions, pipe age and other variables. A partial system test will also require isolating that part 

of the system and communicating closely with customers in that portion of the system. It may 

also require setting up temporary chemical feed facilities, which can be quite expensive and 

difficult to control operationally due to fluctuations in flow. 
Appendix D. Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule Compliance 

Simultaneous Compliance Guidance Manual D-16 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

References 

AwwaRF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd Edition. AwwaRF Report 90508. Project #725. Denver: 

AwwaRF. 

Kirmeyer, G.J., J. Clement, and A. Sandvig. 2000a. Distribution System Water Quality 

Changes Following Implementation of Corrosion Control Strategies. AwwaRF Report 

90764. Project #157. Denver: AwwaRF. 

USEPA. 1992b. Lead and Copper Rule Guidance Manual, Vol. II: Corrosion Control 

Treatment. Prepared by Malcolm Pirnie, Inc. & Black & Veatch. September 1992. 
Appendix E 

Innovative Management Tools for Achieving Simultaneous 

Compliance
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Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Appendix E 

Innovative Management Tools for Achieving Simultaneous 

Compliance

Systems simultaneously complying with the Long Term 2 Enhanced Surface Water 

Treatment Rule (LT2ESWTR), Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR), 

and other drinking water regulations may benefit from a broader, more holistic approach to water 

system management. Therefore, EPA and other organizations are developing integrated, sourceto-tap management programs to assist water systems. These programs can provide a framework 

within which water systems can identify simultaneous compliance concerns, prioritize them, and 

adopt approaches to ensure that they will be in compliance with numerous regulations at the 

same time. 

This appendix identifies existing and developing programs that can help water systems 

comply with regulations and produce consistently high quality water. These programs include 

performance-driven and integrated management approaches that consider treatment processes 

and operating practices throughout the entire water system. Systems are encouraged to consult 

with primacy agencies and other systems with similar treatment facilities and water quality to aid 

in carrying out these programs. 

Performance-Driven Optimization Programs

Several programs have been developed for water systems to optimize treatment plant 

performance and distribution system management. This section briefly describes these programs 

including references for more detailed information. 

Partnership for Safe Water 

The Partnership for Safe Water is a voluntary program organized collaboratively amongst 

EPA, AWWA and other drinking water organizations to optimize water treatment plant 

performance above and beyond regulatory requirements. The Partnership has provided a 

successful approach for systems to improve turbidity removal in their treatment plants and 

reduce microbial risks as addressed in the surface water treatment rules. The Partnership’s 

Information Center, (http://www.awwa.org/science/partnership/InfoCenter/) includes selfassessment checklists, sample reports and fact sheets to help a water system get started. 

QualServe

QualServe is a continuous quality improvement program that helps utilities to improve 

overall service using a self-assessment tool, a peer review process, and a benchmarking 

clearinghouse. The self-assessment tool is a survey of utility employees to gauge their opinions 

and get their buy in and support for improvements. The peer review involves an on-site visit and 

evaluation by a volunteer team of peers from other utilities. Benchmarking is used to track

utility performance and compare it to other utilities, thereby learning from their experiences. 

Additional information can be found on AWWA’s website 

(http://www.awwa.org/science/qualserve/).
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Areawide Optimization Program 

An area-wide optimization program (AWOP) is a multi-state effort in which states work 

together to develop and implement individual state programs to optimize particle removal and 

disinfection capabilities of conventional surface water treatment plants in each state 

(http://www.asdwa.org/index.cfm?fuseaction=Page.viewPage&pageID=523). AWOP is 

designed to assist water systems work toward optimizing their existing treatment processes in an 

effort to increase public health protection. While originally developed to address microbial 

contaminants, AWOP has expanded beyond the original tools and is an ever-changing and evergrowing program that now addresses both microbial contaminants and disinfection byproducts in 

surface water systems. Initial steps are also being taken to investigate how to extend the 

optimization concept to ground water systems. More information is available at the Association 

of State Drinking Water Administrators (ASDWA) website listed in this paragraph.

Microbial and DBP Comprehensive Performance Evaluations

A comprehensive performance evaluation (CPE) is the evaluation phase of EPA’s

Composite Correction Program. A Composite Correction Program is a systematic, 

comprehensive procedure that identifies and corrects a unique combination of factors to improve 

performance at filtration plants using existing facilities. CPEs are designed to identify and 

correct limiting factors in the design, operation, maintenance, and administration of public water 

systems that prevent compliance with drinking water regulations and optimized water system 

operation. CPEs help systems prioritize ways to improve water system operation, and often 

provide options without significant capital improvements as the highest priority option. CPEs 

are designed to ensure that water systems consistently produce high quality drinking water. 

While CPEs have primarily addressed pathogen control, efforts are underway to develop 

a CPE methodology that addresses DBP control. A CPE for microbes or disinfection byproducts 

(DBPs) consists of three components: performance assessment, major unit process evaluation, 

and identification of factors that are limiting performance. The performance assessment 

component determines a facility’s status in achieving compliance for microbial and DBP 

compliance requirements and performance goals and verifies the extent of any performance 

problems at the plant. The major unit process evaluation determines if the various key existing 

treatment processes in the plant, if properly operated, are of sufficient size to meet microbial and 

DBP performance goals at the plant’s current peak instantaneous operating flows. The last and 

most significant component of a CPE is the identification of factors that limit the plant’s 

performance. CPEs are often conducted with the aid of primacy agency personnel or 

consultants.
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

For more information on CPEs, please see:

Association of State Drinking Water Administrators. 2005. Total System Optimization – How Does it Relate to 

AWOP? Area-Wide Optimization Program News. 2(1). March 2005. Contact Alison Dugan at 

dugan.alison@epa.gov or Larry DeMers at LDemersCO@aol.com.

http://www.asdwa.org/index.cfm?fuseaction=Page.viewPage&pageID=523 

Center for Drinking Water Optimization Page (University of Colorado at Boulder) 

http://bechtel.colorado.edu/cdwo/Welcome.html

EPA’s Drinking Water Academy Web site has numerous courses on conducting CPEs. 

http://www.epa.gov/safewater/dwa/course-pwsoper.html

USEPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the Composite Correction 

Program. EPA 625/6-91/027. http://www.epa.gov/ORD/NRMRL/pubs/625691027/625691027.htm

Hegg, B.A. and L.D. DeMers. 2003. Performance Based Training: A Proven Approach to Improve Water 

Treatment Plant Performance. Presented at American Water Works Annual Conference. Anaheim, California. 

(June 15-19, 2003). 

Jeschke, Rick, P.E. Plant Optimization at North Table Mountain Water and Sanitation District. Presented at the 

2004 Joint Annual Conference of the Rocky Mountain Section of the American Water Works Association and 

the Rocky Mountain Water Environment Association. Grand Junction, Colorado. 

http://www.rmwea.org/tech_papers/Admin-finance/NTM_PPT_Pres.ppt

Kentucky Division of Water. Area Wide Optimization Program. 

http://www.water.ky.gov/dw/profi/awop/default.htm

Swanson, Warren J., P.E. Assessing Plant DBP Performance Using the DBP-CPE. Presented at the 2004 Joint 

Annual Conference of the Rocky Mountain Section of the American Water Works Association and the Rocky 

Mountain Water Environment Association. Grand Junction, Colorado 

http://www.rmwea.org/tech_papers/Admin-finance/DBPCPE_final.ppt 

USEPA. 2004c. The Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) Implementation 

Guidance. (Appendix C) EPA 816-R-04-008. 

USEPA. 2002c. Comprehensive Performance Evaluation (CPE): The Basics (Brochure). (EPA 816-F-01-020). 

November 2002. 

USEPA. 1999d. Guidance Manual for Compliance with the Interim Enhanced Surface Water Treatment Rule: 

Turbidity Provisions. EPA 815-R-99-010. 

USEPA. 1998. CPE Training CD Optimizing Water Treatment Plant Performance Using the Composite 

Correction Program. EPA 625/6-91/027. 

USEPA. 1998. Introduction to Comprehensive Performance Evaluations. EPA/625/C-01-011. 

USEPA. Area Wide Optimization Program. http://www.epa.gov/reg3wapd/drinkingwater/optimization/
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Integrated Management Systems

 It can be challenging for water systems to consider the impacts of specific management 

or operations decisions on their entire water system. Efforts have been made to develop or adopt 

management programs that consider the entire water system. For example, ISO 9000 addresses 

general quality management issues, ISO 14001 focuses on protection of the environment, and 

HACCP addresses drinking water safety to the consumer. Most of these programs serve as 

frameworks that managers can use to tailor a source-to-tap management program addressing 

issues and concerns specific to their water system. Because this approach is holistic (source-totap), such programs can serve as effective ways to consider simultaneous compliance issues. 

Integrated management systems are becoming a new trend in the water industry where these 

programs are considered in an integrated manner as one quality assurance system that covers all 

business management aspects, including general quality management (ISO 9000), protection of 

the environment (ISO 14001), drinking water safety to the user (HACCP), and worker health and 

safety. The benefit of implementing one integrated system is that only one audit would be 

required and utility staff will implement only one set of policies and procedures (Martel et al. 

2006). The AwwaRF report, Application of HACCP for Distribution System Protection (Martel 

et al. 2006) describes utility experiences with implementing integrated management systems. 

This section briefly describes these management programs that, if used properly, could help a 

system achieve simultaneous compliance. 

Hazard Analysis and Critical Control Point

 The Hazard Analysis and Critical Control Point (HACCP) program is an integrated risk 

management approach that examines and assesses potential sources of contamination to a 

process and develops control measures to mitigate these risks. HACCP has been used by the 

U.S. Food and Drug Administration for years, and has become an accepted management practice 

internationally to ensure the safety of food. Recent research indicates that HACCP principles 

may be successfully applied to drinking water systems (Martel et al. 2006). This information 

may then be used by drinking water systems to reduce the risk of contamination to the general 

public. A HACCP Plan can be created and implemented by utility staff with appropriate 

knowledge of the chemical, physical, and microbiological hazards in water supplies, and the 

control measures used to manage them. Although outside experts are sometimes utilized as 

advisors to the HACCP team, development of the HACCP Plan should be driven by utility staff 

as successful implementation of the HACCP Plan requires buy-in and support at all levels of the 

organization.

 Seven basic principles are employed: hazard analysis; critical control point identification; 

establishing critical limits; monitoring procedures; corrective actions; verification procedures; 

and record-keeping and documentation. If a deviation occurs that indicates a loss of control, the 

water system detects the deviation and takes the appropriate, defined steps to reestablish control 

in a timely manner and ensure that potentially contaminated water does not reach the consumer 

and cause compliance problems with one or more regulation. 
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

ISO 9001 and 14001

 The International Organization for Standardization (ISO) is the internationally recognized 

source of standards that are commonly applied in Europe, Australia, and Asia. Two ISO 

Standards commonly employed by water utilities include ISO Standards 9001 and 14001. ISO 

Standard 9001 defines a Quality Management System that demonstrates the ability of an 

organization to consistently provide products and services that meet customer needs, regulatory 

requirements and internal goals. ISO Standard 14001 provides management system standards 

that businesses, including drinking water systems, may use to minimize adverse impacts on the 

environment, and to continually improve environmental performance, enabling them to 

simultaneously comply with multiple objectives. ISO 14001 is typically implemented by a 

system’s management staff, possibly with the aid of consultants. 

For additional information on HACCP, please refer to the following resources: 

AIChE. 2000. Guidelines for Chemical Process Quantitative Risk Analysis, Second Edition. Wiley. 

Dewettinck T., E. Van Houtte, D. Geenens, K. Van Hege, and W. Verstraete. 2001. HACCP (Hazard 

Analysis and Critical Control Points) to Guarantee Safe Water Reuse and Drinking Water Production--

a Case Study. Water Science & Technology. 43(12): 31-8. 

Martel, K., G. Kirmeyer, A. Hanson, M. Stevens, J. Mullenger, and D. Deere. 2006. Application of 

HACCP for Distribution System Protection. AwwaRF Project #2856. Denver, CO: AwwaRF.

Mullenger, J., G. Ryan, and J. Hearn. 2002. A Water Authority's Experience with HACCP. Water

Supply. 2(5-6): 149-155. ©© IWA Publishing. 

U.S. Food and Drug Administration. 1997. Hazard Analysis and Critical Control Point Principles and 

Application Guidelines. http://www.cfsan.fda.gov/~comm/nacmcfp.html

U.S. Food and Drug Administration Website. http://www.cfsan.fda.gov/~lrd/haccp.html

World Health Organization. 2004. Water Treatment and Pathogen Control: Process Efficiency in 

Achieving Safe Drinking Water. Edited by M.W. LeChevallier and K.K. Au. ISBN: 1 84339 069 8. 

Published by IWA Publishing, London, UK. 

World Health Organization. 2004. Guidelines for Drinking Water Quality, 3rd Edition. Geneva, 

Switzerland. World Health Organization. 

http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/index.html 
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Additional Resources

AWWA. 1999d. Design and Construction of Small Water Systems. 2nd Edition. 228 pp. Denver: 

AWWA. 

Logsdon, G.S., A.F. Hess, M.J. Chipps, and A.J. Rachwal. 2002. Filter Maintenance and 

Operations Guidance Manual. AwwaRF Report 90908. Project #2511. Denver: AwwaRF. 

For more information on ISO 14001 please see:

American National Standards Institute (ANSI) Website. http://web.ansi.org /

Global Environment & Technology Foundation. Implementing Environmental Management Systems 

(EMS) in Public Entities. http://www.getf.org/projects/muni.cfm

Global Environment & Technology Foundation. 2002. Final Report: Second EMS Initiative for 

Government Entities (2000-2002). Annandale: GETF. 

Global Environment & Technology Foundation. 2000. Final Report: The EPA Environmental 

Management System Pilot Program for Local Government. Annandale: GETF. 

Grant, G., B.Sc., CEA, EMS(LA), CEAS. 2004. ISO 14001 and Drinking Water Quality. 

Environmental Science and Engineering. January, 2004. http://www.esemag.com/0104/xcg.html

International Organization for Standardization. http://www.iso.org

ISO 1400 Information Center. http://www.iso14000.com/

NSF International. 1996. NSF International Environmental Management System Demonstration 

Project - Final Report.

Pennsylvania’s Multi State Working Group Pilot. 1999. The Effects of ISO 14001 Environmental 

Management Systems on the Environmental and Economic Performance of Organizations. March 27, 

1999. http://www.dep.state.pa.us/dep/deputate/pollprev/Tech_Assistance/mswgreport1.htm

Redaud, J.L. 2005. ISO/TC 224 “Service Activities Relating to Drinking Water Supply Systems and 

Wastewater Systems - Quality Criteria of the Service and Performance Indicators". ISO. March 31, 

2005. http://www.pacinst.org/inni/WATER/ISOTC224Description.pdf

Roig, R. and A. Saponara. 2003. ISO 14001 Environmental Management Systems: A Complete 

Implementation Guide. ISO. Available for purchase from: http://www.stpub.com/pubs/allpubs.htm

USEPA Web site. Voluntary Environmental Management Systems/ISO 14001. 

http://www.epa.gov/owm/iso14001/

USEPA Mid-Atlantic Region Web site. http://www.epa.gov/region3/ems/emslinks.htm
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Lauer, B. 2001. Self-Assessment for Treatment Plant Optimization, International Edition.

AWWA Publication. 256 pp. Denver: AWWA. 

Renner, R.C. and B.A. Hegg. 1997. Self-Assessment Guide for Surface Water Treatment Plant 

Optimization. AwwaRF Report 90736. Project #274. Denver: AwwaRF. 

Smith, C.D. (editor). 2005. Water Distribution System Assessment Workbook. 85 pp. Denver: 

AWWA. 

Westerhoff, G.P., D. Gale, P.D. Reiter, S.A. Haskins, J.B. Gilbert, and J.B. Mannion. 1998a. The

Changing Water Utility: Creative Approaches to Effectiveness and Efficiency. Denver: AWWA.
Appendix E. Innovative Management Tools for Achieving Simultaneous Compliance 

Simultaneous Compliance Guidance Manual E-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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Appendix F 

Considerations for Systems Complying with the Ground Water Rule 
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Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-1 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Appendix F 

Considerations for Systems Complying with the Ground Water Rule 

Ground water systems will likely face challenges similar to those faced by surface water 

systems when making treatment or operational changes to comply with the Stage 2 DBPR.

Unique challenges, however, may emerge when systems make treatment or source changes to 

comply with the Ground Water Rule (GWR), particularly when adding a disinfectant for the first 

time. This appendix focuses on these unique challenges for systems complying with the GWR, 

referring to the main body of this guidance manual for additional information as appropriate. 

This appendix begins with a brief overview of the GWR, focusing on the provisions that 

involve a decision to add or change treatment, or to change to an alternate source of water. This 

overview is followed by a discussion of corrective actions that could potentially create 

simultaneous compliance issues, followed by more detailed discussion of the issues for each type 

of corrective action. A list of references where the reader can find additional information is 

presented at the end of this appendix and in Chapter 7 of this manual. 

Additional guidance on complying with the GWR will be included in the following EPA 

publications: 

x Complying with the Ground Water Rule: Small Entity Compliance Guide 

x Consecutive System Guide for the Ground Water Rule 

x Ground Water rule Corrective Action Guidance Manual 

x Ground Water Rule Source Water Monitoring Guidance Manual 

x Ground Water Rule Source Water Assessment Guidance Manual 

x Ground Water Rule Sanitary Survey Guidance Manual 

x The Ground Water Rule Implementation Guidance 

These guidance manuals are under development and will be posted on EPA’s website 

when they are complete. (http://www.epa.gov/safewater/disinfection/gwr/compliancehelp.html)

F.1 Overview of the Ground Water Rule 

The GWR applies to all public water systems (PWS) serving ground water (except those 

serving only ground water under the direct influence of surface water) including: 

x Wholesale systems that supply ground water; 

x Consecutive systems that buy ground water; and 

x Mixed systems that use both surface water and ground water (except systems that 

blend all of their ground water with surface water or ground water under the direct 

influence of surface water prior to treatment under the Surface Water Treatment 

Rules).
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-2 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

The GWR uses a targeted risk-based approach for systems susceptible to fecal 

contamination and employs four major components: 

x Periodic sanitary surveys 

x Source water monitoring 

x Corrective action 

x Compliance monitoring 

Under the GWR, a system is required to take corrective action if it is found to have a 

significant deficiency. Significant deficiencies are defined by the states, and may be found 

during sanitary surveys or at another time when a regulator is visiting a system. If a system is 

found to have a significant deficiency it must do at least one of the following: 

x eliminate the source of contamination; 

x correct the significant deficiency; 

x provide an alternate source of water; and/or

x provide treatment that achieves 4-log virus inactivation or removal.

Systems that choose to provide 4-log virus inactivation or removal or that already provide 

such inactivation or removal must monitor to demonstrate 4-log virus inactivation or removal. 

Systems may also be required to undertake actions as a result of monitoring. Under the 

GWR triggered monitoring requirements, systems that experience a positive total coliform 

sample during TCR monitoring are required to monitor their source water for a fecal indicator. In 

addition, states may require source water assessment monitoring on a monthly basis for a fecal 

indicator. If a system detects a fecal indicator via either process, it may be required by the state 

to take five additional source water samples and have them analyzed for a fecal indicator. 

Alternatively, a state may require the system to take corrective action without collecting the 

additional samples. If any of the five additional samples are positive for the fecal indicator, the 

system must take corrective action by either eliminating the source of contamination, providing 

an alternate source of water, or providing treatment that achieves 4-log virus inactivation or 

removal. Systems that choose to provide 4-log virus inactivation or removal or that already 

provide such inactivation or removal must monitor to demonstrate continuing 4-log virus 

inactivation or removal. 

F.2 Corrective Actions of the Ground Water Rule That Could Create 

Simultaneous Compliance or Operational Issues 

The corrective action provisions involve a decision-making process about treatment, 

source water, and other actions such as eliminating the contamination source or correcting a 

significant deficiency as illustrated in Exhibit F.1. The remainder of this appendix provides 

information for systems that may be implementing corrective actions involving new treatment, a 

treatment change, or an alternate source of water. It is these systems that are more likely to face 

simultaneous compliance challenges and other operational issues as the GWR is implemented. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-3 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

Exhibit F.1 Decision Tree for Identifying Potential Simultaneous Compliance 

Issues Associated with GWR Corrective Actions

System is required to 

implement corrective 

action

Does

the system eliminate 

the source of 

contamination or 

correct the significant 

deficiency?

No change in treatment 

or source water so no 

expected simultaneous 

compliance issues

Does the 

system provide 

4-log 

inactivation or 

removal of 

viruses?

The system provides an 

alternate source of water, 

for potential simultaneous 

compliance issues see 

section F.5

Does the 

system use 

membranes 

alone to achieve 

4-log virus 

removal?

See Section F.4 for 

potential simultaneous 

compliance issues

Does the system 

use chemical 

disinfection or UV 

alone to achieve 

4-log virus 

inactivation?

The system uses 

combination of technologies 

See sections for individual 

technologies

Does the 

system use 

chlorine to 

achieve 4-log 

virus 

inactivation?

The system uses alternative 

disinfectant for potential 

simultaneous compliance 

issues see Section:

F.3.2.1 for Ozone

F.3.2.2 for UV

F.3.2.3 for Chlorine Dioxide

Does the 

system 

already 

disinfect?

See section F.3.1.1 for 

potential simultaneous 

compliance issues

See Section F.3.1.2 for 

potential simultaneous 

compliance issues

No

No

No

No

No

No

Yes

Yes

Yes

Yes

Yes

Yes

System is required to 

implement corrective 

action

Does

the system eliminate 

the source of 

contamination or 

correct the significant 

deficiency?

No change in treatment 

or source water so no 

expected simultaneous 

compliance issues

Does the 

system provide 

4-log 

inactivation or 

removal of 

viruses?

The system provides an 

alternate source of water, 

for potential simultaneous 

compliance issues see 

section F.5

Does the 

system use 

membranes 

alone to achieve 

4-log virus 

removal?

See Section F.4 for 

potential simultaneous 

compliance issues

Does the system 

use chemical 

disinfection or UV 

alone to achieve 

4-log virus 

inactivation?

The system uses 

combination of technologies 

See sections for individual 

technologies

Does the 

system use 

chlorine to 

achieve 4-log 

virus 

inactivation?

The system uses alternative 

disinfectant for potential 

simultaneous compliance 

issues see Section:

F.3.2.1 for Ozone

F.3.2.2 for UV

F.3.2.3 for Chlorine Dioxide

Does the 

system 

already 

disinfect?

See section F.3.1.1 for 

potential simultaneous 

compliance issues

See Section F.3.1.2 for 

potential simultaneous 

compliance issues

No

No

No

No

No

No

Yes

Yes

Yes

Yes

Yes

Yes
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-4 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

F.3 Inactivation Using Disinfection 

Inactivation through disinfection is one of several possible corrective actions that could 

be implemented by ground water systems with significant deficiencies or fecal contamination. 

Systems can use free chlorine or a state-approved alternative disinfection technology (40 CFR 

141.403(a)(6)(iv)). The dose required will be set by the state using either existing CT tables or 

state approved alternatives. Exhibit F.2 summarizes EPA’s recommended CT values to achieve 

4-log virus inactivation using the various chemical disinfectants. For UV, the required dose for 

4.0-log inactivation of viruses is 186 millijoules per centimeter squared (mJ/cm2

) (40 CFR 

141.720(d)(1)).

Exhibit F.2 CT Values for Inactivation of Viruses Using Different Disinfectants 

(min*mg/L), pH range 6 - 9

Temperature (o Disinfectant C)

d1 5 10 15 20 25 

Chlorine 12 8 6 4 3 2 

Chlorine Dioxide 50.1 33.4 25.1 16.7 12.5 8.4 

Ozone 1.8 1.2 1.0 0.6 0.5 0.3 

Source: USEPA 1991 

In some cases, systems will already be disinfecting but will need to increase disinfectant 

dose or contact time before the first customer to provide 4-log inactivation of viruses. In other 

cases, systems may be disinfecting for the first time. A ground water system that initiates 

chemical disinfection will be required to meet the Stage 2 DBP Rule (and possibly the Stage 1 

DBPR depending on timing). In addition, systems may face LCR or TCR challenges in balancing 

disinfectant selection, CT requirements, etc. Simultaneous compliance issues specific to chlorine 

and alternative disinfectants are discussed in Sections F.3.1 and F.3.2, respectively. Section 

F.3.1 addresses potential issues for those systems initiating chlorine as well as those systems 

increasing chlorine dose or CT.
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-5 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

F.3.1 Chlorine 

Because chlorine is not a technology that systems will use for LT2ESWTR compliance, 

chlorination is not discussed separately in the main text of this Simultaneous Compliance 

Guidance Manual. Instead, it is used as the baseline for comparison to other disinfection 

technologies. Some ground water systems, however, will either begin chemical disinfection 

using free chlorine, or will increase CT by increasing the free chlorine dose or contact time as a 

corrective action for the GWR. Thus, a brief description of chlorination and an overview of its 

simultaneous compliance issues are provided below. 

Chlorination is the oldest disinfection process used to treat drinking water. This process 

utilizes free chlorine to kill most bacteria, viruses, and other pathogens. Chlorine may be 

introduced into water in the form of gas, sodium/calcium hypochlorite (tablets, solutions, or 

powder), and other compounds. Free chlorine refers to the chlorine that is not combined with 

ammonia or organic nitrogen in the water (i.e., elemental chlorine gas (Cl2), hypochlorous acid, 

and hypochlorite). A free chlorine residual may remain in the water after adequate CT has been 

achieved and thus provide for residual (or secondary) disinfection throughout a water distribution 

system. Residual disinfection can help control biofilm growth in the distribution system and 

protect against pathogen intrusion through cross connections, infiltration, or line breaks.

A free chlorine residual impacts water chemistry in a number of ways that are important 

for water treatment. It increases the oxidation-reduction potential (ORP) of the receiving water. 

The consequences of this effect are system-dependent (White 1999) and subsequently may either 

be advantageous or not. ORP can control the reactions on the surface of pipes, including the 

formation of passivating scales. Changes in ORP can lead to alteration of these reactions and 

release of metals. Lytle and Schock (2005) discovered a change in ORP could cause changes to 

lead-containing scales and release of lead into the water. Chlorine addition also affects pH; 

chlorine gas decreases pH while sodium or calcium hypochlorite increases pH (White 1999). 

Both pH and total alkalinity of water after chlorination must therefore be taken into careful 

consideration.

In general, systems using chlorine to disinfect may have to contend with the following 

issues:

x Chlorinated DBP (TTHM and HAA5) formation 

x Compliance with free chlorine MRDL of 4.0 mg/L (40 CFR 141.65(b)(1)) 

x Taste and odor concerns 

x Change in pH 

x Change in ORP 

x Increased corrosivity towards iron and copper (Cantor et al. 2003) 

F.3.1.1 Initiating Chlorination 

The initiation of disinfection using free chlorine can alter the water chemistry entering 

the distribution system. All of the simultaneous compliance considerations described in section 

3.1 of this appendix apply to most surface water, ground water, and blended water sources. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-6 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

 However, there are some special considerations with regard to initiating disinfection or 

increasing disinfectant dose when using free chlorine for ground water systems. 

Ground water sources are often anoxic, or contain very low levels of dissolved oxygen.

Addition of free chlorine can cause a significant increase in the redox potential of the water, 

which in turn can cause precipitation of dissolved constituents in the source water, and/or 

oxidation and precipitation of dissolved constituents in corrosion scales. Precipitation can lead 

to discolored water reaching the customer’s tap. 

Introduction of a disinfectant residual into the distribution system and the subsequent 

destabilization of corrosion scales can result in sloughing of established biofilms. Release of 

biofilm organisms could impact TCR compliance. Over the long term, however, a disinfectant 

residual is expected to achieve better control over microbial growth (USEPA 2002e) and 

improve TCR compliance. 

The form of free chlorine used for treatment can impact the pH of the finished water, 

depending on the buffering capacity. The use of chlorine gas (hypochlorous acid) can lower the 

pH and the use of sodium hypochlorite can increase the pH. Generally, ground water supplies 

have greater buffering capacity compared to surface water supplies. Thus, pH impacts may be 

less for ground water systems. Potential simultaneous compliance issues associated with 

decreasing pH are discussed in Section 3.4 of the main text of this guidance manual. Increasing 

the pH in ground water systems may enhance precipitation of dissolved metals such as iron and 

manganese. Increasing the pH may also decrease the adsorptive capacity of iron scales for 

arsenic, resulting in increased arsenic levels at the tap.

For ground water systems with low dissolved oxygen (DO), adding chlorine has a similar 

effect on copper corrosion as increasing DO. Consequently ground water systems that 

implement disinfection with chlorine may experience increased copper corrosion and LCR 

compliance challenges. High alkalinity/dissolved inorganic carbon (DIC) ground water systems 

are also susceptible to increased copper corrosion which may be exacerbated when a chlorine 

residual is present (USEPA 2003h; Schock and Fox 2001). 

If organic material is present in the groundwater, adding a disinfectant can form DBPs. If 

the organic concentration is high enough there could be problems complying with the Stage 2 

DBPR (or Stage 1 DBPR depending on the timing). Systems with high organic carbon 

concentrations in their groundwater may need to consider an alternative disinfectant or remove 

the organic carbon to keep DBP levels under the Stage 2 DBPR MCL. 

F.3.1.2 Increasing Chlorine Dose or Contact Time 

Increasing the chlorine dose can also increase the redox potential of water, which can 

cause precipitation of dissolved constituents in the distribution system, and/or oxidation and 

precipitation of dissolved constituents in corrosion scales. Increasing the chlorine dose or contact 

time to achieve CT would most likely have less of this effect than when a system adds 

disinfection for the first time. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-7 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

If a ground water source contains organic material, TTHM and HAA5 levels may 

increase when the chlorine dose is increased, potentially causing problems with compliance with 

the Stage 2 DBPR (or the Stage 1 DBPR depending on timing). Increasing chlorine contact time 

prior to the first customer may be a lesser impact on TTHM and HAA5 formation than 

increasing chlorine dose.

F.3.2 Alternative Disinfectants 

Chapter 5 of this manual presents simultaneous compliance and operational issues 

associated with initiation of chlorine dioxide, ozone, and UV for both surface and ground water 

systems. Some additional considerations for ground water systems are provided below. 

F.3.2.1 Ozone 

Some ground water systems may face challenges in meeting the bromate MCL. As 

discussed in Section 5.2 of this manual, ozone can react with bromide in the source water to form 

bromate, which has an MCL of 10 ppb under the Stage 1 D/DBPR. Ground water sources 

generally have higher levels of bromide than surface waters (USEPA 1999j). Consequently 

ground water systems may face more difficulty in complying with the bromate MCL under the 

Stage 1 and Stage 2 D/DBPR. 

Ground water sources are often anoxic, or contain very low levels of dissolved oxygen.

Addition of ozone can cause a significant increase in the redox potential of the water, which in 

turn can cause precipitation of dissolved constituents in the source water, and/or oxidation and 

precipitation of dissolved constituents in corrosion scales. Precipitation can lead to discolored 

water reaching the customer’s tap. 

Ozonation is a more complex treatment process (compared to liquid feed systems such as 

hypochlorite) which may pose implementation challenges for ground water systems with 

multiple wells. 

Ozonation increases AOC levels. AOC acts as a food source for microbes and can lead 

to increased microbial growth within the distribution system and potential simultaneous 

compliance issues with the TCR, especially for ground water systems that do not provide a 

disinfectant residual. EPA recommends that systems consider AOC reduction through use of 

biological filtration prior to water entering the distribution system. 

F.3.2.2 UV Disinfection 

Simultaneous compliance issues associated with adding UV disinfection are discussed in 

Section 5.3 of this guidance manual. This section presents special considerations for ground 

water systems adding UV to achieve 4-log virus inactivation for the GWR. 

 As noted in Section 5.3, the UV dose needed for 4-log inactivation of viruses is very 

high. At present, EPA is unaware of available challenge testing procedures that can be used to 

validate the performance of UV reactors at dose levels needed for this level of virus inactivation. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-8 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

EPA recommends, therefore, that UV technology be used in a series configuration or in 

combination with other technologies to provide a total 4-log treatment of viruses to meet the 

GWR’s requirements. 

Dissolved minerals such as iron, manganese, and calcium can impact the disinfection 

effectiveness of UV and cause fouling of the UV lamp sleeves. Because ground waters typically 

have higher dissolved mineral content, systems using ground water may face these problems 

more frequently than surface water systems. 

When UV disinfection is applied to water with a free or total chlorine residual, some 

reduction of the residual may occur. The reduction in free chlorine residual is proportional to the 

delivered dose and independent of flow rate (Brodkorb and Richards 2004; USEPA 2006b). The 

reduction in total chlorine residual is also proportional to the delivered dose (Wilczak and Lai 

2006). Ground water systems that already provide a disinfectant residual will need to consider 

the appropriate placement of the UV disinfection system. 

UV systems tend to be more sensitive to power quality than pumping equipment. It is 

possible that the UV system lamps could lose arc, but the pumping system is unaffected, and 

then untreated or inadequately treated water can pass through the system. This could be a 

concern for ground water systems that do not provide residual disinfection. Additionally, 

because ground water systems typically involve pumping, there may be issues with hydraulic 

surge and negative pressures. Careful design and operation are important to address these issues. 

F.3.2.3 Chlorine Dioxide 

Chlorine dioxide dose is limited both by the MRDL of 0.8 mg/L, and the chlorite MCL of 

1.0 mg/L under the Stage 1 DBPR. The dose restrictions and relatively high CT for chlorine 

dioxide, compared to chlorine, under cold water conditions may mean additional new 

infrastructure such as a clearwell is necessary for ground water systems to allow sufficient 

contact time to meet 4-log virus inactivation requirements. 

As discussed in Section 5.4 of this manual, systems using chlorine dioxide must monitor 

daily at entry points to the distribution system. Some ground water systems may have multiple 

entry points thereby increasing overall monitoring requirements, which may be especially 

challenging for small ground water systems. 

Also as discussed in Section 5.4, chlorine dioxide is a strong oxidant and can oxidize 

iron, arsenic, and other inorganics present in source water, causing precipitants to form. Ground 

water sources can have higher levels of these and other inorganic constituents compared to 

surface water systems. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-9 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

F.4 Membrane Processes 

Simultaneous compliance issues and operational concerns associated with using 

membranes to treat surface water and ground water are described in detail in Sections 4.2 and 4.3 

of this guidance manual. Specific considerations when using membrane processes for virus 

removal from groundwater are described here. Items of interest stem primarily from the removal 

of constituents from the feed water and are thus highly dependent on the properties of the 

membrane(s) used and should be considered accordingly.

Membrane systems generally require some form of pretreatment to minimize fouling and 

reduce the number of cleaning periods required. Typically some form of media filtration 

precedes a membrane process, particularly for NF and RO membranes. The type of pretreatment 

process used is primarily dictated by the groundwater chemistry, specifically regarding hardness, 

iron, manganese, calcium, magnesium, sulfate, and silica.

Anoxic groundwater sources that become exposed to the atmosphere during pumping or 

aeration may result in the mineral precipitation and membrane scaling. Systems that aerate the 

groundwater to oxidize the iron, manganese, or other compounds must remove the precipitated 

minerals before they reach the membrane unit to reduce fouling and scaling. 

Reductions in pH, hardness, alkalinity, and other minerals may upset the distribution 

system chemical equilibrium, causing corrosion and/or scale destabilization. This may lead to 

compliance issues with the LCR. Post-treatment of membrane product waters may be required 

for those treated using NF and RO membranes to reduce the corrosivity of the water. 

Before installing membranes, ground water systems should be sure to factor in increased 

capital and O&M costs associated with pre- and post-treatment requirements, especially for 

ground water systems with multiple wells. 

F.5 Selection of an Alternative Source 

A ground water system may decide to provide an alternate source of water as a corrective 

action under the GWR. Selecting an alternative source may be more technically and 

economically feasible than other corrective actions using the existing source.

Ground water systems considering an alternate source as their corrective action for the 

GWR will face similar challenges to systems that select an alternate source to comply with the 

Stage 2 DBPR or LT2ESWTR. These issues are discussed in section 3.1 of this guidance 

manual and summarized below. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-10 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

x Blending of different waters when only one of multiple sources is replaced; 

x Changes in water quality parameters (WQPs) such as DO, temperature, pH, 

alkalinity/DIC, redox potential, turbidity, NOM/TOC, dissolved iron and manganese, 

and the presence of other contaminants and need for additional treatment; 

x Impact of the change in WQP on corrosion control for LCR compliance, DBP 

formation (if already disinfecting), or AOC levels that might impact TCR 

compliance; 

x Introduction of new contaminants or higher concentrations of existing contaminants 

(e.g., iron, manganese, hydrogen sulfide); 

x A change in raw water pH that could adversely affect water treatment and compliance 

with the LCR; 

x For GWR systems that are already disinfecting, an alternate source water under 

reduced conditions (e.g., little or no dissolved oxygen) may exert increased 

disinfectant demand; and 

x Changes in aesthetic quality may generate customer complaints. 

References 

AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

Rule Corrosion Control Treatment. Denver: AWWA. 

Brodkorb, T. and D. Richards. 2004. UV disinfection design to avoid chlorine destruction 

in high UVT waters. Presented at Ontario Water Works Association. Niagara Falls, 

Ontario, Canada. May, 2004. 

Cantor, A., J.K. Park, and P. Vaiyavatjamai. 2003. Effect of Chlorine on Corrosion in 

Drinking Water Systems. Journal of American Wwater Works Association. 95(5): 112-

123.

Schock, M.R. and J.C. Fox. 2001. Solving Copper Corrosion Problems while Maintaining 

Lead Control in a High Alkalinity Water using Orthophosphate. Presented at the Ohio 

AWWA Annual Conference. August 30, 2001. Cleveland: AWWA.

U.S. EPA. 1991. Guidance Manual for Compliance with the Filtration and Disinfection 

Requirements for Public Water Systems Using Surface Water Sources. Developed by 

Malcolm Pirnie and HDR. 568 pp. Washington D.C.: USEPA. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-11 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

USEPA. 1999j. M/DBP Stage 2 Federal Advisory Committee (FACA2) Distribution 

Systems & ICR Data Analysis (12 months). 

http://www.epa.gov/safewater/mdbp/st2oct99.html

USEPA. 2002e. Health Risks from Microbial Growth and Biofilms in Drinking Water 

Distribution Systems. Office of Ground Water and Drinking Water. 

USEPA. 2003h. Revised Guidance Manual for Selecting Lead and Copper Control 

Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 

USEPA. 2006b. Ultraviolet Disinfection Guidance Manual for the Final Long Term 2 

Enhanced Surface Water Treatment Rule. Office of Water. EPA 815-R-06-007. 

November, 2006. 

http://www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_uvguidance.pdf

White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. 4th Edition. 

New York: Van Nostrand Reinhold Co. 

Wilczak, A. and H. Lai. 2006. Preliminary bench and pilot evaluation of UV-irradiation 

for nitrification control. In Proceedings of the American Water Works Association Annual 

Conference. June 11 – 16. San Antonio: AWWA. 
Appendix F. Considerations for Systems Complying with the Ground Water Rule 

Simultaneous Compliance Guidance Manual F-12 March 2007 

For the Long Term 2 and Stage 2 DBP Rules 

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