United States 

Environmental 

Protection 

Agency 

Office of Ground Water and 

Drinking Water 

(4601) 

EPA 817-D-06-003 

June 2006 

SIMULTANEOUS COMPLIANCE 

GUIDANCE MANUAL (DRAFT) 

FOR THE FINAL STAGE 2 M-DBP RULES 

1 
1 This page intentionally left blank.
DRAFT - DO NOT CITE OR QUOTE JUNE 2006 i 

1 Note on the Simultaneous Compliance Guidance Manual (DRAFT) for 

2 the Final Stage 2 Microbial and Disinfection Byproducts Rules

3 

4 

5 

6 Purpose: 

7 

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

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

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

11 Drinking Water Act (SDWA) regulations. This draft version of the guidance manual is 

12 specifically intended for stakeholder comments. This guidance is not a substitute for applicable 

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

14 requirements on any party, including EPA, states, or the regulated community. Interested parties 

15 are free to raise questions and objections to the guidance and the appropriateness of its use in a 

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

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

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

19 commercial products does not constitute endorsement or recommendation for use. 

20 

21 

22 Authorship: 

23 

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

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

26 concerning this document should be addressed to: 

27 

28 Tom Grubbs or Jimmy Chen 

29 Office of Ground Water & Drinking Water 

30 U.S. Environmental Protection Agency 

31 Mail Code 4607M 

32 1200 Pennsylvania Avenue NW 

33 Washington, DC 20460-0001 

34 Email: grubbs.thomas@epa.gov or chen.jimmy@epa.gov 

35 

36 
DRAFT - DO NOT CITE OR QUOTE JUNE 2006 ii 

1 Acknowledgments: 

2 

3 Gary Burlingame ― Philadelphia Water Department 

4 Chris Hill ― Malcolm Pirnie, Inc. 

5 Rick Sakaji ― California Department of Health Services 

6 David Schendel ― Malcolm Pirnie, Inc. 

7 Ann Arbor Utilities 

8 City of Englewood, Colorado 

9 Gulf Coast Water Authority 

10 City of Higginsville, Missouri 

11 Kansas City Water Services 

12 Owenton Water Works and Kentucky American TriVillage 

13 Palm Beach County Water Utilities Department 

14 City of Poughkeepsie, New York 

15 Skagit County Public Utility District #1 

16 City of Tampa, Florida 

17 Washington Suburban Sanitary Commission 

18 Village of Waterloo, New York 

19 City of Wilmington, North Carolina

20 
DRAFT - DO NOT CITE OR QUOTE JUNE 2006 iii 

1 Contents

2 

3 1 Introduction............................................................................................................................1-1 

4 1.1 What is the purpose of this guidance manual?.............................................................. 1-1 

5 1.2 What is “Simultaneous Compliance”?..........................................................................1-2 

6 1.3 Does this manual address compliance with environmental regulations other than 

7 SDWA regulations? ...................................................................................................... 1-2 

8 1.4 Who should use this guidance manual and how should it be used? .............................1-2 

9 1.5 How is this manual organized?.....................................................................................1-6 

10 1.6 Can I rely on this guidance manual alone to make compliance decisions?..................1-9 

11 1.7 Are there quick references I can use to screen for potential simultaneous compliance 

12 problems?......................................................................................................................1-9 

13 1.8 What additional resources are available?......................................................................1-9 

14 2 Quick Reference Materials for Simultaneous Compliance....................................................2-1 

15 3 Improving and Optimizing Current Operations.....................................................................3-1 

16 3.1 Source Management...................................................................................................... 3-1 

17 3.1.1 Advantages of Source Management ....................................................................3-4 

18 3.1.2 Potential Operational and Simultaneous Compliance Issues Associated with 

19 Source Management Changes..............................................................................3-5 

20 3.1.3 Recommendations for Gathering More Information ...........................................3-9 

21 3.2 Distribution System Best Management Practices.......................................................3-11 

22 3.2.1 Advantages of Distribution System BMPs ........................................................3-13 

23 3.2.2 Potential Operational and Simultaneous Compliance Issues Associated with 

24 Distribution System BMPs ................................................................................3-14 

25 3.2.3 Recommendations for Gathering More Information .........................................3-16 

26 3.3 Moving the Point of Chlorination...............................................................................3-18 

27 3.3.1 Advantages of Moving the Point of Chlorination..............................................3-19 

28 3.3.2 Potential Operational and Simultaneous Compliance Issues Associated with 

29 Moving the Point of Chlorination......................................................................3-20 

30 3.3.3 Recommendations for Gathering More Information .........................................3-25 

31 3.4 Decreasing pH............................................................................................................. 3-27 

32 3.4.1 Advantages of Decreasing pH ........................................................................... 3-27 

33 3.4.2 Potential Operational and Simultaneous Compliance Issues Associated with 

34 Decreasing pH.................................................................................................... 3-30 

35 3.4.3 Recommendations for Gathering More Information .........................................3-34 

36 3.5 Reducing Chlorine Dose under Warm Water Conditions...........................................3-36 

37 3.5.1 Advantages of Reducing Chlorine Dose under Warm Water Conditions .........3-36 

38 3.5.2 Potential Operational and Simultaneous Compliance Issues Associated with 

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

40 3.5.3 Recommendations for Gathering More Information .........................................3-39 

41 3.6 Modifying Presedimentation Basin Operations..........................................................3-40 

42 3.6.1 Advantages of Modifying Presedimentation Basin Operations.........................3-41 

43 3.6.2 Potential Operational and Simultaneous Compliance Issues Associated with 

44 Modifying Presedimentation Basin Operations.................................................3-41 
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1 3.6.3 Recommendations for Gathering More Information .........................................3-42 

2 3.7 Enhanced Coagulation ................................................................................................3-43 

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

4 3.7.2 Potential Operational and Simultaneous Compliance Issues Associated with 

5 Enhanced Coagulation .......................................................................................3-46 

6 3.7.3 Recommendations for Gathering More Information .........................................3-50 

7 3.8 Enhanced Softening .................................................................................................... 3-53 

8 3.8.1 Advantages of Enhanced Softening................................................................... 3-54 

9 3.8.2 Potential Operational and Simultaneous Compliance Issues Associated with 

10 Enhanced Softening ...........................................................................................3-56 

11 3.8.3 Recommendations for Gathering More Information .........................................3-59 

12 4 Installing New Total Organic Carbon or Microbial Removal Technologies.........................4-1 

13 4.1 Granular Activated Carbon........................................................................................... 4-1 

14 4.1.1 Advantages of GAC............................................................................................. 4-2 

15 4.1.2 Potential Operational and Simultaneous Compliance Issues Associated with 

16 Using GAC........................................................................................................... 4-3 

17 4.1.3 Recommendations for Gathering More Information ...........................................4-6 

18 4.2 Microfiltration/Ultrafiltration .......................................................................................4-8 

19 4.2.1 Advantages of MF/UF ......................................................................................... 4-8 

20 4.2.2 Potential Operational and Simultaneous Compliance Issues Associated with 

21 MF/UF.................................................................................................................. 4-9 

22 4.2.3 Recommendations for Gathering More Information .........................................4-11 

23 4.3 Nanofiltration..............................................................................................................4-13 

24 4.3.1 Advantages of Nanofiltration.............................................................................4-13 

25 4.3.2 Potential Operational and Simultaneous Compliance Issues Associated with 

26 Nanofiltration..................................................................................................... 4-14 

27 4.3.3 Recommendations for Gathering More Information .........................................4-17 

28 4.4 Other Microbial Removal Technologies.....................................................................4-20 

29 4.4.1 Advantages.........................................................................................................4-21 

30 4.4.2 Potential Operational and Simultaneous Compliance Issues.............................4-22 

31 4.4.3 Recommendations for Gathering More Information .........................................4-24 

32 5 Alternative Disinfection Strategies........................................................................................5-1 

33 5.1 Chloramines ..................................................................................................................5-1 

34 5.1.1 Advantages of Chloramines................................................................................. 5-2 

35 5.1.2 Potential Operational and Simultaneous Compliance Issues Associated with 

36 Chloramines .........................................................................................................5-3 

37 5.1.3 Recommendations for Gathering More Information .........................................5-11 

38 5.2 Ozonation....................................................................................................................5-14 

39 5.2.1 Advantages of Ozonation................................................................................... 5-14 

40 5.2.2 Potential Operational and Simultaneous Compliance Issues Associated with 

41 Ozonation...........................................................................................................5-16 

42 5.2.3 Recommendations for Gathering More Information .........................................5-22 

43 5.3 Ultraviolet Light (UV) ................................................................................................5-25 

44 5.3.1 Advantages of UV.............................................................................................. 5-25 
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1 5.3.2 Potential Operational and Simultaneous Compliance Issues Associated with 

2 UV Disinfection................................................................................................. 5-26 

3 5.3.3 Recommendations for Gathering More Information .........................................5-33 

4 5.4 Chlorine Dioxide......................................................................................................... 5-35 

5 5.4.1 Advantages of Chlorine Dioxide ....................................................................... 5-35 

6 5.4.2 Potential Operational and Simultaneous Compliance Issues Associated with 

7 Chlorine Dioxide Use ........................................................................................ 5-37 

8 5.4.3 Recommendations for Gathering More Information .........................................5-42 

9 5.5 Primary and Residual Disinfectant Use ......................................................................5-45 

10 5.5.1 Noteworthy Issues About Disinfectant Combinations.......................................5-48 

11 5.5.2 Recommendations for Gathering More Information .........................................5-48 

12 6 Making Compliance Decisions..............................................................................................6-1 

13 6.1 Introduction...................................................................................................................6-1 

14 6.2 Issues to Consider When Making a Compliance Decision...........................................6-2 

15 6.3 Tools for Gathering Information...................................................................................6-8 

16 6.3.1 Water Quality Monitoring....................................................................................6-9 

17 6.3.2 Hydraulic and Water Quality Modeling for Distribution System......................6-11 

18 6.3.3 Desktop Evaluations ..........................................................................................6-12 

19 6.3.4 Bench-Scale Testing .......................................................................................... 6-14 

20 6.3.5 Pilot Testing....................................................................................................... 6-17 

21 6.3.6 Full-Scale Applications......................................................................................6-18 

22 6.3.7 Cost Estimation..................................................................................................6-20 

23 6.3.8 Community Preferences.....................................................................................6-22 

24 7 References..............................................................................................................................7-1 

25 7.1 References Organized by Topic.................................................................................... 7-1 

26 7.1.1 General................................................................................................................. 7-1 

27 7.1.2 Formation and Control of Chlorinated DBPs ......................................................7-8 

28 7.1.3 Corrosion............................................................................................................ 7-10

29 7.1.4 Source Management........................................................................................... 7-12 

30 7.1.5 Distribution System Management......................................................................7-13 

31 7.1.6 Problem Organisms in Water Treatment ...........................................................7-15 

32 7.1.7 Presedimentation................................................................................................7-16 

33 7.1.8 Enhanced Coagulation and Enhanced Softening ............................................... 7-16 

34 7.1.9 GAC ................................................................................................................... 7-17 

35 7.1.10 Membranes.........................................................................................................7-18 

36 7.1.11 Riverbank Filtration...........................................................................................7-19 

37 7.1.12 Chloramines .......................................................................................................7-19 

38 7.1.13 Ozone ................................................................................................................. 7-21 

39 7.1.14 Ultraviolet Light.................................................................................................7-22 

40 7.1.15 Chlorine Dioxide................................................................................................ 7-24 

41 7.1.16 Tools for Gathering More Information..............................................................7-24 

42 7.2 References Organized Alphabetically.........................................................................7-27 

43 

44 

45 
DRAFT - DO NOT CITE OR QUOTE J vi UNE 2006 

1 Appendices

2 

3 

4 Appendix A Summary of Pertinent Drinking Water Regulations 

5 

6 Appendix B Case Studies 

7 

8 Appendix C Guidelines for Evaluating Potential Impacts of Treatment Changes on 

9 Distribution Systems 

10 

11 Appendix D Tools for Evaluating Impacts of Treatment Changes on Lead and Copper Rule 

12 Compliance 

13 

14 Appendix E Innovative Management Tools for Achieving Simultaneous Compliance 

15 

16 
DRAFT - DO NOT CITE OR QUOTE J vii UNE 2006 

1 List of Exhibits 

2 

3 

4 Exhibit 1.1 Existing SDWA Regulations as of March, 2006 ......................................................1-3 

5 Exhibit 1.2 Organization of the Simultaneous Compliance Guidance Manual – Chapters.........1-7 

6 Exhibit 1.3 Organization of the Simultaneous Compliance Guidance Manual – Appendices ....1-8 

7 

8 Exhibit 2.1 Checklist for Identifying Key Operational and Simultaneous Compliance Issues...2-2 

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

10 Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies: ...................................2-6 

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

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

13 Exhibit 2.6 Tools for Gathering System-Specific Information on Different Treatment 

14 Technologies............................................................................................................ 2-16 

15 

16 Exhibit 3.1 Typical Chlorine Points of Application and Uses................................................... 3-18 

17 Exhibit 3.2 Percent Reduction in DBP Formation by Moving Point of Chlorination ...............3-19 

18 Exhibit 3.3 Impact of pH on Giardia lamblia CT99.9 at 10 ̊C Using Free Chlorine .................. 3-29 

19 Exhibit 3.4 Impacts of pH on Formation of DBPs..................................................................... 3-30 

20 Exhibit 3.5 CT values (CT99.9) for 99.9 percent inactivation of Giardia lamblia cysts by free 

21 chlorine at pH 7.0..................................................................................................... 3-37 

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

23 Corrosionof Piping System Materials......................................................................3-55 

24 

25 Exhibit 5.1 Comparison of CT (mg-min/L) values for Inactivation of Viruses and Giardia by 

Free Chlorine and Chloramines at pH 7 and 10o 26 C..................................................... 5-9 

Exhibit 5.2 CT values (mg-min/L) for Chemical Disinfectants at 10o 27 C....................................5-15 

Exhibit 5.3 Ratio of CT values for Inactivation of Viruses and Cryptosporidium at 10o 28 C .......5-30 

29 Exhibit 5.4 CT Values for Inactivation of Microorganisms by Chlorine Dioxide Compared 

 with Other Chemical Disinfectants at 10o 30 C and pH 6-9 (in mg-min/L).................5-36 

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

32 Chlorine Dioxide...................................................................................................... 5-39 

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

34 Combinations of Primary and Residual Disinfectants.............................................5-46 

35 

36 Exhibit 6.1 Issues to Consider When Deciding How to Comply with Stage 2 DBPR and/or 

37 LT2ESWTR ............................................................................................................... 6-3 

38 Exhibit 6.2 Application of Information Gathering Tools at Various Project Implementation 

39 Stages ......................................................................................................................... 6-9 

40 

41 

42 
DRAFT - DO NOT CITE OR QUOTE J viii UNE 2006 

1 Acronyms 

2 

3 

4 AOC Assimilable Organic Carbon 

5 As(III) Arsenite 

6 As(V) Arsenate 

7 BAT Best Available Technology 

8 BMPs Best Management Practices 

9 BDOC Biodegrable Dissolved Organic Carbon 

10 CDPHE Colorado Department of Health and Environment 

11 CFE Combined Filter Effluent 

12 CPE Comprehensive Performance Evaluation 

13 CT Disinfectant Residual Concentration × Contact Time 

14 CWS Community Water System 

15 DBP Disinfection Byproduct 

16 DBPR Disinfectants and Disinfection Byproducts Rule 

17 DE Diatomaceous Earth 

18 DO Dissolved Oxygen 

19 DOC Dissolved Organic Carbon 

20 EBCT Empty Bed Contact Time 

21 EPA Environmental Protection Agency 

22 FBRR Filter Backwash Recycling Rule 

23 IESWTR Interim Enhanced Surface Water Treatment Rule 

24 GAC Granular Activated Carbon 

25 GWUDI Ground Water Under the Direct Influence 

26 HAA Haloacetic Acid 

27 HAA5 The Sum of Five HAA Species 

28 HOCl Hypochlorous Acid 

29 HPC Heterotrophic Plate Count 

30 HRT Hydraulic Residence Time 

31 ICR Information Collection Rule 

32 IESWTR Interm Enhanced Surface Water Treatment Rule 

33 IFE Individual Filter Effluent 

34 LCR Lead and Copper Rule 

35 LRAA Locational Running Annual Average 

36 LT1ESWTR Long Term 1 Enhanced Surface Water Treatment Rule 

37 LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule 

38 MCL Maximum Contaminant Level 

39 MCLG Maximum Containment Level Goal 

40 M/DBP Microbial Disinfection Byproducts 

41 MF Microfiltration 

42 MGD Million Gallons per Day 

43 MRDL Maximum Residual Disinfection Level 

44 MRDLG Maximum Residual Disinfection Level Goal 
DRAFT - DO NOT CITE OR QUOTE JUNE 2006 ix 

1 MWCO Molecular Weight Cutoff 

2 NF Nanofiltration 

3 NOM Natural Organic Matter 

4 NTNCWS Nontransient Noncommunity Water System 

5 NTU Nephelometric Turbidity Units 

6 OCl Hypochlorite Ion 

7 PAC Powdered Activated Carbon 

8 POTW Publicly Owned Treatment Works 

9 PWS Public Water System 

10 SDWA Safe Drinking Water Act 

11 SDS Simulated Distribution System 

12 SOC Synthetic Organic Chemicals 

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

14 Stage 2 DBPR Stage 2 Disinfectants and Disinfection Byproducts Rule 

15 SUVA Specific Ultraviolet Absorbance 

16 SWTR Surface Water Treatment Rule 

17 TCR Total Coliform Rule 

18 TDS Total Dissolved Solids 

19 THM Trihalomethane 

20 TTHM Total Trihalomethane 

21 TTHMFP Total Trihalomethane Formation Potential 

22 TOC Total Organic Carbon 

23 UF Ultrafiltration 

24 UPS Universal Power Supply 

25 UV Ultraviolet Light 

26 VOC Volatile Organic Compound 

27 WTP Water Treatment Plant 

28 WWTP Wastewater Treatment Plant 

29 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 

2 

3 

4 

5 

6 

7 

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

9 2 Disinfectants and Disinfection Byproducts Rule (DBPR) were developed and promulgated 

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

11 pathogens and disinfection byproducts. EPA recognizes that systems may encounter compliance 

12 issues with the Stage 2 DBPR when making changes to comply with the LT2ESWTR, and vice 

13 versa. In addition to the challenges of complying with the suite of microbial/disinfection 

14 byproduct (M-DBP) rules simultaneously, a water system must also ensure that changes in 

15 treatment do not adversely affect compliance with other drinking water regulations. 

16 

17 This chapter answers the questions: 

18 

19 1.1 What is the purpose of this guidance manual? 

20 1.2 What is “simultaneous compliance”? 

21 1.3 Does this manual address compliance with environmental regulations other than 

22 Safe Drinking Water Act regulations? 

23 1.4 Who should use this guidance manual? How should it be used? 

24 1.5 How is this manual organized? 

25 1.6 Can I rely on this guidance manual alone to make compliance decisions? 

26 1.7 Are there quick references I can use to screen for potential simultaneous 

27 compliance problems? 

28 1.8 What additional resources are available? 

29 

30 1.1 What is the purpose of this guidance manual? 

31 

32 The purpose of this guidance manual is to 

33 help water systems and their regulators identify 

34 and mitigate potential simultaneous compliance 

35 issues that may arise when systems make changes 

36 to comply with the LT2ESWTR and/or the Stage 2 

37 DBPR. The manual also lists possible ways that 

38 simultaneous compliance issues could be 

39 addressed. In addition, tools are recommended and 

40 described to help determine if potential issues may 

41 affect a given system 

42 

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.
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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

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

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

4 LT2ESWTR compliance treatment technologies. Instead, EPA has designed this manual to raise 

5 potential simultaneous compliance issues, and directs readers to other references for more in6 depth information. 

7 

8 1.2 What is “Simultaneous Compliance”? 

9 

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

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

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

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

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

15 

16 1.3 Does this manual address compliance with environmental regulations other than 

17 SDWA regulations? 

18 

19 In addition to regulatory issues, systems should always weigh operational issues and 

20 compliance with other environmental regulations when considering a treatment change. While 

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

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

23 other technical references for addressing these compliance issues. 

24 

25 1.4 Who should use this guidance manual and how should it be used? 

26 

27 This manual should be used by systems 

28 that already know they need to make a change to 

29 comply with the requirements of the LT2ESTWR 

30 and/or the Stage 2 DBPR. It is intended to serve 

31 as a tool for systems and their regulators as 

32 systems select a treatment alternative or 

33 operational change. Example 1.1 shows how 

34 managers of a hypothetical system could use this 

35 manual as they decide on treatment changes to 

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

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

38 

This manual is for systems that 

already know they need to make 

a change in operations or 

treatment. It can also help 

regulators evaluate proposed 

changes.
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 Exhibit 1.1 Existing SDWA Regulations as of March, 2006

2 

Rule Date of 

Promulgation 

Contaminant of 

Concern 

Rule Summary Information 

Available from EPA

Long Term 2 Enhanced Surface 

Water Treatment Rule 

(LT2ESWTR) 

December 2005 Microbial 

Pathogens 

Fact Sheet, included in 

Appendix A 

Stage 2 Disinfectants and 

Disinfection Byproducts Rule 

(Stage 2 DBPR) 

December 2005 Disinfectants 

and 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 

March 2004 Lead and 

Copper 

 Fact Sheet, included in 

Appendix A 

Total Coliform Rule (TCR) June 1989 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 Microbial 

Pathogens 

Quick Reference Guide, 

included in Appendix A 

Long Term 1 Enhanced Surface 

Water Treatment Rule 

(LT1ESWTR) 

January 2002 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 Microbial 

Pathogens 

Summary information on the 

web at 

http://www.epa.gov/safewate

r/therule.html#Surface 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 

2 

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 

past source water Cryptosporidium monitoring, 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 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 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. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 

2 

3 

4 

5 

6 

7 

Example 1.2 How This Manual Can Help Regulators Understand Potential 

Simultaneous Compliance Issues 

The state has just received notification of System A’s intent to install 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 prepared to discuss the proposed 

treatment technique with them. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 1.5 How is this manual organized? 

2 

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

4 guidance manual. 

5 

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

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

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

9 causing simultaneous compliance problems. 

10 

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

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

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

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

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

16 chloramines. Within these chapters, each section on a treatment technique is organized as 

17 follows: 

18 

19 • A summary of Advantages of the treatment technique

20 

21 • Potential Operational and Simultaneous Compliance Issues, including 

22 recommendations for addressing each issue 

23 

24 • Recommendations for Gathering More Information, including suggestions for 

25 additional monitoring, tools that are available for collecting additional system 

26 information, and a short description of related case studies.

27 

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

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

30 applicable and helpful for making their compliance decisions. 

31 

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

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

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

35 for corrosion, and general water treatment references. 

36 

37 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 Exhibit 1.2 Organization of the Simultaneous Compliance Guidance Manual – 

2 Chapters

3 

4 

5 

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 

• 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 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 

2 Exhibit 1.3 Organization of the Simultaneous Compliance Guidance Manual – 

3 Appendices 

4 

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. 

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 (LCR) 

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 Programs Water Systems 

Can Use to Achieve 

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. 

5 

6 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 

2 1.6 Can I rely on this guidance manual alone to make compliance decisions? 

3 

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

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

6 this manual as a tool to identify potential issues and possible solutions to those issues. Chapter 7 

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

8 more information as they plan treatment modifications. 

9 

10 Each state may have its own rules and regulations pertaining to treatment modifications. 

11 For example, many states have review and approval procedures that must be followed before 

12 making any compliance decisions. Systems should contact their state or EPA office for further 

13 information. 

14 

15 1.7 Are there quick references I can use to screen for potential simultaneous compliance 

16 problems? 

17 

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

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

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

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

22 

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

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

25 Benefits and Potential Conflicts 

26 • Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications 

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

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

29 Technologies 

30 

31 1.8 What additional resources are available? 

32 

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

34 references are discussed below. 

35 

36 The 1999 M-DBP Simultaneous Compliance Guidance Manual 

37 

38 The Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

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

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

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

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

43 Some readers may be more comfortable with that layout. Since several issues discussed in the 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 1999 manual continue to be issues that present challenges for systems trying to comply with the 

2 LT2ESWTR and Stage 2 DBPR, EPA recommends that readers also consider referring to the 

3 1999 manual for guidance. 

4 

5 Additional EPA References

6 

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

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

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

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

11 references include the following: 

12 

13 • Handbook: Optimizing Water Treatment Plant Performance Using the Composite 

14 Correction Program (USEPA 1998a) 

15 

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

17 

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

19 

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

21 

22 • Guidance Manual for Compliance with the Interim Enhanced Surface Water 

23 Treatment Rule: Turbidity Provisions (USEPA 1999d)

24 

25 • Unfiltered Systems Guidance Manual (USEPA 1999e) 

26 

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

28 Water and Ground Water Under the Direct Influence (GWUDI) of Surface Water

29 (USEPA 1999g) 

30 

31 • Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual 

32 (USEPA 1999h) 

33 

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

35 (USEPA 2001a)

36 

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

38 (USEPA 2001c)

39 

40 • Draft LT2ESWTR Toolbox Guidance Manual (USEPA 2003a) 

41 

42 • Draft Ultraviolet Disinfection Guidance Manual (USEPA 2003b) 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 1 INTRODUCTION 

 

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1 

2 • Draft Stage 2 DBPR Implementation Guidance (USEPA 2006b)

3 

4 • Draft Significant Excursion Guidance Manual (USEPA 2003c)

5 

6 • Draft LT2ESWTR Implementation Guidance (USEPA 2006c)

7 

8 • Draft Filter Surveillance Manual (USEPA 2004a)

9 

10 • Draft Coagulation Control Manual (USEPA 2004b)

11 

12 • Draft Process Monitoring Manual (USEPA 2004c) 

13 

14 • Membrane Filtration Guidance Manual (USEPA 2005b)

15 

16 Information on future guidance manuals to be published in conjunction with the Stage 2 

17 DBPR and LT2ESWTR can be found on EPA’s website at 

18 http://www.epa.gov/safewater/disinfection/lt2/compliance.html and 

19 http://www.epa.gov/safewater/disinfection/stage2/compliance.html. 
1 This page intentionally left blank. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 QUICK REFERENCE MATERIALS 

 

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1 

2 

3 

4 

5 

6 

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

8 to quickly identify potential simultaneous compliance issues. 

9 

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

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

12 systems or systems with limited resources. 

13 

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

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

16 UV will increase CT for Cryptosporidium, it may decrease CT for viruses. 

17 

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

19 individual LT2ESWTR and Stage 2 DBPR compliance technologies. For some treatment 

20 strategies listed, no significant impact on drinking water regulations is anticipated. 

21 Systems may, however, encounter other challenges, such as an increase in waste residuals 

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

23 

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

25 LT2ESWTR and Stage 2 DBPR compliance technologies. 

26 

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

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

29 dealt with simultaneous compliance issues with past regulations and in anticipation of the 

30 Stage 2 DBPR and LT2ESWTR. 

31 

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

33 system may be affected by a treatment change. 

34 

2 Quick Reference Materials for 

Simultaneous Compliance 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 Exhibit 2.1 Checklist for Identifying Key Operational and Simultaneous Compliance 2 

3 If you are considering a treatment modification or a new treatment to meet the LT2ESWTR or Stage 2 DBPR, th

4 you see if you might have problems complying with other drinking water regulations. If you answer “yes” to any 5 go to the section in Chapter 3, 4, or 5 that addresses your treatment change. There you will find a list of potentia6 compliance issues, suggestions for how to address them, and other helpful information. 7 

Yes No

□ □ Will you be getting less CT as a result of the treatment change? If you answered “yes” and are a s

you must conduct disinfection profiling. 

□ □ Will the treatment change cause an increase (seasonal or permanent) in organic carbon? If yes, 

have problems complying with the Stage 1 DBPR, the Stage 2 DBPR, or the TCR. 

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

more corrosive and you could have problems complying with the LCR. 

□ □ Will you be using a different residual disinfectant? Disinfectant residual changes can impact TCR □ □ Will the treatment change affect the quality of water being filtered? A change in coagulation or pr

affect filter performance and compliance with the LT1ESWTR or IESWTR. 

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

sulfate, chloride, or sodium in your finished water? If yes, your water could become more corrosivproblems 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 coag

your system to produce more sludge)? This is not typically a compliance issue, but increased residupresent operational challenges for your system. 

8 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 Exhibit 2.2 Technology Alternatives and How They Potentially Affect Water Qua2 

CT pH alkalinity disinfectant 

residual1

iron or 

manganese

turbidity NOM DBPs corrosiv

Source Management2

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 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
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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CT pH alkalinity disinfectant 

residual1

iron or 

manganese

turbidity NOM DBPs corrosiv

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

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 

Chloramines3 decrease may 

increase 

TTHM and 

HAA5 will 

decrease 

may 

increase 

decreas
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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CT pH alkalinity disinfectant 

residual1

iron or 

manganese

turbidity NOM DBPs corrosiv

Ozone3 increase for 

protozoa 

may 

decrease, but 

increase in 

bromate 

may 

increase 

decreas

UV Disinfection3 UV dose is 

low for 

protozoa, 

need higher 

dose for 

viruses 

decrease 

Chlorine Dioxide3 increase for 

protozoa, 

decrease for 

viruses 

may 

decrease if 

followed 

by filtration

TTHM and 

HAA5 

decrease, 

chlorite will 

be formed 

1 1 Refers to the disinfectant residual in distribution system water. 2 2 For the purpose of this guidance, source management refers to techniques water systems can use to manipulate their w

3 with Stage 2 DBPR or LT2ESWTR regulations. In this context, source management does not refer to source water prote4 watershed efforts to improve water quality. The source management techniques discussed in this section are operationa5 water systems to use the source with the least amount of natural organic matter (NOM), or selecting a blend of sources t6 most effective treatment for organics and turbidity removal. Source management strategies can affect raw water quality 7 finished water quality directly (e.g., blending or alternating sources). 3 8 Water quality changes for alternative disinfectants are compared to conditions when free chlorine is used. 9 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 Exhibit 2.3 Stage 2 DBPR and LT2ESWTR Compliance Technologies: 2 Summary of Benefits and Potential Conflicts 3 

Used for Compliance 

with Potential Issues 

System 

Modification / 

Compliance 

Technology

Stage 2 

DBPR LT2ESWTR

Potential Benefits

Description

4 

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 

• 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 watetreatment and/or corrosion control • may increase coagulant demand • may increase disinfectant demand 

Distribution System BMPs 

X • targets specific problem areas 

• can improve microbial control • reduces DBPs • can reduce corrosion 

• can stir up sediments • issues with disposal of chlorinated water • lining materials leaching into water • less storage available for emergencies, increase

water loss 

5 

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 reduce CT • increases chances of filter fouling • may impact taste and odor control • may reduce Asiatic clam or zebra mussel control • provides less effective treatment for iron or manganese • may require adjustment of water treatment chemistry • may need to increase disinfectant dosage, which could produce more DBPs 

6 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Decreasing pH X • same CT can be achieved with lower 

disinfectant dose • lower pH may reduce some DBPs 

• may increase HAA5 • may impact ability to filter • can cause corrosion problems • can adversely affect treatment plant equipment • may impact settling and sludge dewatering • solubility of inorganics may increase • varying pH can create changes in distribution system surfaces 

1 

Modifying Chlorine Dose Under Different Temperature Conditions 

X • lower chlorine dose needed for 

microbial protection in warm water • lower chlorine dose when DBP formation rates may be high 

• pathogen concentrations may be higher when water is warm (e.g., recreational waters) • less disinfection when coliform incidents are more common in distribution systems • systems may have trouble maintaining required inactivation 

2 

Presedimentation X • removes Cryptosporidium

• can remove DBP precursors 

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

3 

Enhanced Coagulation 

X • decreases TTHM and HAA5 

• may improve disinfection effectiveness • can reduce bromate formation • can reduce chloroform 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 • can impact Cryptosporidium removal • systems may have issues with disposal of additional residuals • systems may have issues with disposal of residuals with high levels of radioactivity 

4 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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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 

• lowers HAA5 • increases effectiveness of chloramines • two stage plants can achieve Cryptosporidium removal credit • high calcium sludges may de-water more easily 

• lower chlorine effectiveness at high pH • may cause aluminum carryover • may increase scaling in treatment plant and distribution system piping • higher TTHM formation at high pH • need to lower pH before ozonation • prechlorination may reduce TOC removal • increased process residuals • increased concrete corrosion 

1 

Granular Activated Carbon (GAC) 

X X • removes DBP precursors 

• removes taste and odor compounds • if used as secondary filter, removes Cryptosporidium• removes AOC after ozone when used as biological filter 

• may release previously adsorbed compounds • precursor removal may be limited by type of TOC • bacteria can be released • fines can foul downstream processes at startup • water with disinfectant residual should not pass through • ammonia added before GAC may increase nitrification 

2 

Microfiltration/ Ultrafiltration 

 X • removes bacteria and protozoa 

• decreases turbidity • can lower DBPs by allowing lower disinfectant doses 

• pore size will not reliably remove DBP precursors or viruses • although bacteria and protozoa are removed, system must still provide disinfectant residual • may have increased loss of process water 

3 4 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Nanofiltration X X • removes microbial pathogens 

• can remove DBP precursors 

• produces corrosive water • although microbes are removed, system must still provide a disinfectant residual • can lower pH • increased loss of process water 

Watershed Control Program 

X X • reduces microbial risk 

• reduces DBP precursor loading • reduces chemical contamination 

• none known 

Bank Filtration X • increases pathogen removal 

• decreases turbidity • decreases DBP precursors 

• hydraulic issues • iron/manganese problems 

Bag Filtration X • reduces microbial risk • hydraulic issues Cartridge Filtration 

X • reduces microbial risk • hydraulic issues 

• disposal issues 

Second Stage Filtration 

X X • reduces particulate matter 

• reduces DBPs and DBP precursors • reduces microbial risk • reduces assimilable organic carbon (AOC) 

• hydraulic issues • increased residuals 

Slow Sand Filtration 

X • reduces microbial risk 

• may reduce DBP precursors • may improve disinfection effectiveness 

• hydraulic issues 

2 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Diatomaceous Earth (DE) Filtration 

X • reduces microbial risk • hydraulic issues 

2 

Improved Filter Performance 

X • reduces microbial risk 

• reduces chemical contaminants • improves disinfection effectiveness • improves aesthetic quality 

• increased residuals • disposal issues 

Chloramines X • reduce DBPs 

• may improve biofilm control • may increase ability to maintain disinfectant residual throughout distribution system • minimal impact on water treatment plant process • relatively easy to install and operate • may improve taste and odor 

• nitrification may occur in distribution system • may cause corrosion problems with some materials • potential taste and odor problems if improper ratio is used • less help eliminating some taste and odor compounds • can be difficult to blend with other chlorinated sources • weaker disinfectant, increases required CT • ozone and GAC can lead to faster residual deca• issues for dialysis patients, fish owners and industrial users. 

3 

Ozone X X • Inactivates Cryptosporidium and 

Giardia• does not form TTHM or HAA5 • effective pre-oxidant • raises UV transmittance of water • may aid coagulation • can help taste and odor problems 

• forms bromate • forms AOC • does not provide a residual • can cause taste and odor problems • can cause corrosion problems • ozone bubbles can hinder filter performance if not operated properly 

4 5 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 

Used for Compliance 

with System Potential Issues Modification / 

Compliance 

Technology Stage 2 DBPR LT2ESWTR

Potential Benefits

Description 

Ultraviolet (UV) Disinfection 

X X • inactivates Cryptosporidium and 

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

• need higher light intensities to inactivate viruse• does not provide a residual 

2 

Chlorine Dioxide X X • achieves some Cryptosporidium

inactivation • less TTHM and HAA5 formation than with chlorine • can work well for taste and odor control • oxidizes iron and manganese 

• forms chlorite • reduced effectiveness at low temperatures • may be challenged by chlorine dioxide Maximum Residual Disinfectant Level (MRDL) • can form brominated DBPs • degrades under UV light • potential odor problems 

3 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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Topic is marked with an “X” 

if it may be a concern for the

treatment modification 

1 Exhibit 2.4 Potential Operational Issues for Different Treatment Modifications 2 

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 

3 1. It is important to note that costs are associated with any modification or new treatment. This column is meant to identify change4 costly compared to others. Also note that some distribution system BMPs, such as looping dead end pipes, can have relatively h5 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 2. Exhibit 2.5 Case Studies in this Guidance Manual and Issues they Addres2 

Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

1 Moving the Point of 

Chlorination Downstream 

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) 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

6 Enhanced 

Coagulation - Managing Radioactive Residuals 

Allen Water Filtration Plant 

Englewood, Colorado 48,000 8.5 Surface Wate

(river, creek, diversions) 

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 Surface 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) 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

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) 

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) 

1 2 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 2 Q

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1 

2 Exhibit 2.6 Tools for Gathering System-Specific Information on Different Treatment Tec3 

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 Distribution System BMPs X X X Moving the Point of Chlorination Downstream X X X X Decreasing pH X X X X Decreasing Chlorine Dose Under Warm Water Conditions X X X Presedimentation X Enhanced Coagulation X X X X Softening/Enhanced Softening X X X X X GAC X X X Microfiltration/Ultrafiltration X X Nanofiltration X X X Bank Filtration X X Chloramines X X X X X X Ozone X X X X X UV Disinfection X X Chlorine Dioxide X X X X X 

4 
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1 

2 

3 

4 

5 

6 

7 

8 Public water systems (PWSs) may want 

9 to consider whether they can modify their source 

10 water management, treatment processes, or 

11 distribution system operations before taking on 

12 the challenge of installing a new treatment 

13 technology to meet the requirements of the Stage 

14 2 DBPR and LT2ESWTR. This chapter 

15 addresses ways that water systems might change 

16 how they operate their existing facilities to 

17 achieve compliance with the Stage 2 DBPR and 

18 LT2ESWTR, and potential simultaneous 

19 compliance challenges that can arise when such 

20 operational changes are made. 

21 

22 Several of the sections in this chapter 

23 address ways that water systems may change 

24 how they chlorinate. Before making any 

25 changes to disinfection practices, systems that 

26 are required to develop a disinfection profile must calculate a disinfection benchmark for the 

27 treatment configuration currently in place. To learn more about disinfection profiling and 

28 benchmarking, refer to EPA’s Disinfection Profiling and Benchmarking Guidance Manual

29 (1999a). 

30 

31 3.1 Source Management 

32 

33 For the purpose of this guidance, the term source management refers to techniques that 

34 water systems can use to manipulate their water source or sources to comply with 

35 Stage 2 DBPR or LT2ESWTR regulations. In this context, source management does not refer to 

36 source water protection or other long-term watershed efforts to improve water quality. The 

37 source management techniques discussed in this section are operational changes made by water 

38 systems to use the source with the least amount of natural organic matter (NOM), or selecting a 

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

40 

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 Presedimentation 

Basin Operations 

• Enhanced Coagulation 

• Enhanced Softening 
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1 Examples of source management include: 

2 

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

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

5 to draw water from different depths or 

6 locations, depending on the source 

7 water quality during that time of year 

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

9 storm upsets, etc). 

10 

11 • Blending various sources. Systems 

12 that have multiple sources may 

13 consider blending surface and ground 

14 water sources to attain the best blended 

15 raw water for compliance. 

16 

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

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

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

20 of time when impacts are expected or water quality is poor. 

21 

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

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

24 byproduct (DBP) precursors and/or turbidity; the availability of alternate, additional, or new 

25 sources; and the impact the water chemistry change has on the rest of the system. For example, a 

26 system may only have seasonal issues with DBP precursor concentrations and, therefore, may 

27 decide to apply one or more source management techniques on a seasonal basis. 

28 

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

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

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

32 may be able to use source management strategies to avoid or mitigate simultaneous compliance 

33 issues. These factors include: 

34 

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

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

37 bottom of the reservoir can be stirred up and re-suspended. This can lead to an 

38 increase in organic load, algal blooms causing taste and odor, turbidity, and higher 

39 pathogen concentrations entering the plant. 

40 

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. 
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Jar testing should be conducted 

when a system is considering a 

source water change. 

1 • Precipitation events - Heavy rainfall or snowmelt can wash organic matter from soils 

2 into surface water sources. A runoff event upstream of the intake can result in an 

3 increase in organic load and pathogens entering the plant. 

4 

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

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

7 contribute organics to sediment that later become problematic during turnover. Algal 

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

9 Cryptosporidium and Giardia. 

10 

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

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

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

14 stream flow decreases and there is less dilution. 

15 

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

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

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

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

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

21 source. 

22 

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

24 the ground water needs to be considered, including its pH, iron and manganese concentrations, 

25 oxidation reduction (redox) potential of the water, and any nearby contaminant plumes. 

26 

28 While changes to the source may be 

30 advantageous for minimizing DBP precursor 

32 concentrations or turbidity, any major changes in the 

34 source water entering plants are likely to be 

36 accompanied by corresponding changes in other raw 

37 water chemistry. These may include changes in pH, temperature, alkalinity, organics, 

38 inorganics, radionuclides, etc. As a result, these changes will have an impact on the treatment 

39 processes employed by the system and may impact the distribution system as well. Therefore, 

40 when a source water change is considered, water quality monitoring and jar testing should be 

41 conducted to determine the impacts the change in water chemistry will have on the plant, as well 

42 as the stability of the distribution system. 

43 

44 
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1 3.1.1 Advantages of Source Management 

2 

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

4 

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

6 

7 • Reduce amount of disinfectant used 

8 

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

10 

11 Reduce DBPs

12 

13 Selecting a source water or combination of 

14 source waters containing the least amount of 

15 organic matter can reduce finished water DBP 

16 concentrations. The water chemistry of stratified 

17 lakes and reservoirs can change seasonally and vary significantly depending on water depth. 

18 Different depths in a stratified source may contain different concentrations of organics with 

19 different characteristics (e.g., particulate vs. dissolved, high vs. low molecular weight). Water 

20 systems can use this to their advantage by determining the depth containing the lowest DBP 

21 precursor concentrations or precursors that are most easily removed, and then draw their source 

22 water from this depth. Systems should keep in mind, however, that the depth producing the 

23 lowest concentration of DBP precursors may change seasonally. It is important for an effective 

24 source management program to include routine monitoring to detect changes in water quality at 

25 different intake depths and guide decision-making. Section 3.1.3 provides some suggestions for 

26 additional monitoring that can help in this way. 

27 

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

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

30 

31 Reduce Amount of Disinfectant Used

32 

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

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

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

36 chlorine demand than the poorer quality water previously used. 

37 

38 Raw Water Treatability

39 

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

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

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

Routine reservoir monitoring can 

help a system select the best 

intake depth for minimizing 

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

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

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

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

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

6 

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

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

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

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

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

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

13 water. 

14 

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

16 the water. Avoiding algal blooms can also reduce taste and odors compounds, which are 

17 difficult to remove during conventional treatment. 

18 

19 3.1.2 Potential Operational and Simultaneous Compliance Issues Associated with Source 

20 Management Changes 

21 

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

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

24 minimize organic loading or provide optimum conditions for DBP precursor and turbidity 

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

26 

27 • Water temperature changes affecting CT calculations and coagulation and 

28 flocculation 

29 

30 • Introduction of new contaminants or higher concentrations of existing 

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

32 

33 • Variation in raw water pH adversely affecting water treatment 

34 

35 • Reduction in coagulation effectiveness through other chemistry changes or 

36 increased coagulant demand (e.g., alkalinity, type of turbidity) 

37 

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

39 no dissolved oxygen) 

40 

41 • Changes in aesthetic quality may generate customer complaints 

42 
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1 General suggestions for addressing some of these issues that may arise as a result of source 

2 changes are provided below. 

3 

4 Changes in Water Temperature

5 

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

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

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

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

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

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

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

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

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

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

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

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

18 

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

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

21 inactivation and therefore less required CT. 

22 

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

24 and therefore, decreased efficiency of turbidity removal (Faust and Aly 1998). 

25 

26 Recommendations for Addressing this Issue

27 

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

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

30 months. Therefore, the disinfectant concentration (C) may need to be increased. 

31 

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

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

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

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

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

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

38 chemistry change. 

39 

40 Introducing New Contaminants or Higher Concentrations of Existing Contaminants 

41 

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

43 may be introduced or their concentrations may be increased depending on source management 
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1 decisions. For example, in the summer months a system may alternate its surface water source 

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

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

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

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

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

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

8 metals. 

9 

10 Another potential problem with a system introducing new contaminants or contaminants 

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

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

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

14 concentrated in the sludge and backwash water. 

15 

16 Recommendations for Addressing this Issue

17 

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

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

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

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

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

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

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

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

26 option that works best in terms of meeting all treatment goals. 

27 

28 Problems with a Change in Raw Water pH

29 

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

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

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

33 controlled ahead of and through the treatment plant. 

34 

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

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

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

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

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

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

41 

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

43 be in the optimum range for coagulation using pH-dependent coagulants such as alum. Less 
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1 effective coagulation is likely to result in less DBP precursor removal, leaving more DBP 

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

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

4 may pass through the filters if alum is overdosed. If the pH is raised for corrosion control before 

5 the water reaches the distribution system, the aluminum ions that passed through the filters will 

6 then precipitate, causing the water to appear turbid. 

7 

8 Recommendations for Addressing this Issue

9 

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

11 optimum treatment conditions based on the new pH. Systems should ensure that corrosion 

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

13 system. 

14 

15 Reduced Coagulant Effectiveness

16 

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

18 may increase or decrease as a result. An increase in turbidity may require an increased 

19 coagulation chemical demand as well as alkalinity demand depending on the coagulant used. 

20 Water with increased turbidity may be more difficult to treat, especially for systems that are not 

21 optimized or are nearing the design capacity of the coagulation process. A decrease in turbidity 

22 may be a problem if there are not enough particles present for effective coagulation. Fewer 

23 particles can be more difficult to coagulate because they do not come into contact as easily with 

24 one another to form larger flocs that settle well or can be filtered out effectively. Higher influent 

25 turbidity can also lead to higher settled water turbidity and problems with filtration. 

26 

27 Recommendations for Addressing this Issue

28 

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

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

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

32 or temperature change significantly. 

33 

34 Increased Disinfectant Demand for Waters under Reduced Conditions

35 

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

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

38 manganese, and hydrogen sulfide may be present in these waters. These reducing agents are 

39 readily oxidized by disinfectants and, therefore, increase the disinfectant demand. In addition, 

40 dissolved iron and manganese precipitate when oxidized, creating more turbid water and 

41 increasing the particle load onto the filters. 

42 
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1 Recommendations for Addressing this Issue

2 

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

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

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

6 periodic use of an additional oxidant, such as potassium permanganate, to oxidize reduced iron, 

7 manganese, or sulfide (Cooke and Kennedy, 2001). Aerating the water before it is treated can be 

8 another effective way to eliminate reduced conditions. 

9 

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

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

12 additional particle loading onto the filters is not stressing them. Systems should also conduct jar 

13 tests to determine how to adjust their coagulant dose to improve removal of the additional 

14 particle load. 

15 

16 Changes in Aesthetic Quality May Generate Customer Complaints 

17 

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

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

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

21 

22 Recommendations for Addressing this Issue

23 

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

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

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

27 they become problematic by blending sources or by softening processes. 

28 

29 3.1.3 Recommendations for Gathering More Information 

30 

31 See Additional References

32 

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

34 source management. 

35 

36 Consider Additional Monitoring

37 

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

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

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

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

42 quality at its various intake depths can use measurements such as turbidity or TOC to decide 
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1 which intake gates to open and use. Many of these parameters can be monitored in real time to 

2 provide immediate feedback into plant operation. 

3 

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

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

6 the treatment plant: 

7 

8 9 Dissolved Oxygen (DO) 

9 <Ground water and stratified surface water sources 

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

11 

12 9 Temperature 

13 <All sources 

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

15 meter 

16 

17 9 pH 

18 <All sources 

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

20 

21 9 Secchi disk depth 

22 <Lakes and reservoirs to determine water clarity 

23 

24 9 Oxidation-reduction (redox) potential 

25 <Ground water and stratified surface water sources using a field meter, if possible 

26 

27 9 Turbidity 

28 

29 9 Alkalinity 

30 

31 9 NOM measured as TOC or SUVA 

32 

33 9 Dissolved iron 

34 

35 9 Dissolved manganese 

36 

37 9 Hydrogen sulfide 

38 

39 9 Other chemicals known to be problematic for ground or surface water sources in the 

40 area. 

41 

42 9 Chlorophyll a and algal counts 

43 
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1 Consider Other Tools 

2 

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

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

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

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

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

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

9 

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

11 

12 

13 3.2 Distribution System Best Management Practices 

14 Many water quality problems can be addressed by implementing best management 

15 practices (BMPs) for the distribution system. Many of these BMPs are directed at minimizing 

16 the hydraulic residence time (HRT) of the water in the distribution system. Others are aimed at 

17 maintaining appropriate disinfectant residuals while minimizing disinfectant demand. These 

18 BMPs are described in more detail in the Draft Significant Excursion Guidance Manual (USEPA 

19 2003c), in the AWWARF report, Guidance Manual for Maintaining Distribution System Water 

20 Quality (Kirmeyer, 2000b), and in the new AWWA publication, Distribution System Water 

21 Quality Challenges in the 21st Century – A Strategic Guide (AWWA 2005b). While these 

22 BMPs can be particularly effective for systems using free chlorine for residual disinfection, they 

23 can aid any system. 

24 

25 BMPs for the distribution system include the following: 

26 

27 • Overall strategy to reduce HRT in distribution system 

28 

29 • Improving mixing in storage facilities to eliminate stagnant zones 

30 

31 • Minimizing the average HRT in finished water storage facilities 

32 

33 • Decommissioning excess storage 

34 

35 • Minimizing HRT and disinfectant demand in pipes through physical system changes 

36 and flushing 

37 

38 • Booster disinfection 

39 
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1 Overall Strategy to Reduce HRT in Distribution System

2 

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

4 form DBPs. In addition to higher DBP concentrations, excessive water age can result in other 

5 water quality problems including reduced levels of residual chlorine, reduced effectiveness of 

6 chlorine residual through formation of organochlorine compounds, increased microbial activity, 

7 nitrification, and taste and odor problems. Water systems should develop an overall strategy to 

8 manage the water age in their distribution systems. Water age can be controlled through a 

9 variety of techniques including management of finished water storage facilities, flushing of 

10 piping in the distribution system, looping of dead-ends, re-routing of water by changing the 

11 settings on valves, and using blow-offs to move water. The next several sections provide more 

12 detailed steps systems can take as part of this overall strategy. 

13 

14 Improving Mixing in Storage Facilities

15 

16 Improving mixing in finished water storage facilities can help eliminate stagnant zones. 

17 Old water in stagnant zones can often have very high DBPs and no or low disinfectant residual. 

18 This water can be released into the system during periods of high demand. Mixing can be 

19 improved by increasing inlet momentum, changing the inlet configuration, increasing the fill 

20 time, and by installing mixing devices within the storage facility. Hydraulic experts should be 

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

22 configuration. 

23 

24 Minimizing the Average HRT in Storage Facilities

25 

26 Increasing volume turnover reduces the average HRT in finished water storage facilities, 

27 thereby reducing DBP formation. This BMP can also reduce disinfectant loss and microbial 

28 growth. Turnover can be accomplished by increasing the water level fluctuation or drawdown 

29 between fill and draw cycles. Increasing the number of cycles per day may help if the cycles are 

30 deep into the facility and not minor fluctuations. Converting tanks to hydraulic plug-flow 

31 conditions and eliminating common inlet/outlet configurations can also reduce average HRT. 

32 

33 Decommissioning Excess Storage

34 

35 Decommissioning excess storage may also be an appropriate strategy if finished water 

36 storage facilities are oversized and not needed for emergency conditions or for maintaining 

37 system pressure. Removing excess storage facilities that retain water for long periods can help 

38 reduce overall system water age. 

39 

40 Minimizing HRT and Disinfectant Demand in Pipes

41 

42 Minimizing the HRT in pipes can help reduce the time available for DBP formation, 

43 although it is possible for an increase in HAA5 to occur because of less biological degradation. 
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1 Reducing HRT can also minimize disinfectant residual loss and allow systems to use a lower 

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

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

4 blow-offs, and replacing oversized pipes. These can be expensive, however, and cost prohibitive 

5 for some systems. HRT can also be reduced through flushing, particularly if it is targeted at 

6 areas with very long residence times. 

7 

8 Systems can reduce the disinfectant residual demand by replacing, cleaning, or lining cast 

9 iron pipes with materials that are less prone to microbial growth or have less potential for 

10 consuming oxidants. Chlorine demand can also be reduced through unidirectional flushing 

11 programs, aimed at removing sediment and scale from the system that would otherwise exert a 

12 disinfectant demand. 

13 

14 Booster Disinfection

15 

16 In certain instances, booster disinfection can reduce DBP formation by allowing the 

17 disinfectant residual to be lowered at the plant and boosting disinfectant only in those areas 

18 where it is necessary to maintain an adequate residual. This BMP can reduce DBPs at the plant 

19 and throughout the system. 

20 

21 3.2.1 Advantages of Distribution System BMPs 

22 

23 The main advantages of distribution system BMPs are that many are relatively cost 

24 efficient ways to control DBPs in the distribution system and can be implemented in a short time 

25 without the need for major treatment plant improvements. Other advantages to using distribution 

26 system BMPs may include: 

27 

28 • Target specific problem areas rather than the entire system 

29 

30 • Improve microbial control as well as reduce DBP formation 

31 

32 • Improve chlorine residual maintenance 

33 

34 • Reduce corrosion 

35 

36 • Reduce nitrification 

37 

38 Target Specific Problem Areas

39 

40 Many of the BMPs such as flushing, booster disinfection, pipe lining and replacement, and 

41 those dealing with finished water storage facilities can target specific problem areas rather than 

42 apply a solution to the entire system. This can lead to lower DBPs throughout the system. 

Distribution System BMPs can be a 

relatively cost efficient way to 

control DBPs in the distribution 

system.
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1 Improve Microbial Control

2 

3 In additional to reducing DBP formation, most BMPs will improve microbial control by 

4 helping to maintain a disinfectant residual and/or reducing biofilms and sediments that encourage 

5 biological growth. Improved microbial control can result in fewer Total Coliform Rule (TCR) 

6 violations, fewer violations of the Surface Water Treatment Rule (SWTR) requirement to 

7 maintain a disinfectant residual, and less potential for microbiologically-induced corrosion. 

8 

9 Improve Chlorine Residual Maintenance

10 

11 Long hydraulic residence times, microbial growth, and corrosion products will all deplete 

12 the disinfectant residual. The BMPs seek to reduce these factors and will therefore result in 

13 higher and more consistent residuals throughout the distribution system. 

14 

15 Reduce Corrosion

16 

17 Corrosion can cause Lead and Copper Rule (LCR) compliance problems, aesthetic 

18 problems, and may eventually lead to leaks that can be sources of contamination to the system. 

19 Corrosion of cast iron pipes can provide a habitat for microorganisms and increase the likelihood 

20 of TCR violations. Some BMPs, such as pipe replacement or lining, can reduce corrosion. 

21 

22 Reduce Nitrification 

23 

24 The occurrence of nitrification in chloraminated systems can be reduced through the use of 

25 distribution system BMPs. Reducing water age and controlling microbial growth will help 

26 reduce nitrification episodes. Reducing chlorine demand will slow the decay of chloramines and 

27 provide less free ammonia for nitrification. 

28 

29 3.2.2 Potential Operational and Simultaneous Compliance Issues Associated with 

30 Distribution System BMPs 

31 

32 Challenges of implementing the BMPs depend largely on the specific BMP. Examples of 

33 some of these challenges include: 

34 

35 • Re-suspension of sediments 36 

37 • Issues with disposal of disinfected water 38 

39 • Lining materials leaching into the water 40 

41 • Less storage available for emergencies 42 

43 • Increased water loss 

44 
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1 Flushing Can Stir Up Sediments

2 

3 Some BMPs such as increasing storage pumping rates, using blow-offs, or flushing of 

4 pipes can cause re-suspension of sediments that had settled in the storage facilities or pipes. 

5 Sediments can also accumulate in storage tanks, and increasing drawdowns can resuspend the 

6 sediments. These sediments can cause temporary aesthetic complaints and may also contain 

7 microbes or particulate metals such as lead, copper, and iron. 

8 

9 Recommendations for Addressing this Issue

10 

11 A properly implemented flushing program can remove the sediments from the pipes and 

12 can result in a positive long term impact. There are many references listed in the Section 7.5, 

13 Distribution System Management, that can that can be used to plan, design, implement, and 

14 monitor a good flushing program that removes sediment from the system and minimizes 

15 aesthetic problems (AWWA 2002b, AWWA 2005b, Kirmeyer et al., 2000b). 

16 

17 Issues with Disposal of Disinfected Water

18 

19 Utilities flushing their distribution systems should be aware of state or local regulations 

20 on disposal of chlorinated or chloraminated water. If flushed water flows directly into natural 

21 waters, systems should consider removing the disinfectant chemicals prior to discharge to protect 

22 the aquatic environment. 

23 

24 Recommendations for Addressing this Issue

25 

26 The AWWARF report, Guidelines for the Disposal of Chlorinated Water (Tikkanen, M. 

27 et al. 2001) provides information on dechlorination techniques in use by water systems. Some 

28 utilities use straightforward field methods such as a bag filled with a de-chlorinating agent placed 

29 in the flowing water, while other systems have sophisticated metering and storage equipment 

30 installed in trailers. 

31 

32 Lining Materials Can Leach Into Water

33 

34 Some lining materials can leach chemicals into the water if not properly handled or 

35 applied. 

36 

37 Recommendations for Addressing this Issue

38 

39 It is important to make sure the lining material has been independently certified against 

40 NSF/ANSI Standard 61. Manufacturers' instructions and appropriate standards should be 

41 followed in lining the pipe and returning it to service as well. In addition to following the 

42 certifying agency’s and manufacturer's recommendations, many utilities will conduct their own 

43 water quality tests for compounds of interest including VOCs and taste and odor causing 
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1 compounds before a new lining is returned or released to service. 

2 

3 Less Storage Available for Emergencies

4 

5 Removing finished water storage facilities from service, while reducing DBPs and 

6 improving microbial control, can result in less storage available for emergencies such as drought, 

7 earthquakes, main breaks, firefighting, etc. To a lesser extent, some of the other finished water 

8 storage BMPs can also reduce the amount of storage available for such events. 

9 

10 Recommendations for Addressing this Issue

11 

12 Before changes are made to finished water storage, an analysis should be made of system 

13 demand and pressure needs and fire flow requirements. This analysis should review appropriate 

14 fire ordinances to determine the amount needed. In addition, emergency storage requirements 

15 need to be addressed. Hydraulic models in combination with source planning can help determine 

16 the amount of water to be maintained in storage in various parts of the system. Section 6.3 

17 identifies several hydraulic models that may be helpful. 

18 

19 Increased Water Loss 

20 

21 Flushing programs will lead to a loss of water. This is an added expense and could be 

22 troublesome in areas where sufficient water supply is a concern. 

23 

24 Recommendations for Addressing this Issue

25 

26 The advantages of system flushing often outweigh the cost of lost water. Systems may, 

27 however, want to minimize water loss through careful design of the flushing program. 

28 Examining customer complaint and water quality records can help to focus flushing to the areas 

29 and times where they are most needed. 

30 

31 3.2.3 Recommendations for Gathering More Information 

32 

33 See Additional References

34 

35 Readers can turn to Section 7.1.5 in Chapter 7 for technical references associated with 

36 implementing distribution system BMPs. 

37 

38 Consider Additional Monitoring

39 

40 The following are some suggestions for additional monitoring that may benefit water 

41 systems implementing distribution system BMPs: 

42 
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1 9 Routine chlorine residual and heterotrophic plate count (HPC-R2A) measurements in 

2 water leaving storage tanks and other distribution system locations with long 

3 residence times and in chloraminated systems. Online chlorine analyzers at storage 

4 facilities can be helpful as well. 

5 

6 9 Increased total coliform, HPC, chlorine residual, and turbidity measurements in 

7 distribution system locations in areas being flushed. 

8 

9 9 Periodic monitoring of pipe metals (e.g., iron if cast iron pipes are used, lead if lead 

10 solder is used) in distribution system regions where corrosion is suspected. 

11 

12 9 Monitoring of pertinent chemicals and odor downstream of pipes that have been 

13 recently lined or replaced. 

14 

15 Consider Other Tools 

16 

17 In addition to water quality monitoring, there are additional tools available in Chapter 6 to help 

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

19 may face when modifying their operation or treatment practices. Examples of tools that can be 

20 used when distribution system best management practices are used for Stage 2 DBPR 

21 compliance include: 

22 

23 • Computer hydraulic and water modeling software, such as EPANET (U.S. EPA 

24 2002b), that can be used to simulate hydraulic detention time and water quality in the 

25 distribution system 

26 

27 • The AWWA manual “Computer Modeling of Water Distribution Systems” (AWWA 

28 2004a) that provides step-by-step instructions for the design and use of computer 

29 modeling for water distribution systems 

30 

31 • The “Stage 2 DBPR Initial Distribution System Evaluation Guidance Manual” (U.S. 

32 EPA 2006a) that provides distribution system water quality monitoring requirements 

33 for the Stage 2 DBPR and can be used to identify locations that tend to have high 

34 DBP levels 

35 

36 • The AwwaRF report, “Guidance Manual for Monitoring Distribution System Water 

37 Quality” (Kirmeyer 2002) which can be used to assist water utilities in implementing 

38 a distribution system water quality data collection and analysis program 

39 

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

41 
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1 3.3 Moving the Point of Chlorination 

2 

3 At conventional surface water treatment plants, chlorine can be added for prechlorination 

4 at either the raw water intake or flash mixer, for intermediate chlorination ahead of the filters, for 

5 postchlorination at the clearwell, or for rechlorination of the distribution system. While 

6 inactivation of pathogenic organisms is its primary function, chlorine is used in drinking water 

7 treatment for several other purposes, including: 

8 

9 • Control of nuisance Asiatic clams and zebra mussels 

10 • Oxidation of iron and manganese 

11 • Improved coagulation 

12 • Taste and odor control 

13 • Preventing algal growth in sedimentation basins and filters 

14 • Removing color 

15 

16 Exhibit 3.1 summarizes the typical uses for each point of chlorine application 

17 

18 

19 Exhibit 3.1 Typical Chlorine Points of Application and Uses 

20 

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 

21 Source: Alternative Disinfectants and Oxidants Guidance Manual, USEPA 1999b. 1 22 Not included as a typical use in the above reference, but documented by research

23 

24 

25 Public water systems with conventional treatment might consider moving the application 

26 point for chlorine downstream within the plant to a point after DBP precursors have been 

27 removed. Depending on the treatment plant, THM formation potential can be decreased by up to 

28 50 percent as a result of precursor removal during coagulation and sedimentation (Singer and 

29 Chang 1989). 

30 
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1 3.3.1 Advantages of Moving the Point of Chlorination 

2 

3 By moving the point of chlorination downstream in the treatment process, a PWS can: 

4 

5 • Reduce DBP concentrations in the finished water 

6 

7 • Reduce amount of disinfectant used 

8 

9 • Facilitate monthly TOC source water monitoring 

10 

11 Reduces DBPs

12 

13 Summers et al. (1996) presented the results from four studies evaluating the impact of 

14 pretreatment on DBP formation. Jar tests were conducted to simulate water treatment through 

15 rapid mix, coagulation, flocculation, and sedimentation. Chlorine was added at various points in 

16 the jar testing to simulate the impact of various dose points on production of DBPs. The results 

17 demonstrate the benefits of delaying the point of chlorination downstream in the treatment train 

18 to take advantage of precursor removal during flocculation and sedimentation processes. Exhibit 

19 3.2 summarizes the results from this study. 

20 

21 

22 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

23 Notes: Source: USEPA 1997 based on Summers et al. 1996 

24 Baseline = Baseline coagulant (alum) dose for optimal turbidity removal (30 mg/L) 

25 Enhanced = Enhanced coagulant (alum) dose for optimal TOC removal ( 52 mg/L)

26 

27 

28 Exhibit 3.2 also includes a comparison of total trihalomethane (TTHM) and haloacetic 

29 acid (five) (HAA5) concentrations when enhanced coagulation was used, and the benefits of 

30 enhanced coagulation for reducing DBP production. The TTHM formation reduction of 21 

31 percent by moving the chlorination point to post sedimentation is more than doubled to 48 

32 percent by enhanced coagulation. The reduction in HAA5 formation increases from 45 to 61 

33 percent under enhanced coagulation with post sedimentation chlorination. Therefore, DBP 

34 control by selecting the optimal dose location and conditions, along with enhanced precursor 

35 removal, can significantly reduce DBP formation. For a more detailed discussion of enhanced 
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1 coagulation and its simultaneous compliance issues, refer to Section 3.7 of this manual. 

2 

3 Reduces Amount of Disinfectant Used

4 

5 If a system moves its point of chlorination downstream after a significant amount of 

6 organic matter has been removed, the chlorine demand of the water will be lower. In some 

7 cases, the system may be able to take advantage of the reduced chlorine demand to reduce the 

8 overall chlorine dose needed to achieve the required CT. The system would benefit not only in 

9 reduced chemical costs, but may also reduce operational costs if they decrease their number of 

10 chlorine injection points. 

11 

12 Facilitates Source Water TOC Monitoring

13 

14 The Stage 1 D/DBPR requires surface water systems (or systems using ground water 

15 under the direct influence of surface water) using conventional filtration treatment to monitor 

16 each treatment plant for TOC. Systems are required to collect TOC samples from the source and 

17 the finished water. Source water TOC samples must be collected prior to any treatment, 

18 including chlorination. 

19 

20 Some PWSs that are required to conduct TOC sampling prechlorinate at or near the 

21 source water intake. These systems currently have to turn off their chlorination in order to 

22 collect a proper source water TOC sample. Although it’s a minor benefit of moving chlorination 

23 downstream in the treatment process, those systems would no longer have to turn off their 

24 chlorination in order to collect their source water TOC sample. 

25 

26 3.3.2 Potential Operational and Simultaneous Compliance Issues Associated with Moving 

27 the Point of Chlorination 

28 

29 Many PWSs benefit from other functions of prechlorination in addition to its use as a 

30 disinfectant. Chlorine can oxidize iron and manganese, improve coagulation, enhance color 

31 removal, improve taste and odor, as well as control biological growth at different stages of 

32 treatment. Because it has several other functions, some PWSs may find that there are drawbacks 

33 to moving the point of chlorination further downstream in the treatment process. Moving the 

34 point of chlorination further downstream in the treatment process can: 

35 

36 • Reduce CT and thus decrease disinfection effectiveness 

37 

38 • Increase filter fouling 

39 

40 • Limit Asiatic clam or zebra mussel control 

41 

42 • Limit coagulation and filtration effectiveness 
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1 

2 • Provide less effective treatment for iron and manganese 

3 

4 • Affect pH of water being treated, possibly requiring adjustment of water 

5 treatment chemistry 

6 

7 • Require a higher disinfectant dosage to meet CT requirements downstream

8 

9 This section discusses these issues and provides some recommendations for addressing them. 

10 

11 Reduces CT

12 

13 Disinfection effectiveness is measured in terms of CT (concentration H contact time). If a 

14 PWS receives CT credit for contact time prior to filtration and then moves its point of 

15 chlorination further downstream in the treatment process, which system may have to adjust its C 

16 to accommodate reduced T. 

17 

18 Recommendations for Addressing this Issue

19 

20 Systems should examine hydraulic conditions and maximize contact time where possible. 

21 Clearwells can be modified (e.g., baffling and/or improved inlet and outlet structures added) to 

22 improve their hydraulic performance. Constructing additional storage or dedicated disinfection 

23 contact basins can also increase CT. 

24 

25 A water system should evaluate the CT that it can achieve downstream of the new 

26 application point to ensure that sufficient CT can be maintained once the point of chlorination 

27 has been moved. The evaluation should be done for the organism for which the disinfectant is 

28 least effective. A system may also want to break up its CT segments into smaller segments. For 

29 example, if the section from the raw water intake until the filters had been considered as a single 

30 section for performing CT calculations and the point of chlorination is moved until after the 

31 flocculation basin, a system can still receive some credit for section between the flocculation 

32 basin and the filters. See the Disinfection Profiling and Benchmarking Guidance Manual

33 (USEPA 1999a) for more details on calculating CT and using segments. This evaluation should 

34 review seasonal impacts on CT (e.g., cold water conditions when higher CT values are needed or 

35 if the water’s pH increases during algae blooms in the warmer water months). 

36 
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1 Potential for Increased Filter Fouling

2 

3 Prechlorination is often used to minimize operational problems associated with biological 

4 growth in water treatment plants. Prechlorination can prevent slime formation on filters, pipes, 

5 and tanks, and reduce potential taste and odor problems associated with such slimes. It can also 

6 prevent algal growth which can clog filters and cause turbidity problems. Many sedimentation 

7 and filtration facilities operate with a small chlorine residual to prevent growth of algae and 

8 bacteria in the launders and on the filter surfaces. 

9 

10 Recommendations for Addressing this Issue

11 

12 If a system is concerned about the potential for algal growth and filter fouling after 

13 prechlorination is stopped, there are alternatives the system can consider. If chlorine is being 

14 added before the coagulation and flocculation steps, operators may want to consider moving the 

15 chlorination point so that it follows these steps but comes before filtration. Adding chlorine 

16 immediately before the filters may be an effective way for the system to prevent filter fouling, 

17 yet not allow the chlorine to come into contact with the water when the water still contains 

18 unsettled DBP precursors (see case study No. 1 in Appendix B). 

19 

20 Systems may be able to eliminate the 

21 prechlorination step at certain times of the year, 

22 and return to prechlorination when microbial 

23 fouling is more likely to occur during the 

24 treatment process, such as when there is algal 

25 growth in the source water. They may also 

26 consider continuing to prechlorinate, but 

27 adjusting the prechlorination dose depending on 

28 source water conditions or water temperature. 

29 

30 Lastly, a system may consider using an alternative preoxidant, such as potassium 

31 permanganate or chlorine dioxide. These oxidants can provide benefits similar to chlorine in 

32 terms of iron, manganese, or algae control without forming significant amounts of TTHM or 

33 HAA5. They can also reduce chlorine demand before chlorination is applied. Readers should 

34 refer to the Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b) for more 

35 information. 

36 

37 Asiatic Clam and Zebra Mussel Control

38 

39 The Asiatic clam (Corbicula fluminea) was introduced to the United States from 

40 Southeast Asia in 1938 and now inhabits almost every river system south of 40E latitude (Britton 

41 and Morton 1982, Counts 1986). This mollusk has invaded many source waters, clogging source 

42 water transmission systems and valves, screens, and meters; damaging centrifugal pumps; and 

43 causing taste and odor problems. 

Adding chlorine immediately 

before the filters may be an 

effective way for the system to 

prevent filter fouling from 

biological growth.
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1 

2 The zebra mussel (Dreissena polymorpha) population in the United States has expanded 

3 very rapidly. Zebra mussels have been found in the Great Lakes, Ohio River, Cumberland River, 

4 Arkansas River, Tennessee River, and the Mississippi River south to New Orleans (Lange 1994). 

5 

6 Many PWSs add chlorine at their intakes to control Asiatic clam and zebra mussel 

7 growth. For those systems with intakes a significant distance from their treatment plants, 

8 prechlorinating for zebra mussel control may allow a substantial amount of time for TTHM or 

9 HAA5 formation prior to any precursor removal process. 

10 

11 Recommendations for Addressing this Issue

12 

13 Systems that add chlorine to control Asiatic clams and have problems with elevated 

14 TTHM or HAA5 concentrations may want to consider using an alternative oxidant, such as 

15 monochloramine or chlorine dioxide, to control clam growth in their systems. If 

16 monochloramine is used, water systems using the monochloramine to also satisfy CT 

17 requirements will need to perform a disinfection benchmark, bearing in mind that the CT 

18 required for viral inactivation using chloramines is substantially greater than that for chlorine, 

19 and should ensure that adequate disinfection is being provided after switching disinfectants. 

20 

21 Cameron et al. (1989) compared the 

22 effectiveness of free chlorine, potassium 

23 permanganate, monochloramine, and chlorine 

24 dioxide for controlling the juvenile Asiatic clam. 

25 Monochloramine was found to be the best for 

26 controlling juvenile clams without forming DBPs. Further research showed that the 

27 effectiveness of monochloramine increased greatly as the temperature increased (Cameron et al. 

28 1989). Belanger et al. (1991) showed that pre-formed monochloramine with excess ammonia 

29 was more effective for controlling Asiatic clams than either total residual chlorine, 

30 monochloramine, bromine, or copper. Chlorination at 0.25 to 0.40 mg/L total chlorine residual 

31 at 20 to 25E C controlled clams of all sizes, but the same dosage had minimal effect at 12 to 15E

32 C. 

33 

34 Systems with elevated DBPs may also want to consider using an alternative zebra mussel 

35 control strategy. Permanganate has been found to be effective for zebra mussel control and has 

36 been used. Chlorine dioxide and ozone have shown promise as effective oxidants that can be 

37 used for zebra mussel control. Antifouling coatings can work by slowly releasing into the water 

38 a toxic substance, often an organo-metallic compound that prevents the zebra mussel larvae from 

39 settling on the pipes. PWSs should check with their State if they are considering a chemical 

40 control method, to make sure that the chemical is approved for use in a drinking water supply. 

41 

Monochloramine was found to 

work well for controlling juvenile 

clams without forming DBPs. 
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1 There are many other approaches to zebra mussel control being developed and tested. 

2 These methods include: 

3 

4 • the use of electrical fields to kill veligers (zebra mussel larvae) 

5 • ultrasonic treatment to prevent settlement 

6 • oxygen deprivation 

7 • sand infiltration beds 

8 • thermal control (AWWA 2003c) 

9 

10 In addition, some polymers have been tested recently that show promise. 

11 

12 Coagulation and Filtration Effectiveness

13 

14 Research has shown that using a preoxidant ahead of coagulation can have a positive 

15 effect on coagulation and filtration with respect to particle removal (Becker et al. 2004). By 

16 moving chlorination to a point after filtration, a water system may find that it needs to develop 

17 new strategies for turbidity and particle control. 

18 

19 Recommendations for Addressing this Issue

20 

21 Water systems moving chlorination to a point after filtration that can no longer achieve 

22 low filter effluent turbidity values or particle counts may want to consider using a preoxidant 

23 other than chlorine to improve filter performance. The strongest preoxidants have shown the 

24 maximum benefit to filtration, so a system can achieve similar benefits by applying chlorine 

25 dioxide or ozone. Systems that choose to do this should consult the Section 5.4 (chlorine 

26 dioxide) or Section 5.2 (ozone) of this guidance manual to determine possible effects of these 

27 steps. 

28 

29 Iron and Manganese Control

30 

31 Although not harmful to human health at the low concentrations typically found in water, 

32 iron and manganese can cause staining and taste problems. Iron and manganese compounds are 

33 treated by oxidation to produce a precipitate that is subsequently removed by sedimentation and 

34 filtration. Systems with high manganese levels should also be aware that a manganese coating 

35 may have developed on their filters when pre-oxidation was practiced. This layer could dissolve 

36 if pre-oxidation is no longer practiced and/or the pH drops (Angara et al 2004). 

37 

38 Recommendations for Addressing this Issue

39 

40 Systems should be careful to consider how eliminating prechlorination may impact other 

41 removal mechanisms during the treatment process. Some may be able to use and alternative 

42 oxidant or reduce their prechlorination dose if the chlorine dose required for iron or manganese 
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1 removal is lower than what is currently being added. The oxidation of iron and manganese can 

2 usually be accomplished while maintaining a minimum residual. Potassium permanganate is an 

3 effective alternative oxidant to chlorine for iron and manganese oxidation and does not result in 

4 TTHM or HAA5 formation. Various alternatives are discussed in greater detail in the 

5 Alternative Disinfectants and Oxidants Guidance Manual (USEPA 1999b) and the Guidance 

6 Manual for Enhanced Coagulation and Precipitative Softening (USEPA 1999h). 

7 

8 Problems with a Change in pH

9 

10 Moving the point of chlorination or 

11 eliminating prechlorination may result in a change in 

12 water pH. Adding gaseous chlorine decreases 

13 water’s pH, whereas adding hypochlorite increases 

14 water’s pH. 

15 

16 Recommendations for Addressing this Issue

17 

18 Water systems that use a coagulant should consider whether the elimination of 

19 prechlorination and the resulting change in pH would require the system to adjust its coagulant 

20 dose or add other chemicals to control pH. Systems with corrosion control should also consider 

21 whether a pH change due to the elimination of prechlorination would require the system to alter 

22 its corrosion control chemical dose. Impacts of pH changes on compliance and operational 

23 issues are described in Section 3.4. 

24 

25 Problems with MRDL Compliance 

26 

27 If prechlorination is reduced or eliminated and contact time is decreased, CT can be 

28 increased by raising the residual concentration through the disinfection zone. If this approach is 

29 taken, high disinfectant residuals may persist into the distribution system. A public water 

30 system, however, must maintain disinfectant residual concentrations that meet the MRDL 

31 requirements of the Stage 1 D/DBPR. The running annual average (RAA) of the free chlorine 

32 residual measured in the distribution system must not exceed the 4.0 mg/L MRDL. Also, if the 

33 chlorine residual in the delivered water is increased, the number of customers that will notice a 

34 chlorinous odor may increase and generate more frequent customer complaints. 

35 

36 3.3.3 Recommendations for Gathering More Information 

37 

38 Read the Case Study

39 

40 For more information on simultaneous compliance issues associated with moving the 

41 point of chlorination and how to address them, see Case Study #1 - Moving the Point of 

42 Chlorination starting on page B-3 of Appendix B. This case study describes how two small 

43 PWSs with high THM concentrations were able to comply with the requirements of the Stage 1 

Impacts of pH changes on 

compliance and operational 

issues associated with pH are 

described in Section 3.4. 
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1 D/DBPR and Stage 2 DBPR by adjusting their coagulation methods and changing the point of 

2 chlorination, while also optimizing distribution operations to minimize water age and optimizing 

3 booster chlorine use. Their greatest operation issue was a need for increased attention to solids 

4 removal as a result of enhanced coagulation. 

5 

6 See Additional References

7 

8 Readers can turn to Sections 7.1.1, 7.1.2, and 7.1.6 in Chapter 7 for technical references 

9 associated with moving the point of chlorination. 

10 

11 Consider Additional Monitoring

12 

13 The following are some suggestions for additional monitoring that may benefit water 

14 systems moving their point of chlorination: 

15 

16 9 Water systems that reduce or eliminate prechlorination should carefully review pH 

17 data to ensure that treatment processes and materials will not be adversely affected. 

18 

19 9 Systems with the potential for iron or manganese problems that move, reduce, or 

20 eliminate prechlorination should consider monitoring for those metals at the entry 

21 point to the distribution system. Those systems with clearwells and long residence 

22 times may want to check whether iron or manganese solids are accumulating in the 

23 clearwell. 

24 

25 9 Customer complaint monitoring can be traced along with color and taste and odor 

26 evaluations to make sure aesthetic quality has not been lost. 

27 

28 9 The impact of algal blooms on sedimentation and filter performance can be tracked 

29 by measuring turbidity and/or particle counts before and after filtration. 

30 

31 Consider Other Tools

32 

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

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

35 issues they may face when modifying their operation or treatment practices. Examples of tools 

36 that can be used when moving the point of chlorination is used as a Stage 2 DBPR compliance 

37 technique include: 

38 

39 • The AwwaRF report “Internal Corrosion of Water Distribution Systems” (AWWARF 

40 and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

41 testing protocols that can be used to evaluate the impacts of pH changes on corrosion 

42 potential. Such pH changes may occur if a utility switches disinfectants 

43 
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1 • The paper “Predicting the Formation of DBPs by the Simulated Distribution System” 

2 published by Koch et al. (1991) can be used to predict the amounts of DBPs that 

3 would form in a distribution system. Key parameters (including chlorine dosage, 

4 incubation temperature, and incubation holding time) are chosen to simulate the 

5 conditions of the treatment plant and the distribution 

6 

7 • The second version of “Water Treatment Plant Model” (U.S. EPA. 2001h.) developed 

8 by USEPA that assists utilities with implementing various treatment changes while 

9 maintaining adequate disinfection and meeting the requirements of the Stage 2 

10 DBPR. 

11 

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

13 

14 

15 3.4 Decreasing pH 

16 

17 Pathogen inactivation by chlorine is affected by 

18 pH. This is because the germicidal efficiency of 

19 hypochlorous acid (HOCl) is much higher than that of 

20 hypochlorite ion (OCl G), and the distribution of chlorine species between HOCl and OClG is 

21 determined by pH. Because HOCl dominates at low pH values (< 7.5), chlorination provides 

22 more effective disinfection at low pH. At high pH values (> 8.0), OCl G dominates, which 

23 causes a decrease in disinfection efficiency. 

24 

25 Public water systems can reduce their pH to increase disinfectant efficiency, enabling 

26 them to lower their disinfectant dose and still achieve the same amount of disinfection, thereby 

27 potentially limiting DBP formation. The system may want to raise the pH again before it enters 

28 the distribution system to avoid corrosion problems within the distribution system. 

29 

30 pH can also impact the reactions between chlorine and NOM, resulting in conditions that 

31 favor either TTHMs or HAA5 formation. At higher pH, more THMs tend to be formed. Lower 

32 pH tends to favor HAA formation. This information can be used by systems to influence TTHM 

33 or HAA5 formation at the plant or in the distribution system by controlling the pH. Systems that 

34 have high TTHM levels but relatively low HAA5 may be able to reduce TTHM formation by 

35 lowering pH. However, these systems will need to pay special attention to corrosion issues. 

36 

37 3.4.1 Advantages of Decreasing pH 

38 

39 Advantages to decreasing pH include: 

40 

41 • The same CT can be achieved with a lower disinfectant dose 

42 

Pathogen inactivation by 

chlorine depends on pH.
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1 • Can reduce formation of some DBPs 

2 

3 Same CT Can Be Achieved with Lower Disinfectant Dose 

4 

5 Virus inactivation studies have shown that 50 percent more contact time is required at pH 

6 7.0 than at pH 6.0 to achieve comparable levels of chlorine inactivation. These studies also 

7 demonstrated that an increase in pH from 7.0 to 8.8 or 9.0 requires six times the contact time to 

8 achieve the same level of virus inactivation (Culp and Culp 1974). 

9 

10 Exhibit 3.3 uses the required CT values in the National Primary Drinking Water 

11 Regulations to show how a PWS complying with the CT requirements for water at a higher pH 

12 value could reduce its pH and decrease its free chlorine residual. For example, at 10EC, pH 7.0 

13 and 1.0 mg/L free chlorine, a water system would need a minimum CT of 112 to achieve 99.9 

14 percent inactivation of Giardia lamblia cysts. If the water temperature were to stay the same but 

15 the water's pH were reduced to 6.5, a minimum CT of 94 would be needed to achieve 99.9 

16 percent Giardia inactivation. Exhibit 3.3 shows that a water system that had been in compliance 

17 with CT requirements for pH 7.0 could reduce its free chlorine residual from 1.0 to 0.6 mg/L and 

18 still have enough CT to satisfy the CT requirement if they reduced their pH to 6.5. 

19 

20 
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1 Exhibit 3.3 Impact of pH on Giardia lamblia CT99.9 at 10 ̊C Using Free Chlorine 

2 

50

100

150

200

6 6.5 7 7.5 8 8.5 9 9.5

pH

Free Chlorine Giardia lamblia CT at 10 degrees 

C

0.6 mg/L

1.0 mg/L

pH=7.0, free Cl 2 = 1.0 mg/L, CT = 112 mg-min/L

pH=7.0, free Cl 2 = 0.6 mg/L, CT = 107 mg-min/L 107

112

pH=6.5, Cl 2 94 = 1.0 mg/L, CT required is 94 mg-min/L

A water system satisfying CT requirements for 1.0 mg/L 

free Cl2 at pH 7.0 would have enough CT to satisfy CT 

requirements for 0.6 mg/L free Cl2 at pH 6.5.

3 

4 

5 Adapted from CT tables in 40 CFR 141.74 National Primary Drinking Water Regulations 

6 

7 

8 Can Reduce DBP Formation

9 

10 The pH of water can impact the formation of halogenated byproducts (Reckhow and 

11 Singer 1985, Stevens et al. 1989). Exhibit 3.4 compares formation of byproducts at three pH 

12 levels (adapted from Stevens et al., 1989). Note that TTHM show generally lower formation at 

13 the lowest pH level. The formation of HAAs, however, generally increases at lower pH levels. 

14 
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1 

2 Exhibit 3.4 Impacts of pH on Formation of DBPs 

3 

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 

4 Source: adapted from Stevens et al. 1989

5 

6 

7 Other studies show that limiting pH levels in the distribution system to less than 8.2 may 

8 help to limit TTHM formation (Edwards and Reiber 1997). Four LCR compliance strategy case 

9 studies showed that TTHM increases were less than 20 percent if the pH shift implemented for 

10 lead and/or copper corrosion control was near neutral (7.0) to less than 8.2. When the pH was 

11 shifted from near neutral to greater than 8.5, TTHM production increased as much as 40 percent. 

12 At one plant, TTHM increases due to pH adjustment ranged from 2 percent at a pH of 8.1 to 43 

13 percent at a pH of 8.7. HAA production was shown to decrease about 10 percent for all of the 

14 pH increases implemented (Edwards and Reiber 1997). 

15 

16 3.4.2 Potential Operational and Simultaneous Compliance Issues Associated with 

17 Decreasing pH 

18 

19 Potential issues associated with reducing pH to enhance chlorine disinfection include: 

20 

21 • May increase HAA5 formation 

22 

23 • Can adversely affect treatment plant structures and coatings (i.e., corrosion of 

24 pipes, tanks, etc.) 

25 

26 • Can affect treatment chemistry, sludge dewatering, and inorganic solubility 

27 

28 • Can cause problems with corrosion control and LCR compliance 

29 

30 • If chlorine dose is reduced during primary disinfection, it may be difficult to 

31 maintain secondary disinfection levels throughout the distribution system. 
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1 HAA5 May Increase

2 

3 Lower pH conditions may result in higher HAA5 concentrations. Reckhow and Singer 

4 (1985) studied humic acid chlorination in laboratory tests and found that trichloracetic acid 

5 concentrations reached a maximum when the water was in the acidic pH range. When pH levels 

6 were increased, trichloroacetic acid concentrations decreased and chloroform (a key component 

7 of TTHM) concentrations increased. Other studies, such as Stevens et al. (1989), have not found 

8 comparable increases in HAA5 concentrations when pH levels decreased from neutral to slightly 

9 acidic. 

10 

11 Recommendations for Addressing this Issue

12 

13 In general, pH values in distribution systems are unlikely to fall in the acidic range given 

14 the requirements of the Lead and Copper Rule and good corrosion control practices. Systems 

15 can conduct simulated distribution system (SDS) studies to simultaneously evaluate impacts of 

16 pH adjustment on both TTHM and HAA5 formation. The results of these bench-scale tests can 

17 help identify the optimal pH for balancing the need to control both TTHM and HAA5. 

18 

19 Systems can also evaluate pH fluctuation trends throughout their distribution systems. 

20 For poorly buffered waters, the pH can tend to drift upward as the water reacts with cement-lined 

21 pipes. Increases in pH throughout the distribution system would tend to favor TTHM formation 

22 and reduce HAA5 formation. 

23 

24 Adverse Effects on Treatment Plant Materials

25 

26 If pH levels are lowered to enhance disinfection, components of the treatment plant may 

27 be adversely affected by the acidic conditions. Metal components of the plant may corrode; 

28 plastic or rubber components may deteriorate more quickly; cement/concrete leaching and 

29 deterioration may be exacerbated. 

30 

31 Recommendations for Addressing this Issue

32 

33 Systems should evaluate the effects of decreased pH on treatment plant components, such 

34 as pipes and linings. Based on their evaluation, systems should adjust the: 

35 

36 • maintenance schedules, 

37 • materials, or 

38 • point of pH adjustment 

39 

40 so that the chances of leaks, leaching, or equipment failure are minimized. 

41 
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A pH change can disrupt 

distribution system surfaces 

causing aesthetic problems 

or the release of inorganic 

contaminants and microbes.

1 Adverse Effects on Treatment Chemistry, Inorganics Solubility, Settling, and Sludge Dewatering

2 

3 Reducing the water pH can cause problems with increased solubility of inorganics, and 

4 may result in increased iron and manganese levels. Lower treated water pH can also result in 

5 recalcification of lime-softened waters, resulting in increased turbidity. Variation of pH levels 

6 can affect treatment chemistry and impact settling and sludge dewatering. System operators 

7 should carefully consider the impacts of pH adjustment before implementing such a significant 

8 change to their treatment process. 

9 

10 Manganese is typically removed from water using direct oxidation/coagulation/filtration 

11 or filter adsorption/oxidation (i.e., green sand). Chlorine is sometimes used for the oxidation 

12 step of this process. A low pH hinders the direct oxidation process because the rate of 

13 manganese oxidation increases as pH increases. Therefore, systems using chlorine or potassium 

14 permanganate for manganese oxidation should be aware that, if the pH is reduced before 

15 manganese oxidation, more time may be needed for the manganese to be removed. 

16 

17 The minimum solubility of aluminum occurs at a pH of 6.2 to 6.5. Those water systems 

18 that use alum as a coagulant and operate at a pH of less than 6.0 that do not increase their pH 

19 before filtration may be impacted by the solubility of aluminum at this low pH. If the pH is not 

20 adjusted before filtration, aluminum carryover problems may result. 

21 

22 Recommendations for Addressing this Issue

23 

24 Systems with high manganese levels that lower the pH prior to filtration may want to 

25 consider using an oxidant that is less pH dependent to oxidize manganese, such as ozone. 

26 Alternatively, a system could choose to lower the pH after oxidation and filtration. 

27 

28 Systems using alum as a coagulant can adjust pH to greater than 6.5 before the filters to 

29 avoid aluminum passing into the distribution system. 

30 

31 Corrosion Control and LCR Problems

32 

33 A lower pH in the distribution system can increase corrosion of cement linings and iron 

34 pipe. It can also favor corrosion of lead and copper plumbing, causing LCR compliance 

36 problems. Corrosion of unlined cast iron water mains 

38 can favor microbial regrowth, which can affect TCR 

40 compliance. 

42 

44 Any changes in the pH levels historically 

46 maintained in a distribution system can disrupt films 

48 and scales that have accumulated on natural corrosion 

49 surfaces. These films and scales have formed over long periods of time and may be helping to 

50 passivate the corrosion process from further development. A pH change can disrupt these 
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Water systems should carefully 

research the implications of 

using a corrosion inhibitor before

adding it as a treatment step. 

Appendix D provides additional 

guidelines for systems 

evaluating their corrosion control 

options and information on 

proper piloting procedures. 

1 surfaces, releasing inorganic contaminants as well as microbes and organic carbon trapped in the 

2 films and scales. Although the disruption of films or scales in the distribution system may not 

3 result in a direct violation of either the DBP or microbial rules, the disruption could cause 

4 aesthetic problems or the release of microbes. Disruption of scale can also cause maintenance 

5 problems in utility facilities such as tanks, valves and pumps, as well as in customer sprinkler 

6 systems and commercial facilities. 

7 

8 Recommendations for Addressing this Issue

9 

10 If pH is lowered during disinfection, systems should consider adjusting pH upward and 

11 possibly adjusting alkalinity before the water enters the distribution system to reduce corrosion 

12 of pipe materials. If finished water pH is reduced, the system should consider other corrosion 

13 control strategies. 

14 

16 Systems can control corrosion by optimizing pH, 

18 alkalinity, and dissolved inorganic carbon (DIC). 

20 Another alternative is to add a corrosion inhibitor that is 

22 phosphate- or silica-based to form a protective coating 

24 on pipes. Some utilities, however, have elected not to 

26 use phosphate-based corrosion inhibitors because the 

27 publicly owned treatment works (POTW) receiving the wastewater has phosphorus limits in their 

28 NPDES and sludge disposal permits. 

29 

31 Regardless of the type of corrosion treatment 

33 used, it should be tested before it is introduced, if 

35 possible. Pilot testing is discussed in more detail in 

37 Section 6.5 of this manual. Large systems should 

39 have completed corrosion control studies, as required 

41 by the LCR. Smaller water systems may have 

43 conducted studies if required by the state. Any 

44 system that subsequently changes their treatment must notify the state and may be required to 

45 conduct a new corrosion control study. In any event, LCR corrosion control studies should be 

46 used as a starting point to assess the impacts of changes in distribution system water quality on 

47 corrosion and LCR compliance and determine the best corrosion control treatment strategy. 

48 Appendix D provides additional guidelines for systems evaluating their corrosion control options 

49 and information on proper testing procedures. 

50 

51 Reduced Disinfectant Residual Concentration 

52 

53 Systems that are considering lowering their disinfectant dose to take advantage of 

54 additional CT credit at a lower pH should consider impacts on maintaining the desired 

55 disinfectant residual level throughout the distribution system. A lower disinfectant dose may 

56 mean a lower disinfectant residual concentration leaving the treatment plant if the system does 
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1 not have a chlorine dose point after the clearwells. 

2 

3 Recommendations for Addressing this Issue

4 

5 Additional chlorine will be needed prior to entry to the distribution system, or through 

6 booster disinfection, to account for the decrease in chlorine during primary disinfection. 

7 

8 3.4.3 Recommendations for Gathering More Information 

9 

10 Read the Case Study 

11 

12 For more information on simultaneous compliance issues associated with modifying pH, 

13 see Case Study #2 Modifying pH During Chlorination starting on page B-13 of Appendix B. 

14 This case study describes how one PWS used pH depression via carbon dioxide injection ahead 

15 of the flocculation basins to reduce DBPs and DBP precursors. The system was also able to 

16 increase coagulation efficiency, increase CT throughout the treatment plant (allowing for 

17 reduced chlorine injection), and increase and stabilize pH levels in the distribution system by 

18 increasing the buffering capacity following caustic soda addition. Their greatest operation issue 

19 was a need for a pressurized solution feed to solubilize CO2. 

20 

21 See Additional References

22 

23 Sections 7.1.2 and 7.1.3 in Chapter 7 contain technical references associated with DBP 

24 formation and corrosion, including references on how each process is affected by pH. General 

25 water treatment references in Section 7.1.1 can also provide useful information. 

26 

27 Consider Additional Monitoring 

28 

29 The following are some suggestions for additional monitoring that may benefit water 

30 systems that are reducing their pH during chlorination: 

31 

32 9 If alum is used as a coagulant and pH is not adjusted back up before filtration, 

33 systems should test periodically for aluminum in the finished water. 

34 

35 9 Systems should perform routine pH and alkalinity monitoring at significant locations 

36 throughout the treatment plant, especially after corrosion control chemicals have been 

37 added. 

38 

39 9 Where it may be a problem, systems should perform periodic monitoring of iron and 

40 manganese in the finished water. 

41 
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1 9 Systems can perform additional HPC and total coliform monitoring in the distribution 

2 system near locations where there is reason to believe that scale may have been 

3 dislodged. 

4 

5 9 Systems can track customer complaints, color, and turbidity in the distribution system 

6 if there is reason to believe that changes in pH can affect scales and films. 

7 

8 The purpose of these monitoring suggestions is specifically to address and prevent potential 

9 simultaneous compliance issues. 

10 

11 Consider Other Tools

12 

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

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

15 issues they may face when modifying their operation or treatment practices. Examples of tools 

16 that can be used when modifying pH during chlorination is used for Stage 2 DBPR compliance 

17 include: 

18 

19 • The SDS and material-specific (MS-SDS) procedures described by Koch et al (1991) 

20 and Brereton and Mavinic (2002), respectively, which describe bench-scale and pilot21 scale tests that can be used to evaluate DBP formation under varying chlorine, 

22 temperature, pH conditions 

23 

24 • The AwwaRF report “Internal Corrosion of Water Distribution System” (AWWARF 

25 and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

26 testing protocols that can be used to evaluate changes in corrosion potential due to pH 

27 changes; 

28 

29 • The AwwaRF report “Optimizing Corrosion Control in Water Distribution System” 

30 which provides techniques for instantaneous corrosion monitoring 

31 

32 • The “Guidance Manual for Monitoring Distribution System Water Quality” 

33 (Kirmeyer, 2002) which can be used to assist water utilities in implementing a 

34 distribution system water quality data collection and analysis program 

35 

36 • The second version of “Water Treatment Plant Model” (U.S. EPA 2001h) developed 

37 by USEPA that assists utilities to implement various treatment changes while 

38 maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR. 

39 

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

41 
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1 3.5 Reducing Chlorine Dose under Warm Water Conditions 

2 

3 In general, as temperature increases, chlorine reaction kinetics increase. The increased 

4 kinetics mean that disinfection effectiveness will improve, but it also means rates of DBP 

5 formation reactions will increase. This section discusses the advantages and disadvantages of 

6 adjusting chlorine dose based on the temperature of the source water. 

7 

8 3.5.1 Advantages of Reducing Chlorine Dose under Warm Water Conditions 

9 

10 The main advantage to reducing the chlorine dose under warm temperature conditions is 

11 that fewer DBPs are likely to form when a lower chlorine dose is used. This is especially 

12 pertinent because 

13 

14 • Chlorine doses can be reduced when the water is warmer and still provide 

15 comparable pathogen protection 

16 

17 • TTHM and HAA5 formation tends to be higher when water temperature 

18 increases 

19 

20 Comparable Disinfection Protection with Less Chlorine

21 

22 Since chlorine effectiveness increases at higher temperatures, systems may want to 

23 consider reducing their disinfectant dose in warm weather to reduce the formation of DBPs. 

24 Disinfectant dose may not be lowered below the point of compliance with the CT requirements 

25 dictated by the SWTR (USEPA 1989). 

26 

27 Exhibit 3.5 shows how water temperature affects the amount of CT needed to achieve 3-

28 log Giardia lamblia inactivation using chlorine to disinfect water with a pH of 7.0. Note, for 

29 example, how the CT required at 5.0E C and a free chlorine dose of 1.0 mg/L is 149 mg-min/L. 

30 But when the water temperature increases to 20E C and a free chlorine dose of 1.0 mg/L is used, 

31 the CT required for 3-log Giardia lamblia inactivation decreases to 56 mg-min/L. Many water 

32 systems are able to provide sufficient CT in the summer months and still use a lower 

33 concentration of free chlorine than the concentration they are using during the winter to provide 

34 the same pathogen protection. 

35 

36 Systems should proceed carefully if they choose this option to make sure that they 

37 continue to meet CT requirements and do not diminish microbial quality in the distribution 

38 system. 

39 

40 
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1 Exhibit 3.5 CT values (CT99.9) for 99.9 percent inactivation of Giardia lamblia cysts 

2 by free chlorine at pH 7.0 

3 

Free chlorine residual (mg/L) 0.5° C 5.0° C 10.0° C 15.0° C 20° C 25° C

 0.4 195 139 104 70 52 35 

 0.6 200 143 107 72 54 36 

 0.8 205 146 110 73 55 37 

 1.0 210 149 112 75 56 37

4 Adapted from 40 CFR Part 141 National Primary Drinking Water Regulations § 141.74

5 

6 

7 Less Chlorine When Rate of TTHM and HAA5 Formation Increases

8 

9 By reducing the chlorine dose when water temperatures increase, a system may be able to 

10 reduce the formation of TTHM and HAA5. Krasner et al. (1990) found that the median TTHM 

11 concentrations in 35 systems were highest for those systems with the highest water temperature. 

12 

13 3.5.2 Potential Operational and Simultaneous Compliance Issues Associated with 

14 Reducing Chlorine Dose under Warm Water Conditions 

15 

16 Some potential issues associated with reducing the chlorine dose under warm temperature 

17 conditions are: 

18 

19 • There may be seasonal variations in pathogen concentrations in the source water 

20 (e.g., water is used for recreational purposes, flowing waters with permitted 

21 wastewater discharges when flows are low) 

22 

23 • Some systems may need to maintain a higher disinfectant residual in the summer 

24 months to comply with the TCR 

25 

26 • Systems may encounter higher disinfectant demand in warm months, requiring 

27 higher disinfectant doses in order to meet chlorine demand and provide a stable 

28 finished water 

29 

30 • A reduction in chlorine dose may change the oxidation reduction potential of 

31 water in the distribution system 

32 

33 Seasonal Variability of Pathogen Concentrations in the Source Water

34 

35 Pathogen concentrations may increase in some surface water sources during the summer 

36 months. Concentrations of viruses and enteric bacteria are of particular concern, especially if the 
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1 source water is also used for recreational activity. Other pathogens such as Cryptosporidium

2 have been found to peak during spring runoff. 

3 

4 Recommendations for Addressing this Issue

5 

6 Systems should evaluate uses of their source water and examine historical data to 

7 determine if there is a trend in pathogen occurrence in the warmer months. Systems should also 

8 consider consulting with their states to determine if others have collected data for the same 

9 source. If data are not available, systems may want to collect surveillance fecal coliform or E. 

10 coli samples at their intake to track whether they should be concerned about increased microbial 

11 risk. 

12 

13 Need to Maintain a Higher Residual in Warm Water Months to Comply with the TCR 

14 

15 Increased water temperatures and corresponding increases in organic matter can enhance 

16 coliform re-growth in the distribution system (LeChevallier et al. 1996). At the same time, 

17 increased water temperatures result in faster chlorine residual decay in the distribution system, 

18 which may allow for an increase in biofilm growth. 

19 

20 Recommendations for Addressing this Issue

21 

22 If a PWS is considering reducing its chlorine dose, operators should understand how such 

23 a decrease may affect the chlorine residual concentrations in the distribution system. Although 

24 lower chlorine concentrations may reduce TTHM and HAA5 formation in the distribution 

25 system, systems should carefully monitor the impacts of a low residual on microbial growth and 

26 total coliform occurrence. Unidirectional flushing may also be a practical, cost-effective way to 

27 reduce microbiological problems in the distribution system. 

28 

29 Higher Disinfectant Demand in Warm Water Months 

30 

31 Organic concentrations in raw water may increase in warm weather due to algae blooms, 

32 aquatic plant growth, and other sources, creating an increase in chlorine demand. In addition, 

33 since chlorine reaction rates increase as water temperature increases, chlorine demand and decay 

34 will increase. 

35 

36 Recommendations for Addressing this Issue

37 

38 Systems may need to add higher levels of chlorine to meet the chlorine demand prior to 

39 distribution to maintain an adequate residual. Increases in taste and odor compounds from algal 

40 blooms and other biotic activity may also motivate systems to maintain higher chlorine levels in 

41 the summer months. 

42 
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1 Some systems may want to consider the possibility of maintaining a lower chlorine 

2 residual and boosting chlorination at points throughout the distribution system, rather than 

3 adding a high dose at the entry point to try to maintain a residual throughout the distribution 

4 system. See Section 3.2 for other BMPs that can be used to improve water age and maintain 

5 more consistent disinfectant residuals. 

6 

7 Change in Oxidation Reduction Potential 

8 

9 Systems reducing their chlorine dose may see a change in the oxidation reduction (redox) 

10 potential of their distribution system water. Since less oxidant will be added to the water, water 

11 conditions may be more reduced. As a result, systems may see consequent electrochemical 

12 reduction and dissolution of lead oxide in the distribution system, which could result in higher 

13 lead concentrations at consumers’ taps. Manganese deposits in the distribution system could also 

14 increase causing taste, odor, and color complaints. 

15 

16 Recommendations for Addressing this Issue

17 

18 Operators should measure the redox potential in their distribution system water before 

19 and after the chlorine dose has been decreased. If a measurable change is noted, systems should 

20 watch their lead concentrations closely to see if there is an increase that might be due to the more 

21 reduced conditions. Systems with manganese in their water should track customer complaints 

22 closely to see if manganese deposits have become more of an issue. If these issues arise, the 

23 system should consider pre-treating the water with another oxidant, such as potassium 

24 permanganate. 

25 

26 3.5.3 Recommendations for Gathering More Information 

27 

28 See Additional References

29 

30 Readers can turn to Sections 7.1.1 and 7.1.4 in Chapter 7 for general references 

31 associated with disinfection and technical references related to distribution system management. 

32 

33 Consider Additional Monitoring

34 

35 The following are some suggestions for additional monitoring that may benefit water 

36 systems that are reducing their chlorine dose: 

37 

38 9 Routine raw and finished water monitoring for E. coli and total coliform, especially 

39 during the periods when the system is reducing its chlorine dose. 

40 

41 9 Increased chlorine residual measurements throughout the distribution system. 

42 

43 9 Increased HPC and total coliform surveillance monitoring in the distribution system. 
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1 

2 9 Chlorine demand monitoring prior to chlorine addition for secondary disinfection to 

3 make sure stable water is sent into the distribution system. 

4 

5 9 Inspection of distribution system pipe scales (including service lines and domestic 

6 plumbing) to see if reductions in disinfectant residual and/or lower redox potential 

7 may cause a problematic change in scale integrity and metal release. 

8 

9 The purpose of these monitoring suggestions is specifically to address and prevent potential 

10 simultaneous compliance issues. 

11 

12 Consider Other Tools

13 

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

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

16 issues they may face when modifying their operation or treatment practices. Examples of tools 

17 that can be used when varying the chlorine dosage is used for Stage 2 DBPR compliance include: 

18 

19 • The Guidance Manual for Monitoring Distribution System Water Quality (Kirmeyer 

20 2002) which can be used to assist water utilities in implementing a distribution 

21 system water quality data collection and analysis program 

22 

23 • The Standard Method 2350 (Oxidant Demand/Requirement) (APHA 1998) that 

24 provides step-by-step instructions for the determination of chlorine demand during 

25 various water quality conditions 

26 

27 • The paper “Predicting the Formation of DBPs by the Simulated Distribution System” 

28 published by Koch et al. (1991) that can be used to closely monitor and predict 

29 changes in DBP formation in the distribution system due to frequent chlorine dose 

30 changes 

31 

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

33 

34 

35 3.6 Modifying Presedimentation Basin Operations 

36 

37 Presedimentation basins are basins placed before the rapid mix chamber and the 

38 flocculation basins. Their purpose is to allow large particles and debris to settle out before the 

39 main coagulation process and before any disinfectant is added. Presedimentation basins provide 

40 a buffer to turbidity fluctuations and can lower DBP precursors entering the plant. Existing 

41 basins can be modified to increase Cryptosporidium removal by adding a coagulant or increasing 

42 residence time. 
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1 

2 3.6.1 Advantages of Modifying Presedimentation Basin Operations 

3 

4 The advantages of presedimentation basins include: 

5 

6 • Can lower DBP precursors prior to the addition of disinfectants 

7 

8 • Can possibly achieve 0.5 logs of Cryptosporidium removal credit under the 

9 LT2ESWTR 

10 

11 Lower DBP Precursor Concentrations

12 

13 By modifying presedimentation basins, systems can remove additional DBP precursors 

14 and decrease TTHM and HAA5 formation. Presedimentation basins are especially useful to 

15 systems with high levels of solids in their raw water 

16 or highly fluctuating turbidity. Addition of a 

17 coagulant in the presedimentation basin may increase 

18 the removal of DBP precursors. 

19 

20 Cryptosporidium Removal Credit

21 

22 Systems with presedimentation basins can receive 0.5-log removal credit for 

23 Cryptosporidium. In order to get the credit for the presedimentation basin, all of the plant’s 

24 water must pass through the basin and a coagulant must be added whenever the basin is 

25 operating. Alternatively, systems can conduct their LT2ESWTR monitoring for 

26 Cryptosporidium after the presedimentation basin to determine their treatment bin. If a system 

27 monitors for bin selection after the presedimentation basin, it cannot get the 0.5 log 

28 Cryptosporidium removal credit for the basin. These systems may, however, end up in a lower 

29 treatment bin due to Cryptosporidium removal in the presedimentation basin. See the

30 LT2ESWTR Toolbox Guidance Manual (U.S. EPA 2003a) for additional information on 

31 receiving the removal credit. 

32 

33 3.6.2 Potential Operational and Simultaneous Compliance Issues Associated with 

34 Modifying Presedimentation Basin Operations 

35 

36 Potential issues associated with using presedimentation basins include: 

37 

38 • Algal growth in presedimentation basins can increase DBP precursors 

39 

40 • Removal of settled solids can be difficult 

41 

Addition of a coagulant in the 

presedimentation basin may 

increase the removal of DBP 

precursors. 
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Solids should be removed on 

a regular basis to prevent 

interference with plant 

performance and compliance 

with regulatory requirements.

1 Algal Growth

2 

3 Algae can grow in uncovered presedimentation basins that are not treated with a 

4 disinfectant. The algae can add NOM to the water, increasing the chlorine demand, and can 

5 negate DBP precursor removal obtained during presedimentation. Algae are also known to 

6 produce taste and odor compounds and interfere with flocculation/sedimentation and filtration. 

7 

8 Recommendations for Addressing this Issue

9 

10 There are several ways to prevent algae growth in presedimentation basins. Potassium 

11 permanganate addition has been used with mixed success in efforts to stop algae growth and 

12 control resulting tastes and odors. Covering basins to block ultraviolet (UV) light will also 

13 prevent algae growth. Although this can be a more expensive solution, floating covers are 

14 available that can provide a lower-cost alternative. 

15 

16 Removal of Settled Solids

18 

20 Solids that accumulate in the bottom of 

22 presedimentation basins should be removed 

24 periodically. This is especially true when a 

26 coagulant is added. If a coagulant is not added, 

28 systems may be able to manage solids with periodic 

29 manual removal. Systems may not be able to use a coagulant if they cannot add solids removal 

30 equipment to the basin. Although it presents additional costs to the plant, solids removal should 

31 not interfere with plant production if it is done on a regular basis. 

32 

33 Recommendations for Addressing this Issue

34 

35 If a coagulant is not used, systems should consider using two basins, taking one off-line 

36 while the other is being cleaned to avoid stirring up sediment and allowing it to enter the plant. 

37 Solids should be removed on a regular basis to prevent interference with plant performance and 

38 compliance with regulatory requirements. Solids can be removed in various ways such as using 

39 a sloped floor and center drain or specially designed vacuums or pumps. Removal can be 

40 accomplished manually by regular cleaning or dredging. 

41 

42 3.6.3 Recommendations for Gathering More Information 

43 

44 Read the Case Study 

45 

46 For more information on simultaneous compliance issues associated with 

47 presedimentation basins and how to address them, see Case Study #3 Presedimentation starting 

48 on page B-21 of Appendix B. This case study describes how one PWS used was able to monitor 

49 effluent from their presedimentation basins to determine their Cryptosporidium bin classification 
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1 for the LT2ESWTR. Operational issues include problems with algae blooms, which the system 

2 was typically able to control by adding potassium permanganate to the basins. 

3 

4 See Additional References

5 

6 Readers can turn to Section 7.1.1 in Chapter 7 for general technical references associated 

7 with water treatment. The Draft LT2ESWTR Toolbox Guidance Manual (USEPA 2003a) 

8 provides additional information on presedimentation. 

9 

10 Consider Additional Monitoring

11 

12 The following are suggestions for additional monitoring that may benefit water systems using 

13 presedimentation: 

14 

15 9 Turbidity measurements as water leaves the presedimentation basin and enters the 

16 treatment plant, in order to detect impacts of sediment buildup or short-circuiting on 

17 water quality entering the plant. 

18 

19 9 If algae growth is a problem, routine algal counts, chlorophyll a measurements, or Secchi 

20 disk depth readings as feasible, to guide algae management efforts. 

21 

22 The purpose of these monitoring suggestions is specifically to address and prevent potential 

23 simultaneous compliance issues. 

24 

25 

26 3.7 Enhanced Coagulation 

27 

28 One way to remove NOM is to practice enhanced coagulation. Enhanced coagulation has 

29 been shown to be an effective strategy for reduction of DBP precursors for many systems 

30 (Krasner and Amy 1995). Enhanced coagulation can be accomplished by one or more of the 

31 following operational changes: 

32 

33 • Increasing coagulant dose 

34 

35 • Changing coagulant 

36 

37 • Adjusting pH (using acid to lower the pH as low as 5.5) 

38 

39 • Improving mixing or applying moderate dosage of an oxidant 

40 

41 As one part of the treatment process is modified, PWSs should consider the impacts on 

42 subsequent processes and within the distribution system. Systems considering whether enhanced 
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1 coagulation may be an effective way to reduce DBPs should refer to the Guidance Manual for 

2 Enhanced Coagulation and Precipitative Softening (USEPA 1999h). 

3 

4 This section discusses the advantages and disadvantages of enhanced coagulation, and 

5 provides recommendations for how systems may be able to address and minimize the 

6 disadvantages. 

7 

8 3.7.1 Advantages of Enhanced Coagulation 

9 

10 Some advantages to enhanced coagulation include: 

11 

12 • May improve disinfection effectiveness 

13 

14 • Can reduce DBP formation 

15 

16 • Can reduce bromate formation 

17 

18 • Can enhance arsenic and radionuclide removal 

19 

20 Improved Disinfection Effectiveness 

21 

22 Conventional filtration plants must achieve a 3.0 log Giardia removal/inactivation and 

23 4.0 log virus removal/inactivation. Enhanced coagulation can improve disinfection effectiveness 

24 in three ways: 

25 

26 • Lower the pH during disinfection 

27 • Reduce disinfectant demand 

28 • Remove particles to which pathogens are attached 

29 

30 The pH may be suppressed artificially using an acid or may be the result of heavy alum or ferric 

31 coagulant doses. 

32 

33 Chlorine is pH-sensitive, being more effective at low pH values (see Section 3.2 for a 

34 more complete discussion of chlorine sensitivity to pH). Therefore, a decrease in pH results in 

35 greater inactivation of Giardia and viruses. Ozone also exhibits increased performance at lower 

36 pH values (Carlson et al. 2000). Conversely, chlorine dioxide can be less effective at low pH 

37 values. 

38 

39 The removal of NOM through enhanced coagulation may allow increased disinfectant 

40 efficiency by decreasing the demand on the disinfectants exerted by organics (Carlson et al. 

41 2000). For a system to realize this benefit, the system should inject the disinfectant at a location 

42 in the treatment process where NOM removal has been achieved. This operational scenario may 
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1 allow the system, in consultation with their regulatory agency, to reduce the amount of 

2 disinfectant used compared to dosages required prior to practicing enhanced coagulation. A 

3 reduction in the amount of disinfectant applied should result in fewer DBPs being formed. The 

4 system should, however, ensure that the necessary microbial inactivation is maintained at all 

5 times by measuring: 

6 

7 • the disinfectant residual 

8 • flow, temperature, and pH 

9 • calculating the resulting inactivation contact times and CTs being achieved 

10 

11 By increasing the removal of particles and organic matter, pathogens that are attached to 

12 these substances will also be removed. 

13 

14 Reduced DBP Formation 

15 

16 Enhanced coagulation improves the removal of DBP precursors in a conventional water 

17 treatment plant. The removal of TOC (a surrogate measure of NOM) by coagulation has been 

18 demonstrated in several laboratory research, pilot demonstrations, and full-scale studies 

19 (Chowdhury et al. 1997, Edwards 1997). Removal of TOC can result in a decrease in TTHM 

20 and HAA5 formation. In fact, the Stage 1 D/DBPR uses TOC to define enhanced coagulation 

21 for DBP precursor removal requirements. 

22 

23 A reduction in pH has also been demonstrated to result in a reduction in formation of 

24 chloroform (Singer 1999). A more detailed discussion of this topic is provided in Section 3.4. 

25 

26 Reduced Bromate Formation 

27 

28 The reduction of pH that may be practiced as part of enhanced coagulation can result in 

29 better control of bromate formation for those systems using ozone. Williams et al. (2003) 

30 indicated that a pH of about 6.5 provided effective reduction of bromate formation. The 

31 effectiveness of bromate control at lower pH values depends on the source water, particularly its 

32 alkalinity. 

33 

34 Arsenic and Radionuclide Removal

35 

36 Compliance with the new arsenic maximum contaminant level (MCL) of 0.010 mg/L 

37 may require systems to consider treatment modifications for improved arsenic removal. Some 

38 systems may realize improved arsenic removal by using a ferric coagulant as part of the 

39 enhanced coagulation process. Scott et al (1995) observed that arsenate (As(V)) removal was in 

40 the range of 80 to 95 percent for a ferric coagulant dose ranging from 3 to 10 mg/L. Alum 

41 coagulation has been shown to remove arsenic, but at higher doses (up to 20 mg/L) Removal of 

42 arsenite (As(III)) is much less efficient than As(V), though iron coagulants are still more 
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1 effective at removing As(III) than alum coagulants (Hering et al. 1996; Edwards et al.1994). 

2 Modified coagulation is identified by EPA as a Best Available Technology (BAT) for the 

3 Arsenic Rule. 

4 

5 Enhanced coagulation may also provide better radionuclide removal since radionuclides, 

6 such as uranium, have been shown to be removed by coagulation/filtration (Sorg 1988). Systems 

7 will want to understand fully their requirements for disposal of residuals containing 

8 radionuclides and check with their State or Primacy Agency for instructions on special handling 

9 or disposal of residuals containing radionuclides. 

10 

11 3.7.2 Potential Operational and Simultaneous Compliance Issues Associated with 

12 Enhanced Coagulation 

13 

14 Potential issues associated with enhanced coagulation include: 15 

16 • Adverse impacts to finished water turbidity 17 

18 • Corrosion concerns 

19 

20 • Increased concentrations of inorganics in the finished water 21 

22 • Additional issues with residual disposal 

23 

24 This section discusses these issues briefly and provides suggestions for reducing their impacts. 

25 

26 Finished Water Turbidity

27 

28 In most cases, lowering the pH and/or increasing coagulant feed will result in lowering 

29 turbidity in the finished water. However, lower pH levels can sometimes lead to the formation of 

30 a less dense, more fragile floc. This type of floc can carry over from the clarifier and may result 

31 in shorter filter run times or premature filter breakthrough (Singer 1999). A lower pH and higher 

32 coagulant dose may also result in restabilization of particles. These conditions can create upsets 

33 in solids blanket-type clarifiers (Carlson et al. 2000). 

34 

35 Premature filter breakthrough as a result of higher particle loading to the filter could 

36 result in shorter filter runs or, if a system does not adjust its operations in response to the higher 

37 particle loading, the system might not meet the turbidity limits established by the IESWTR and 

38 LT1ESWTR. This may also trigger individual filter follow-up actions as required by IESWTR 

39 and LT1ESWTR. Conversely, enhanced coagulation may have a positive effect on subsequent 

40 treatment steps, resulting in lower finished water turbidity, potentially longer filter runs, and 

41 better compliance with effluent turbidity limits. 

42 
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1 Recommendations for Addressing this Issue

2 

3 Systems may want to pilot test different coagulants to identify the coagulant type and 

4 dose that produces the most stable, settleable floc. Lovins et al. (2003) found that ferric sulfate 

5 produced a larger, more durable and more settleable floc relative to alum in Peace River water, a 

6 high DOC water, at a pH of around 7.5. 

7 

8 Systems should consult the “Enhanced Coagulation and Enhanced Precipitative Softening 

9 Guidance Manual” (USEPA 1999h) for recommendations on how to maintain low turbidity 

10 while performing enhanced coagulation. 

11 

12 Corrosion Concerns

13 

14 Corrosion control within the distribution system can be affected by a change in pH, 

15 change in the chloride to sulfate ratio, change in organics concentration, or a significant change 

16 in the alkalinity of the finished water (Carlson et al. 2000). Any of these conditions can occur as 

17 a result of enhanced coagulation and can potentially create compliance issues with the LCR. 

18 

19 Enhanced coagulation lowers TOC. Changes in TOC have been found to have differing 

20 impacts on corrosion. Schock et al. (1996) found that in some cases, NOM can form soluble 

21 complexes with lead which can increase corrosion. In other cases, NOM was found to coat the 

22 pipes and lower corrosion rates. Edwards et al. (1996) have reported similar results for copper 

23 corrosion. Edwards et al. (2004) found that lower TOC in combination with higher aluminum 

24 may cause pinholes leaks in copper piping. 

25 

26 Enhanced coagulation can lower alkalinity. The effect of an alkalinity change depends 

27 on the initial alkalinity; for water with moderate to low alkalinity, a decrease in alkalinity can 

28 increase corrosion. Systems are encouraged to maintain a minimum alkalinity of 10 to 20 mg/L 

29 as calcium carbonate. If the initial alkalinity is high, however, a decrease may be beneficial 

30 since a decrease in alkalinity can also decrease copper corrosion rates. 

31 

32 Enhanced coagulation lowers pH. Lower pH generally increases corrosion rates. 

33 Changing distribution system pH can also alter the condition of pre-existing scale. The lower the 

34 initial pH, the smaller the pH change needed to affect the corrosion rate. At an initial pH of 7, a 

35 pH change of 0.2 can affect corrosion, while with an initial pH of 9 it takes a pH change of over 

36 0.5 to significantly affect corrosion. Softened scale can break off and entrain materials contained 

37 in it into the distribution system. 

38 

39 Lower pH can also have adverse impacts within the treatment plant. Cement can degrade 

40 in acidic conditions. Metals in pipes and pumps may also be susceptible to corrosion. 

41 
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1 If aluminum coagulants are used and overdosing occurs, efforts to perform enhanced 

2 coagulation may result in increased aluminum concentrations. Aluminum can increase corrosion 

3 of lead and copper, though it will decrease corrosion of copper byproducts. 

4 

5 The increased use of coagulants in enhanced coagulation will raise the concentration of 

6 the anion, either sulfate or chloride, and will affect the chloride to sulfate ration. A low chloride 

7 to sulfate ratio has been shown to decrease corrosion rates (Edwards et al.1999). 

8 

9 Recommendations for Addressing this Issue

10 

11 Systems should consider adjusting their pH upward before the water enters the 

12 distribution system in order to reduce corrosion of pipe materials. Systems will want to identify 

13 the optimum pH within the distribution system that 

14 enables compliance with the LCR and does not result 

15 in substantial increases in DBP levels. If the system 

16 cannot readjust the pH to a high enough level using 

17 caustic to prevent corrosion, it can consider adding a 

18 corrosion inhibitor (i.e., a substance that is phosphate19 or silica-based) to the finished water to form a protective coating on the pipes. 

20 

21 Water systems should carefully research the implications of using a corrosion inhibitor 

22 before adding it as a treatment step. Some utilities have elected not to use phosphate-based 

23 corrosion inhibitors because the POTW receiving the wastewater violated phosphorus limits in 

24 their disposal permits. Zinc toxicity to wastewater treatment biota can also be a concern. Lime 

25 addition can potentially cause turbidity problems if the dosing and mixing are not done properly. 

26 Conversely, research has shown that corrosion control often has the added benefit of controlling 

27 biological growth in the distribution system, which can lead to improved compliance with the 

28 TCR. 

29 

30 Regardless of the type of corrosion inhibitor used, it should be carefully pilot tested 

31 before it is introduced. Large water systems were required to conduct corrosion control studies 

32 under the LCR. Smaller systems may have conducted studies if required by the state. Any 

33 system that subsequently changes their treatment must notify the state and may be required to 

34 conduct a new corrosion control study. In any event, LCR corrosion control studies should be 

35 used as a starting point to assess the impacts of changes in distribution system water quality on 

36 corrosion and LCR compliance and determine the best corrosion control treatment strategy. 

37 Appendices C and D provide additional guidelines for systems evaluating their corrosion control 

38 options and information on proper piloting procedures. 

39 

40 Systems should also monitor inside the plant for signs of corrosion of cement or metal. If 

41 corrosion is noticed, corrosion may be prevented by applying an epoxy coating. For metals such 

42 as pipes and pumps, using a sacrificial anode is an option in addition to epoxy coatings. Exterior 

43 fittings in buildings should be painted to reduce corrosion. Finally, when designing new 

Water systems should carefully 

research the implications of 

using a corrosion inhibitor before 

adding it as a treatment step. 
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1 processes materials compatible with the anticipated pH and water quality in the plant should be 

2 specified. 

3 

4 Increased Inorganics in Finished Water

5 

6 Enhanced coagulation can cause an increase in inorganics, such as manganese, 

7 aluminum, sulfate, chloride, and sodium, in the finished water. The low pH that frequently 

8 results from enhanced coagulation reduces the oxidation rate of manganese from the dissolved 

state (Mn2+ 9 ) to the solid form (MnO2) that allows it to be removed during sedimentation and 

10 filtration. Ideally, manganese is completely oxidized before the coagulation step, and enhanced 

11 coagulation should not deter manganese removal. Systems should note, however, that even very 

12 low concentrations of manganese (e.g., 0.05 mg/L) in the finished water could result in aesthetic 

13 problems. 

14 

15 Manganese may also be present in concentrations above the secondary standard of 0.05 

16 mg/L if high dosages of ferric coagulants are used (Carlson et al. 2000). Ferric chloride and 

17 ferric sulfate coagulants can contain relatively high concentrations of manganese. If a water 

18 system switches from low doses of ferric or alum to high doses of ferric, the coagulant itself may 

19 significantly increase the amount of dissolved manganese in the water. 

20 

21 The presence of high concentrations of sulfate or chloride may affect the corrosivity of 

22 the water (Carlson et al. 2000). The mass ratio of chloride to sulfate can also affect the 

23 corrosivity of the water. Edwards et al. (1999) found that of 24 utilities surveyed, none of the 

24 utilities with a chloride to sulfate ratio of less than 0.58 exceeded the lead action level, while 64 

25 percent of utilities with a ratio greater than 0.58 exceeded the lead action level. 

26 

27 Increased aluminum in the distribution system may result when high alum dosages are 

28 used in an effort to perform enhanced coagulation. Increased aluminum can lead to aesthetic 

29 problems, such as solids precipitation, in the distribution system (Carlson et al. 2000). Increased 

30 alum can be kept from passing through filters by addition of filter aids and more frequent 

31 backwashing. More frequent backwashing, however, has costs and other implications. 

32 

33 Recommendations for Addressing this Issue

34 

35 System operators should consider their source water specifically when making choices 

36 about coagulant use. Systems should jar test and, ideally, pilot test under different water quality 

37 conditions the coagulants that they are considering before making full-scale coagulant treatment 

38 changes. NSF and manufacturer recommendations should be followed in coagulant dosing. 

39 Specifications for coagulants and other treatment chemicals should also specify allowable 

40 concentrations of trace contaminants. Section 6.3 describes some ways systems can test their 

41 water to determine which coagulant is best suited for their water quality and particular treatment 

42 needs. Systems with a high chloride to sulfate ratio may be able to mitigate corrosion by 

43 switching from a chloride-based coagulant to a sulfate-based coagulant. 
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1 

2 Residuals Handling

3 

4 Because more coagulant is added and more organics are being removed, enhanced 

5 coagulation will likely result in the production of more waste residuals. The conditions for 

6 existing disposal of water treatment plant (WTP) sludge should be reviewed and even 

7 renegotiated, and increased costs of waste disposal should be factored into a system’s decision. 

8 

9 If the source water has high concentrations of hazardous contaminants such as arsenic or 

10 radionuclides, the waste residuals may concentrate these contaminants to the extent that the 

11 waste is considered unfit for disposal in a sanitary landfill. States have limits on toxics 

12 concentrations in waste residuals disposed of in sanitary landfills, and exceeding any of those 

13 limits could cause the waste to be classified as hazardous. In addition, some states have 

14 additional disposal requirements for residuals that have been characterized as technologically 

15 enhanced naturally occurring radioactive material (TENORM) that can further complicate 

16 disposal. 

17 

18 Recommendations for Addressing this Issue

19 

20 Systems will likely experience higher costs with managing an increased residual load. 

21 Depending on how residuals are managed, additional facilities may need to be constructed or 

22 new permits may be necessary. Aluminum is toxic to aquatic life, so increased alum use may 

23 result in limitations on the discharge of the residual stream to surface water bodies. 

24 

25 Systems should properly analyze the sludge that results from enhanced coagulation for 

26 increased metals and other contaminants that may create issues with final sludge disposal. The 

27 regulatory agency should be consulted regarding disposal of residuals if hazardous chemicals are 

28 concentrated in the residuals. EPA has recently released A Regulator’s Guide to the 

29 Management of Radioactive Residuals from Drinking Water Treatment Technologies, (USEPA 

30 2005c) which deals with the issue of radioactive compounds concentrated in residuals. 

31 

32 Typically, ferric sulfate sludges are more easily dewatered as compared to alum sludges 

33 (Thompson et al. 1998). 

34 

35 3.7.3 Recommendations for Gathering More Information 

36 

37 Read the Case Studies 

38 

39 Three case studies in Appendix B describe simultaneous compliance challenges faced by 

40 utilities using enhanced coagulation. 

41 

42 Case Study #4 Switching Coagulants starting on page B-25 describes how a system 

43 could simultaneously comply with the TOC removal requirements of the Stage 1 D/DBPR and 
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1 the turbidity removal requirements of the IESWTR by switching coagulants. The system found 

2 that enhanced coagulation with ferric sulfate not only increased TOC removal significantly, but 

3 also reduced turbidity levels in the finished water. The major problem experienced in 

4 implementing the treatment modification was the control of manganese and corrosion in the 

5 rapid mix chamber due to the addition of sulfuric acid.

6 

7 Case Study #5 Enhanced Coagulation-Problems with Copper Pitting starting on page 

8 B-33 describes a system that experienced pinhole leaks in their copper piping following 

9 alterations to the coagulation process. The system implemented orthophosphate addition to 

10 address the pinhole leaks, which also had an effect on finished water turbidity and iron release 

11 from unlined cast iron mains. 

12 

13 Case Study #6 Enhanced Coagulation - Managing Radioactive Residuals starting 

14 on page B-39 provides a discussion of a system's options for disposing of radioactive 

15 residuals resulting from enhanced coagulation. As a result of enhanced coagulation, 

16 radionuclides can become concentrated in residuals at levels that require special 

17 consideration for regulatory approval of sludge disposal. 

18 

19 See Additional References

20 

21 Readers can turn to Section 7.1.8 in Chapter 7 for technical references associated with 

22 using enhanced coagulation. 

23 

24 Consider Additional Monitoring

25 

26 The following are some suggestions for additional monitoring that may benefit water 

27 systems using enhanced coagulation: 

28 

29 9 Routine turbidity or particle count monitoring of water leaving the sedimentation basin to 

30 ensure that a consistently stable and dense floc is forming. 

31 

32 9 Routine finished water pH and alkalinity monitoring to help ensure that corrosion control 

33 is being implemented correctly. 

34 

35 9 Periodic aluminum measurements in the finished water to watch for aluminum carryover 

36 from the combination of alum floc and low pH. 

37 

38 The purpose of these monitoring suggestions is specifically to address and prevent potential 

39 simultaneous compliance issues. 

40 
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1 Consider Other Tools

2 

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

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

5 issues they may face when modifying their operation or treatment practices. Examples of tools 

6 that can be used when enhanced coagulation is used for Stage 2 DBPR compliance include: 

7 

8 • The “Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual” 

9 (U.S. EPA 1999h) that provides procedures for conducting jar testing to determine the 

10 optimum coagulation conditions for achieving desirable total organic carbon removal 

11 and coagulated/settled water turbidity 

12 

13 • The AwwaRF report “Internal Corrosion of Water Distribution System” (AWWARF 

14 and DVGW-Technologiezentrum Wasser 1996), which provides bench-scale and 

15 pilot testing protocols that can be used to evaluate changes in corrosion potential due 

16 to changes in pH 

17 

18 • The “Guidance Manual for Monitoring Distribution System Water Quality” 

19 (Kirmeyer, 2002) which can be used to assist water utilities in implementing a 

20 distribution system water quality data collection and analysis program 

21 

22 • The second version of “Water Treatment Plant Model” (U.S. EPA 2001h) developed 

23 by USEPA that assists utilities with implementing various treatment changes while 

24 maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR. 

25 

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

27 

28 
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1 3.8 Enhanced Softening 

2 

3 Precipitative softening with lime addition is typically practiced with the objective of 

4 removing hardness in the form of calcium and magnesium from water. Total hardness removal 

5 goals vary between treatment plants. Lime softening processes are generally divided into three 

6 distinct groups: 

7 

8 • Conventional lime softening to remove calcium carbonate where only lime is fed 

9 

10 • Lime-soda softening to remove calcium carbonate and noncarbonate hardness by 

11 feeding both lime and either soda ash or potassium carbonate 

12 

13 • Excess lime softening to remove both calcium and magnesium (and sometimes silica) 

14 by adding an excess of lime 

15 

16 All softening plants operate at higher pH levels than conventional coagulation plants. 

17 Calcium carbonate begins to precipitate above pH of 9.5 and as the pH increases above 10, 

18 magnesium hydroxide precipitation increases. 

19 

20 Softening has some similarities to 

21 coagulation with respect to the mechanisms 

22 operating to remove particles and TOC, so that 

23 when coupled with appropriate settling, DBP 

24 precursors can be removed effectively by softening. Generally, removal of TOC in softening is 

25 enhanced by the addition of a small amount of coagulant. The regulatory requirement for 

26 enhanced softening in the Stage 1 D/DBPR is based on the assumption that raising the lime dose 

27 will foster the precipitation of CaCO3 and the associated coprecipitation of precursors. The 

28 resulting increase in pH causes increased precursor removal, presumably by promoting stronger 

29 interactions between the precursors and calcium ions. In addition, the increase in pH may be 

30 sufficient to precipitate magnesium hydroxide, which strongly adsorbs precursors (Randtke 

31 1999, Shorney and Randtke 1994). 

32 

33 When the pH of softening is changed significantly, differences in process chemistry 

34 affect the nature of the solids that are formed with respect to settling and dewatering 

35 characteristics. Enhanced softening criteria do not require plants to alter the softening process to 

36 the extent that major changes in settling conditions and solids handling are generally required. A 

37 plant is considered to be practicing enhanced softening if it meets the appropriate TOC removal 

38 target in the 3x3 TOC removal matrix. Most softening plants have raw water alkalinity above 

39 120 mg/L as CaCO3, so that they are classified in the right hand column of the matrix, but a few 

40 fall into the classification for influent with alkalinity of 60 – 120 mg/L. Plants that cannot meet 

41 the removal requirements in the 3x3 matrix may remain in compliance by removing a minimum 

Generally, removal of TOC in

softening is enhanced by the 

addition of a small amount of 

coagulant. 
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1 of 10 mg/L of magnesium as CaCO3. Alternatively, softening plants that reduce their finished 

2 water alkalinity to 60 mg/L are in compliance with enhanced softening. 

3 

4 3.8.1 Advantages of Enhanced Softening 

5 

6 The main advantages of enhanced softening are: 

7 

8  Adequate removal of TOC 

9 

10  Two stage plants may achieve additional Cryptosporidium removal credit 

11 

12  Lower corrosion impacts 

13 

14 Adequate Removal of TOC 

15 

16 Softening plants typically do not have difficulty meeting the TOC removal requirements 

17 of the 3x3 matrix in the Stage 1 D/DBPR. Information from a survey of softening plants (1999) 

18 indicated that operational data showed TOC being removed at least at the level defined by the 

19 matrix, and this fact is substantiated by the data from the Information Collection Rule (ICR). 

20 Since plants were not necessarily striving to meet the enhanced softening criteria during the ICR 

21 sampling period, apparently the standard operating scheme for most softening plants actually 

22 falls within the criteria of “enhanced softening” as defined by the rule (Clark et al. 2002). 

23 

24 The only instances reported by softeners which lead to difficulty in removing TOC occur 

25 when raw water alkalinity drops significantly causing the calcium hardness:carbonate alkalinity 

26 ratio to be elevated. This situation can arise when surface water is diluted by major rain events 

27 or when a blend of ground and surface water is altered in proportions. In these cases, some 

28 addition of carbonate alkalinity in the form of soda ash or potassium carbonate may be warranted 

29 to facilitate the softening reactions and the coprecipitation of organic material. Softening utilities 

30 are expected to be able to meet the requirements of the Stage 2 DBPR as effectively, or more so, 

31 as conventional coagulation plants (USEPA 2003a). 

32 

33 Two Stage Plants May Achieve Additional Cryptosporidium Removal Credit 

34 

35 Plants that include a two-stage lime softening process are eligible for an addition 0.5-log 

36 Cryptosporidium removal credit toward compliance under the proposed LT2ESWTR (USEPA 

37 2003a). The two-stage process must consist of a second clarification step between the primary 

38 clarifier and filters that is operated continuously. Both clarifiers must treat all of the plant flow 

39 and must contain a coagulant, which can be lime, magnesium hydroxide or a metal coagulant. 

40 Refer to the Draft LT2ESWTR Toolbox Guidance Manual (USEPA 2003a) for additional 

41 requirements for receiving this credit. 

42 
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1 Lower Corrosion Impacts

2 

3 Softening systems have an advantage with respect to managing corrosion for two reasons. 

4 Since the softening process takes place at a pH above 10, systems generally add carbon dioxide 

5 to reduce pH and stabilize the water prior to distribution. Selection of an appropriate finished 

6 water pH goal takes into consideration the optimum pH for corrosion control. At the same time, 

7 softening systems generally produce water that tends to develop scale in the distribution system. 

8 If the scale formation is not managed appropriately, it can be a liability with respect to flow 

9 restriction, but from a corrosion control standpoint, scale formation is a distinct benefit. 

10 

11 As noted in EPA's “Enhanced Coagulation and Enhanced Precipitative Softening 

12 Guidance Manual” (USEPA 1999h), the information in Exhibit 3.6 is intended only to 

13 characterize existing and future corrosion control strategies. The figure can be used proactively 

14 to anticipate problems that may develop if enhanced softening is used. 

15 

16 

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

18 Softening on Corrosion of Piping System Materials 

19 

Parameter Potential Impact on Corrosion of Material

Change 

Resulting From 

Enhanced 

Softening

Pb Cu Fe Pb from 

Brass

Concret

e

TOC ▼ ► ►1

▼2 ▼ ▼ ► ▲

Alkalinity ▼ ► ► ► ▲ ► ▼ ► ▲ ►

Ca Hardness ▼ ► ► ▲ ► ► ▲

pH ▲ ► ▼ ► ▼ ► ▼ ► ▼ ► ►

Sulfate ► ► ► ► ► ►

Chloride ► ► ► ► ► ► 1 applies to copper 

2

 applies to copper by-products ►= decrease ▲= increase ►= same (no change)

20 

21 Source: EPA’s Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual (USEPA 1999h)

22 

23 
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1 3.8.2 Potential Operational and Simultaneous Compliance Issues Associated with 

2 Enhanced Softening 

3 

4 Potential issues associated with enhanced softening include: 

5 

6  Options for disinfection are limited 

7 

8  Higher TTHM formation at high pH 

9 

10  Can cause scaling 

11 

12  pH adjustment required for distribution and for disinfection effectiveness 

13 

14  Increased sludge volume and changes in sludge characteristics 

15 

16 This section briefly describes these issues and provides suggestions for minimizing their impacts.

17 

18 Options for Disinfection Are Limited 

19 

20 One of the most complex issues facing softening plants with respect to regulatory 

21 compliance is selection and implementation of disinfection processes. Disinfection with 

22 chlorine, chloramines, chlorine dioxide, and ozone requires specific consideration of issues that 

23 arise in high pH waters. 

25 

27 Based on data from an AWWA survey 

29 of softening plants completed in 1997 to inform 

31 the regulatory development process, more than 

33 one third of softening plants predisinfect with 

35 chlorine, ozone, or a combination of 

37 chlorine/chloramines and they take CT credit 

39 for some or all predisinfection contact time. In 

40 addition, the survey indicated that the finished water pH in softening plants ranges from 7.5 to 

41 10, with approximately half reporting average finished water pH greater than 9. CT values for 

42 inactivation of Giardia by free chlorine and chloramines are not identified for pH levels greater 

43 than 9 in the SWTR Guidance (USEPA 1991). Thus, disinfection credit using chlorine or 

44 chloramines through the softening portion of the treatment process must be evaluated on a case45 by-case basis by the primacy agency. Some softening plants have resolved this problem by 

46 providing appropriate contact time after softening and pH reduction to meet required CT values 

47 with their selected disinfectant. 

48 

49 Use of chlorine dioxide in softening plants is governed by the regulated levels for 

50 chlorine dioxide and chlorite. Chlorine dioxide reacts with many organic and inorganic 

51 constituents in water. It disinfects by oxidation, but does not chlorinate. Chlorine dioxide 

Disinfection credit using chlorine or

chloramines through the softening

portion of the treatment process

must be evaluated on a case-by-case

basis by the primacy agency.
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1 functions as a highly selective oxidant due to its unique, one-electron transfer mechanism where 

2 it is reduced to chlorite. The reactions produce chlorite and chlorate as endpoints. In drinking 

water, chlorinate (ClO2

- 3 ) is the predominant reaction endpoint, with approximately 50 to 70 

percent of the chlorine dioxide converted to chlorite and 30 percent to chlorate (ClO3

- 4 ) and 

chloride (Cl- 5 ) (USEPA 1999). The balance between these two species varies frequently and is 

6 affected by the exposure to bright sunlight, aeration, and recarbonation, among other factors 

7 (Gates 1997). The disproportionation of ClO2 is accelerated by increased pH, which means that 

8 the addition of lime soon after the addition of ClO2 may result in minimal disinfection time and 

9 development of both chlorite and chlorate (Hoehn 1993). There may be situations in which 

10 chlorine dioxide can be used as a preoxidant in softening plants, but they would be governed by 

11 the contact time available prior to the addition of lime and initiation of the softening process. 

12 

13 Ozone use at high pH (above pH = 7) will form significant bromate when bromide is 

14 present in the water. Ozonation at lower pH can control the formation of bromate, but will 

15 increase the formation of brominated organic byproducts produced from the interaction between 

16 hypobromous acid and NOM, producing an overall increase in TTHMs by weight (Reckhow 

17 1999). In softening plants, the use of ozone generally requires reduction of pH from the 

18 softening pH (between 10 and 11) to a pH between 6 and 7. To obtain such a shift in pH, 

19 significant amounts of acid are often consumed. Thus, unless a unique water quality concern 

20 requires use of ozone, other disinfection options should be considered. 

21 

22 Higher THM Formation 

23 

24 THM formation has been shown to be higher with increasing chlorination pH, while 

25 some of the HAAs appear to have lower formation at higher pH (Krasner 1999). A number of 

26 softening plants have constructed a large chlorine contact chamber/clearwell to provide 

27 disinfection contact time after the pH of the water is lowered from the softening pH to a pH that 

28 minimizes DBP production. 

29 

30 Many raw water sources that are treated by softening contain significant levels of 

31 bromide. As plants practice enhanced softening to remove precursors, the ratio of the amount of 

32 bromide in the water to the amount of TOC goes up because bromide is not removed by 

33 softening. Research has shown that as the ratio of bromide to TOC increases the percentage of 

34 brominated DBPs increases. Thus, when bromide-containing enhanced softened water is 

35 disinfected with chlorine, formation of brominated THMs increases, resulting in a higher total 

36 weight of THMs formed. Thus, softening plants may be forced into a balancing of TOC removal 

37 with DBP formation to optimize the finished water DBP formation based on speciation of the 

38 THMs and total weight of TTHMs. 

39 

40 Recommendations for Addressing this Issue

41 

42 If softening plants have problems complying with the proposed Stage 2 DBPR TTHM 

43 MCLs, three possible alternatives should be considered. 
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1 

2 • Systems may be able to reduce finished water pH somewhat to reduce the TTHM 

3 formation potential in the system. Changes in system pH should be cautiously 

4 undertaken to ensure that the existing system scale is not altered significantly, 

5 softened, or stripped from pipes, thereby causing major operational problems. 

6 

7 • Systems may be able to utilize alternative disinfectants, including chloramines, 

8 chlorine dioxide, or ozone. Chloramines are best suited for use as a distribution 

9 system residual although some softening plants operate with a chloramine residual 

10 carried through the softening process. Chlorine dioxide and ozone disinfection must 

11 be evaluated with care in both quantity and placement to ensure that neither chlorate 

12 nor bromate MCLs are violated. Use of UV for disinfection may reduce the level of 

13 chlorine or chloramine residual required for residual disinfection in the distribution 

14 system. 

15 

16 • Softening plants may also evaluate the possible conversion from conventional 

17 softening to membrane softening. The use of microfiltration followed by 

18 nanofiltration can remove TOC as well as provide softened water, thereby reducing 

19 the DBP formation potential. Cost may be a factor that prohibits a system from 

20 making this change. In addition, membrane conversion can necessitate the need to 

21 consider other simultaneous compliance issues such as ensuring that distribution 

22 system chemical equilibrium is not altered in a way that will cause either corrosion or 

23 scale sloughing. 

24 

25 Scaling 

26 

27 Depending on the raw water quality and the physical configuration of the treatment 

28 processes in a softening plant, the addition of extra lime to provide enhanced softening 

29 conditions can lead to increased scaling conditions in both the treatment plant and the 

30 distribution system piping. In general, if the Langelier Saturation Index (LSI) is positive, the 

31 water is oversaturated with CaCO3 and has the potential to precipitate and form scale. 

32 

33 pH Adjustment Required for Distribution and for Disinfection Effectiveness 

34 

35 Most softening plants adjust pH to meet finished water pH goals, to meet pH 

36 requirements for disinfection effectiveness after the completion of the softening process, and to 

37 satisfy distribution system chemical equilibrium. As the pH of softening is increased in an effort 

38 to remove more TOC, the quantity of chemical required for pH adjustment increases. 

39 Historically, the finished water pH in softening plants has ranged between 7.5 and 10. 

40 
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1 Increased Sludge Volume and Changes in Sludge Characteristics 

2 

3 Significant increases in lime doses will result in increased lime sludge production. 

4 Residuals production may also increase when lime addition results in a pH greater than 10.25 in 

5 plants with significant magnesium present that have not historically softened at pH greater than 

6 10. At that pH, the magnesium hydroxide is precipitated along with calcium carbonate. If 

7 significant noncarbonate hardness exists, then addition of soda ash may be necessary, resulting in 

8 increased residuals production and higher sodium levels in the finished water. In addition, the 

9 handling and dewatering characteristics may be significantly altered (Randtke 1999). 

10 

11 In the softening process, calcium carbonate forms a dense crystal that is negatively 

12 charged, while magnesium hydroxide forms large, light floc that has a high surface area and 

13 positive surface charge. This difference in particle characteristics is what makes magnesium 

14 hydroxide a better adsorbent for dissolved precursors; however magnesium hydroxide solids 

15 have settling and dewatering characteristics that are quite different from calcium carbonate 

16 solids. In fact, softening plants that are designed to settle calcium carbonate may very well have 

17 inadequate settling time to settle magnesium hydroxide. If the previous softening pH was less 

18 than 10.25 and the water has significant magnesium, then enhanced softening in which the pH is 

19 increased to greater than 10.25 can cause formation of magnesium hydroxide, which may not be 

20 effectively removed in the settling process, or may change the characteristics of the process 

21 solids. 

22 

23 3.8.3 Recommendations for Gathering More Information 

24 

25 See Additional References

26 

27 Readers can turn to Section 7.1.8 of Chapter 7 for technical references associated with 

28 enhanced softening 

29 

30 Consider Additional Monitoring

31 

32 The following are some suggestions for additional monitoring that may benefit softening 

33 systems. The purpose of these monitoring suggestions is specifically to address and prevent 

34 potential simultaneous compliance issues. 

35 

36 9 Routine LSI measurements, or another comparable calcium carbonate saturation index, of 

37 water entering the distribution system to monitor the potential for excess scale formation. 

38 Weekly measurements may be sufficient when raw water quality is relatively consistent. 

39 More frequent checks may be useful under changing raw water conditions. 

40 
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1 Consider Other Tools

2 

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

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

5 issues they may face when modifying their operation or treatment practices. Examples of tools 

6 that can be used when enhanced softening is used for Stage 2 DBPR compliance include: 

7 

8 • The “Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual” 

9 (U.S. EPA 1999h) that provides procedures for conducting jar testing to determine the 

10 optimum coagulation and softening conditions for achieving desirable total organic 

11 carbon removal and coagulated/settled water turbidity 

12 

13 • The AwwaRF report “Internal Corrosion of Water Distribution System” (AWWARF 

14 and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

15 testing protocols that can be used to evaluate changes in corrosion potential due to 

16 changes in pH 

17 

18 • The “Guidance Manual for Monitoring Distribution System Water Quality” 

19 (Kirmeyer 2002) which can be used to assist water utilities in implementing a 

20 distribution system water quality data collection and analysis program 

21 

22 • The second version of “Water Treatment Plant Model” (U.S. EPA 2001h) developed 

23 by USEPA that assists utilities with implementing various treatment changes while 

24 maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR. 

25 

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

27 

28 
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TREATMENTS COVERED 

 

• Granular Activated Carbon 

• Microfiltration/Ultrafiltration 

• Nanofiltration 

• Other Microbial Removal Technologies 

1 

2 

3 

4 

5 

6 

7 

8 Some water systems will choose to install a new type of treatment in order to comply 

9 with the Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR) and/or the Long Term 

10 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). This chapter describes treatment 

11 technologies that can be installed to remove disinfection byproduct (DBP) precursors and 

12 microbial pathogens. Advantages of using each treatment are described, along with summaries 

13 of operational and simultaneous compliance issues associated with the treatment. General 

14 recommendations for addressing those issues are also provided. 

15 

16 While most of the issues presented in the following sections address simultaneous 

18 compliance concerns, some 

20 additional operational and aesthetic 

22 issues are discussed. Each 

24 technology includes a section with 

26 recommendations for gathering 

28 more information. 

30 

32 4.1 Granular Activated 

34 Carbon 

36 

37 The main benefit of granular activated carbon (GAC) is that it is effective in adsorbing 

38 and removing organic compounds from water. Removing organic matter prevents it from 

39 forming DBPs, causing taste and odor complaints, and stimulating microbial activity in the 

40 distribution system. Additionally, if GAC is used in series with a conventional filter, systems 

41 may be able to receive additional Cryptosporidium removal credit under the LT2ESWTR. The 

42 main drawbacks to using GAC are the possibility of release of bacteria or carbon fines into the 

43 system, the possibility of chromatographic peaking, and its reaction with disinfectants. These 

44 issues are discussed in more detail in Section 4.1.2. 

45 

46 GAC can be used as an additional layer on top of an existing filter (GAC cap), or it can 

47 be placed in a separate contactor. Design will vary depending on whether it is used as a separate 

48 adsorber or if it is added as a filter cap. Its efficiency is determined by the contact time and the 

49 relative adsorption strength of the compounds that are to be removed. Some physical removal by 

50 filtration will occur in GAC beds as well. 

51 

4 Installing New Total Organic Carbon or 

Microbial Removal Technologies 
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1 4.1.1 Advantages of GAC 

2 

3 The advantages of GAC include: 

4 

5 6 • Removes DBP precursors through adsorption 

7 

8 • Can remove taste and odor compounds 

9 

10 • If used as a secondary filter, the system may be able to receive a 0.5-log 

11 Cryptosporidium removal credit 

12 

13 • Can be used as a biologically active filter after ozone to remove assimilable 

14 15 organic carbon (AOC)

16 

17 DBP Precursor Removal

18 

19 DBP precursor removal before the addition of a disinfectant can significantly lower DBP 

20 production and ease compliance with the Stage 2 DBPR. GAC10, a GAC contactor with a 10 

21 minute empty bed contact time (EBCT), is considered a best available technology (BAT) for the 

22 Stage 1 Disinfectants/Disinfection Byproducts Rule (D/DBPR). GAC10 in combination with 

23 enhanced coagulation or enhanced softening or GAC20 are considered BATs for the Stage 2 

24 DBPR. GAC has been found to reduce total organic carbon (TOC) by 30 to 90 percent 

25 depending on the contact time, the nature of the organic matter, and other parameters (USEPA 

26 2005d). Generally, AOC is removed relatively quickly while other organic fractions take longer 

27 to remove. 

28 

29 Taste and Odor Removal

30 

31 Because many taste and odor compounds are organic, the ability of GAC to adsorb 

32 organics also makes it a useful treatment technique in this respect. For example, GAC has been 

33 found to remove 30 to 40 percent of geosmin from drinking water (Youngsug et al. 1997). The 

34 removal efficiency was increased to 80 percent or more with the addition of ozone or ozone 

35 peroxide. Similar reductions can be achieved for 2-methylisoborneol (MIB). 

36 

37 Cryptosporidium Removal

38 

39 Systems can receive a 0.5-log Cryptosporidium removal credit for having a second set of 

40 filters in series in a conventional treatment plant. Both a GAC contactor and a conventional dual 

41 media filter with a GAC cap are eligible for this credit. In both cases the Cryptosporidium is 

42 removed through physical filtration onto the filter media. The GAC filter must treat the entire 

43 flow of the plant to obtain the credit. Refer to the LT2ESWTR Toolbox Guidance Manual

44 (USEPA 2003a) for detailed requirements for receiving credit. 
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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 

1 

3 Removes AOC After Ozone

5 

7 Ozonation often results in 

9 organic matter becoming AOC, 

11 which serves as a food source for 

13 microbes. This can cause 

15 difficulties with compliance with 

17 the Total Coliform Rule (TCR) and 

19 can lead to nitrification problems. 

20 GAC, acting as an adsorbent, can remove some AOC before it enters the distribution system. 

21 

22 Additionally, systems can take advantage of the high surface area per mass ratio of GAC 

23 and the fact that it adsorbs organics to operate the GAC filter in biologically active mode. By 

24 not having a disinfectant residual in the water passing through the filter and allowing biological 

25 growth, the system can achieve high removals of AOC. Using biologically active GAC filters 

26 after ozonation can reduce biological growth in the distribution system and lower DBPs. See 

27 Section 5.2 for further details on the use of biological filtration with ozone. 

28 

29 4.1.2 Potential Operational and Simultaneous Compliance Issues Associated with Using 

30 GAC 

31 

32 Potential issues associated with GAC use include: 

33 34 

35 • Can limit the ability to prechlorinate 

36 37 

38 • Previously adsorbed compounds can be released 

39 

40 • Bacteria can be released 

41 

42 • Carbon fines released from GAC filters can foul downstream processes 

43 

44 • Chlorate can be formed when GAC comes in contact with chlorine dioxide 

45 

46 • Ammonia added before a GAC filter has been found to increase nitrification in 

47 48 the distribution system

49 

50 This section briefly describes each of these issues and provides some suggestions for 

51 addressing them. 

52 
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1 Limits Ability to Prechlorinate

2 

3 Most disinfectants react quickly when they come into contact with GAC. This leads to a 

4 rapid loss of disinfectant residual, and in the case of chlorine, can lead to a faster depletion of the 

5 GAC. 

6 

7 Recommendations for Addressing this Issue

8 

9 Systems should not use GAC filters at the same time as achieving CT for purposes of 

10 meeting disinfection requirements. Disinfectants should be added after the GAC filter. If the 

11 disinfectant addition points are moved, an evaluation of the CT throughout the plant must be 

12 made and any effects of moving the disinfection point, such as changes in coagulation and 

13 precipitation, pre-oxidation of contaminants, and growth of algae must be evaluated. If pre14 oxidation is needed in treatment before GAC, alternative oxidants (e.g., potassium 

15 permanganate) or lower chlorine doses should be used so as not to carry a residual onto the 

16 GAC. 

17 

18 Release of Adsorbed Compounds

19 

20 Organic materials adsorbed onto GAC will generally remain on the GAC until it is 

21 regenerated. But if a stronger adsorbing compound passes through the GAC when the GAC is 

22 relatively saturated, and the GAC does not have a significant number of free adsorption sites, 

23 weaker binding compounds can be expelled. It is possible for the concentration of these expelled 

24 compounds to be higher than the original concentration. This phenomenon is referred to as 

25 chromatographic peaking. Strongly adsorbing compounds that can have this effect include 

26 hydroxide used to adjust pH, or chloride as a byproduct of chlorination. 

27 

28 Recommendations for Addressing this Issue

29 

30 To avoid chromatographic peaking and the desorption of contaminants from the GAC, 

31 pH adjustment should be made after the GAC filter. Chlorine should also generally be added 

32 after the GAC filter, both to avoid chromatographic peaking and to lower DBP formation. Any 

33 other sudden changes in water chemistry entering the GAC contactor should be avoided as well. 

34 If sudden swings in water chemistry are unavoidable, then GAC regeneration frequency should 

35 be increased and the filter effluent should be monitored carefully to prevent breakthrough of any 

36 contaminants. 

37 

38 Release of Bacteria

39 

40 Heterotrophic bacteria growth occurs in GAC filters. Studies have found that the average 

41 number of bacteria in the effluent of GAC systems can be significantly higher than influent 

42 levels (Parson et al. 1980, Klotz et al. 1976). This may present problems with biofilms or 
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1 opportunistic pathogens for water systems with inadequate post-GAC disinfection. It can also 

2 contribute to nitrification problems when ammonia is present naturally or through use of 

3 chloramines. 

4 

5 Recommendations for Addressing this Issue

6 

7 The amount of bacteria in the effluent of GAC systems can often be reduced by proper 

8 backwashing and GAC regeneration frequencies. However, some bacteria are still likely to be 

9 shed from GAC filters. Introducing a disinfectant residual in the filter itself is not recommended 

10 because most disinfectants react with GAC, spending the GAC and not penetrating the full depth 

11 of the bed. The best strategy to deal with bacteria shed from GAC filters is to add a disinfectant 

12 after the GAC filter. 

13 

14 Release of Carbon Fines

15 

16 Small particles of carbon are usually present in GAC filters when they are first installed. 

17 These carbon fines appear gray or black and can cloud the water. If carbon fines from GAC 

18 filters are released into the product water, they can interfere with downstream treatment 

19 processes, particularly fouling of membrane filters and absorbing ultraviolet (UV) light in UV 

20 disinfection units, and cause poorer performance of these subsequent treatment steps. 

21 

22 Recommendations for Addressing this Issue

23 

24 GAC filters should be placed after membrane or UV disinfection processes to avoid 

25 problems associated with the release of carbon fines. If this is not possible, proper backwashing 

26 procedures, good maintenance of the filter underdrains, and more frequent cleaning of the UV 

27 reactor or membrane unit can help to minimize the problem. 

28 

29 Formation of Chlorate

30 

31 Chlorine dioxide, in addition to losing its residual, will form chlorate when it comes into 

32 contact with GAC. Chlorate can further react to form chlorite, a DBP regulated by the Stage 1 

33 D/DBPR. 

34 

35 Recommendations for Addressing this Issue

36 

37 Chlorine dioxide should be added after the GAC filters to avoid the formation of chlorate. 

38 If chlorine dioxide is used for pre-oxidation, it should be added far enough ahead of the GAC 

39 filter that no residual enters the contactor. If the treatment sequence first has conventional 

40 filtration and then the GAC filter, adding the chlorine dioxide prior to the first set of filters will 

41 usually solve the problem. 

42 
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1 Nitrification with Chloramines

2 

3 Systems that add ammonia prior to a GAC contactor have been found to have more 

4 frequent incidents of nitrification in the distribution system (Krasner et al. 2003). This may be 

5 caused by the ammonia stimulating growth of nitrifying bacteria on the GAC media and seeding 

6 the distribution system with these bacteria, though the research has not been conclusive. 

7 

8 Recommendations for Addressing this Issue

9 

10 To reduce the potential for nitrification, systems using ammonia to form chloramines or 

11 to raise pH should add the ammonia after the GAC filters.

12 

13 4.1.3 Recommendations for Gathering More Information 

14 

15 Read the Case Study 

16 

17 For more information on simultaneous compliance issues associated with GAC and how 

18 to address them, see Case Study #7 - Granular Activated Carbon for TOC removal starting on 

19 page B-45 of Appendix B. This case study describes how a utility used GAC to address high 

20 levels of atrazine in its source water and high TTHM levels in its finished water. The system 

21 was able to reduce their atrazine levels 30 to 60 percent and their UV254 levels 20 percent six 

22 months after installing the GAC cap. The greatest operational issue faced by the system was a 

23 build up of inorganic precipitates on the GAC filter, and occasional taste and odor episodes. 

24 

25 See Additional References

26 

27 Readers can turn to Chapter 7 for more references on this topic. Section 7.1.1 includes 

28 general references on water treatment, Section 7.1.2 contains references on controlling DBP 

29 formation, and section 7.1.9 contains references on GAC use. 

30 

31 Consider Additional Monitoring

32 

33 The following are some suggestions for additional monitoring that may benefit water 

34 systems implementing GAC. Note that the purpose of these monitoring suggestions is 

35 specifically to address and prevent potential simultaneous compliance issues. Water system 

36 managers should discuss process control monitoring with the GAC manufacturer or their 

37 engineer. 

38 

39 9 Periodic monitoring of volatile organic chemicals (VOCs) and synthetic organic 

40 chemicals (SOCs), as appropriate, in water leaving the GAC unit to detect 

41 breakthrough and desorption of contaminants. 

42 
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1 9 Turbidity or particle count measurements of the GAC effluent, especially when new 

2 or re-activated carbon is first being used. 

3 

4 9 Heterotrophic plant counts (HPC) in water leaving the GAC units to watch for an 

5 increase in bacteria numbers. 

6 

7 Consider Other Tools 

8 

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

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

11 issues they may face when modifying their treatment practices. Examples of tools that can be 

12 used when GAC is used for Stage 2 DBPR compliance include: 

13 

14 • The AwwaRF report “Prediction of GAC Performance Using Rapid-Small Scale 

15 Column Tests” (Crittenden 1989) that describes the use of RSSCT techniques to 

16 predict full-scale GAC’s useful lifetime when it is used to remove dissolved organic 

17 matter from a drinking water source. This report also demonstrates how to use pilot18 scale testing data to further refine the RSSCT prediction 

19 

20 • The “Handbook of Public Water Systems” (HDR Engineering, Inc. 2001) which 

21 provides detailed engineering design aspects of various drinking water treatment 

22 processes including granular activated carbon 

23 

24 • The second version of “Water Treatment Plant Model” (U.S. EPA 2001h) developed 

25 by USEPA in 2001 that assists utilities with implementing various treatment changes, 

26 including GAC addition, while maintaining adequate disinfection and meeting the 

27 requirements of Stage 2 DBPR 

28 

29 • Various cost estimation models that can be used to estimate the cost of constructing 

30 and operating a new GAC facility. 

31 

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

33 
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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. 

1 4.2 Microfiltration/Ultrafiltration 

2 

3 Microfiltration/Ultrafiltration (MF/UF) is a low-pressure membrane technology. The 

4 membranes remove particulate matter larger than the membrane pore size. MF membranes 

5 generally operate at slightly lower pressure and have larger pore sizes than UF membranes. In 

6 some cases, MF/UF membranes will be used together, with the MF membranes acting as a pre8 filter for the UF membranes. MF/UF 

10 units are often supplied on skid 

12 mounted assemblies that can easily 

14 be installed and have high degrees of 

16 automation. 

18 

20 4.2.1 Advantages of MF/UF 

22 

23 The advantages of MF/UF include: 

24 25 

26 • Removes bacteria and protozoa 

27 

28 • Can lower DBPs by using lower disinfectant doses

29 

30 31 • Removes arsenic

32 

33 Bacteria and Protozoa Removal

34 

35 Membrane processes remove all particles larger than the pore size of the membrane, 

36 provided the membrane integrity is not compromised. Bacteria, Cryptosporidium oocysts, and 

37 Giardia cysts can all be reliably removed by MF/UF. Although MF membranes do not generally 

38 remove viruses, some UF membranes can remove viruses. MF/UF units that are challenge-tested 

39 before installation and undergo daily membrane integrity tests qualify for 2.5 log additional 

40 Cryptosporidium removal credit above that of conventional treatment under the LT2ESWTR. 

41 See the LT2ESWTR Toolbox Guidance Manual (USEPA 2003a) for more information. Systems 

42 should also consult with their state to determine applicable credits and requirements. 

43 

44 If surface water systems use MF/UF instead of chemical disinfection to get 

45 inactivation/removal credit, they must add chlorine, chloramines, or chlorine dioxide to maintain 

46 a disinfectant residual in the distribution system. 

47 

48 DBP Reduction

49 

50 Because MF/UF can achieve high levels of microbial removal, systems installing MF/UF 

51 can lower their disinfectant dose and still achieve the same level of microbial protection. The 
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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). 

1 lowered disinfectant dose may result in lower DBPs and aid in meeting Stage 2 DBPR 

2 requirements. 

3 

4 4.2.2 Potential Operational and Simultaneous Compliance Issues Associated with MF/UF 

5 

6 Potential issues associated with MF/UF use include: 

7 8 

9 • Can be fouled by organics and minerals 

10 

11 • Increased loss of process water

12 

13 14 • Additional training required

15 

16 This section provides brief descriptions of these issues and suggestions for minimizing 

17 their impacts. 

18 

19 Membrane Fouling

20 

21 Membranes can be fouled by organic matter, iron, manganese, and carbonate deposits. 

22 Sources of these fouling compounds include source water and treatment chemicals. Ground 

23 water systems that do not treat their water before it passes through the MF/UF unit may have 

24 particular problems with iron, manganese, and other minerals. This is especially true if the 

25 ground water is anoxic and is exposed to the atmosphere during pumping or an aeration process, 

26 resulting in dissolved minerals settling out. 

27 

28 Recommendations for Addressing this Issue

29 

30 Systems with high TOC can reduce fouling by placing the MF/UF after existing 

31 sedimentation and/or filtration processes. If TOC is high even after filtration or if a conventional 

32 filter is not present, TOC can be lowered by adding other pretreatment techniques. Pretreatment 

33 to lower TOC levels includes: pre-sedimentation, enhanced coagulation and, less often, GAC 

34 filtration. TOC removal can often be accomplished by good coagulation before the membranes. 

35 If iron based coagulants are used, jar testing should be carried out to ensure optimal dosing and 

37 settling, because iron based 

39 coagulants can foul some 

41 membranes. GAC filtration removes 

43 much of the organic matter, although 

45 not all organic compounds are 

47 adsorbed easily. A cartridge filter 

49 may need to be installed before the 

51 MF/UF unit, however, to prevent 

53 carbon fines from entering the 
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1 membrane unit. 

2 

3 Systems that aerate their ground water to oxidize iron, manganese or other compounds 

4 should remove any precipitated minerals before the water reaches the MF/UF unit to prevent 

5 fouling. The manufacturer of the MF/UF unit and other utilities with experience using the same 

6 units should be consulted before a system makes any changes to the chemistry of the treated 

7 water, since many treatment chemicals can also foul membranes. 

8 

9 Regardless of the pretreatment involved and the quality of the water, membranes will 

10 eventually foul and will need to be cleaned. Cleaning the membranes will improve performance 

11 and prolong membrane life. The appropriate length between cleanings can be determined by 

12 monitoring the long-term decrease in productivity and backwash efficiency. 

13 

14 Loss of Process Water

15 

16 Membrane processes produce a reject stream as well as backwash water. Therefore, the 

17 amount of wastewater that has to be handled can be higher than that produced during 

18 conventional filtration. Although improvements have been made in efficiency, some water 

19 systems lose as much as 15 percent of the process water as a waste stream. Other membrane 

20 projects have been bid with approximately 92 percent recovery in summer and 90 percent 

21 recovery in winter (Sarah Clark, personal communication). In a recent survey of MF/UF 

22 systems, however, the median value for feed water recovery was 95 percent (Adham et al., 

23 2005). 

24 

25 Recommendations for Addressing this Issue

26 

27 To handle the higher quantities of process water produced by MF/UF units, systems may 

28 need to increase the capacity of their wastewater storage and residuals processing facilities. This 

29 is especially true of systems that recycle their reject water. 

30 

31 To minimize the lost water, systems may also be able to recycle some of the reject stream 

32 if the membranes are added onto a conventional treatment train. In this case, the recycle must be 

33 sent to the head of the plant according to the Filter Backwash Recycling Rule (FBRR). The 

34 effect of additional particle loading should be taken into account when determining coagulant 

35 dosing and filter loading rates. 

36 

37 Additional Training Required

38 

39 MF/UF membranes are significantly different to operate than other water treatment units. 

40 The control parameters are different and many new parameters must be monitored to prove 

41 regulatory compliance. 

42 
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1 Recommendations for Addressing this Issue

2 

3 Systems should consult with their state to determine what parameters will need to be 

4 monitored for approval and regulatory compliance. Systems should also work with the state and 

5 the vendor to provide adequate training for operators. 

6 

7 4.2.3 Recommendations for Gathering More Information 

8 

9 See Additional References

10 

11 Readers can turn to chapter 7 for further references on this topic. Section 7.1.1 contains 

12 general references on water treatment, and section 7.1.10 contains references on membranes, 

13 including MF/UF. 

14 

15 Consider Additional Monitoring 

16 

17 The following are some suggestions for additional monitoring that may benefit water 

18 systems implementing MF/UF. Note that the purpose of these monitoring suggestions is 

19 specifically to address and prevent potential simultaneous compliance issues. Water system 

20 managers should discuss process control monitoring with the MF/UF manufacturer and other 

21 experienced utilities. 

22 

23 9 Periodic monitoring of iron, manganese, and other minerals in the water entering the 

24 MF/UF unit to detect an increase in minerals that may need to be addressed by pre25 treatment. 

26 

27 9 Particle counting to indirectly monitor membrane integrity and determine if a direct 

28 integrity test should be conducted. 

29 

30 9 Total organic carbon (TOC) in the membrane unit’s influent and effluent to track 

31 removal performance. 

32 

33 9 Heterotrophic plate counts (HPC) in the membrane unit’s effluent if membrane 

34 integrity is lost. 

35 

36 9 Membrane autopsies on any failed membranes to determine the cause of failure and 

37 determine possible corrective actions. 

38 
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1 Consider Other Tools

2 

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

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

5 issues they may face when modifying their treatment operations. Examples of tools that can be 

6 used when MF/UF membranes are used for LT2ESWTR and Stage 2 DBPR compliance include: 

7 

8 • The “Membrane Filtration Guidance Manual” published by USEPA in 2005 provides 

9 general guidelines for membrane pilot testing; 

10 • The AwwaRF report “Integrated Membrane Systems” (Schippers et al. 2004) that 

11 provides guidance on the selection, design, and operating an integrated membrane 

12 system that can function as a synergistic system for removing microbiological 

13 contaminants and DBP precursors; 

14 • The AwwaRF report “Integrating Membrane Treatment in Large Water Utilities” 

15 (Brown and Hugaboom 2004) that provides guidance to issues related to the 

16 integration of low pressure membranes into larger water treatment facilities, including 

17 membrane layout, piping, cost comparison, and operations and maintenance; 

18 • The second version of “Water Treatment Plant Model” (U.S. EPA. 2001h) developed 

19 by USEPA in 2001 that assists utilities with implementing various treatment changes 

20 while maintaining adequate disinfection and meeting the requirements of Stage 2 

21 DBPR; and 

22 • Various cost estimation models that can be used to estimate the cost of constructing 

23 and operating a new membrane facility. 

24 

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

26 

27 
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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. 

1 4.3 Nanofiltration 

3 

5 Nanofiltration is a membrane process 

7 that physically removes contaminants from 

9 water that are larger than the pore size of the 

11 membranes. Nanofiltration uses pore sizes 

13 and operating pressures that fall between 

15 those of UF and reverse osmosis. 

16 

17 Nanofiltration’s main advantage over MF/UF is that it can remove virtually all particulate 

18 matter as well as larger dissolved compounds, including dissolved organic matter. In addition to 

19 meeting all removal requirements for pathogens, it leads to lower DBPs by removing DBP 

20 precursors. Its main disadvantages are that it can be fouled by organics or precipitated minerals, 

21 it can increase corrosiveness of the water, it has a large reject stream, and it requires additional 

22 training. 

23 

24 4.3.1 Advantages of Nanofiltration 

25 

26 Some advantages of nanofiltration include: 

27 28 

29 • Significant removal of bacteria, protozoa, and viruses 

30 

31 • Can remove organics that act as DBP precursors

32 

33 34 • Can remove arsenic

35 

36 Significant Removal of Bacteria, Protozoa, and Viruses

37 

38 Nanofiltration has small pore sizes that exclude essentially all particulate matter, as long 

39 as the membrane is intact. Therefore, nanofiltration units that are capable of being integrity 

40 tested may receive credit for Cryptosporidium removal under LT2ESWTR. With state approval, 

41 if nanofiltration is used to satisfy pathogen removal/inactivation requirements instead of a 

42 combination of filtration and disinfectant, the system must still add chlorine, chloramines, or 

43 chlorine dioxide for residual disinfection in the distribution system. 

44 

45 Removes DBP Precursors

46 

47 Nanofiltration can remove dissolved organic compounds that serve as DBP precursors. 

48 When little or no bromide ion was present in the source water, nanofiltration membranes with 

49 molecular weight cutoffs (MWCOs) of 400 to 800 daltons were shown to effectively control 

50 DBP formation (Laine et al. 1993). Nanofiltration with the same pore size produced higher 

51 bromoform concentrations when bromide was present, although total THMs decreased. 
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1 Membranes with smaller pore sizes controlled bromoform formation better but required 

2 pretreatment to avoid membrane fouling. 

3 

4 DBP formation may be lowered even further if the state allows the system to reduce its 

5 disinfectant dose and the amount of primary disinfection because of the high microbial removal 

6 rate of the nanofiltration units. When this is the case, nanofiltration can accomplish both high 

7 pathogen removal and low DBP formation. 

8 9 

10 4.3.2 Potential Operational and Simultaneous Compliance Issues Associated with 

11 Nanofiltration 

12 

13 Potential issues associated with nanofiltration include: 

14 15 

16 • Can be fouled by organics and precipitated minerals 

17 

18 • Can increase corrosiveness of water 

19 

20 • Issues with reject stream

21 

22 23 • Additional training required

24 

25 This section briefly describes these issues and provides suggestions for addressing their 

26 impacts. 

27 

28 Membrane Fouling

29 

30 Organics and precipitating minerals can foul nanofiltration membranes and cause them to 

31 operate inefficiently, shortening their useful life. Fouling also increases operating pressures and 

32 causes more frequent backwashing, which raises operating expenses. Fouling agents can come 

33 from the source water or be introduced as part of the treatment process. Ground waters that are 

34 not filtered before the water passes through the membranes may have more difficulties with 

35 fouling. 

36 

37 Recommendations for Addressing this Issue

38 

39 If nanofiltration membranes are being used in conjunction with a conventional filtration 

40 plant, the membranes should be placed after the filters to allow for the maximum removal of 

41 fouling compounds before water passes through the membranes. Treatment processes that can 

42 change the chemistry of the water should be located downstream of the nanofiltration unit if 

43 possible. These include aeration, pH adjustment, and disinfectants. Systems should bear in 

44 mind, however, that nanofiltration generally works better at acid pH. 

45 
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If coagulants or disinfectants must be 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. 

1 If the treatment train in place is not sufficient to reduce fouling compounds, some sort of 

2 pretreatment will be required. The simplest pretreatment is adding a cartridge filter before the 

3 membranes. If the water being treated is anoxic ground water, aeration may be considered to 

4 oxidize and precipitate any minerals before the cartridge filter. Other options for pretreatment 

5 include enhanced coagulation and pre-sedimentation. If enhanced coagulation is used, jar testing 

6 should be conducted to optimize the dose to ensure that unflocculated coagulant does not enter 

7 the membrane unit. 

8 

9 Regardless of the pretreatment involved and the quality of the water, membranes will 

11 eventually foul. Cleaning the 

13 membranes is necessary for 

15 improving performance and 

17 prolonging membrane life. The 

19 appropriate length between 

21 cleanings can be determined by 

23 monitoring the long-term decrease 

25 in productivity and back wash 

27 efficiency. 

28 

29 Increase Corrosiveness

30 

31 Nanofiltration can soften water by removing minerals such as calcium and magnesium. It 

32 can also result in a lowering of the pH of the water. The less alkaline, lower pH water will be 

33 more corrosive to distribution system piping and other process equipment, while not providing a 

34 passivating layer as harder water can. The lower pH can also shift the carbonate equilibrium to 

35 produce carbon dioxide. In groundwaters, hydrogen sulfide can also pass through the 

36 membranes. All these factors combine to increase the corrosiveness of the water. 

37 

38 Increased corrosiveness can cause problems with Lead and Copper Rule (LCR) 

39 compliance. Depending on the magnitude of the pH drop, it may also affect the disinfection 

40 efficiency of the secondary disinfectant as well. See Section 3.4 for more discussion of 

41 disadvantages associated with lowering water pH. It is also possible that the removal or minerals 

42 such as calcium can be so significant as to cause the water to taste significantly different to 

43 customers, possibly generating customer complaints. 

44 

45 Recommendations for Addressing this Issue

46 

47 The simplest way to avoid problems associated with a low pH is to adjust the pH after the 

48 membranes. The fittings for the membrane unit, as well as any equipment between the 

49 nanofiltration unit and the point where the pH is readjusted, should be made of materials that can 

50 resist the lower pH of the water. Water systems should also adjust the alkalinity after 

51 nanofiltration to prevent changes in pH in the distribution system that can enhance corrosion. 
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1 Passive treatment technologies, such as neutralizing filters or limestone contactors, are one way 

2 to achieve a good pH and carbonate balance in membrane-treated waters. 

3 

4 Aeration may help to remove any sulfide or carbon dioxide accumulated as well as raise 

5 oxygen levels to oxidize the sulfide to sulfate. Adding a disinfectant after the membranes can 

6 also aid in oxidizing sulfide. 

7 

8 Another approach some systems have taken is to only pass part of the influent stream 

9 through the NF unit and blend that NF product with water that has not received NF treatment. 

10 However, this negates many of the microbial benefits of NF and would require an alternative 

11 microbial treatment on the stream not treated by NF. 

12 

13 Issues with Reject Stream

14 

15 Membrane processes produce a reject stream as well as backwash water. Therefore, the 

16 amount of wastewater that has to be handled can be significantly higher than that produced 

17 during conventional filtration. Although improvements have been made in efficiency, losing 10 

18 to 20 percent of the process water as a waste stream is not unusual. The amount of process water 

19 lost can be reduced by a second membrane unit in series with the first unit. 

20 

21 Due to the small pore size associated with nanofiltration, other feed water constituents 

22 will also be removed. As a result, divalent salts, some metals, and some soluble organic carbon 

23 may be concentrated in the waste stream. This may increase the cost associated with disposing 

24 of the waste stream compared to disposal costs associated with MF, UF, and conventional 

25 treatment processes. If regulatory limits or plant locations prohibit sending the waste stream to a 

26 receiving body or wastewater treatment plant, costs for waste handling and disposal can be 

27 substantial. 

28 

29 Recommendations for Addressing this Issue

30 

31 To handle the higher quantities of waste water produced by nanofiltration units without 

32 causing upset to the system, utilities may need to increase the capacity of their wastewater 

33 storage and residuals processing facilities. This is especially true of systems that recycle their 

34 reject water. If water is recycled, the Filter Backwash Recycling Rule (FBRR) requires that it be 

35 recycled to the head of the plant. 

36 

37 Water systems using nanofiltration will most likely need to increase the amount of water 

38 they withdraw from their source to account for their process water losses. This could be an issue 

39 in arid regions where water is scarce and water restrictions are in place. 

40 

41 Disposal of the reject stream is easiest if located near an ocean, as the brine can easily be 

42 disposed of there. Otherwise systems will need to discuss the possibility of disposing of the 
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1 brine to the sanitary sewer which may have limits on brine or on certain metals and may involve 

2 additional charges. 

3 

4 Additional Training Required

5 

6 NF membranes are significantly different to operate than other water treatment units. 

7 The control parameters are different and many new parameters must be monitored to prove 

8 regulatory compliance. 

9 

10 Recommendations for Addressing this Issue

11 

12 Systems should consult with their state to determine what parameters will need to be 

13 monitored for approval and regulatory compliance. Systems should also work with the state and 

14 the vendor to provide adequate training for operators. 

15 

16 4.3.3 Recommendations for Gathering More Information 

17 

18 Read the Case Study 

19 

20 For more information on simultaneous compliance issues associated with nanofiltration 

21 and how to address them, see Case Study #8 - Nanofiltration Membrane Technology for TOC 

22 Removal starting on page B-49 of Appendix B. This case study describes the challenges faced 

23 by one PWS switching to nanofiltration in response to growing demands for water and the 

24 implementation of new drinking water standards. Specifically, the NF plant would facilitate the 

25 removal of hardness, color, TOC, and its related chlorinated DBPs. The greatest operational 

26 issue involved numerous leaks in the acid feed system, and sagging in the micron cartridge filter 

27 housings and the string wound filter. 

28 

29 See Additional References

30 

31 Readers can turn to chapter 7 for further references on this topic. Section 7.1.1 contains 

32 general references on water treatment, and section 7.1.10 contains references on membranes, 

33 including NF. 

34 

35 Consider Additional Monitoring

36 

37 The following are some suggestions for additional monitoring that may benefit water 

38 systems implementing nanofiltration. Note that the purpose of these monitoring suggestions is 

39 specifically to address and prevent potential simultaneous compliance issues. Water system 

40 managers should discuss process control monitoring with the manufacturer of their nanofiltration 

41 units or their engineer. 

42 
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1 T The pH of water leaving the nanofiltration unit should be monitored to ensure that 1) 

2 CT is being calculated accurately; and 2) chemical dosages for corrosion control are 

3 correct. 

4 

5 T Hardness and alkalinity of water leaving the nanofiltration unit should be measured to 

6 ensure that chemical dosages for corrosion control are correct. 

7 

8 T TOC in the NF influent and effluent should be monitored to measure removal 

9 effectiveness. 

10 

11 T Particle counting to indirectly monitor membrane integrity and determine if a direct 

12 integrity test should be conducted. 

13 

14 T HPC should be measured in the NF effluent to identify breakthrough. 

15 

16 T Membrane autopsies on any failed membranes to determine the cause of failure and 

17 determine possible corrective actions. 

18 

19 T Taste and odor quality should be measured to ensure customer acceptance. 

20 

21 Consider Other Tools

22 

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

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

25 issues they may face when modifying their treatment operations. Examples of tools that can be 

26 used when nanofiltration is used for Stage 2 DBPR compliance include: 

27 

28 • The AwwaRF report “Integrated Membrane Systems” (Schippers et al. 2004) that 

29 provides guidance on the selection, design, and operation of an integrated membrane 

30 system that can function as a synergistic system for removing microbiological 

31 contaminants and DBP precursors 

32 

33 • The AwwaRF report “Integrating Membrane Treatment in Large Water Utilities” 

34 (Brown and Hugaboom 2004) that provides guidance on issues related to the 

35 integration of low pressure membranes into larger water treatment facilities, including 

36 membrane layout, piping, cost comparison, and operations and maintenance 

37 

38 • The AwwaRF report “NOM Rejection by, and Fouling of, NF and UF Membranes” 

39 (Amy et al. 2001) that provides information on the selection of appropriate 

40 nanofiltration membranes to achieve high NOM rejection, and also presents 

41 information on how water quality (such as the presence of calcium and pH) and 

42 operational condition might affect NOM rejection by NF membranes 
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1 

2 • The second version of “Water Treatment Plant Model” (U.S. EPA. 2001h) developed 

3 by USEPA in 2001 that assists utilities to implement various treatment changes while 

4 maintaining adequate disinfection and meeting the requirements of Stage 2 DBPR 

5 

6 • Various cost estimation models, such as WTCost©, 2003, that can be used to estimate 

7 the cost of implementing a new membrane facility (see Section 6.3.7). 

8 

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

10 

11 
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The LT2ESWTR Toolbox Guidance 

Manual provides more information on 

the advantages and disadvantages of 

different Cryptosporidium oocyst 

removal technologies. 

1 4.4 Other Microbial Removal Technologies 

2 

3 Other microbial removal technologies can be used to meet LT2ESWTR requirements. 

4 All of the technologies listed below use some type of filtration media to remove 

5 Cryptosporidium oocysts and other microbes from drinking water. The LT2ESWTR Toolbox 

6 Guidance Manual (USEPA 2003a) provides information on the requirements for receiving 

7 Cryptosporidium oocyst removal credits using these technologies. The state should also be 

8 consulted on the requirements for obtaining pathogen removal credit for these technologies. 

9 Although these technologies are not expected to present significant compliance problems with 

10 other drinking water regulations if implemented properly, there are operational issues that 

11 utilities should consider if they use these options. These technologies are: 

12 

14 Bank Filtration

16 Bank filtration uses 

18 vertical or horizontal wells 

20 drilled near a riverbank. 

22 The riverbed and material 

24 between the well and the 

26 riverbank act as the 

28 filtration media. 

29 

30 Improved Filter Performance

31 Improved filter performance results from optimizing existing filtration to achieve 

32 consistently low filter effluent turbidity. In order to meet the lower finished water 

33 turbidity requirements, systems need a high level of process control from the source 

34 water intake to the filters. The Guidance Manual for Compliance with the IESWTR: 

35 Turbidity Provisions (USEPA 1999d) discusses many design and operational aspects 

36 water systems should consider for achieving low effluent turbidity. 

37 38 

39 Bag Filtration 

40 Bag filtration is a pressure driven filtration process using a fabric filter media. Flow is 

41 from inside the vessel to outside the vessel. 

42 

43 Cartridge Filtration

44 Cartridge filters are pressure driven filtration devices that have rigid or semi-rigid filter 

45 media housed in pressure vessels. Water flows from outside the cartridge filter's vessel to 

46 the inside. 

47 
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1 Second Stage Filtration

2 Second stage filtration involves placing a second set of granular media filters in series 

3 with an existing set of filters. The media can be rapid sand filters, slow sand filters, or 

4 GAC filters. 

5 

6 Slow Sand Filtration

7 Slow sand filtration uses sand as a filtration media and gravity as the driver at relatively 

8 low loading rates. 

9 

10 Diatomaceous Earth Filtration

11 Diatomaceous earth (DE) filtration, often referred to as “pre-coat” filtration, uses a layer 

12 of diatomaceous earth placed on a permeable cover or porous filter septum to filter water. 

13 DE filters are operated as either pressure filters or vacuum filters. 

14 

15 This section briefly describes issues associated with the use of these technologies, 

16 provides suggestions for addressing those issues, and recommends additional monitoring that can 

17 be conducted. 

18 

19 4.4.1 Advantages 

20 

21 There are several advantages to these microbial removal technologies. The following 

22 paragraphs list these advantages and briefly discuss which of these technologies provide each 

23 advantage. 

24 25 

26 • Ease of use (bag filtration, cartridge filtration bank filtration) 

27 

28 • Removal of Cryptosporidium and other pathogens (all technologies listed) 

29 

30 • Removal of other contaminants/ DBP precursors (bank filtration, second stage 

31 filtration, slow sand filtration) 

32 

33 Most operators are familiar with filtration. Second stage filtration, DE, and slow sand 

34 filtration can all be easily implemented by any system familiar with conventional filtration. 

35 Cartridge and bag filters are even easier to use as the only routine maintenance required is 

36 replacing the cartridge or bag when a pre-set trigger is reached, either a pressure drop or a given 

37 time. 

38 

39 All of these technologies will remove matter that is larger than the filter's effective pore 

40 size. Therefore, in addition to Giardia cysts and Cryptosporidium oocysts, they will remove 

41 some other microbial pathogens as well. 

42 
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1 Some of these technologies can also be effective in removing DBP precursors. Slow 

2 sand filtration can remove some DBP precursors, especially if operated in biologically active 

3 mode. Second stage filtration can offer additional DBP precursor removal, especially when GAC 

4 is used as the second filter media. Bank filtration often provides additional DBP removal 

5 through biological activity in the riverbank (Weiss et al. 2003). 

6 

7 4.4.2 Potential Operational and Simultaneous Compliance Issues 

8 

9 The disadvantages of these microbial removal technologies include: 

10 11 

12 • Hydraulic problems or scouring (all technologies listed) 

13 

14 • Clogging (cartridge filters, bank filtration) 

15 

16 • Increased residuals/ backwash (second stage filtration) 

17 

18 • Iron/manganese problems (bank filtration) 

19 

20 • Filter fouling (bag filters, cartridge filters)

21 

22 With careful planning, many of the disadvantages of these technologies can be overcome. 

23 The following paragraphs briefly describe steps that can be taken to mitigate these 

24 disadvantages. 

25 

26 Hydraulic Problems or Scouring

27 

28 All of these technologies can add significant hydraulic head to a plant’s hydraulic profile. 

29 Changes in head, especially when filters are restarted, can disturb the filter and cause poor 

30 performance. 

31 

32 Bank filtration can experience riverbank scouring during periods of high flow. The 

33 riverbank scour can remove much of the finer grained sediment responsible for a large portion of 

34 the removal associated with this filtration method. 

35 

36 Recommendations for Addressing this Issue

37 

38 Hydraulic loss due to additional filtration can often be overcome by conducting a 

39 hydraulic profile of the plant. Pumps can be installed to add additional head. The pumps should 

40 be installed and operated in such a way as to not cause hydraulic disturbances to surrounding 

41 processes, such as flocculation. Installing additional storage upstream of filtration is also a way 
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1 to smooth out hydraulic disturbances before they upset the filtration. Filtering to waste can 

2 eliminate some of the problems associated with filter start-up. 

3 

4 Clogging

5 

6 Bank filtration can also be subject to clogging by biomass growth in the pores or settling 

7 of finer grained material in the pores. Although this may increase removal efficiency of 

8 contaminants, it will increase pumping costs and drop yield. If too much coagulant is used 

9 before cartridge filters, they can also clog, necessitating more frequent replacement and higher 

10 costs. 

11 

12 Recommendations for Addressing this Issue

13 

14 Some types of clogging in bank filtration can be avoided by proper siting of the wells. 

15 Changes in chemistry in the aquifer that could precipitate minerals and areas of high 

16 sedimentation should be avoided. Otherwise, some clogging is inevitable and even necessary. 

17 Systems may have to account for this by designing for higher pumping rates than necessary or 

18 installing multiple wells. 

19 

20 Increased Residuals or Backwashing

21 

22 Many of these technologies can create disposal problems. Cartridge and bag filters have 

23 to be disposed of periodically. Second stage filtration will generate additional backwash water 

24 and residuals that will need to be disposed. Systems considering replacing their filter bed media 

25 as part of an effort to improve filter performance should consider whether there will be 

26 challenges associated with the disposal of old media that may contain high concentrations of 

27 metals or other contaminants. 

28 

29 If significant amounts of additional backwash and residuals are generated, a system may 

30 need to change its residuals disposal procedures. This may include treating backwash water 

31 through the addition of coagulant, or adding new sludge dewatering technologies or other 

32 residuals handling equipment. 

33 

34 Recommendations for Addressing this Issue

35 

36 To handle the higher quantities of process water produced by backwashing filter units, 

37 systems may need to increase the capacity of their wastewater storage and residuals processing 

38 facilities. This is especially true of systems that recycle their reject water. Manufacturers can 

39 also be consulted for disposal recommendations for bag and cartridge membranes. 

40 
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1 Iron and Manganese Problems

2 

3 Bank filtration can result in elevated levels of iron and manganese if the portion of the 

4 aquifer the wells draw from is anoxic. This will allow reduced manganese and iron to dissolve 

5 6 and enter the water. 

7 

8 Recommendations for Addressing this Issue

9 

10 If bank filtration is carried out through an anoxic zone, aeration may need to be added to 

11 oxidize dissolved iron, manganese, and any other reduced chemical species that could cause 

12 operational or aesthetic problems. 

13 

14 Filter Fouling

15 

16 Cartridge and bag filters can be fouled by biofilm if there is insufficient disinfectant 

17 residual present to control the growth. This can increase the pressure loss across the filter and 

18 shorten filter life. 

19 

20 Recommendations for Addressing this Issue

21 

22 Adding disinfectant before the filters can prevent biofilm growth from clogging bag and 

23 cartridge filters. Systems should evaluate the potential for DBP formation before taking this 

24 step. Systems should also confirm that the filter media is compatible with the disinfectant. 

25 

26 4.4.3 Recommendations for Gathering More Information 

27 

28 See Additional References

29 

30 Readers can turn to chapter 7 for additional references on this topic. Section 7.1.1 

31 includes general references on water treatment, including filtration, Section 7.1.8 includes 

32 references on enhanced coagulation and softening, and Section 7.1.11 includes references on 

33 riverbank filtration. 

34 

35 Consider Additional Monitoring

36 

37 Monitoring is important for determining the performance of these technologies. It can 

38 provide a good indication of performance and help make operating determinations such as when 

39 to backwash or replace filters. 

40 

41 9 Turbidity is used to determine filter performance as well as warn that a filter needs to 

42 be backwashed. Monitoring of individual and combined filter effluents is required 
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1 for conventional filters. Even if the filter is installed as a second filter or in series 

2 with another treatment technology, turbidity monitoring should be conducted. 

3 

4 9 Particle counters can also provide useful information, and can frequently determine 

5 breakthrough before turbidity measurements can. 

6 

7 9 Flow measurements help to spot potential hydraulic upset and adjust loading rates 

8 appropriately. 

9 

10 9 Pressure measurements are used to indicate how frequently a system needs to 

11 backwash or whether filter media needs to be replaced. 

12 

13 9 Streaming current detectors can be used to detect the charge on particles and optimize 

14 coagulant dose. 

15 

16 Consider Other Tools

17 

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

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

20 issues they may face when modifying their treatment operations. Examples of tools that can be 

21 used when implementing the other microbial removal technologies described in this section 

22 include: 

23 

24  The AwwaRF report “Evaluation of Riverbank Filtration as a Drinking Water 

25 Treatment Process” (Wang et al. 2002) that provides a general guideline for the 

26 design and operation of a riverbank system that can be used for the removal of DBP 

27 precursors and microbial contaminants 

28 

29 • The second version of “Water Treatment Plant Model” (U.S. EPA 2001h) developed 

30 by USEPA in 2001 that assists utilities with implementing various treatment changes, 

31 including GAC addition, while maintaining adequate disinfection and meeting the 

32 requirements of Stage 2 DBPR 

33 

34 • Various cost estimation models that can be used to estimate the costs of designing, 

35 constructing, and operating one of the technologies described above. 

36 

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

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ALTERNATIVE DISINFECTION 

STRATEGIES COVERED 

 

• Chloramine 

• Ozonation 

• Ultraviolet Light 

• Chlorine Dioxide 

• Primary and Residual 

Disinfectant Use 

1 

2 In their efforts to comply with the Stage 2 DBPR and LT2ESWTR, public water systems 

3 may consider switching to an alternative disinfectant for either primary or residual disinfection 

4 (or both). This chapter describes potential simultaneous compliance issues associated with using 

5 any of the following disinfectants: 

6 

7 T chloramines 

8 T ozone 

10 T ultraviolet (UV) 

12 14 T chlorine dioxide 

16 

18 Suggestions are also provided for how systems can 

20 mitigate simultaneous compliance and operational 

22 issues that are identified. 

24 

26 In addition, Section 5.5 of this chapter 

28 discusses different possible combinations of primary 

30 and residual disinfectants, and simultaneous 

32 compliance issues that may arise as a result of using 

34 the disinfectants in combination. 

36 

37 

38 5.1 Chloramines 

39 

40 Chloramines are formed when free chlorine reacts with ammonia. Chloramines may be 

41 present as monochloramine, dichloramine, and/or trichloramine. Monochloramine is generally 

42 considered the most desirable form for disinfection purposes. The chloramines compounds react 

43 more slowly than free chlorine. As a result, they form fewer DBPs, and are more persistent in 

44 the distribution system. Some studies have shown that chloramine compounds can penetrate 

45 biofilms more effectively than free chlorine. Monochloramine is also a preferred residual for 

46 odor quality of water, especially at residuals greater than 1 mg/L. 

47 

48 Because chloramine compounds are weaker disinfectants than free chlorine, they are not 

49 usually used for primary disinfection but more frequently as a residual disinfectant in the 

50 distribution system. If not properly controlled, chloramines can lead to nitrification episodes in 

51 the distribution system and may cause taste and odor issues, loss of disinfectant residual, and 

52 other problems. 

5 Alternative Disinfection Strategies 
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1 

2 5.1.1 Advantages of Chloramines 

3 

4 The use of chloramination to comply with the Stage 2 DBPR presents numerous benefits 

5 in terms of implementation and operation. Advantages include: 

6 7 

8 • Lower DBP formation 

9 

10 • Chloramine residual concentrations are generally more persistent than free 

11 chlorine residuals 

12 

13 14 • May help control of biofilm in the distribution system 

15 

16 Lower DBP Formation

17 

18 Chloramines react more slowly with organic matter than free chlorine. Total 

19 trihalomethane (TTHM) and haloacetic acid (five) (HAA5) concentrations are usually lower than 

20 when free chlorine is used for residual disinfection. Although detectable concentrations of 

21 mono- and dichloroacetic acids can be produced, these are generally significantly lower than 

22 corresponding concentrations produced by free chlorine. Replacing chlorine with chloramines as 

23 a secondary disinfectant typically reduces TTHM levels 40 to 80 percent. Depending on the 

24 system’s water quality, the actual TTHM reduction can vary from 10 to 95 percent (Kirmeyer et 

25 al. 2004a). 

26 

27 If chlorine is added to the water before ammonia, the byproducts associated with the use 

28 of free chlorine can be formed, although additional formation will be significantly retarded once 

29 the ammonia has been added. Because virus inactivation with free chlorine is more effective, 

30 however, surface water systems frequently add chlorine early enough in the treatment train so 

31 that CT requirements are achieved before the ammonia is added. 

32 

33 More Persistent in the Distribution System

34 

35 Chloramines reacts more slowly than free chlorine. Chloramines also have a lower 

36 oxidation-reduction potential than chlorine, so they are less likely to be consumed by reacting 

37 with organics and reduced metals. They therefore last longer in the distribution system and are 

38 generally more persistent than a free chlorine residual. The more persistent chloramine residual 

39 means greater protection in the areas of the distribution system with long detention time and less 

40 likelihood of violating the Surface Water Treatment Rule (SWTR) by failure to maintain a 

41 disinfectant residual. 

42 
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1 Reduce Biofilm

2 

3 According to EPA (1992) and Jacangelo et al. (1987), chloramine compounds are better 

4 able to penetrate the biofilm layer and inactivate attached organisms because they are more 

5 limited than chlorine in the types of compounds with which they will react. LeChevallier et al. 

6 (1988a, 1988b) found that chloramines were more effective at inactivating biofilms than free 

7 chlorine. LeChevallier (1990) also found that, in iron pipes, 3 to 4 mg/L doses of free chlorine 

8 did not control biofilm growth. Chloramines, however, did control biofilm growth at doses 

9 starting at 2 mg/L. Recent research suggests that the factors affecting biofilm growth and 

10 disinfection are complicated and may depend on many factors, thus varying between systems 

11 (Ollos et al. 2003). 

12 

13 5.1.2 Potential Operational and Simultaneous Compliance Issues Associated with 

14 Chloramines 

15 

16 Potential issues associated with the use of chloramines include: 

17 18 

19 20 • Onset of nitrification in the distribution system 

21 

22 • Increased corrosion and metal release 

23 

24 • Taste and odor issues 

25 

26 • Issues for systems wanting to blend chloraminated and chlorinated waters 

27 

28 • Weaker disinfectant, generally not used as primary disinfectant 

29 

30 • Blending Issues - chloraminated and chlorinated waters 

31 

32 • Although ammonia feed operation is fairly straightforward, there are safety 

33 concerns 

34 

35 • Ozone and granulated activated carbon (GAC) can lead to faster residual decay 

36 

37 38 • Issues for dialysis patients, fish owners, and industrial customers 

39 

40 Nitrification 

41 

42 Biological nitrification is the 

43 oxidation of ammonia to nitrite and then 

More Information on Nitrification 

can be found at 

http://www.epa.gov/safewater/tcr/tcr.html
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1 eventually to nitrate by bacteria and other organisms. Systems that carry an ammonia residual 

2 along with the chloramines, and have warm temperatures, long distribution system residence 

3 times, and low chloramine residuals can experience nitrification episodes (Kirmeyer et al., 

4 2004a). Nitrifying bacteria exhibit slow growth and are inhibited by sunlight. They have been 

5 found in higher numbers in the sediment of distribution systems than in the biofilm (Wolfe et al. 

6 1988, 1990). As part of the TCR review process, EPA has published a white paper on the issue 

7 of nitrification. The paper can be found at: http://www.epa.gov/safewater/tcr/tcr.html. 

8 

9 Nitrification can have various adverse effects on water quality, including: 

10 

11 • a loss of total chlorine and ammonia residuals (Cowman and Singer 1994) 

12 • consumption of dissolved oxygen 

13 • an increase in nitrite and nitrate levels 

14 • an increase in HPC 

15 • a decrease in pH 

16 • a decrease in ORP (relative to chlorinated water) 

17 

18 An increase in microbial activity can cause systems to violate the Total Coliform Rule (TCR) 

19 and SWTR. 

20 

21 Research has shown that a chlorine demand of 5.0 mg/L is exerted by 1.0 mg/L of nitrite 

22 (Cowman and Singer 1994). The nitrite rapidly reduces free chlorine, accelerates decomposition 

23 of chloramines, and can interfere with the measurement of free chlorine (Skadsen 1993). If 

24 nitrification episodes are allowed to continue, very low (or zero) total chlorine residual 

25 concentrations may result. 

26 

27 As part of the TCR review process, EPA has published a white paper on the issue of 

28 nitrification. The paper can be found at: http://www.epa.gov/safewater/tcr/tcr.html. 

29 

30 Several factors can contribute to nitrification, including, but not limited to: 

31 

32 • low chlorine to ammonia ratio 

33 • long detention times, such as in storage tanks 

34 • high (25EC - 30EC) temperatures (Wolfe et al. 1988, 1990) 

35 • pH - Water systems operating with pH between approximately 7 and 8.5 have been 

36 shown to be particularly vulnerable to nitrification. 

37 

38 Nitrifying bacteria are more resistant to disinfection by chloramines than by free chlorine 

39 (Wolfe 1990). For this reason, many systems using chloramines as their residual disinfectant 

40 will periodically switch to free chlorine to carry out a “chlorine burn.” By changing over to free 
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1 chlorine for a few weeks or months, nitrifying bacteria numbers can often be significantly 

2 reduced. 

3 

4 Recommendations for Addressing this Issue

5 

6 Nitrification may be controlled by taking corrective action when chloramine residuals are 

7 depleted in the distribution system. This can be done by monitoring the monochloramine 

8 residual at strategic locations throughout the distribution system (White 1999). As stated earlier, 

9 monitoring water, pH, nitrite, and temperature can also help determine when conditions are 

10 favorable for nitrification. Alkalinity decreases without a loss in inorganic carbon concentration 

11 has also been indicative of nitrification in some water systems. Decreases in pH alone may be 

12 hard to detect in well-buffered waters. 

13 

14 Mechanisms for controlling the occurrence of coliform growth and nitrification include: 

15 

16 • higher chloramine residuals, 

17 • higher chlorine: ammonia-nitrogen ratios, 

18 • periodic switching to free chlorine (particularly during warmer months), 

19 • operations to reduce water residence time, such as more frequent turnover in storage 

20 reservoirs, 

21 • distribution system flushing (Kirmeyer et al., 2004a), and 

22 • optimization of corrosion control operation for high pH. 

23 

24 Systems should monitor source water for ammonia and take that into account when 

25 calculating the necessary ammonia dose. The easiest way to reduce excess ammonia is to 

26 increase the chlorine to ammonia ratio. Wolfe (1990) found that increasing the chlorine to 

27 ammonia weight ratio from 3:1 to 5:1 reduced the free ammonia concentration from 0.2 mg/L to 

28 nearly zero with a residual chloramine concentration of 1.5 mg/L. 

29 3012 

33 The distribution system should be evaluated to identify the low-flow or dead-end 

34 sections. Detention times in the system should be operationally minimized (Skadsen 1993). 

35 Flushing dead ends can also decrease holding time and control nitrification. 

36 

37 Reducing the residence time in storage tanks can be an important factor in preventing 

38 nitrification. Reductions in residence times can be achieved by structural changes to the 

39 reservoir, such as changing the inlet/outlet structure, using recirculation pumps, and changing 

40 41 system-pumping procedures. 

42 

43 Increased Corrosion and Metal Release in the Distribution System

44 
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1 Nitrification resulting from the use of chloramines can lower the alkalinity and the pH of 

2 the water in the distribution system. The dissolved inorganic carbon level would be unaffected, 

3 the alkalinity decrease being a function of the amount of pH drop observed. This can prove 

4 detrimental for lead and copper control. Corrosion products and tubercles also interfere with the 

5 disinfection of coliform and heterotrophic bacteria, which can lead to increased microbially6 induced corrosion. 

7 

8 Changing from free chlorine to chloramines in the distribution system could potentially 

9 impact the stability of pipe scales, particularly redox-sensitive minerals such as those of lead, 

10 copper, manganese, and iron. Changes in the solubility, permeability and/or stability of scales 

11 could possibly result in the release of metals from pipe materials, increased oxidant demand or 

12 desorption of materials which had adsorbed to or been incorporated in the scales. 

13 

14 Systems with lead service lines could possibly see changes in lead levels as a result of a 

15 switch to chloramines. Pipe scale analysis has shown that, in some distribution systems where 

16 free chlorine is used, the corrosion by-products on lead service lines contain significant amounts 

17 of lead (IV) oxide compounds (Schock 2001; Schock, Wagner and Oliphant 1996; AWWARF 

18 and DVGW-Technologiezentrum Wasser 1996; Lytle and Schock 2005; Schock and Giani 2004; 

19 Schock et al. 2005). Lead (IV) oxide scales are highly oxidized and considered to be relatively 

20 insoluble in water. If a water system switches from a strong oxidant (chlorine) to a weaker 

21 oxidant (chloramines), the redox potential necessary to maintain Pb(IV) stability may no longer 

22 remain. As a result, lead (IV) compounds may be reduced to more soluble lead (II) solids and a 

23 subsequent increase in lead concentrations in water may be observed. This is the suspected 

24 cause of the LCR action level exceedances experienced by Washington, D.C.’s Water and Sewer 

25 Authority (DCWASA) beginning in 2002. DCWASA had made the conversion from free 

26 chorine to chloramines in late 2000 with the goal of reducing TTHM and HAA5 levels in the 

27 distribution system. The Washington, D.C. system does not contain any lead water mains; 

28 however, more than 20 percent of its service lines are known to be made of lead. To address the 

29 lead corrosion problem, the city accelerated its lead service line replacement program and began 

30 orthophosphate treatment in August 2004. The treatment program appears to be successful in 

31 reducing substantially elevated lead levels. LCR monitoring results for 2005 showed that the 

calculated 90th 32 percentile values were below the lead action level. 

33 

34 There have been some indications that chloramines can corrode brass. Edwards et al. 

35 (2004) found accelerated brass corrosion in 7 of 8 brass samples tested, and a slight increase with 

36 chloramines as opposed to free chlorine. Reiber et al. (1993) did not observe any additional 

37 corrosion of brass in the presence of chloramines above what was seen with free chlorine. 

38 Ammonia is known to be corrosive to brass and it is possible that excess ammonia and nitrate, 

39 caused by nitrification can accelerate brass corrosion. Uchida and Okuwaki (1999) found lead 

40 corrosion (lead is a component of brass) to be higher in the presence of ammonia and nitrate 
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1 together. Maas et al. (2005) found that fluoridation of water in combination with chloramines 

2 can cause accelerated brass corrosion. 

3 

4 Chloramines have also been found to be corrosive to some elastomer materials. 

5 Prolonged exposure of elastomer materials, such as those used in gaskets and valve seals, can 

6 lead to cracking and loss of integrity (Reiber 1991). Although free chlorine can also cause 

7 corrosion of these materials, chloramines show significantly higher corrosion rates. 

8 

9 A recent study (Bonds 2004) showed that, although there is significant corrosion of 

10 vulcanized elastomers by chloramine compounds, components that have a low surface area to 

11 volume ratio, such as gaskets, do not corrode significantly. One system in the study showed no 

12 degradation of gaskets after over 20 years of exposure to chloramine residuals. Components 

13 with higher surface area to volume ratios such as flappers or valve seats may experience more 

14 significant deterioration. 

15 

16 Reiber (1993) noted that deterioration by monochloramine is less noticeable than by 

17 dichloramine. Therefore maintaining a high chlorine to ammonia ratio may help prevent 

18 material deterioration as well as help control nitrification. Both Reiber (1991) and Bonds (2004) 

19 found that fluorocarbon elastomers showed the least corrosion of the elastomers tested. 

20 Therefore, using fluorocarbon elastomers in components that will receive high exposure to 

21 chloramines will help prevent failure. 

22 

23 Recommendations for Addressing this Issue

24 

25 Systems can minimize lead corrosion by: 

26 

27 • Optimizing the pH, alkalinity and dissolved inorganic carbon (DIC) of the water 

28 

29 • Adding a corrosion inhibitor (i.e., a substance that is phosphate- or silica-based) to the 

30 finished water to form a protective coating on the pipes 

31 

32 Systems concerned with brass corrosion can take steps to limit free ammonia and nitrification as 

33 listed in the section on nitrification. The steps listed above will also help mitigate brass 

34 corrosion. 

35 

36 To prevent elastomer corrosion, components such as gaskets and flappers should be made 

37 of elastomers such as fluorocarbons that have good resistance to chloramines. Education and 

38 outreach programs can help customers select the appropriate materials. 

39 

40 Taste and Odor Issues

41 
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1 Chlorine based disinfectants have some taste and odor impact associated with them. 

2 Monochloramine has a higher odor threshold and variations in residual concentrations produce 

3 less noticeable odors than free chlorine. Dichloramine and trichloramine, however, have much 

4 stronger odors than either monochloramine or free chlorine (Krasner and Barrett 1985). Taste 

5 and odor problems can also arise from nitrification episodes caused by excess ammonia. Control 

6 measures to prevent nitrification are discussed earlier in this section. 

7 

8 Recommendations for Addressing this Issue

9 

10 To prevent the formation of dichloramine and trichloramine that cause taste and odor 

11 problems, the chlorine to ammonia ratio should be carefully controlled and pH should be kept 

12 above 7.0. When the chlorine to ammonia ratio exceeds 5:1, dichloramine frequently begins to 

13 form. In general, maintaining a ratio between 3:1 and 5:1 should minimize odor problems. 

14 

15 Blending Chloraminated Water with Chlorinated Water

16 

17 When water with a chloramine residual is mixed with water with a free chlorine residual, 

18 the chlorine to ammonia ratio changes and the resulting changes in distribution system water 

19 quality may cause customer complaints and/or possible violations of SDWA regulations. If the 

20 additional free chlorine raises the ratio to higher than 5:1, dichloramine and trichloramine can 

21 form which have low odor thresholds and can cause customer complaints. If the ratio is raised to 

22 7.6:1 or higher by the additional free chlorine residual, breakpoint reactions can occur. 

23 Breakpoint reactions can lead to a total loss of residual, which can result in a violation of the 

24 SWTR and possibly the TCR. Blending could also cause the water to have excess free chlorine, 

25 causing DBP formation and a possible violation of the DBPR. 

26 

27 Recommendations for Addressing this Issue

28 

29 To avoid breakpoint chlorination, utilities mixing waters with chloramines and free 

30 chlorine residuals should determine the residuals in both waters and determine the chlorine to 

31 ammonia ratio of the resulting mixture. Some systems have developed computer models to 

32 predict these ratios. The models need to be calibrated to the specific distribution system in order 

33 to be useful. Keeping the chlorine to ammonia ratio below 5:1 in the chloraminated water, which 

34 allows an ammonia residual to exist, will allow some addition of water with a chlorine residual 

35 before problems occur. A system could also choose to add ammonia again at the point where the 

36 waters are mixed to maintain the chlorine to ammonia ratio in the proper range. In either case, 

37 the water system also needs to take into account the possibility of excess ammonia causing 

38 nitrification. Careful monitoring of excess ammonia, free chlorine, and total chlorine residuals 

39 should be carried out to ensure that appropriate ratios are maintained. 

40 

41 Weaker Disinfectant
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1 

2 Chloramines are a weaker disinfectant than free chlorine. Exhibit 5.1 displays the CT 

3 required for free chlorine and chloramines to achieve inactivation of viruses and Giardia cysts. 

4 Both chlorine and chloramines are ineffective against Cryptosporidium oocysts. 

5 

6 

7 Exhibit 5.1 Comparison of CT (mg-min/L) values for Inactivation of Viruses and 

Giardia by Free Chlorine and Chloramines at pH 7 and 10o 8 C 

9 

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

Chloramines 643 1491 310 1850

10 

1 11 CT values are for free chlorine of <0.4 mg/L 

12 

13 

14 Even at relatively high doses of chloramines, extremely long residence times are required 

15 to achieve required levels of inactivation for viruses and Giardia cysts using chloramines alone. 

16 Systems that switch from free chlorine to chloramines as their primary disinfectant must 

17 benchmark for viruses and Giardia. 

18 

19 Recommendations for Addressing this Issue

20 

21 Systems can compensate for the lower disinfection power of chloramines by using a 

22 different disinfectant as a primary disinfectant and using chloramines to maintain a disinfectant 

23 residual in the distribution system. Frequently this is done by adding the ammonia some time 

24 after the chlorine has been added. This allows a period of time for free chlorine disinfection. 

25 While this scheme will result in higher DBPs than using chloramines as the primary disinfectant, 

26 it will still result in lower DBP concentrations than when free chlorine is used as both a primary 

27 and residual disinfectant. One water system found as little as a two minutes of free chlorine 

28 contact time achieved desired inactivation results and reduced TTHM by 50 percent over free 

29 chlorine alone (Means et al. 1986). Another system found it could have as much as an hour of 

30 free chlorine contact time before converting to chloramines without exceeding TTHM regulatory 

31 levels (Gianatasio 1985). 

32 

33 Systems with very high total organic carbon (TOC) may wish to avoid free chlorine 

34 altogether. These systems can switch to a different primary disinfectant such as ozone, UV, or 
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1 chlorine dioxide. See Sections 5.2, 5.3, and 5.4 for more details on these disinfectants, and their 

2 advantages and drawbacks. 

3 

4 Safety Concerns

5 

6 There are safety issues that need to be considered when switching to chloramines. They 

7 will vary somewhat depending on the type of ammonia used. Ammonia, if it reacts with chlorine 

8 in high concentrations, can form an explosive mixture of trichloramine. Ammonia gas is also 

9 toxic if released to the atmosphere in sufficient concentrations. Ammonium sulfate does not 

10 have as many safety issues as either anhydrous ammonia or aqueous ammonia, but it is 

11 considerably more expensive and must be kept dry to avoid feed problems. 

12 

13 Recommendations for Addressing this Issue

14 

15 To avoid the possibility of an explosive reaction between bulk chlorine and bulk 

16 ammonia, the two chemicals should be stored in separate rooms. Feed points and pipes for 

17 chlorine and ammonia should also be placed at least five feet apart (USEPA 1999b). 

18 

19 To avoid the release of ammonia into the atmosphere, several precautions should be 

20 taken. Anhydrous ammonia should be stored in pressurized containers away from temperature 

extremes (temperatures greater than 125o 21 F will cause pressure buildups in the tank). Aqueous 

22 ammonia tanks should be vented to keep pressure from building up from ammonia volatilization. 

23 Keeping the temperature low will also help to prevent volatilization, which can cause vapor lock 

24 in pumps. Buildings where ammonia is stored should be well ventilated and respirators should 

25 be stored just outside the ammonia storage area. If large amounts of ammonia are stored an 

26 emergency scrubber should installed as well. 

27 

28 Ozone and GAC Issues

29 

30 Wilczak et al. (2003) found that ozone use prior to chloramination could destabilize the 

31 chloramine residual, leading to problems with residual concentrations at the ends of the 

32 distribution system. The loss of residual was attributed to the increased assimilable organic 

33 carbon (AOC) resulting from ozonation. 

34 

35 Adding chloramines before a GAC filter may lead to nitrification in the GAC filter. It 

36 has been found that a reaction between chloramines and GAC may free up ammonia and 

37 encourage the growth of ammonia oxidizing bacteria in the GAC filters (Tokuno 1999). 

38 

39 Recommendations for Addressing this Issue

40 
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1 Installing a GAC filter after ozone, then allowing a few minutes of free chlorine contact 

2 time to oxidize any organics before ammonia is added can be a more reliable way to allow the 

3 formation of a stable chloramine residual. Chloramines should not be added prior to GAC 

4 filters. 

5 

6 Issues for Dialysis Patients, Fish Owners, and Other Customers

7 

8 Chloramines can be toxic to dialysis patients and must be removed before water is used 

9 in dialysis machines. Chloramines are also toxic to fish and therefore must be removed from the 

10 water before it is used for pet fish or before water is discharged to natural fish habitats. The 

11 removal of chloramines from tap water is more difficult to achieve, and more costly, than free 

12 chlorine. This also impacts water customers who produce foods, beverages, and 

13 pharmaceuticals. 

14 

15 Recommendations for Addressing this Issue

16 

17 Because the process for removing chloramines is different from that for removing 

18 chlorine, dialysis patients and fish owners should be notified in advance of the switch to 

19 chloramines. Water systems may also want to consider adding special notification language for 

20 fish owners and dialysis patients to their consumer confidence reports, so that the information is 

21 provided on an annual basis. Information on how other systems conducted community outreach 

22 before, during, and after treatment with chloramines are presented in the AWWARF document, 

23 Optimizing Chloramine Treatment, Second Edition (Kirmeyer et al., 2004a). 

24 

25 5.1.3 Recommendations for Gathering More Information 

26 

27 Read Case Studies 

28 

29 Two case studies in Appendix B address simultaneous compliance issues associated with 

30 using chloramines. Both of the systems described in these case studies switched to chloramines 

31 as part of an effort to reduce DBP concentrations. 

32 

33 Case Study #9 - Modifying Chloramination Practices to Address Nitrification Issues on 

34 page B- 57 describes a surface water system serving 115,000 people that took steps to address 

35 nitrification and potential total coliform problems in the distribution system after switching to 

36 chloramines. Case Study #14 - Chlorine Dioxide for Primary Disinfection and Chloramines 

37 for Secondary Disinfection on page B-89 describes a small surface water system that achieves 

38 its CT with chlorine dioxide and maintains its disinfectant residual in the distribution system 

39 with chloramines. 

40 

41 See Additional References
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1 

2 Readers can turn to Chapter 7 for more references on this topic. Section 7.1.1 includes 

3 general references on water treatment, Section 7.1.2 includes references on controlling DBP 

4 formation, and section 7.1.12 includes references on chloramines. Section 7.1.3 includes several 

5 references on corrosion/disinfection interrelationships. 

6 

7 Consider Additional Monitoring

8 

9 The following are some suggestions for additional monitoring that may benefit water 

10 systems using chloramines. The purpose of these monitoring suggestions is specifically to 

11 address and prevent potential simultaneous compliance issues. Water system managers should 

12 discuss process control monitoring with the manufacturer of their units or their engineer. 

13 

14 9 Systems should consider a monitoring program targeted at identifying the potential for 

15 nitrification. Primary monitoring parameters should include: 

16 

17  Chemical balance of nitrogen species: This can be determined by measuring the free 

18 and total ammonia, nitrate, and nitrite concentrations, and calculating the differences 

19 between the treatment plant finished water and a given point in the distribution 

20 system. 

21 

22  Heterotrophic plate counts (HPC). Standard plate counts may be useful, but they are 

23 not as sensitive to changes as counts using the R2A agar. (Kirmeyer et al. 1995) 

24 recommends the use of R2A agar for HPC analysis for all utilities practicing 

25 chloramination. 

26 

27  Chloramine (or total chlorine) residual: A sharp decrease in the chloramine residual 

28 could signal the onset of nitrification. However, caution needs to be exercised since 

29 chloramine residuals degrade over time in open reservoirs in the presence of biofilm 

30 and under other distribution system conditions, such as backflow incidents. 

31 Chloramine residual monitoring is required by the SWTR and Stage 1 D/DBPR. 

32 33 

34 9 Other monitoring parameters (i.e., those which should not be used without corroboration with 

35 a primary parameter) include the following: 

36 

37  Dissolved Oxygen (DO): Decreases in DO levels frequently correlate with 

38 nitrification in some utilities. 

39 

40  Customer complaints: monitoring customer complaints can identify problem areas to 

41 monitor for signs of nitrification. 

42 
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1 The following water system locations should be monitored to ensure the proper use of 

2 chloramines and nitrification control: 

3 

4  Raw water 

5  Treatment plant finished water 

6  Reservoirs 

7 8  Dead-end mains 

9  Designated coliform monitoring locations 

10 

11 Consider Other Tools 

12 

13 In addition to water quality monitoring, there are additional tools listed in Chapter 6 to 

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

15 they may face when modifying their treatment operations. Examples of tools that can be used 

16 when chloramines are used for Stage 2 DBPR compliance include: 

17 

18 • The “Guidance Manual for Monitoring Distribution System Water Quality” 

19 (Kirmeyer 2002) which can be used to assist water utilities in implementing a 

20 distribution system water quality data collection and analysis program. 

21 

22 • The AwwaRF report “Internal Corrosion of Water Distribution System” (AWWARF 

23 and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

24 testing protocols that can be used to evaluate changes in corrosion potential due to the 

25 switch to chloramines. 

26 

27 • The AwwaRF report “Optimizing Corrosion Control in Water Distribution System” 

28 (Duranceau et al. 2004) which provides techniques for instantaneous corrosion 

29 monitoring 

30 

31 • The AwwaRF report “Water Utility Self-Assessment for the Management of 

32 Aesthetic Issues” (McGuire et al. 2004) which can be used to guide utilities in 

33 conducting a self-assessment of their taste and odor issues associated with ozonation 

34 and to identify subsequent control strategies. 

35 

36 • The AwwaRF report “Tools and Methods to Effectively Measure Customer 

37 Perceptions” (Colbourne 2001) which describes tools that allow utilities to measure 

38 customer perceptions and changes in their opinions toward the use of chloramines. 

39 

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

41 
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1 5.2 Ozonation 

2 

3 Ozone is a powerful chemical disinfectant and an alternative to free chlorine. It is an 

4 unstable gas that is generated on-site, using either air or liquid oxygen. It is very effective at 

5 disinfecting many microbes and as a pre-oxidant. It can, however, convert bromide to bromate, a 

6 DBP regulated by the Stage 1 D/DBPR. It also oxidizes organic matter into smaller molecules, 

7 which can provide a more easily degradable food source for microorganisms in the distribution 

8 system. Ozone can also produce odor compounds such as aldehydes and ketones.

9 

10 5.2.1 Advantages of Ozonation 

11 

12 The main advantages of ozone are: 

13 

14 • Effective against pathogens 

15 

16 • Does not form chlorinated DBPs 

17 

18 • Effective pre-oxidant 

19 

20 • Can raise UV transmittance of water and UV disinfection effectiveness 

21 

22 • Independent of pH 

23 

24 25 • Can aid coagulation 

26 

27 Effective Against Many Microbes

28 

29 Ozone is a highly effective disinfectant because of its high oxidation potential. It is the 

30 strongest of all the commonly used chemical disinfectants. It is most effective against viruses 

31 and slightly less effective against Cryptosporidium oocysts. Exhibit 5.2 shows the required CT 

32 values for inactivation of various microbes for each of the commonly used chemical 

33 disinfectants. 

34 

35 
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Exhibit 5.2 CT values (mg-min/L) for Chemical Disinfectants at 10o 1 C 

2 

Disinfectant 4-log 

Inactivation 

(99.99%) of 

Viruses

3-log 

Inactivation 

(99.9%) of 

Giardia

3-log Inactivation 

(99.9%) of 

Cryptosporidium

Ozone 1 1.43 30

Chlorine1 6 104 N/A

Chloramine2 1,491 1,850 N/A

Chlorine 

Dioxide

4.2 23 830

3 Source: USEPA 2003a 

4 N/A - these disinfectants are ineffective against Cryptosporidium 1 5 at pH = 7.0 and chlorine residual = 0.4 mg/L

2 6 for pH values 6 through 9

7 

8 

9 In addition to satisfying microbial disinfection requirements, ozone can aid in compliance 

10 with the Stage 2 DBPR by eliminating chlorine as a primary disinfectant and lowering the 

11 required dose of secondary disinfectant. Systems that switch to ozone from another primary 

12 disinfectant are required to benchmark for Giardia, Cryptosporidium, and viruses.

13 

14 Does Not Form Chlorinated DBPs

15 

16 Ozone by itself does not form chlorinated DBPs. Therefore using ozone can lower DBP 

17 formation and aid in compliance with the Stage 2 DBPR. If chlorine is used as a secondary 

18 disinfectant after ozone, higher concentrations of chloroform can be formed, although total 

19 TTHM levels will generally be lower than if chlorine is used as both a primary and secondary 

20 disinfectant. Ozone can react with bromide, however, to form bromate, which has a MCL of 10 

21 ppb set under the Stage 1 D/DBPR. 

22 

23 Effective Pre-oxidant

24 

25 Ozone’s high oxidation potential also means it acts well as a pre-oxidant. It can be used 

26 to oxidize iron and manganese so they can be removed through coagulation and sedimentation. 

27 It also oxidizes arsenic. Oxidizing arsenic (III) to arsenic (V) enhances removal of arsenic and 

28 aids in compliance with the recently lowered MCL for arsenic. Many organic compounds are 

29 oxidized by ozone as well. It is especially useful in oxidizing taste and odor compounds such as 

30 geosmin and 2 -methylisoborneol (MIB). The efficiency of ozone at degrading geosmin and 
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1 MIB is further increased if hydrogen peroxide is added in addition to the ozone, a process 

2 referred to as peroxone. If the dose is high enough, ozone can even completely mineralize some 

3 organics, lowering the concentration of DBP precursors and aiding in Stage 2 DBPR compliance. 

4 

5 Raises UV Transmittance of Water

6 

7 Low UV transmittance of the water will lead to less efficient UV disinfection. Ozone 

8 treatment before UV can oxidize those compounds that absorb UV, thereby increasing 

9 transmittance and UV’s disinfection effectiveness. Although it is not recommended that a 

10 system install both UV and ozone, a system with ozone in place that is limited by the ozone dose 

11 it can apply because of bromide may want to consider UV after ozonation to achieve the required 

12 Cryptosporidium disinfection. 

13 

14 Independent of pH 

15 

16 The disinfection efficiency of ozone, unlike chlorine, does not depend on pH for the 

17 range of pH values normally encountered in water treatment. This enables plants to adjust pH to 

18 optimize coagulation, prevent corrosion, or alter DBP formation reactions without having to 

19 worry about loss of disinfection capability. It also removes some of the seasonal variability that 

20 is usually found in disinfection benchmarks. Note, however, that bromate formation is impacted 

21 by the pH of the water. This is discussed in more detail later in this section. 

22 

23 Can Aid Coagulation

24 

25 Some systems have reported improvements in coagulation when they switched to adding 

26 ozone prior to coagulation (Reckhow et al. 1993, Stolarik and Christie 1997). Other systems 

27 have found no change or even increases in filtered water turbidity after ozonation. The 

28 interaction between ozonation and coagulation is complex and entails the interaction of many 

29 parameters. Therefore, results will vary significantly from plant to plant. Systems should 

30 conduct bench scale and preferably pilot scale tests to determine how ozone will affect the 

31 systems water quality. 

32 

33 5.2.2 Potential Operational and Simultaneous Compliance Issues Associated with 

34 Ozonation 

35 

36 The main operational and simultaneous compliance issues associated with ozone are: 

37 38 

39 • Forms bromate 

40 

41 • Forms smaller organic compounds 

42 
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1 • Does not provide a residual 

2 

3 • Introduces dissolved oxygen into the water 

4 

5 • Can form taste and odor compounds 

6 

7 • Can increase corrosion 

8 

10 9 • Ozone bubbles can hinder filter performance 

11 

12 • Requires additional training 

13 

14 This section summarizes these issues and provides recommendations for some ways to 

15 address them.

16 

17 Forms Bromate

18 

19 Ozone reacts with bromide to form bromate. In the presence of organic matter, ozone 

20 can also form brominated THMs and HAAs. The Stage 1 D/DBPR requires compliance with a 

21 10 μg/L MCL for bromate. Therefore, systems considering installing ozone should evaluate 

22 whether compliance with the bromate MCL may be an issue. 

23 

24 Whether bromate or brominated organic DBPs form depends on the pH and organic 

25 content of the water. Lower pH water and high DOC concentrations tend to favor the formation 

26 of brominated organic compounds. Systems using ozone may be able to reduce their chlorine 

27 dose, however, and as a result improve compliance with TTHM and HAA5 MCLs. Higher pH 

28 and low dissolved organic concentration generally lead to greater bromate formation. 

29 

30 Recommendations for Addressing this Issue

31 

32 There are several techniques that public water systems can use to control disinfection 

33 byproduct formation when bromide ion is present. These include: 

34 35 

36 • Lowering the pH 

37 

38 • Keeping the ratio of ozone to DOC low 

39 

40 • Adding ammonia 

41 

42 43 • Adding hydrogen peroxide
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1 

2 Lowering the pH favors formation of brominated organic compounds over bromate. 

3 Performing ozonation at a pH below 7 will lower the formation of bromate. This is a particularly 

4 good option for systems that have low DOC concentrations and do not have problems with high 

5 TTHM or HAA5 concentrations in their finished water. If DOC concentrations are high, 

6 however, this method of bromate control may result in exceeding HAA5 or TTHM MCLs. 

7 Systems also need to consider other effects of lowering pH such as increased corrosion, impacts 

8 on the effectiveness of secondary disinfectants, and impacts on coagulation. See Section 3.2 for 

9 a more complete discussion of the effects of changing pH. 

10 

11 If the ratio of ozone to DOC is kept low, the formation of bromate and brominated 

12 organic compounds can be reduced. This can be done by either lowering the ozone dose while 

13 extending the contact time, or by lowering DOC concentrations. If a system does not need to use 

14 ozone for pre-oxidation, it may want to add the ozone after sedimentation, or even after filtration, 

15 to achieve a lower ozone to DOC ratio. It is not typical, however, to ozonate after filtration. If a 

16 system needs to pre-oxidize, a small dose of ozone can be added to the raw water and a higher 

17 dose added after sedimentation or filtration. Using biological filtration in this case can be 

18 especially effective for lowering DBPs, since biological filtration tends to remove aldehydes and 

19 other small organic compounds that can make up a large fraction of the DOC.

20 

21 Adding ammonia to water containing bromide and ozone will lead to bromamine 

22 formation. Bromamines react more slowly with organic matter and form fewer brominated 

23 organic compounds and less bromate. Ammonia addition, however, can lead to nitrification 

24 problems in the distribution system. See Section 5.1 for more details on controlling nitrification 

25 when ammonia is added.

26 

27 Adding hydrogen peroxide in addition to ozone shifts the oxidation pathway from one 

28 that depends on reacting with molecular ozone to one that depends on hydroxyl radical reactions. 

29 One effect of this shift may be a lower concentration of brominated organic compounds in the 

30 treated water. 

31 

32 Methods described above can help control DBP formation for systems with bromide in 

33 their source water. Systems with high bromide concentrations, especially those with high DOC 

34 as well, may not be able to use ozone even if they adopt these mitigation methods. Systems that 

35 use ozone to inactivate Cryptosporidium may have an especially hard time, in this regard, 

36 because Cryptosporidium requires a much higher ozone dose. Since the LT2ESWTR does not 

37 grant disinfection credit for an ozone residual in the first contact chamber, many systems will 

38 want to increase their ozone dose to help them gain CT in subsequent chambers. Bromide can be 

39 removed by the use of anion exchange, but this is generally not a cost-effective solution.

40 
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An effective way to reduce AOC and 

prevent increasing biological growth in 

the distribution system is to remove it 

using biologically active filters. 

1 Forms Smaller Organic Compounds 

2 

3 Ozone breaks down organic compounds into smaller chain organic molecules, especially 

4 aldehydes and ketones. These smaller organic molecules are more readily biodegradable and can 

5 increase biological growth downstream of the ozone addition point. AOC is a measure of the 

6 organic carbon readily available as food for microorganisms. Some systems that have added 

7 ozone without biological filtration have experienced increased AOC and microbial growth in the 

8 distribution system (Van der Kooij 1997). Increased biological growth in the distribution system 

9 can lead to higher disinfectant demand and more frequent TCR violations. Biological growth 

10 can also cause increased corrosion, possibly leading to violations of the Lead and Copper Rule 

11 (LCR) as well as to taste and odor problems. 

12 

13 Recommendations for Addressing this Issue

14 

16 An effective way to reduce 

18 AOC and prevent increasing 

20 biological growth in the distribution 

22 system is to remove it using 

24 biologically active filters. Odor 

26 compounds can be removed along 

27 with the AOC. Biological filtration can be achieved by not having a disinfectant residual in the 

28 water entering the filter. The increased dissolved oxygen that results from the ozonation, 

29 combined with the high surface area per volume of the filter media, provide conditions for 

30 biological growth to occur on the filters. The biological growth on the filters then consumes the 

31 AOC, using it as a food source. Biological filtration has been shown to lower AOC effectively, 

32 even when very short residence times are used. Longer residence times can lead to the reduction 

33 of other organic compounds as well (LeChevallier et al. 1992). See Urfer et al. (1997) for more 

34 details on biological filtration. 

35 

36 Any type of filter media can accommodate biological filtration. Slow sand filters, rapid 

37 rate dual media filters, and GAC filters have all been successfully used for biological filtration. 

38 Rapid rate filters have been shown to remove AOC, though they may not remove all of the 

39 biodegrable dissolved organic carbon (BDOC), which is a portion of organic matter that can still 

40 be used by microbes as a food source but takes longer for the microbes to metabolize than AOC. 

41 Slow sand filters and GAC contactors have been shown to remove both BDOC and AOC. GAC 

42 has the added benefit that it will adsorb or concentrate organics, thus extending the time 

43 available for the microbes to metabolize the organic matter. 

44 

45 Does Not Provide a Disinfectant Residual

46 
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1 Ozone reacts very quickly and therefore is not able to provide a residual for use in the 

2 distribution system. It is also volatile and can be lost in pumps and other equipment with high 

3 flow turbidity. A secondary disinfectant is, therefore, required to maintain a disinfectant residual 

4 in the distribution system as required by the SWTR. 

5 

6 Recommendations for Addressing this Issue

7 

8 Chlorine can often be used as an effective residual disinfectant after ozonation. Since 

9 ozone is used to achieve primary disinfection, lower doses of chlorine can be used, resulting in 

10 lower DBP levels. Ozone followed by biological filtration reduces DBP precursors, which also 

11 leads to lower DBP levels. If biological filtration is not used, the system should be careful that 

12 chlorine addition after ozonation does not result in higher DBP levels than if chlorine alone were 

13 added. Chloroform is of particular concern in this situation. 

14 

15 Chloramines can also be used to provide a distribution system residual after ozonation. 

16 Chloramines will result in lower DBPs than chlorine. As mentioned above, adding ammonia 

17 with the ozone will provide benefits regarding the formation of brominated DBPs. If this 

18 approach is taken, chlorine can be added after filtration to form the chloramines. For a full 

19 discussion on the benefits and drawbacks of chloramines as a secondary disinfectant, see Section 

20 5.1. 

21 

22 Introduces Dissolved Oxygen into the Water 

23 

24 When ozone reacts in water it forms dissolved oxygen. Oxygen can increase corrosion of 

25 metals. It can also cause increased growth of aerobic bacteria and problems with TCR 

26 compliance. 

27 

28 Recommendations for Addressing this Issue

29 

30 Corrosion-resistant materials should be used in the ozone feed equipment, the contact 

31 chamber, and any other plant equipment that comes into contact with the water after ozonation 

32 and before the dissolved oxygen is dissipated. The best way to prevent dissolved oxygen from 

33 entering the distribution system is to run the filters in biologically active mode. This will lower 

34 the dissolved oxygen, as well as remove AOC. 

35 

36 Systems using ozone after filtration and unfiltered systems may need to take steps to 

37 control microbial growth in the distribution system. Control measures include ensuring a 

38 sufficient residual throughout the system, looping dead ends in the distribution system, and 

39 minimizing retention time in reservoirs. Systems may also want to raise the pH of the water or 

40 add a corrosion inhibitor to prevent corrosion. 

41 
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1 Can Form Taste and Odor Compounds 

2 

3 Ozonation of organic matter forms aldehydes and other compounds that can impart tastes 

4 and odors to water. 

5 

6 Recommendations for Addressing this Issue

7 

8 Systems should consider using a GAC filter or biologically active filtration to help 

9 eliminate aldehydes formed during ozonation, before the water reaches customers. 

10 

11 Increases Corrosion

12 

13 Ozone is corrosive and can corrode steel pipes and fittings, concrete, rubber gaskets and 

14 other material with which it comes into contact in the treatment plant. 

15 

16 Recommendations for Addressing this Issue

17 

18 All material that comes into contact with an ozone residual should be resistant to ozone. 

19 Equipment manufacturers should be contacted to ensure compatibility of their equipment with 

20 ozone. 

21 

22 Ozone Bubbles Can Hinder Filter Performance

23 

24 Ozone can de-gas in the filter and bind to the filter media. This can adversely affect filter 

25 performance and reduce the effectiveness of filter backwashing. 

26 

27 Recommendations for Addressing this Issue

28 

29 If ozone is injected under pressure, it should be de-gassed before the filters. 

30 

31 Requires Additional Training 

32 

33 Ozone disinfection is an advanced technology and requires different procedures and 

34 equipment than most operators are familiar with. 

35 

36 Recommendations for Addressing this Issue

37 

38 Additional training will be needed to ensure that operators can use equipment correctly. 

39 Operators should also be aware of safety concerns related to off-gassing and destruct units. 

40 
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1 5.2.3 Recommendations for Gathering More Information 

2 

3 Read Case Studies 

4 

5 Two case studies in Appendix B describe simultaneous compliance challenges faced by 

6 utilities using ozone. 

7 

8 Case Study #10 - Ozonation on page B-63 describes a surface water system serving 

9 approximately 115,000 people that installed ozone to control both Cryptosporidium and 

10 disinfection byproducts. The system was concerned about how ozone might result in increased 

11 AOC in its finished water, so biofiltration was also installed to address potential problems that 

12 could have arisen in the distribution system as a result. 

13 

14 Case Study #11 – Ozonation and Biological Filtration on page B-71 describes a system 

15 that significantly expanded its capacity at the same time that it installed ozone. Its source is a 

16 river with high TOC, so this system was also concerned with ozone’s impact on AOC levels in 

17 the finished water. Four new biological filters were installed and 12 existing filters were 

18 converted to biological filtration. 

19 

20 See Additional References

21 

22 Readers can turn to Chapter 7 for more references on this topic. Section 7.1.1 includes 

23 general references on water treatment, Section 7.1.2 includes references on controlling DBP 

24 formation, and Section 7.1.13 includes references on Ozone. 

25 

26 Consider Additional Monitoring 

27 

28 The following are some suggestions for additional monitoring that may benefit water 

29 systems using ozone. The purpose of these monitoring suggestions is specifically to address and 

30 prevent potential simultaneous compliance issues. Water system managers should discuss 

31 process control monitoring with the manufacturer of their ozonation units or their engineer. 

32 

33 9 Dissolved organic carbon (DOC) measurements in water being ozonated, and 

34 calculation of the ozone: DOC ratio. By keeping the ozone: DOC ratio low, 

35 formation of bromate and brominated organic compounds can be reduced. 

36 

37 9 AOC and/or BDOC monitoring after biological filtration to verify that they are being 

38 removed reliably. 

39 

40 9 If there is no biological filtration treatment step, AOC and/or BDOC monitoring of 

41 finished water before it enters the distribution system to track whether levels are high 
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1 enough to cause problems with biofilm growth. 

2 

3 9 HPC measurements at locations throughout the distribution system and in plant 

4 effluent, to watch for increased biofilm growth. 

5 

6 9 Dissolved oxygen at points after ozonation in the treatment plant, as part of an effort 

7 to control levels and limit corrosion in the plant. 

8 

9 9 Dissolved oxygen at entry points to the distribution system to make sure it has been 

10 reduced to acceptable levels and will not induce distribution system corrosion. 

11 

12 9 Taste and odor in finished water since ozonation can create off-odors. 

13 

14 9 Ozone residual in the contactor to ensure proper CT, and after the contactor to ensure 

15 proper removal and safety. 

16 

17 Consider Other Tools 

18 

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

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

21 issues they may face when modifying their treatment operations. Examples of tools that can be 

22 used when ozone is used for Stage 2 DBPR compliance include: 

23 

24 • The “Guidance Manual for Monitoring Distribution System Water Quality” 

25 (Kirmeyer 2002) which can be used to assist water utilities in implementing a 

26 distribution system water quality data collection and analysis program 

27 

28 • The AwwaRF report “Internal Corrosion of Water Distribution System” (AWWARF 

29 and DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot 

30 testing protocols that can be used to evaluate changes in corrosion potential due to the 

31 switch to ozonation 

32 

33 • The AwwaRF report “Optimizing Corrosion Control in Water Distribution System” 

34 (Duranceau et al. 2004) which provides techniques for instantaneous corrosion 

35 monitoring 

36 

37 • Various cost estimation models that can be used to estimate the cost of designing, 

38 constructing, and operating a new ozonation facility 

39 

40 • The AwwaRF report “Water Utility Self-Assessment for the Management of 

41 Aesthetic Issues” (McGuire et al. 2004) which can be used to guide utilities in 
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1 conducting self-assessment of taste and odor issues caused by ozonation and to 

2 identify subsequent control strategies; and 

3 

4 • The AwwaRF report “Tools and Methods to Effectively Measure Customer 

5 Perceptions” (Colbourne 2001) which describes tools that allow utilities to measure 

6 customer perceptions and changes in their opinions toward the use of ozonation. 

7 

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

9 
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1 5.3 Ultraviolet Light (UV) 

2 

3 Recent research indicating that UV light can inactivate Cryptosporidium at relatively low 

4 lamp intensities (Bukhari et al. 1999) has spurred interest in its use for drinking water 

5 disinfection. UV light works by damaging the genetic material of microorganisms, interfering 

6 with the ability of pathogens to replicate and therefore with their ability to be infective. Similar 

7 to chemical disinfectants, the extent of UV inactivation depends on the intensity of the light and 

8 the time the microorganism is exposed to it. UV is an effective way to disinfect without 

9 producing regulated DBPs. 

10 

11 5.3.1 Advantages of UV 

12 

13 Advantages

14 

15 UV light’s advantages include: 

16 17 

18 • It can inactivate chlorine-resistant pathogens such as Cryptosporidium oocysts 

19 and Giardia cysts at relatively low intensities 

20 

21 • It does not produce regulated DBPs 

22 

23 24 • Its effectiveness is not pH or temperature dependent

25 

26 Inactivates Cryptosporidium and Giardia

27 

28 UV disinfection gained attention in the U.S. drinking water market when it was shown 

29 that it could inactivate Cryptosporidium oocysts and Giardia cysts. This gives UV an advantage 

30 over chlorine or chloramines, which are ineffective against Cryptosporidium. If properly tested 

31 and validated, UV is one of the least expensive options for systems that are required to achieve 

32 additional Cryptosporidium inactivation under the LT2ESWTR (U.S. EPA 2003b). UV can also 

33 meet IESWTR requirements for Giardia inactivation. 

34 

35 Does Not Produce Regulated DBPs

36 

37 UV disinfection, as a photochemical process, does not produce any of the regulated 

38 byproducts that chemical disinfectants such as chlorine, ozone, and chlorine dioxide produce. 

39 Systems may meet Stage 2 DBPR requirements by switching to UV disinfection and lowering 

40 their doses of chemical disinfectants. Systems making this change will be required to benchmark 

41 their disinfection process under LT2ESWTR requirements before making the change. See the 

42 Section 5.3.2 for further discussion of UV benchmarking requirements. Systems will also need 

43 to continue to meet the residual disinfection requirements of the SWTR. 
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A main drawback with UV is the 

possibility of microbes passing 

through when the lamp is operating 

off specification.

1 

2 Not pH or Temperature Dependent

3 

4 UV disinfection, because it is a physical rather than a chemical process, does not vary in 

5 efficiency with changes in pH or temperature. This means that the dose will not need to be 

6 changed seasonally, as temperature and pH vary, to maintain constant disinfection efficiency as 

7 is required for chlorine and other chemical disinfectants. It also gives systems more flexibility to 

8 adjust pH to control coagulation, or to lower production of DBPs without also affecting 

9 disinfection efficiency. Because the disinfection provided is not as affected by seasonal changes 

10 in water temperature or pH, systems benchmarking may see a smaller difference in CT between 

11 minimum and maximum months, requiring less of a safety factor to ensure meeting the 

12 benchmark. This will depend somewhat on how flows vary for the system over the year. 

13 

14 5.3.2 Potential Operational and Simultaneous Compliance Issues Associated with UV 

15 Disinfection 

16 

17 A main drawback with UV is the possibility of microbes passing through at times the 

18 lamp is operating off specification, which may be difficult to detect using traditional water 

19 quality monitoring methods. Complete lamp failures are a serious problem and are discussed at 

20 the end of this section. UV reactors must be validated according to state guidelines and operate 

21 within the validated parameters at least 95 percent of the time (or more often if specified by the 

22 state). Lamps operating within the required LT2ESWTR validation parameters can still cause 

23 problems during shorter periods of off-specification operation. At low UV intensities, some 

24 microbes have shown the ability to repair damage done by UV light. Because of this, even 

25 decreases in lamp intensity not enough to cause a violation of disinfection requirements may 

26 allow microbes into the distribution system where they can repair themselves, colonize biofilms, 

28 and cause problems with TCR compliance. 

30 Therefore any periods of the lamp operating 

32 off specification should be minimized. 

34 

36 Potential operational and 

38 simultaneous compliance issues associated 

39 with UV disinfection include: 

40 41 

42 • Substances in water can interfere with UV disinfection 

43 

44 • Hydraulic upsets can lower the delivered dose and possibly cause lamp breakage 

45 

46 • Much higher doses needed for virus inactivation 

47 

48 • UV disinfection provides no distribution system residual 
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1 

2 • Power outages can cause loss of disinfection 

3 

4 • Requires additional training 

5 

6 This section provides brief descriptions of these issues and suggestions for addressing them. 

7 

8 Substances in Water Can Interfere with UV Disinfection

9 

10 Because UV disinfection relies on UV light interacting with the organism’s genetic 

11 material to be effective, any substance that either absorbs or refracts the UV light in the 

12 germicidal range of 200 to 300 nanometer wavelengths can interfere with disinfection. 

13 Chemicals with the potential to do this include: 

14 

15 • dissolved organic carbon (DOC) 

16 • iron 

17 • manganese 

18 • calcium 

19 • aluminum 

20 • ozone 

21 

22 There are several possible sources of these materials, each having its own implications for 

23 simultaneous compliance. These sources include: 

24 

25 • raw water 

26 • coagulants 

27 • other treatment chemicals 

28 

29 Chemicals used in water treatment that can also absorb UV light include iron based coagulants, 

30 some polymers, and ozone. 

31 

32 If chlorine dioxide is used in addition to UV, it can react with UV light to form chlorate. 

33 This carries with it two consequences: first all chlorine dioxide residual will be lost in the UV 

34 reactors reducing chlorine dioxide CT; and chlorate, which is not itself regulated, can react to 

35 form the regulated DBP chlorite. Note that there are no known effects of passing water with 

36 chlorine or chloramine residual through UV reactors. 

37 

38 Many of the same compounds that absorb light can also cause fouling of UV lamp 

39 sleeves and reduce disinfection efficiency. In addition to iron, manganese, and DOC, calcium 

40 (including that found in corrosion inhibitors), magnesium, and aluminum can also cause fouling. 
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1 

2 Ground water systems using water with high mineral content may face problems with 

3 fouling because they do not typically have filtration installed. Systems using aeration to remove 

4 radon may encounter problems with the oxidation and precipitation of iron and manganese. 

5 

6 Recommendations for Addressing this Issue

7 

8 If the raw water is high in iron, manganese, or DOC, placing the UV reactor after the 

9 filters will often alleviate the problem. If filtration does not sufficiently reduce the 

10 concentrations of these compounds, other measures such as pre-oxidation will need to be taken. 

11 Systems will need to consider the impacts of pre-oxidation on DBP formation. If DBP formation 

12 is a problem and pre-oxidation is desired, alternative oxidants such as potassium permanganate 

13 can be considered. 

14 

15 Systems that already use ozone for taste and odor control may also find it useful for 

16 controlling UV absorbing compounds, if bromate formation can be kept under the Stage 1 

17 D/DBPR MCL (see Section 5.2.2). Systems that cannot pre-oxidize may be able to achieve 

18 higher removal of UV absorbing compounds by optimizing their coagulant dose. They should be 

19 careful, however, to ensure their coagulant dose is truly optimized, since some coagulants can 

20 also absorb UV light if they pass through the filters. 

21 

22 Placing the UV unit after the filter and ensuring proper filter operation should eliminate 

23 significant concentrations of coagulants or polymers. Ozone, if used for taste and odor control, 

24 will generally be added before the filters and will not enter the UV reactor. If this is not the case 

25 and an ozone residual is present in the water before it enters the UV unit, the ozone should be 

26 quenched. Ozone can be quenched by air stripping in the last chamber of the ozone contactor, or 

27 using a reducing agent such as hydrogen peroxide. Some studies suggest, however, that ozone 

28 quenching using hydrogen peroxide can be slow in low-alkalinity water (National Research 

29 Council, 2000). The ozone residual should not be quenched with thiosulfate as it also absorbs 

30 UV. 

31 Chlorine dioxide should be added after the UV reactor. See Section 5.4 for further details 

32 on chlorine dioxide use. There are no known effects of passing water with chlorine or 

33 chloramine residual through UV reactors. If corrosion inhibitors that contain UV absorbing 

34 compounds are used, they should be added after water has passed through the UV reactor. 

35 

36 Automatic wiper blades for the UV sleeves and/or more frequent manual cleanings may 

37 be necessary to remove fouling caused by a variety of compounds that also absorb light. Ground 

38 water systems may be able to handle the problem of mineral deposits by increasing cleaning 

39 frequency of the lamp sleeves if concentrations are not too high and precipitated metals are not 

40 released into the distribution system. Otherwise, systems may need to install cartridge filters 
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While UV disinfection is highly 

effective against protozoa such 

as Cryptosporidium oocysts, it 

is less effective against viruses. 

1 before the UV reactor. In such a system a cartridge filter can also help screen out debris that 

2 could cause lamp breakage. 

3 

4 Lamp Breakage

5 

6 Hydraulic upsets such as water hammer or debris can affect the delivered dose and even 

7 break lamp sleeves. This can result in insufficient inactivation and the possibility of pathogens 

8 passing into the distribution system where they can potentially cause public health problems. 

9 

10 Recommendations for Addressing this Issue

11 

12 The UV reactor should have an automatic shut down. A written containment and cleanup 

13 procedure should also be in place to prevent mercury from broken lamps from entering the 

14 distribution system. Placing the UV unit after the filter will minimize the potential for lamp 

15 breakage from debris. To eliminate hydraulic disturbances, the reactor should have flow control 

16 valves before and after it, and should be sufficiently downstream of any hydraulic disturbances 

17 such as pumps. 

18 

19 Virus Inactivation

20 

22 While UV disinfection is highly 

24 effective against protozoa such as 

26 Cryptosporidium, it is less effective against 

28 viruses. The LT2ESWTR requires that 

30 systems considering substituting current 

32 chlorination with UV disinfection have to 

34 benchmark with respect to viruses, 

35 Giardia, and Cryptosporidium and consult with the state to be sure that sufficient inactivation is 

36 maintained. 

37 

38 Exhibit 5.3 shows the ratio of CT values required for inactivation of Cryptosporidium and 

39 viruses for chlorine dioxide, ozone, and UV. CT is the product of concentration, or intensity in 

40 the case of UV, and the exposure time required to achieve a certain level of inactivation. The 

41 ratios show the relative strengths and weaknesses of the disinfectants in inactivating 

42 Cryptosporidium oocysts versus viruses. 

43 

44 
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1 Exhibit 5.3 Ratio of CT values for Inactivation of Viruses and Cryptosporidium at 

10o 2 C 

3 

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 4 and are calculated using safety factors based on the use of low pressure mercury lamps. 

5 They may vary depending on the reactor validation method see the Ultraviolet Disinfection Guidance Manual (USEPA 

6 2003b) for details. 

7 

8 To receive credit for disinfection with UV light, the proposed LT2ESWTR (40 CFR 141, 

9 Subpart W, Appendix D) requires utilities to demonstrate through validation testing that the UV 

10 reactor can deliver the required UV dose. The testing must determine a range of operating 

11 conditions that can be monitored by the system and under which the reactor delivers the required 

12 UV dose. EPA developed UV dose requirements for Cryptosporidium, Giardia, and viruses that 

13 are used during the validation process (see UV Disinfection Guidance Manual (USEPA 2003b) 

14 for dose requirements and application during validation). 

15 

16 Recommendations for Addressing this Issue

17 

18 Systems that adopt UV disinfection will need to take special care to ensure that the virus 

19 benchmark is achieved. The state should be consulted throughout the planning process to ensure 

20 that inactivation requirements can be met to achieve the necessary credit. Some viruses, in 

particular adenoviruses, are very resistant to UV light. Data show that a dose of 186 mJ/cm2 21 is 

22 required to achieve 4-log inactivation of adenovirus (68 FR 47713, August 11, 2003). 

23 

24 Readers should refer to the Ultraviolet Disinfection Guidance Manual (USEPA 2003b) 

25 for more information on proper procedures for challenge testing. Testing of full-scale UV 

26 reactors is necessary to ensure disinfection performance and a consistent level of public health 

27 protection. However, EPA is not aware of an available challenge microorganism that allows for 

28 full-scale testing of UV reactors to demonstrate 4-log inactivation of adenovirus. Methodologies 
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1 for challenge testing at doses necessary to inactivate UV resistant viruses may be developed in 

2 the future. 

3 Until then, UV technology should be used in a series configuration or in combination 

4 with other inactivation or removal technologies to provide a total 4-log treatment of viruses. 

5 This option uses a second disinfectant to achieve virus inactivation and uses UV only for 

6 Cryptosporidium and Giardia inactivation. The second disinfectant could be added after the UV 

7 reactor to maintain a residual in the distribution system or it could be added prior to the UV 

8 reactor where it could also serve as a preoxidant. Surface water systems will need to add 

9 secondary disinfection anyway to comply with the entry point and distribution system residual 

10 requirements of the SWTR. If a second disinfectant is used also for additional virus inactivation, 

11 it must achieve the required inactivation before the first customer. Chlorine will provide virus 

12 inactivation with a relatively low dose, but may produce DBPs and could create problems with 

13 Stage 2 DBPR requirements. Chloramines will have less DBP formation but will require 

14 significantly longer contact time in the clearwell to ensure appropriate inactivation before the 

15 first customer. See Section 5.1.1 for more details on the use of chloramines. 

16 

17 If pre-oxidation is practiced, chlorine, ozone, or chlorine dioxide can be used. Chlorine 

18 may not be an attractive solution because the production of DBPs. Ozone will likely be cost 

19 prohibitive unless it is already installed; in which case it would have numerous advantages. 

20 

21 UV Does Not Provide a Residual

22 

23 UV disinfection, because it is not a chemical disinfectant, does not leave a residual and 

24 cannot be used to meet SWTR requirements regarding entry point and distribution system 

25 residuals. 

26 

27 Recommendations for Addressing this Issue

28 

29 Chlorine (Chapter 3), chloramines (Section 5.1), or chlorine dioxide (Section 5.4) can be 

30 used to maintain a residual disinfectant. Chlorine is effective against viruses and bacteria but can 

31 cause significant problems with Stage 2 DBPR compliance, especially in portions of the 

32 distribution system with long residence times where organic carbon is present. Chlorine dioxide 

33 is effective against Cryptosporidium and Giardia but its residual does not last as long, and can 

34 form chlorite, a regulated DBP. Chloramines as a residual disinfectant after UV disinfection 

35 have the potential to provide adequate distribution system residual and very low DBPs. 

36 Problems with chloramines include potential issues with nitrification, potential corrosion 

37 problems, and taste and odor issues if the chlorine:ammonia ratio is not maintained properly. 

38 

39 Power Outages Disrupt Disinfection

40 
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1 UV disinfection relies on a power supply to deliver disinfection. If power is interrupted, 

2 the UV reactor loses all disinfection capability. Even fluctuations in power can cause a UV 

3 system to operate outside of validated ranges. After power is restored, UV reactors also require a 

4 warm-up time before they can operate on specification. A major power disruption can cause the 

5 system to be out of compliance with microbial inactivation requirements. 

6 

7 Recommendations for Addressing this Issue

8 

9 To be prepared for power outages, the UV reactor should be equipped with flow 

10 diversion or automatic shut-off valves that prohibit untreated water from entering the distribution 

11 system. Units should be alarmed to alert operators if any power failures occur. The backup 

12 power system for the plant should be designed to provide power to the UV reactor in the case of 

13 a power failure. Backup power supplies such as a Universal Power Supply (UPS) or a second 

14 power leg may alleviate some of these problems. Systems should be configured so that sufficient 

15 “warm-up” time is allowed for the UV lamps before water passes through and on to customers. 

16 

17 Requires Additional Training

18 

19 Operation of the system and understanding parameters that must be monitored to ensure 

20 safe and efficient disinfection are very different than operation of a chemical disinfection system. 

21 Therefore, training will be needed so operators understand the new equipment and operate it 

22 correctly. 

23 

24 Recommendations for Addressing this Issue

25 

26 Equipment vendors and state officials should be contacted early in the process, regarding 

27 the appropriate training for UV disinfection. Systems considering UV should check with their 

28 state to determine whether there are water quality monitoring requirements as well. Systems 

29 may also want to perform pilot tests to be sure the water will not produce excessive fouling of 

30 lamp sleeves and bench scale UV absorbance tests to determine how much UV will be absorbed 

31 in the germicidal range of 200 to 300 nanometers. If such tests are not economically feasible the 

32 likelihood of fouling may be able to be determined by measuring parameters such as the 

33 Langelier Saturation Index (LSI). 

34 

35 UV reactors will also require keeping additional replacement parts in stock. Parts that 

36 will need to be replaced periodically include lamp bulbs, lamp sleeves, reactor seals, and sleeve 

37 seals. Wiper blades and/or cleaning fluid will be needed as well, depending on the method 

38 chosen for cleaning lamp sleeves. Systems should consult the equipment manufacturer, their 

39 state, and other experienced utilities for a list of replacement parts to keep in stock. 

40 
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1 5.3.3 Recommendations for Gathering More Information 

2 

3 Read Case Study 

4 

5 Case Study # 12 – Ultraviolet Disinfection on page B-77 in Appendix B describes a 

6 surface water system with a 16 MGD plant that converted from chlorine to UV treatment to 

7 achieve its CT. The system uses a large river as its source and needed to reduce its DBPs. In 

8 anticipation of LT2ESWTR, it opted for UV because of the additional benefit that UV 

9 inactivates Cryptosporidium. One of the biggest challenges the system faced with the transition 

10 was providing the training needed to operate and maintain the UV system. This case study 

11 describes how the system addressed this and other issues it encountered as one of the first surface 

12 water systems of its size to switch over to UV. 

13 

14 See Additional References

15 

16 Readers can turn to Chapter 7 for further references on this topic. Section 7.1.1 includes 

17 general references on water treatment, section 7.1.2 includes references on controlling DBP 

18 formation, and section 7.1.14 includes references on UV disinfection. 

19 

20 Consider Additional Monitoring 21 

22 The following are some suggestions for additional monitoring that may benefit water 

23 systems implementing UV disinfection. The purpose of these monitoring suggestions is 

24 specifically to address and prevent potential simultaneous compliance issues. Monitoring should 

25 be done before the design process to allow for proper design of the system. Water system 

26 managers should discuss process control monitoring with the manufacturer of their UV units, 

27 their engineer, and other experienced utilities. 28 

29 9 Periodic measurements of inorganic and organic chemicals, as applicable, in the water 

30 entering the UV unit. Tracking their concentrations will help a system make sure levels 

31 are low enough and will not interfere with UV disinfection. Some compounds with this 

32 potential are: 33 

34 • Iron 

35 • Manganese 

36 • Calcium 

37 • Magnesium 

38 • Aluminum 

39 • Dissolved Organic Carbon 

40 • Ozone

41 
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1 Consider Other Tools 

2 

3 In addition to water quality monitoring, there are additional tools listed in Chapter 6 that 

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

5 issues they may face when modifying their treatment operations. Examples of tools that can be 

6 used when UV is used for Stage 2 DBPR compliance include: 

7 

8 • The EPA “Draft Ultraviolet Disinfection Guidance Manual” (U.S. EPA 2003b) which 

9 provides guidance on the validation, selection, design, and operation of UV 

10 disinfection systems as well as general guidelines for UV disinfection pilot testing; 

11 • The AwwaRF report “Integrating UV Disinfection Into Existing Water Treatment 

12 Plants” (Cotton et al. 2006) which provides user-friendly web tools that will assist 

13 utilities in assessing important disinfection decisions and UV implementation issues; 

14 • The AwwaRF report “Full Scale Implementation of UV in Groundwater Disinfection 

15 Systems” (Malley 2001) which provides specific guidance for the selection, design, 

16 and operation of UV systems; 

17 • Various cost estimation models that can be used to estimate the cost of implementing 

18 a new UV facility. 19 

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

21 
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1 5.4 Chlorine Dioxide 

2 

3 Chlorine dioxide is an alternative chemical disinfectant that can be used to lower DBP 

4 production while maintaining adequate levels of inactivation. Because it is unstable, it is 

5 generated onsite using chlorine dioxide generators. 

6 

7 Chlorine dioxide has gained popularity because it produces relatively few THMs and 

8 HAAs. It is also very effective against bacteria, viruses, and Giardia cysts, and can provide 

9 some inactivation of Cryptosporidium oocysts at higher temperatures. The main drawback of 

10 chlorine dioxide is that the chlorine dioxide MRDL of 0.8 mg/L combined with an MCL of 1.0 

11 mg/L for chlorite, the main byproduct of chlorine dioxide, limit the dose that can be applied. In 

12 addition, low water temperatures can make it more difficult to use chlorine dioxide. 

13 

14 5.4.1 Advantages of Chlorine Dioxide 

15 16 

17 Chlorine dioxide’s advantages include: 

18 

19 • Effectively inactivates bacteria, virus, and Giardia cysts; can achieve some 

20 Cryptosporidium oocyst inactivation 

21 

22 • Less TTHM and HAA5 formation than chlorine 

23 

24 • Effective oxidant for the control of iron, manganese, hydrogen sulfide, and 

25 phenolic compounds 

26 

27 28 • Not significantly affected by pH values between 6 and 9

29 

30 Effective Disinfectant

31 

32 Chlorine dioxide is a strong oxidant and can therefore effectively inactivate a wide range 

33 of microbes. Exhibit 5.4 compares the required CT values of chlorine dioxide with those of 

34 chlorine and ozone. Chlorine dioxide is slightly less effective than chlorine against viruses and 

35 bacteria, but is more effective against Giardia and Cryptosporidium. 

36 

37 
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1 Exhibit 5.4 CT Values for Inactivation of Microorganisms by Chlorine Dioxide 

Compared with Other Chemical Disinfectants at 10o 2 C and pH 6-9 (in mg-min/L) 

3 

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 

4 Source: USEPA 2003a 

5 N/A - not applicable. Chlorine is ineffective against Cryptosporidium.

6 1 - Chlorine CT values for pH 7

7 

8 

9 Chlorine dioxide can achieve some inactivation of Cryptosporidium oocysts. Required 

10 CT levels for Cryptosporidium inactivation are relatively high though, so achieving more than a 

11 half log inactivation is unlikely given restrictions on dose. See the following section for a further 

12 discussion of dose restrictions. Chlorine dioxide can, however, be a relatively low cost 

13 alternative for systems that require a 0.5 log Cryptosporidium inactivation to comply with the 

14 LT2ESWTR. 

15 

16 Less TTHM and HAA5 Formation

17 

18 Chlorine dioxide provides a good alternative to chlorine for systems that wish to lower 

19 the formation of TTHM or HAA5. Pure chlorine dioxide does not form significant amounts of 

20 TTHM or HAA5. Most chlorine dioxide generators do produce some chlorine as a byproduct, 

21 however, so some TTHM and HAA5 will still be formed. The DBP of greater concern when 

22 chlorine dioxide is used is chlorite, which has a 1.0 mg/L MCL. See the discussion in the 

23 following section for more information on minimizing chlorite formation. Systems 

24 contemplating changing to chlorine dioxide will be required to perform a disinfection benchmark 

25 for viruses, Giardia, and Cryptosporidium and consult with the state to ensure adequate 

26 disinfection levels are maintained. 

27 

28 Effective Oxidant

29 

30 Another advantage to chlorine dioxide is that it is a strong oxidant. It can effectively 

31 oxidize many compounds including iron and taste and odor compounds. Under the right pH 
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1 conditions it can oxidize arsenic, which is often the first step in arsenic treatment. Oxidation of 

2 arsenic does not alone result in the removal of arsenic from water, but it enhances its removal 

3 during additional treatment. Systems that were previously using chlorine to pre-oxidize these 

4 chemicals may be able to achieve the same goals using chlorine dioxide, and simultaneously 

5 reduce TTHM and HAA5 to comply with the Stage 2 DBPR. 

6 

7 Not Significantly Affected by pH

8 

9 The efficiency of chlorine dioxide does not vary significantly in the pH range of 6 to 9. 

10 This benefits systems trying to meet benchmarks since the CT achieved will not vary with pH. 

11 This also gives systems more flexibility with their treatment. They can adjust pH values to 

12 improve coagulation, reduce corrosion, or reduce DBP formation without concern for losing 

13 disinfection efficiency. It is possible, however, that some plants using enhanced coagulation or 

14 enhanced softening may fall outside the pH range of 6 to 9. See the following section for further 

15 discussion of these cases. 

16 

17 5.4.2 Potential Operational and Simultaneous Compliance Issues Associated with 

18 Chlorine Dioxide Use 

19 

20 21 Potential issues with using chlorine dioxide include the following: 

22 

23 • Forms chlorite, a regulated DBP 

24 

25 • Reduced effectiveness at low temperature 

26 

27 • Chlorine dioxide MRDL of 0.8 mg/L 

28 

29 • Can form brominated DBPs 

30 

31 • Degrades when exposed to UV light 

32 

33 • Residual dissipates quickly 

34 

35 36 • Potential odor problems 

37 

38 • Requires additional training and safety concerns 

39 

40 This section addresses these issues and provides recommendations for addressing them. 

41 

42 Chlorite Formation
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One of the biggest disadvantages of 

using chlorine dioxide as a 

disinfectant is that it forms chlorite. 

1 

2 One of the biggest disadvantages of using chlorine dioxide as a disinfectant is that it 

3 forms chlorite. The MCL for chlorite was set at 1.0 mg/L by the Stage 1 D/DBPR. Systems 

4 using chlorine dioxide must monitor daily at the entrance to the distribution system for chlorite. 

5 They must also collect 3 chlorite samples per month in the distribution system. As much as 70 

6 percent of the chlorine dioxide added to water can break down to form chlorite. This limits the 

7 dose of chlorine dioxide that can be used and therefore the amount of inactivation that can be 

8 achieved. This especially limits Cryptosporidium inactivation, since the required CT values for 

9 Cryptosporidium are much higher than for other microbes. 

10 

11 High oxidant demand and high pH also lead to higher chlorite production. If there is 

12 substantial oxidant demand in a system’s water due to natural organic matter (NOM) or reduced 

13 metals, the oxidant demand will consume the chlorine dioxide and form chlorite, but the 

14 chlorine dioxide consumed in this way will not achieve any disinfection. Systems then have to 

15 add higher chlorine dioxide doses to achieve sufficient inactivation, and as a result generate 

16 higher chlorite concentrations. 

18 

20 Water pH values above 9 also lead to 

22 increased production of chlorite. Systems 

24 with high pH as a result of enhanced 

26 softening or corrosion control may have 

28 trouble complying with the chlorite MCL. 

29 

30 Recommendations for Addressing this Issue

31 

32 There are several ways to minimize chlorite concentrations. Adding chlorine dioxide 

33 after the filters, after the oxidant demand has been reduced, can result in lower chlorite 

34 concentrations. In order to comply with the LT1ESWTR or IESWTR, systems must benchmark 

35 and check with the state before moving the point of disinfection. Systems using chlorine dioxide 

36 as a pre-oxidant may also reduce the water’s oxidant demand by using pre-sedimentation before 

37 chlorine dioxide is injected. 

38 

39 Systems that increase pH during treatment should try to do so after the chlorine dioxide 

40 contact chamber. They may want to reduce the treated water’s pH to below 9 before adding the 

41 chlorine dioxide. 

42 

43 Even if systems control pH and have no oxidant demand outside of microbial 

44 inactivation, 50 to 70 percent of the chlorine dioxide consumed will form chlorite. This puts an 

45 effective limit on the dose that can be applied. Most systems will not be able to apply chlorine 

46 dioxide doses of greater than 1.2 mg/L without risking exceeding the chlorite MCL. Systems 

47 that cannot achieve the desired inactivation with a chlorine dioxide dose of less than 1.2 mg/L 
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1 may want to consider using another disinfectant in addition to chlorine dioxide to achieve the 

2 necessary inactivation. Another possibility is that the chlorite could be reduced using a reductant 

3 such as thiosulfate, which would then allow the use of higher chlorine dioxide doses.

4 

5 Reduced Effectiveness at Low Temperatures

6 

7 The disinfection effectiveness of chlorine dioxide is temperature sensitive. It is much 

8 less effective at colder temperatures. Exhibit 5.5 shows the temperature sensitivity of chlorine 

9 dioxide in terms of Cryptosporidium oocyst inactivation. 

10 

11 

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

13 Inactivation by Chlorine Dioxide 

14 

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 

15 Source: USEPA 2003a

16 

17 

18 As a result of this temperature dependence, systems in cold weather climates may not be 

19 able to use chlorine dioxide to meet the Cryptosporidium inactivation requirements of the 

20 LT2ESWTR. 

21 

22 Recommendations for Addressing this Issue

23 

24 Systems may be able to achieve some inactivation by increasing the chlorine dioxide 

25 dose and then using a reducing agent such as thiosulfate to reduce the chlorite to chloride, or by 

26 using a second disinfectant. In general though, systems that regularly experience near freezing 

27 temperatures should probably investigate other disinfection techniques. 

28 

29 Chlorine Dioxide MRDL

30 

31 Chlorine dioxide itself can have health effects at elevated levels. Therefore it has an 

32 MRDL of 0.8 mg/L. Systems using chlorine dioxide will have to monitor the chlorine dioxide 

33 residual at the entry point to the distribution system, before the first customer. Systems using 

34 chlorine dioxide may have to limit their doses to prevent exceeding the MRDL. 
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1 

2 Chlorite can react with excess chlorine in the distribution system to reform chlorine 

3 dioxide. Some systems may opt to boost with chlorine to maintain a residual in the distribution 

4 system. Systems that use chlorine dioxide and then boost with chlorine in the distribution system 

5 are required by the Stage 1 D/DBPR to monitor the chlorine dioxide residual in the distribution 

6 system. If doses are high enough, systems could exceed either the chlorine dioxide MRDL or the 

7 chlorite MCL. Reformed chlorine dioxide can also volatilize at consumer’s taps and react with 

8 volatile organics to cause odor problems. 

9 

10 If a system intentionally re-forms chlorine dioxide by boosting with chlorine in the 

11 distribution system, it is required by the Stage 1 D/DBPR to monitor both chlorite and chlorine 

12 dioxide in the distribution system. 

13 

14 Recommendations for Addressing this Issue

15 

16 If chlorine dioxide doses are kept below 1 mg/L, exceeding the MRDL should not be a 

17 problem. If reformation of chlorine dioxide is not desired, chloramines can be used in the 

18 distribution system instead of chlorine. If doses much higher than 1.2 mg/L are used, a reducing 

19 agent can be added to the water before it enters the distribution system to reduce any chlorine 

20 dioxide residual or chlorite to chloride. This will also prevent formation of chlorine dioxide in 

21 the system by booster addition of chlorine. 

22 

23 If a system intentionally re-forms chlorine dioxide by boosting with chlorine in the 

24 distribution system, the system should conduct bench scale tests to determine the correct chlorine 

25 dose to add to achieve an adequate residual without exceeding either the chlorine dioxide MRDL 

26 or the chlorite MCL. Systems should take into consideration the expected residence time in the 

27 distribution system. Although some small systems in Canada have maintained adequate 

28 residuals using doses of 0.4 to 0.6 mg/L of chlorine dioxide, other larger systems have found loss 

29 of residual at the end of the distribution system using similar doses (Volk et al. 2002). 

30 

31 Can Form Brominated DBPs

32 

33 Chlorine dioxide can oxidize bromide ions to bromine. The bromine can then react with 

34 organic matter to form brominated DBPs. Systems with high bromide concentrations that are 

35 near the Stage 2 DBPR limits for TTHM or HAA5 will need to take this into account. 

36 

37 Recommendations for Addressing this Issue

38 

39 Systems with high bromide concentrations that are near the Stage 2 DBPR limits for 

40 TTHM or HAA5 can lower DBP formation by adding chlorine dioxide after the filters, where 

41 organic concentrations are lower. Enhancing coagulation will also lower the amount of organic 
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1 matter available to react with chlorine dioxide after the filters. Systems that use chlorine 

2 dioxide for pre-oxidation may be able to achieve some organic removal by using pre3 sedimentation basins. Systems with very high bromide can remove it using ion exchange 

4 columns, but this is rarely an economical solution. 

5 

6 Degrades When Exposed to UV Light

7 

8 Chlorine dioxide is sensitive to UV light and will degrade to form chlorate when exposed 

9 to UV light. This will reduce chlorine dioxide residuals and therefore lower inactivation. 

10 

11 Recommendations for Addressing this Issue 

12 

13 Systems using chlorine dioxide can prevent degradation by light by covering the contact 

14 basin. If a building or hard cover are not cost effective or require too much space, floating 

15 covers can shield the chlorine dioxide from the UV light. The manufacturer should be consulted 

16 in selecting the cover material to be sure it is compatible with chlorine dioxide. 

17 

18 Systems using chlorine dioxide and UV disinfection together should add the chlorine 

19 dioxide either after the UV reactor or sufficiently ahead of the reactor that there is no residual 

20 entering the reactor. Systems should not use the residence time of UV reactors to receive contact 

21 time credit for chlorine dioxide added earlier in the treatment process.

22 

23 Residual Dissipates Quickly

24 

25 Chlorine dioxide is highly reactive and will react with GAC and anthracite in filters. 

26 Chloride formed by the reaction of chlorine dioxide and GAC can also adsorb to the GAC and 

27 cause weaker binding elements to be released. See Section 4.1 for more information on GAC 

28 use. Chlorine dioxide is also volatile and can be lost in rapid mix basins or other unit processes 

29 that have high turbulence and are exposed to the atmosphere. 

30 

31 Recommendations for Addressing this Issue

32 

33 Filters should not be used to achieve contact time for chlorine dioxide. Rapid mix basins 

34 can be used for contact time, but may require higher doses to achieve the same inactivation level. 

35 Adding the chlorine dioxide after filtration will avoid any unnecessary residual loss and will 

36 maximize the chlorine dioxide dose that is available for disinfection. 

37 

38 Systems adding chlorine dioxide as a pre-oxidant can add the chlorine dioxide in the 

39 coagulation basins. Systems with low alkalinity may see a slight rise in pH after chlorine 

40 dioxide addition. 

41 
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1 Potential Formation of Odor Causing Compounds

2 

3 Chlorine dioxide residuals in customers tap water has been found to volatilize at the tap 

4 and to react with volatile organic compounds (VOCs) in customer’s houses forming compounds 

5 with particularly bad kerosene-type odor (Hoehn et al. 1990). It can also sometimes give a 

6 strong chlorinous odor. 

7 

8 Recommendations for Addressing this Issue

9 

10 The appearance of odors in customer’s homes is difficult to predict and therefore prevent. 

11 Utilities can keep good customer complaint records and provide public education on what to do 

12 if such odors occur. Suggestions for dealing with odors in the household include improving 

13 ventilation and using carbon filters to remove the chlorine dioxide residual. 

14 

15 Additional Training Needed, Safety Concerns

16 

17 The nature of chlorine dioxide and the chemicals used to generate it requires additional 

18 training and safety precautions to ensure safe operation of the treatment plant. Sodium chlorite is 

19 often used to generate chlorine dioxide. When acidified, it can produce large amounts of 

20 gaseous chlorine dioxide. Chlorine dioxide at concentrations greater than 0.1 ppm is toxic and 

21 can cause shortness of breath, coughing, respiratory distress, and pulmonary edema. Gaseous 

22 chlorine dioxide concentrations greater than 10 percent can be explosive. Sodium chlorite fires 

23 burn very hot and produce oxygen as a byproduct. 

24 

25 Recommendations for Addressing this Issue

26 

27 Systems should contact their chlorine dioxide equipment manufacturer to schedule any 

28 necessary training. Sodium chlorite should be stored away from other chemicals, especially 

29 acids and reducing agents. It should be stored in an area made of fire resistant materials such as 

30 concrete. The area should be equipped with monitoring equipment to detect chlorine dioxide and 

31 other chlorine components in the atmosphere. Proper ventilation and scrubbers should be 

32 provided in the area. A special plan should be developed to respond to leaks or fires in the area 

33 and the necessary equipment to implement the plan, including respirators, should be stored and 

34 accessible outside the sodium chlorite storage area. If more than 1,000 pounds are stored on site 

35 the plan must be formalized into a Risk Management Plan (RMP) and OSHA’s specific 

36 requirements for storage of chlorine dioxide must be satisfied. 

37 

38 5.4.3 Recommendations for Gathering More Information 

39 

40 Read Case Studies 

41 
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1 Two case studies provided in Appendix B describe systems that switched to chlorine 

2 dioxide to reduce DBPs in their finished water and the simultaneous compliance challenges they 

3 encountered when making the switch. 

4 

5 Case Study #13 - Chlorine Dioxide for Primary Disinfection and Chloramines for 

6 Secondary Disinfection on page B-81 describes a surface water treatment plant in a wholesale 

7 system serving seven municipalities and approximately 92,000 people. The treatment plant 

8 switched from chlorine to chlorine dioxide as its primary disinfectant and from chlorine to 

9 chloramines for residual disinfection. In addition, the system uses chlorine dioxide intermittently 

10 as a pre-oxidant in its raw water. Among the challenges the system has encountered is being 

11 able to achieve sufficient Cryptosporidium inactivation to be granted LT2ESWTR credit and still 

12 comply with the Stage 1 DBPR’s chlorite MRDL. 

13 

14 Case Study #14 – Chlorine Dioxide for Primary Disinfection and Chloramines for 

15 Secondary Disinfection on page B-89 describes a surface water system serving fewer than 

16 10,000 people per day that also switched from chlorine to chlorine dioxide for CT and to 

17 chloramines for residual disinfection. The system, which is challenged by zebra mussels 

18 clogging its intake, found chlorine dioxide pretreatment works well as a replacement for the 

19 potassium permanganate previously used. It also adopted a monitoring program to watch for 

20 nitrification in its extensive distribution system. 

21 

22 See Additional References

23 

24 Readers can turn to Chapter 7 for further references on this topic. Section 7.1.1 contains 

25 general references on water treatment, section 7.1.2 contains references on controlling DBP 

26 formation, and section 7.1.15 contains references on chlorine dioxide. 

27 

28 Consider Additional Monitoring

29 

30 The following are some suggestions for additional monitoring that may benefit water 

31 systems using chlorine dioxide. The purpose of these monitoring suggestions is specifically to 

32 address and prevent potential simultaneous compliance issues. Water system managers should 

33 discuss process control monitoring with the manufacturer of their chlorine dioxide equipment or 

34 their engineer. 

35 

36 9 If a system uses chlorine dioxide and has any kind of uncovered storage, chlorine dioxide 

37 residuals should be measured after the open storage to ensure that a sufficient chlorine 

38 dioxide residual has been maintained. 

39 

40 9 Customer complaints can be monitored to determine if chlorine dioxide residuals are 

41 causing problems. 
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1 

2 

3 Consider Other Tools 

4 

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

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

7 issues they may face when modifying their treatment operations. Examples of tools that can be 

8 used when chlorine dioxide is used for Stage 2 DBPR compliance include: 

9 

10 • The “Guidance Manual for Monitoring Distribution System Water Quality” (Kirmeyer 

11 2002) which can be used to assist water utilities in implementing a distribution system 

12 water quality data collection and analysis program, especially for chlorite and chlorine 

13 dioxide residuals; 

14 • The AwwaRF report “Internal Corrosion of Water Distribution System” (AWWARF and 

15 DVGW-Technologiezentrum Wasser 1996) which provides bench-scale and pilot testing 

16 protocols that can be used to evaluate changes in corrosion potential due to the switch to 

17 chlorine dioxide; 

18 • The Standard Method 2350 (Oxidant Demand/Requirement) (APHA 1998) that provides 

19 step-by-step instruction for the determination of chlorine dioxide demand; 

20 • The AwwaRF report “Water Utility Self-Assessment for the Management of Aesthetic 

21 Issues” (McGuire et al. 2004) which can be used to guide utilities in conducting self22 assessment on their taste and odor issues caused by ozonation and to identify subsequent 

23 control strategies; and 

24 • The AwwaRF report “Tools and Methods to Effectively Measure Customer Perceptions” 

25 (Colbourne 2001) which describes tools that allow utilities to measure customer 

26 perceptions and changes in their opinions toward the use of chlorine dioxide. 

27 

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

29 
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1 5.5 Primary and Residual Disinfectant Use 

2 

3 Different combinations of primary and residual (i.e., secondary) disinfectants can present 

4 different issues and concerns. For example, when ozone is used as the primary disinfectant 

5 followed by chloramines as the residual disinfectant, water systems should be aware that 

6 increased AOC concentrations resulting from ozonation may increase the likelihood of problems 

7 with nitrification in the distribution system. On the other hand, the chlorite ion produced by 

8 chlorine dioxide during primary disinfection may actually be effective at inactivating ammonia9 oxidizing bacteria and, as a result, reduce nitrification in the distribution system. 

10 

11 This section follows a different format than many of the previous sections in this 

12 guidance manual. Exhibit 5.6 provides a summary table of the potential benefits and 

13 simultaneous compliance issues of the various combinations of primary and residual 

14 disinfectants. Brief paragraphs then follow the table, which describe noteworthy issues related to 

15 different disinfectant combinations. 

16 

17 
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1 Exhibit 5.6 Summary of Potential Benefits and Adverse Effects Associated with Different Co2 Primary and Residual Disinfectants 

Disinfection Switch 

(primary/residual, 

 from oto)

Potential Benefits Potential Adverse Effects 

3 3 

Chlorine/Chlorine o

Chlorine/Chloramines 

• improved ability to maintain a 

disinfectant residual 

• lower TTHM and HAA5 • possible improved biofilm 

control 

• improved taste and odor • Giardia and virus inactivation 

• excess ammonia can cause nitrification • possible elevated nitrite/nitrate levels • low Cryptosporidium inactivation • 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 • Giardia and virus inactivation 

• 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 • Giardia and virus inactivation 

• 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/Chlorine o

Chlorine Dioxide/ Chlorine Dioxide 

• lower TTHM and HAA5 • Cryptosporidium inactivation • Giardia and virus inactivation 

• additional chlorine dioxide and chlorite 

monitoring required 

• chlorite MCL concerns • chlorine dioxide MRDL concerns • can be difficult to maintain a chlorine dioxide 

residual 

• safety concerns 

• • • • 
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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/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 

• • • • • 

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 • 

1 
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1 5.5.1 Noteworthy Issues About Disinfectant Combinations 

2 

3 Potential Drawback of Switching from Chlorine/ Chloramines to Ozone/ Chloramines

4 

5 Changing to ozone as a primary disinfectant while maintaining chloramines as a 

6 secondary disinfectant may impact TCR compliance due to the action of ozone on natural 

7 organic matter. Having already established distribution system practices for biofilm growth in 

8 chloraminated distribution water, public water systems making this disinfection practice 

9 modification should focus on the biological stability of their distribution system water. 

10 

11 In cases where the use of ozone as the primary disinfectant increases levels of AOC, 

12 biological stability in the distribution system could be disrupted. AOC provides nutrient value 

13 for cell metabolism. In a previously chloraminated system, control of nitrification may be 

14 achieved using one or more of the techniques described in Section 5.1.2. However, the 

15 additional nutrition provided by the increased AOC may require modification to the practices. 

16 Alternatively, biological filtration can be used to effectively reduce nutrient levels. Biological 

17 filtration can also reduce dissolved oxygen, which can lead to changes in redox chemistry in the 

18 system and potentially change scale chemistry, affecting corrosion control treatment. 

19 

20 Potential Benefit of Switching from Chlorine/ Chloramines or Ozone/ Chloramines to Chlorine 

21 Dioxide/ Chloramines

22 

23 McGuire et al. (2006) provided field and laboratory evidence that the chlorite ion may be 

24 effective at controlling nitrification in distribution systems. The study showed that even low 

25 dosages of chlorite (0.1 mg/L) were effective at inactivating 3 to 4 logs of ammonia-oxidizing 

26 bacteria over several hours. Field investigations at five water systems in Texas showed that the 

27 presence of chlorite in the distribution systems resulted in less loss of chloramines and ammonia28 nitrogen. 

29 

30 5.5.2 Recommendations for Gathering More Information 

31 

32 Read Case Study 

33 

34 Case Study #14 - Chlorine Dioxide for Primary Disinfection and Chloramines 

35 for Residual Disinfection on page B-89 in Appendix B provides an example of a small surface 

36 water system that switched from chlorine for primary and residual disinfection to chlorine 

37 dioxide for primary disinfection and chloramines for residual disinfection. The system pays 

38 close attention to the potential for nitrification in its distribution system as a result of the 

39 chloramines, and has developed a monitoring program and guidelines for action to prevent 

40 nitrification episodes. Chlorite is one of the parameters tracked closely in the distribution 

41 system. The system tries to take advantage of the possibility that chlorite may be toxic to 

42 nitrifying bacteria. 

43 
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1 See Additional References

2 

3 Readers can refer to Chapter 7 for more references on this topic. Section 7.1.1 contains 

4 references on general water treatment, section 7.1.2 contains references on controlling DBP 

5 formation, Section 7.1.12 contains references on chloramines, Section 7.1.13 contains references 

6 on ozone, Section 7.1.14 contains references on UV disinfection, and Section 7.1.15 contain 

7 references on chlorine dioxide. 

8 

9 Consider Tools 

10 

11 There are additional tools available to help systems evaluate and improve their current 

12 water system in relation to the compliance issues they may face when modifying their treatment 

13 operations. Readers are encouraged to read through Chapter 6 before making any final 

14 compliance decision. 

15 
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1 

2 

3 

4 

5 

6 

7 

8 This Chapter covers: 

9 

10 11 6.1 Introduction 

12 6.2 Issues to Consider When Making a Compliance Decision 

13 6.3 Tools for Gathering Information 

14 

15 The information provided in this chapter is meant to help water system managers and 

16 their regulators identify what issues should be considered before a change in treatment or 

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

18 applicable and helpful for making their compliance decisions. 

19 

20 6.1 Introduction 

21 

22 To comply with the Stage 2 DBPR and LT2ESWTR, water systems will be making 

23 changes to their treatment and operations ranging from relatively small adjustments in how they 

24 run existing systems, to major capital improvements, to filtration or disinfection processes. 

25 

26 Systems should consider the impacts of any modifications they are considering, including 

27 impacts related to the issues described in Sections 2.4 and 6.2. They should identify what 

28 information they need to help them decide whether and how they can adjust their treatment to 

29 comply. If they do not have that information, they should identify what monitoring is necessary 

30 to obtain it. Subsection 6.3.1 provides resources system managers can use as guidance for 

31 collecting data about their systems to help them make these decisions. 

32 

33 Subsection 6.3.2 describes available desktop studies that can be useful tools for decision34 making. Subsection 6.3.3 lists resources available about bench scale tests, including those 

35 describing proper jar testing applications and procedures. These are all relatively inexpensive 

36 ways for a system to determine whether it can comply by optimizing its existing treatment. 

37 

38 If a system opts to install new treatment, managers should proceed carefully and in an 

39 informed way. They too should consider the issues described in Sections 2.4 and 6.2 and how 

40 those issues affect what treatment should be installed. 

41 

42 Some water systems will have more resources available than others for evaluating the 

43 potential impacts of a treatment change. The references provided in Section 6.3 give readers 

6 Making Compliance Decisions 
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1 perspective on how involved and expensive different evaluation tools can be. Water system 

2 managers, particularly those with limited resources, are encouraged to take the time to make 

3 informed decisions about what evaluations should be performed before a new treatment is 

4 installed. 

5 6 

7 Finally, simultaneous compliance is a necessary consideration when deciding how to 

8 proceed. System managers should use the information and references available throughout this 

9 and other guidance manuals to make Stage 2 DBPR and LT2ESWTR compliance decisions with 

10 confidence that all regulations will be met. 

11 

12 

13 6.2 Issues to Consider When Making a Compliance Decision 

14 

15 As the previous chapters have indicated, numerous considerations must be taken into 

16 account when deciding on the best strategy for complying with a new regulation. Factors must 

17 be considered and balanced when coming to a conclusion that will satisfy all parties: system 

18 owners; regulatory agencies; customers; and other stakeholders. The earlier sections of this 

19 manual have laid out considerations for specific technologies. This section identifies issues to 

20 consider whenever any change is made to a water system, including changes that may not be 

21 discussed previously, such as novel technologies or seemingly minor operational changes. 

22 

23 Exhibit 6.1 summarizes the types of considerations that should be made before making 

24 changes, along with some direction as to what kind of information would help decision-makers 

25 during their review of those considerations. 

26 
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1 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, especially Sec

issues with treatment tec

• 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 must 

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. 

• Sections 3.3.4, 4.1.4, 4.3

examples of systems that of changing processes. 

• 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
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Issue Description of the Issue

Information to Help 

the Iss

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 must be taken into account both 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. 

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). 

• Sections 3.6.4 and 5.2.4 p

systems that faced challetemperature differences. 

• System-specific studies m

determine how various isSome issues can be suffiliterature reviews and dismanufacturer representatbe investigated more thotechniques discussed in S
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 6 MAK

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Issue Description of the Issue

Information to Help 

the Iss

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. 

• Section 5.1.4 shows how 

corrosion issues. 

• Appendix D also include

can be used to determine rates. 

Compatibility with Distribution System Operations 

• Treatment changes that change 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. 
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Issue Description of the Issue

Information to Help 

the Iss

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. 

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 requires good communication • Good public education is important for public health protection 

and can head off consumer complaints. 

• Section 6.3.4 and 6.3.5 d

pilot testing, which help cause undesired outcome

• Section 6.3 describes way

sources of various taste a

• Section 6.3.8 provides so

planning, such as public 

• Section 5.1.2 discusses th

education. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 6 MAK

   DRAFT - DO NOT CITE OR QUOTE 6-7 

Issue Description of the Issue

Information to Help 

the Iss

Preference of Operations Staff 

• Operator preferences may be based on how chemicals are 

added, what forms of chemicals are used (e.g. hypochlorite vs. chlorine gas), the amount of automation, and positioning of equipment. 

• Positioning of equipment, safety, need for advanced training, 

and additional monitoring. 

• Systems should solicit inp

since they are responsiblimplementation of any chconcerns that others have the planning process, and implications for training. 

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 do 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 Draft Consecutive 

Manual (USEPA 2005a) information that guides dconsecutive systems. 

Cost • Cost has an impact on decisions about compliance strategies, 

but must include all of the previous considerations. 

• Section 6.3.7 describes se

that can help with costing 

1 
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1 6.3 Tools for Gathering Information 

2 

3 The objective of this section is to provide examples of tools that can assist utilities to 

4 evaluate and improve their current water system in relation to the compliance of Total Coliform 

5 Rule (TCR), Lead and Copper Rule (LCR), LT2ESWTR, and Stage 2 DBPR. These tools 

6 include computer software, models, technical publications, and research reports that can be 

7 acquired through public domains, non-profit organizations, or private companies. While some of 

8 the tools can be obtained freely from government agencies or internet (such as reports and 

9 guidance manuals from EPA), the acquisition of some tools may either require member 

10 subscription (such as reports from AwwaRF) and/or fees (such as AWWA publications and 

11 proprietary software). 

12 

13 These tools are organized into the following eight categories: 

14 

15 9 Water quality monitoring 

16 9 Hydraulic and water quality modeling for distribution systems 

17 9 Desktop evaluations 

18 9 Bench-scale testing 

19 9 Pilot testing 

20 9 Full-scale applications 

21 9 Cost estimation 

22 9 Community preferences 

23 

24 A subsection is dedicated to each of these categories and a brief introduction is included to 

25 describe the purpose of tools in that category and the relations to other subsections. The 

26 application of these tools at various project implementation stages is summarized in Exhibit 6.2. 

27 

28 This document does not intend to provide a comprehensive list of tools that may be used 

29 to assist in simultaneous regulatory compliance, but rather to provide examples of available 

30 tools. Readers of this document should consult with regulatory agencies and professional 

31 organizations for other similar tools and updated information. 

32 

33 
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1 Exhibit 6.2 Application of Information Gathering Tools at Various Project 

2 Implementation Stages 

Tool Type Planning

Evaluating 

Compliance 

Options 

Design Operation 

/Monitoring

Water quality monitoring X X X 

Hydraulic and water quality 

modeling for distribution 

systems 

X X X 

 Desktop evaluations X 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 

3 

4 

5 This document does not intend to provide a comprehensive list of tools that may be used to assist 

6 in simultaneous regulatory compliance, but rather to provide examples of available tools. 

7 Readers of this document should consult with regulatory agencies and professional organizations 

8 for other similar tools and updated information. 

9 

10 6.3.1 Water Quality Monitoring 

11 

12 Tools included in this section provide guidance and methodologies for monitoring water 

13 quality in water supplies, water treatment facilities, and transmission and distribution systems. 

14 The first five tools are EPA documents that describe water quality sampling requirements for 

15 various regulations. Utilities should consult with these documents to meet the minimum 

16 monitoring requirements for the compliance of each regulation. 

17 

18 • Total Coliform Rule: A Quick Reference Guide (USEPA 2001f). This EPA 

19 document provides updated information on water quality monitoring requirements for 

20 the TCR. This document can be obtained from the following EPA Web site: 

21 http://www.epa.gov/safewater/tcr/pdf/qrg_tcr_v10.pdf. 

22 

23 • A Small System Guide to the Total Coliform Rule (USEPA 2001g). This EPA 

24 document provides guidance on monitoring requirements for small systems that serve 

25 3,300 or fewer people. This document can be obtained from the following EPA Web 

26 site: http://www.epa.gov/safewater/smallsys/small-tcr.pdf. 

27 
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1 • Drinking Water Regulations; National Primary Drinking Water Regulations for

2 Lead and Copper Rule (USEPA 2000b) & Lead and Copper Rule Minor Revision

3 Fact Sheet (USEPA 1999i). These two documents summarize the monitoring 

4 requirement of the LCR. The quick reference guide of LCR can be found at the 

5 following EPA Web site: 

6 http://www.epa.gov/safewater/lcrmr/pdfs/qrg_lcmr_2004.pdf

7 

8 • Source Water Monitoring Guidance For the Long Term 2 Enhanced Surface 

9 Water Treatment Rule (USEPA 2006d). This EPA guidance manual provides 

10 detailed water quality sampling procedures and requirements for the LT2ESWTR. 

11 The primary monitoring target of this rule is a chlorine-resistant parasite: 

12 Cryptosporidium parvum oocyst, a protozoan oocyst. 

13 

14 • The Stage 2 DBPR Initial Distribution System Evaluation Guidance Manual 

15 (USEPA 2006a). This EPA document provides distribution system water quality 

16 monitoring requirements for the Stage 2 DBPR. This guidance manual describes the 

17 monitoring frequency, number of sampling locations, and the methodologies for 

18 selecting appropriate sampling locations for TTHM and HAA5. 

19 

20 • Design of Early Warning and Predictive Source-Water Monitoring Systems 

21 (AwwaRF Report 90878, Grayman et al. 2001). This research report provides 

22 guidance on the development of early warning systems for real-time source water 

23 contaminant monitoring. These systems will allow utilities to predict water quality 

24 events in the source water that may require subsequent treatment adjustment in the 

25 water treatment facilities. 

26 

27 • Guidance Manual for Monitoring Distribution System Water Quality (AwwaRF 

28 Report 90882, Kirmeyer 2002). This document provides water utilities with 

29 guidance on how to design and implement a distribution system water quality data 

30 collection and analysis program. This document features a comprehensive approach 

31 for collecting and analyzing water quality information, providing important input to 

32 costly infrastructure improvements, documenting benefits of operational procedures, 

33 and addressing consumer complaints. 

34 

35 • Methods for Real-Time Measurement of THMs and HAAs in Distribution 

36 Systems (AwwaRF Report 91003F, Emmert 2004). This document summarizes 

37 existing technologies and methods that can be used to quantify concentrations of total 

38 THMs and the sum of the five regulated HAA5 in near-real time. Some of the 

39 methods are also capable of quantifying individual THM and HAA species. 

40 

41 • Optimizing Corrosion Control in Water Distribution Systems (AwwaRF Report 

42 90983, Duranceau et al. 2004). This report demonstrates the use of a multi-element 
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1 sensor electrochemical technique for instantaneously monitoring corrosion and 

2 optimizing corrosion control in water distribution systems. This document also 

3 describes the uses of real-time corrosion sensors to screen various corrosion 

4 inhibitors. 

5 

6 • You may go to the following documents for national occurrence information to 

7 determine how your source water compares with source waters of other systems, and 

8 to get a sense of the technologies being commonly used by water systems with source 

9 water quality similar to yours. 

10 11 

12 o USEPA. 2005c. Stage 2 Occurrence Assessment for Disinfectants and 

13 Disinfection Byproducts. EPA 815-R-05-011 

14 15678 

19 o USEPA. 2003k. Occurrence and Exposure Assessment for the Long Term 2 

20 Enhanced Surface Water Treatment Rule. EPA 815-R-06-002 

21 

22 o McGuire, M.J., J.L. McLain, and A. Obolensky. 2002. Information Collection 

23 Rule Data Analysis. Awwa Research Foundation and AWWA, Denver. 

24 

25 6.3.2 Hydraulic and Water Quality Modeling for Distribution System 

26 

27 While documents listed in the previous section provide guidance on monitoring actual 

28 water quality, tools described in this section provide means to predict and model water quality 

29 changes in the distribution system based on the calculation of hydraulic retention time (water 

30 age), kinetics of water chemistry, and parameters that could affect water chemistry (e.g., 

31 temperature, pipe material, etc.). In addition to water quality modeling, most of these tools are 

32 also capable of hydraulic modeling. Results from these modeling exercises can assist utilities in 

33 projecting distribution system water quality and planning for simultaneous compliance. 

34 

35 • EPANET (USEPA 2002b). Developed by EPA, EPANET 2.0 is a Windows based 

36 computer program that performs extended period simulation of hydraulic and water 

37 quality behavior within pressurized pipe networks. It is available at the following 

38 EPA Web site: http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html. Several 

39 software companies (including DHI, MWH Soft, Haestad Methods, and Wallingford 

40 Software) use EPANET as the foundation to develop their proprietary versions of 

41 hydraulic and water quality modeling tools. These commercial programs provide 

42 similar functions to that by EPANET, but may be more flexible, and user-friendly. 

43 

44 • SynerGEE® Water. Developed by Advantica, SynerGEE Water is a simulation 

45 software package for modeling and analyzing water distribution systems. It is 

46 capable of conducting steady state analysis, dynamic analysis, and the analyses of 

47 water age, source contribution, water quality, fireflow, and pump operating costs. 
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1 

2 • Water Quality Modeling of Distribution System Storage Facilities (AwwaRF 

3 Report 90774, Grayman 2000). This document describes procedures that can be 

4 used to characterize water quality conditions and changes in water storage reservoirs. 

5 This report also provides a hydraulic model with a water quality model that can be 

6 used to determine the effects of daily fill and draw cycles. Optimum design and 

7 operation of distribution system tanks and reservoirs is also addressed. 

8 

9 • Predictive Models for Water Quality in Distribution Systems (AwwaRF Report 

10 91023F, Powell 2004). This research report provides a comprehensive review of the 

11 current state of predictive water quality modeling covering water quality processes 

12 models for corrosion and metal release, discoloration, disinfectant decay, DBPs, and 

13 microbial water quality. This review also describes how these models can be applied 

14 to distribution networks, including water quality network models, storage tank 

15 models, and zone level models. 

16 

17 • Computer Modeling of Water Distribution Systems (AWWA 2004a). This 

18 manual provides step-by-step instructions for the design and use of computer 

19 modeling for water distribution systems. Distribution system operators can build an 

20 accurate and detailed “virtual” model of the system using computer software. 

21 Computer models can help the operators to uncover problems and explore different 

22 scenarios to solve the problems without actually entering or changing the physical 

23 distribution system. This manual also includes results from a survey of U.S. and 

24 Canadian water utilities on future trends of water distribution and water quality 

25 modeling. 

26 

27 6.3.3 Desktop Evaluations 

28 

29 Desktop evaluation tools included in this section can be used to assist utilities in 

30 evaluating and optimizing treatment strategies to comply with LT2ESWTR and Stage 2 DBPR. 

31 These tools are particularly helpful in identifying the best combination of treatment components 

32 for simultaneous regulatory compliance. 

33 • Water Treatment Plant Model (Version 2.0) (USEPA 2001h). Originally 

34 developed by EPA in 1992 to support Stage 1 Disinfectants/Disinfection Byproducts 

35 Rule (D/DBPR), the Water Treatment Plant Model was updated in 2001 to include 

36 more data and alternative treatment processes to assist utilities in achieving total 

37 system optimization (TSO), i.e., a method by which treatment processes can be 

38 implemented such that a utility meets the required levels of disinfection while 

39 maintaining compliance with requirements of Stage 1 and, potentially, Stage 2 DBPR. 
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1 • The Surface Water Analytical Tool (Version 1.1) (USEPA 2001i). Developed by 

2 EPA, Malcolm Pirnie, and TPMC, the Surface Water Analytical Tool (SWAT) can be 

3 used to select treatment processes to meet the Stage 2 DBPR and desirable 

4 disinfection level. 

5 • Draft Significant Excursion Guidance Manual (USEPA 2003c). The purpose of 

6 this guidance manual is to provide technical information and guidance for water 

7 systems and States to use for identifying and reducing significant excursions of DBP 

8 levels. 

9 • Self-Assessment Guide for Surface Water Treatment Plant Optimization 

10 (AwwaRF Report 90736, Renner and Hegg 1997). This self-assessment guide was 

11 developed to assist water utilities in evaluating their ability to produce reliable and 

12 consistent supplies of high quality treated drinking water with maximum removal of 

13 microbial contaminants. With the completion of the self-assessment, a water utility 

14 can evaluate its current level of plant performance with respect to turbidity goals and 

15 determine if performance improvements are needed. This self-assessment helps the 

16 utility to identify the reasons for less-than-optimum performance and implement 

17 appropriate improvements. 

18 

19 • The Rothberg, Tamburini & Winsor Blending Application Package 4.0 (AWWA 

20 2001a). This new RTW program is the successor of Model for Water Process and 

21 Corrosion Chemistry 4.0. This computer program is developed to simplify the task of 

22 evaluating water chemistry associated with precipitation/coagulation and corrosion 

23 potential of water. The model provides prediction on the change of water quality 

24 (such as pH, hardness, alkalinity, and Langelier Saturation Index) in response to the 

25 changes in operating conditions. The new version can handle more than one water 

26 source under multiple blending scenarios. Although the RTW model adequately 

27 predicts the changes in water quality, any intent of correlating these information to 

28 actual corrosion potential should also include more detail and direct corrosion 

29 assessment as described in other sections of this document. 

30 

31 • Metals Solubility Prediction Tools. Additional models have been developed to 

32 evaluate the solubility of metals in the distribution system. The AWWARF report, A 

33 General Framework for Corrosion Control Based on Utility Experience and Control 

34 of Pb and Cu Corrosion By-Products Using CORRODE Software. (Edwards and 

35 Reiber 1997) includes chemical equilibrium software that can be used to identify 

36 causes of corrosion problems and test the validity of different corrosion control 

37 strategies. The USGS PHREEQC is a computer program designed to perform a wide 

38 variety of low-temperature aqueous geochemical calculations. Information on 

39 PHREEQC is available on the USGS website at 

40 http://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/ 
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1 

2 6.3.4 Bench-Scale Testing 

3 

4 This section includes bench-scale testing procedures and methods for acquiring technical 

5 information on water quality, treatment efficacy, and internal corrosion potential. This 

6 information is critical to water quality modeling and system evaluation and optimization. Five 

7 categories of bench-scale testing methods are presented in this section, including: 

8 

9  Disinfectant Demand and Decay 

10  DBP Growth and Decay 

11  Taste and Odor Profiles 

12  Jar/Column Testing Procedures 

13  Internal Corrosion Assessment 

14 

15 Each of these bench-scale testing tools is described follow. 

16 

17 • Disinfectant Demand and Decay 

18 

19 o Standard Method 2350, Oxidant Demand/Requirement (APHA et al. 1998). 

20 Information on chlorine demand in the transmission and distribution system is critical to 

21 the assurance of public health as well as an effective internal control practice. Increasing 

22 chlorine dosage to compensate excessive chlorine demand may also result in high DBP 

23 formation. This standard method provides step-by-step instruction on four methods for 

24 the determination of oxidant demands: one method each for chlorine and chlorine dioxide 

25 and two methods for ozone (batch and semi-batch methods). 

26 

27 • DBP Formation and Decay 

28 

29 o Field and material-specific simulated distribution system testing as aids to 

30 understanding trihalomethane formation in distribution systems (Brereton and 

31 Mavinic 2002). This paper presents results from a comprehensive study using an 

32 extensive field monitoring program and an improved simulated distribution system (SDS) 

33 bench-scale test. The SDS bench test includes the potential increased chlorine demand 

34 caused by internal pipe walls in the evaluation of DBP formation. During field testing, 

35 this study compared both pre-formed THM and THM formation potential among several 

36 distribution system locations to eliminate inherent uncertainties associated with the 

37 complexities of network hydraulics, leaving exposure to the internal pipe environment as 

38 the primary factor of interest. Findings in this paper suggest the reliability of using the 

39 material-specific SDS (MS-SDS) test is a better representation of DBP evolution in a real 

40 distribution system. The MS-SDS test is readily adaptable for pilot-plant studies where 

41 real distribution system conditions are inaccessible. This article can be acquired from the 
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1 following internet Web site: http://pubs.nrc-cnrc.gc.ca/cgi-bin/rp/rp2_abst_e?cjce_l01-

2 074_29_ns_nf_cjce.

3 

4 o Simulated Distribution System DBP development procedure 

5 

6  Predicting the formation of DBPs by the simulated distribution system (Koch et 

7 al. 1991). This study developed a simulated distribution system (SDS) method 

8 that can be used to predict the amounts of DBPs that would form in a distribution 

9 system. Key parameters (including chlorine dosage, incubation temperature, and 

10 incubation holding time) are chosen to simulate the conditions of the treatment 

11 plant and the distribution. Results from this study show good correlation between 

12 the SDS samples and the samples collected from the distribution systems. 

13 

14  Assessing DBP yield: uniform formation conditions (Summers et al. 1996). This 

15 paper presents a new chlorination approach, the uniform formation conditions 

16 (UFC) test. The UFC test can be used to assess disinfection DBP formation under 

17 constant, yet representative conditions. Results from this study suggest that UFC 

18 test can be used for a direct comparison of DBP formation among different waters 

19 and allows the evaluation of how treatment changes affect DBP formation in a 

20 specific water. 

21 

22 • Taste and Odor Profiles 

23 

24 o Practical Taste-and-Odor Methods for Routine Operations: Decision Tree 

25 (AwwaRF Report 91019, Dietrich 2004). This report describes the existing and newly 

26 developed sensory methods for monitoring the taste-and-odor quality of drinking water, 

27 as well as the odor quality of source or partially treated water, in order to understand the 

28 reasons for customers’ attitudes and complaints, to make decisions for treatment, to track 

29 problems to their sources, and to provide early warning of problems that are expected to 

30 recur. The new methods are described in detail in this report while existing methods are 

31 already described in Standard Methods for the Examination of Water and Wastewater 

32 (APHA 1998). The new methods provide early warning to geosmin and 2-MIB, 

33 information about treatment, information for the approval of new installations in 

34 distribution, and the confirmation of customer complaints. 

35 

36 o Water Utility Self-Assessment for the Management of Aesthetic Issues (AwwaRF 

37 Report 90978F, McGuire et al. 2004). This report provides guidance for utility to 

38 conduct self-assessment on its T&O control strategies. This self-assessment tool 

39 improves a utility’s ability to quickly identify the source of problems, implement control 

40 strategies, and communicate with its stakeholders. 

41 

42 
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1 • Jar/Column Testing Procedures 

2 

3 o Enhanced Coagulation and Enhanced Precipitative Softening Guidance Manual, 

4 Section 3: The Step 2 Procedure and Jar Testing (USEPA 1999h). This document 

5 provides procedures for conducting jar testing to determine the optimum coagulation 

6 conditions for achieving desirable total organic carbon (TOC) removal and 

7 coagulated/settled water turbidity. This document can be found at the following EPA 

8 Web site: http://www.epa.gov/safewater/mdbp/coaguide.pdf.

9 

10 o Procedures Manual for Polymer Selection in Water Treatment Plants (AwwaRF 

11 Report 90553, Dentel et al. 1989). This manual describes the bench-scale testing 

12 protocols for the selection of coagulants as well as the appropriate types of polymer for 

13 coagulant aids, filter aids, and sludge dewatering aids. 

14 

15 o Operational Control of Coagulation and Filtration Processes (AWWA Manual M37, 

16 AWWA 2000). This manual provides information on standard jar testing procedure for 

17 bench-scale coagulation testing. 

18 

19 o Enhanced and Optimized Coagulation for Particulate and Microbial Removal 

20 (AwwaRF Project #155, Bell et al. 2001). This research project evaluated the effect of 

21 enhanced and optimized coagulation on particulate and microbial removal. This study 

22 demonstrates the use of bench-scale studies on 18 waters corresponding to the EPA TOC 

23 – alkalinity matrix and removal of protozoan cysts and oocysts, viruses, enteric bacteria, 

24 spores, and bacteriophage. The bench-scale jar testing protocol described in this report 

25 can be used to determine the optimum coagulant type, coagulant dose, and coagulation 

26 pH for the compliance of Stage 2 DBPR as well as LT2ESWTR and TCR. 

27 

28 o Design of Rapid Small-Scale Adsorption Test for a Constant Diffusivity (Crittenden 

29 et al. 1986) This paper describes the fundamental theory and bench scale testing 

30 procedure for using a small adsorptive media column to quickly predict effective GAC 

31 adsorption capacity for specific organic compounds in full-scale operation. This 

32 technique, know as RSSCT, has been widely accepted by chemical engineering industry 

33 and has also been used to estimate useful GAC life time when used for the removal of 

34 aquatic organic contaminants. 

35 

36 o Prediction of GAC Performance Using Rapid-Small Scale Column Tests (AwwaRF 

37 Project #230, Crittenden 1989) This document describes the use of RSSCT techniques 

38 to predict full-scale GAC useful life time when it is used to remove dissolved organic 

39 matter in drinking water source. This report also demonstrates how to use pilot-scale 

40 testing data to further refine the RSSCT prediction. 

41 

42 
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1 

2 • Internal Corrosion Assessment 

3 

4 o Internal Corrosion of Water Distribution Systems (AwwaRF Report 90508, 

5 AWWARF and DVGW-Technologiezentrum Wasser 1996). This report covers a 

6 wide range of topics related to internal corrosion, such as corrosion principles, corrosion 

7 of various materials including copper alloys and solder, mitigation of corrosion impacts, 

8 assessment technologies, and approaches to corrosion control studies. This document 

9 also describes a bench-scale testing protocol of using various techniques (such as 

10 electrochemical techniques and coupon techniques) to evaluate corrosion potential. 

11 Other useful topics covered by this report include types of chemicals used for corrosion 

12 control, corrosion assessment options for metal plumbing materials, water quality 

13 conditions that affect corrosion of various types of materials, and benefits and drawbacks 

14 of bench testing versus flow-through pipe loops. 

15 

16 6.3.5 Pilot Testing 

17 

18 After performing water quality monitoring, modeling, and desktop analyses, a utility may 

19 decide to implement specific technologies to comply with certain regulations. In some cases 

20 pilot testing is desired prior to the implementation of the selected technologies. Tools described 

21 in this section provide guidelines on how to conduct pilot testing in order to obtain information 

22 on performance, design, operation and maintenance issues, and cost estimation. Since 

23 technology development proceeds at a very fast pace in the water industry, to ensure a successful 

24 project, utilities are strongly encouraged to consult with experienced engineers, reputable 

25 equipment providers, and regulatory agencies when planning a pilot testing program. 

26 

27 • Membrane Filtration Guidance Manual (USEPA 2005b). The purpose of this 

28 guidance manual is to provide technical information on the use of membrane filtration 

29 and application of the technology for compliance with the LT2ESWTR, which would 

30 require certain systems to provide additional treatment for Cryptosporidium. Section 

31 6 of this guidance manual provides general guidelines for membrane pilot testing. 

32 Utilities who are considering using membrane technology to comply with 

33 LT2ESWTR should consult with this document before conducting on-site pilot 

34 testing and membrane selection. This document can be found at the following EPA 

35 Web site: http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

36 

37 • Ultraviolet Disinfection Guidance Manual (USEPA 2003b). Similar to the 

38 Membrane filtration Guidance Manual, this manual provides guidance on the 

39 validation, selection, design, and operation of ultraviolet (UV) disinfection to comply 

40 with treatment requirements under the LT2ESWTR. Appendix J of this guidance 

41 manual provides general guidelines for UV disinfection pilot testing. Utilities who 

42 are considering using UV technology to comply with LT2ESWTR should consult 
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1 with this document before conducting on-site pilot testing and equipment selection. 

2 The final version of the document will be posted on EPA’s web site: 

3 http://www.epa.gov/safewater/disinfection/lt2/compliance.html 

4 

5 • Long Term 2 Enhanced Surface Water Treatment Rule: Toolbox Guidance 

6 Manual (USEPA 2003a). While there is no specific standardized pilot testing 

7 protocol developed for each of the treatment processes identified in the LT2ESWTR 

8 Toolbox, with the exception of UV and membranes, this Toolbox Guidance Manual 

9 provides a general guidance on the Demonstration of Performance (DOP) protocol 

10 that can be used as the guideline to develop a specific pilot testing protocol for each 

11 treatment technology of interest. The final version of the document will be posted on 

12 EPA’s Web site: http://www.epa.gov/safewater/disinfection/lt2/compliance.html

13 

14 • Internal Corrosion of Water Distribution Systems (AwwaRF Report 90508, 

15 AWWARF and DVGW-Technologiezentrum Wasser 1996). As described in the 

16 Bench-Scale Testing section, this report provides a wide range of useful information 

17 on internal corrosion, including the description of an on-site pilot testing protocol for 

18 using a single-pass pipe loop tester to evaluate corrosion potential. 

19 

20 6.3.6 Full-Scale Applications 

21 

22 This section provides useful guidelines and tools for utilities to conduct treatment plant 

23 assessment and optimization. The goals for these exercises are to improve treatment 

24 performance and to comply with multiple regulations without major capital expenditure. 

25 Treatment enhancement through these practices is usually achieved by optimizing operating 

26 conditions and minor equipment updates or additions. Major capital improvement, such as the 

27 construction of a new membrane facility, is not within the scope of these plant optimization 

28 protocols, but may be needed after other options are exhausted. 

29 

30 • Comprehensive Performance Evaluations (CPE). Optimizing Water Treatment 

31 Plant Performance Using the Composite Correction Program (USEPA 1998a). 

32 This handbook consists of two components: the Comprehensive Performance 

33 Evaluations (CPE) and Comprehensive Technical Assistance (CTA). The CPE 

34 provides a set of tools that assist a utility to review and analyze its performance-based 

35 capabilities and associated administrative, operations, and maintenance practices. 

36 The goal of CPE is to help a utility to identify factors that might adversely impact a 

37 plant’s ability to achieve permit compliance without major capital improvements. 

38 The CTA provides guidance for the performance improvement phase once the CPE 

39 identifies performance improvement potential. Information on this EPA manual can 

40 be found at the following EPA Web site: 

41 http://www.epa.gov/ORD/NRMRL/pubs/625691027/625691027.htm.

42 
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1 • Texas Optimization Program (TNRCC 2005). The Texas Optimization Program 

2 (TOP) is a voluntary, non-regulatory program designed to improve the performance 

3 of existing surface water treatment plants without major capital improvements. 

4 Information on TOP can be found at the following Web site: 

5 http://www.tnrcc.state.tx.us/permitting/waterperm/pdw/top.html.

6 

7 • Self-Assessment for Treatment Plant Optimization (Lauer 2001). This guidebook 

8 presents protocols on how to optimize conventional treatment plants without 

9 investing in major capital improvements. This document provides procedures for 

10 optimizing particulate removal and disinfection through improvements in 

11 administration, maintenance, design, and operations. 

12 

13 • Full Scale Implementation of UV in Groundwater Disinfection Systems 

14 (AwwaRF Report 91024, Malley 2001). This document identifies key issues related 

15 to full-scale UV implementation, including the importance of UV reactor hydraulic 

16 design, water quality evaluation, sensor calibration, and proper cleaning techniques to 

17 insure optimal UV performance. The report provides specific guidance for the 

18 selection, design, and operation of UV systems. 

19 

20 • Integrating UV Disinfection Into Existing Water Treatment Plants (AWWARF 

21 Report 91086. Cotton et al. 2006.). This document provides user-friendly web tools 

22 that will assist utilities in assessing important disinfection decisions and UV 

23 implementation issues. This report also finds that power quality will most likely not 

24 cause a water utility to exceed the proposed regulatory requirements on UV 

25 application; however, power quality problems may reduce operational flexibility as 

26 well as UV lamp operations. The analysis protocol for the Cryptosporidium downtime 

27 and off-specification risk assessment could be used to assist regulators in developing 

28 criteria based on Cryptosporidium occurrence and risk.

29 

30 • Handbook of Public Water Systems, Second Edition (HDR, 2001) This handbook 

31 provides detailed engineering design information for various drinking water treatment 

32 processes, including granular activated carbon. 

33 

34 • Integrated Membrane Systems (AwwaRF Report 90899, Schippers et al. 2004) 

35 This document provides guidance on the selection, design, and operation of an 

36 integrated membrane system that can function as a synergistic system for removing 

37 microbiological contaminants and DBP precursors. The integrated system may 

38 include membranes (including RO, NF, UF, and MF) and any pre- or post-treatment. 

39 This document also provides procedures for bench and pilot testing for membrane 

40 elements.

41 
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DRAFT - DO NOT CITE OR QUOTE 6-20 JUNE 2006 

1 • Integrating Membrane Treatment in Large Water Utilities (AwwaRF Report 

2 91045F, Brown and Hugaboom 2004) This study addresses issues related to the 

3 integration of low pressure membranes into existing or planned water treatment 

4 facilities. Results from this study can be used as guidance for membrane layout, 

5 piping, cost comparison, and operations and maintenance. 

6 

7 • NOM Rejection by, and Fouling of, NF and UF Membranes (AwwaRF Report 

8 90837, Amy et al. 2001) Nanofiltration (NF) membranes can effectively remove 

9 natural organic matter (NOM) from a water supply, while ultrafiltration provides very 

10 limited NOM removal capability. This report provides information on the selection 

11 of appropriate membranes to achieve high NOM rejection, and also presents 

12 information on how water quality (such as the presence of calcium and pH) and 

13 operational conditions might affect NOM rejection by NF membranes. 

14 

15 • Evaluation of Riverbank Filtration as a Drinking Water Treatment Process 

16 (AwwaRF Report 90922, Wang et al. 2002) This reports describes the effectiveness 

17 of using river bank filtration for the removal of DBP precursors and microbial 

18 contaminants as a function of design and operation variables. This document also 

19 provides a general guideline for riverbank system design and operation.

20 

21 6.3.7 Cost Estimation 

22 

23 Accurate cost estimation for facility upgrades requires a comprehensive database that 

24 consists of updated equipment and construction cost information. While engineering consultants 

25 and construction companies usually keep their proprietary cost estimation tools refined and 

26 updated with major cost indices, very few cost estimation tools for drinking water industry are 

27 available to the general public. The cost estimation tools listed in this section represent the 

28 starting points for budgetary planning. It is recommended that utility budgetary planning 

29 personnel should consult with the authors of these tools and the additional information sources 

30 listed at the end of this section for a more accurate and updated cost estimation. 

31 

32 • 1999 Drinking Water Infrastructure Needs Survey: Modeling the Cost of 

33 Infrastructure (USEPA 2001j). This document provides cost models for water 

34 sources (such as surface water intake, well development, and aquifer storage & 

35 recovery wells), various treatment processes, storage, transmission/distribution 

36 systems, pumping, and other (i.e., SCADA). The cost of rehabilitation is also 

37 provided along with new installation in some cases. 

38 

39 • W/W Costs, Windows Version 3.0, Copyright 1994-2000, George Mack Wesner, 

40 PhD, PE. This computer software provides detailed capital and O&M costs of any 

41 combination of treatment processes based on the treatment processes and design 
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DRAFT - DO NOT CITE OR QUOTE 6-21 JUNE 2006 

1 criteria selected by the users. It should be noted that not all of the cost information of 

2 every treatment component were updated during the 2000 revision. 

3 

4 • WTCost©, 2003. This computer program is developed by the U.S. Bureau of 

5 Reclamation and I. Moch & Associates (sponsored by the American Membrane 

6 Technology Association, AMTA) for estimating membrane treatment plant costs. It 

7 allows the evaluation and comparison of water treatment processes that employ 

8 reverse osmosis/nanofiltration, electrodialysis, microfiltration/ultrafiltration, and ion 

9 exchange. Using flexible cost indices and adjustable inputs, WTCost includes costs 

10 equations for estimating different pre and post treatment unit operations such as 

11 gravity media filtration; coagulation and flocculation with powered activated carbon 

12 (PAC), granulated activated carbon (GAC), alum, ferric chloride ferrous sulfate or 

13 polyelectrolyte; disinfection by chlorine, monocloramine, ozone and UV; lime/soda 

14 softening; electrical, including energy recovery, and chemical consumption and 

15 various intake and outfall infrastructures. Labor and supervision, membrane 

16 replacements, amortization rates and tanks, piping and instrumentation are also 

17 included in the cost model, permitting calculation of plant capital requirements and 

18 operating and maintenance costs. 

19 

20 • WaterCAD (Haestad Methods). This commercial software can be used to design 

21 and analyze distribution systems, including pipelines and pump stations. With the 

22 Cost Manager component, this program is capable of assessing the capital costs 

23 associated with the water distribution network including pumps, valves, and storage 

24 facilities and recommend future improvements based on both hydraulic and financial 

25 impacts. Another cost function provided by this program is to estimate energy costs 

26 for constant speed and variable-speed pumps. This program can further examine the 

27 tradeoffs between energy costs and the capital costs required to improve pump 

28 efficiency. 

29 

30 • USEPA 2005d. Technologies and Costs for Control of Microbial Contaminants 

31 and Disinfection Byproducts. Office of Ground Water and Drinking Water. 

32 Standards and Risk Reduction Branch. Standards and Risk Management Division. 

33 U.S. EPA Contract 68-C-02-026. May 2003. While this publication does not provide 

34 system-specific cost information, systems may use it to determine approximate and 

35 relative costs. 

36 

37 • Additional Resources for Cost Information 

38 

39 o Most recent cost information or cost curves of a specific technology are published 

40 in professional journals or conferences 

41 
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DRAFT - DO NOT CITE OR QUOTE 6-22 JUNE 2006 

1 o Utilities from the same region that have conducted similar projects at similar scale 

2 in recent years 

3 

4 o Reputable equipment suppliers 

5 

6 o Reputable engineering consultants 

7 

8 6.3.8 Community Preferences 

9 

10 This section includes six AwwaRF research reports that provide utility survey data and 

11 practical guidance to assist water utilities in improving their customer communications, public 

12 perception, and public involvement of the water quality issues, regulatory compliance issues, and 

13 potential capital improvement projects. 

14 

15 • Consumer Attitude Survey Update (AwwaRF Report 394, AwwaRF 2000). This 

16 report discusses trends in public confidence and expectations, perceptions, and 

17 satisfaction. Also identified in this report are the driving factors behind these 

18 attitudes and trends and the impact of media on public confidence and customer 

19 satisfaction. The implications of these findings for measuring customer attitudes at 

20 the local utility level are also discussed. 

21 

22 • Tools and Methods to Effectively Measure Customer Perceptions (AwwaRF 

23 Report 90856, Colbourne 2001). This report evaluates available assessment tools 

24 and methods that measure customer perceptions and changes in their opinions toward 

25 drinking water utilities and utility services. 

26 

27 • Best Practices for a Continually Improving Customer Responsive Organization 

28 (AwwaRF Report 90868, Olstein 2001). This report provides case studies of five 

29 successful customer-driven water utilities that have used different approaches to 

30 achieving a continually improving customer responsive organization. This document 

31 presents public input to the best practices, and a toolkit for utilities that includes a 

32 self-assessment questionnaire, a technology identification matrix, and benchmarking 

33 data. 

34 

35 • Public Involvement . . . Making It Work (AwwaRF Report 90865, Nero et al. 

36 2001). In 1995, AwwaRF published the Public Involvement Strategies: A Manager's 

37 Handbook (AwwaRF 1995) to provide a framework for building consensus on 

38 difficult decisions. It presents a ten-step process to help water utility managers 

39 identify, understand, and plan public involvement and project implementation. This 

40 new report reduces the ten-step public involvement process to three essential steps, 

41 and provides a new handbook to guide utility managers through the public 

42 involvement process. 

43 
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DRAFT - DO NOT CITE OR QUOTE 6-23 JUNE 2006 

1 • Public Involvement Strategies on the Web (AwwaRF Report 90865, AwwaRF 

2 2003). This web-based interactive tool was provided by AwwaRF in 2003 to expand 

3 the AwwaRF Report 90865 (Nero et al. 2001) by offering public involvement case 

4 studies and interactive features on the internet. This interactive tool can be found at 

5 the following AwwaRF Web site: 

6 http://www.awwarf.org/research/TopicsAndProjects/Resources/webTools/ch2m/defau

7 lt.html.

8 

9 • Customer Attitudes, Behavior and the Impact of Communications Efforts 

10 (AwwaRF Report 90975, Tatham et al. 2004). This report provides guidelines on 

11 the following three areas that are critical to communication with customers: (1) 

12 determine whether or not communication can be used as a tool by water utilities to 

13 positively affect the attitudes and behaviors of residential water utility customers, (2) 

14 identify the types of information that should be communicated by water utilities to 

15 enhance customer satisfaction and the methods for communicating this information to 

16 customers, and (3) reports on ways to inform customers about water quality issues, 

17 and provides guidance on communication strategies. This report includes a CD-ROM 

18 that contains 18 Microsoft Word documents that illustrate the survey data for various 

19 demographic groups. 

20 

21 • Effective Practices to Select, Acquire, and Implement a Utility CIS (AwwaRF 

22 Report 91071, Rettie et al. 2005). This report provides guidance to utilities as they 

23 select, acquire, and implement a customer information system (CIS). Guidelines 

24 provided in this document focus on four areas: (1) characterizing the current status of 

25 water utilities regarding CIS solutions, (2) identifying and documenting critical 

26 success factors (and barriers to success) related to CIS implementations, (3) 

27 documenting successful CIS implementations and associated practices, and (4) 

28 providing a CIS projects roadmap for utilities. 

29 
 

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REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-1 UNE 2006 

1 

2 

3 

4 

5 

6 

7 

8 The references in this chapter have been organized as follows under the following headings in 

9 Section 7.1, with a complete alphabetical list in Section 7.2: 

10 

11 7.1 References Organized by Topic......................................................................................... 7-1 

12 7.1.1 General..................................................................................................................... 7-1 

13 7.1.2 Formation and Control of Chlorinated DBPs .......................................................... 7-8 

14 7.1.3 Corrosion................................................................................................................ 7-10 

15 7.1.4 Source Management............................................................................................... 7-12 

16 7.1.5 Distribution System Management.......................................................................... 7-12 

17 7.1.6 Problem Organisms in Water Treatment ............................................................... 7-14 

18 7.1.7 Presedimentation.................................................................................................... 7-15 

19 7.1.8 Enhanced Coagulation and Enhanced Softening ................................................... 7-15 

20 7.1.9 GAC ....................................................................................................................... 7-16 

21 7.1.10 Membranes........................................................................................................... 7-17 

22 7.1.11 Riverbank Filtration............................................................................................. 7-18 

23 7.1.12 Chloramines ......................................................................................................... 7-18 

24 7.1.13 Ozone ................................................................................................................... 7-20 

25 7.1.14 Ultraviolet Light................................................................................................... 7-22 

26 7.1.15 Chlorine Dioxide.................................................................................................. 7-23 

27 7.1.16 Tools for Gathering More Information................................................................ 7-23 

28 7.2 References Organized Alphabetically.............................................................................. 7-26 

29 

30 

31 7.1 References Organized by Topic 

32 

33 7.1.1 General 

34 

35 Angers, J. 2001. Question of the Month: Which Disinfectant Will Work Best for Us? 

36 Opflow. 27(5): 6-7, 22. 

37 AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). McGraw-Hill, New 

38 York, NY. 

39 AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water 

40 Supplies. Fifth Edition. Letterman, R.D. (editor). McGraw-Hill 

7 References 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-2 UNE 2006 

1 AWWA. 1999d. Design and Construction of Small Water Systems, Second Edition. 228 

2 pp. 

3 AWWA. 1999e. Hydraulic Design Handbook. Mays, L.W.(editor). McGraw-Hill. 

4 AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd Edition. 

5 AWWA Manual M37. pp. 1-34. 

6 AWWA. 2005. Biodegradable Organic Matter in Drinking Water Treatment and 

7 Distribution. M. Prevost et al. (editor). 

8 AWWARF and Lyonnaise des Eaux. 1995. Advances in Taste and Odor Treatment and 

9 Control. AWWARF Report 90610. Project #629. 

10 Becker, W.C., K. Au, C.R. O'Melia, and J.S. Young, Jr. 2004. Using Oxidants to 

11 Enhance Filter Performance. AWWARF Report 90998. Project #2725. 

12 Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 

13 174 pp. 

14 Culp, G.L. and R.L. Culp. 1974. New Concepts in Water Purification. Van Norstrand 

15 Reinhold Co., New York. 

16 DeMers, L.D. and R.C. Renner. 1993. Alternative Disinfection Technologies for Small 

17 Drinking Water Systems. AWWARF Report 90619. Project #621. 

18 Dewettinck T., E. Van Houtte, D. Geenens, K. Van Hege, and W. Verstraete. 2001. 

19 HACCP (Hazard Analysis and Critical Control Points) to Guarantee Safe Water Reuse 

20 and Drinking Water Production--a Case Study. Water Science and Technology. 43(12): 

21 31-8. 

22 DeWolfe, J. et al. Guidance Manual for Coagulant Changeover. AWWARF Report 

23 90958. Project #2512. 

24 Faust, S. and O. Aly. 1998. Chemistry of Water Treatment. Second Edition. Lewis 

25 Publishers. New York. 

26 Finch, G.R., D.W. Smith, and M. Belosevic. 2001. Sequential Disinfection Design 

27 Criteria for Inactivation of Cryptosporidium Oocysts in Drinking Water. AWWARF 

28 Report 90831. Project #348. 

29 Friedman, M. and G. Hamilton. 1997. Enhancing CTs, Coagulation, and Corrosion 

30 Control through Carbon Dioxide Injection. Proceedings 1996 Water Quality Technology 

31 Conference, Part II. American Water Works Association. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-3 UNE 2006 

1 Global Environment & Technology Foundation. 2000. Final Report: The US EPA 

2 Environmental Management System Pilot Program for Local Government. 

3 Global Environment & Technology Foundation. 2002. Final Report: Second EMS 

4 Initiative for Government Entities (2000-2002). 

5 Grant, G.B. Sc., CEA, EMS(LA), CEAS. 2004. ISO 14001 and Drinking Water Quality. 

6 Environmental Science and Engineering. January, 2004. 

7 HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd ed. 

8 Huck, P.M., B.M. Coffey, A. Amirtharajah, and E.J. Bouwer. 2000. Optimizing Filtration 

9 in Biological Filters. AWWARF Report 90793. Project #252. 

10 Hulsey, R.A. et al. 2004. Evaluation of Ozone and Ultraviolet Light. AWWARF Report 

11 91046F. Project #2749. 

12 Jacangelo, J.G., C. Gerba, and C.N. Haas. 2002. Inactivation of Waterborne Emerging 

13 Pathogens by Selected Disinfectants. AWWARF Report 90886. Project #442. Denver, 

14 CO. 

15 Kawamura, Susumu. 2000. Integrated Design and Operation of Water Treatment 

16 Facilities. 2nd ed. John Wiley & Sons, Inc. 

17 Kim, Y., Y. Lee, C.S. Gee, and E. Choi. 1997. Treatment of Taste and Odor Causing 

18 Substances in Drinking Water. Water Science and Technology. 35(8): 29-36. 

19 LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988a. Factors Promoting Survival 

20 of Bacteria in Chlorinated Water Supplies. Applied and Environmental Microbiology. 

21 54(3): 649-654. 

22 LeChevallier, M.W., G. Di Giovanni, J.L. Clancy, Z. Bukhari, S. Bukhari, J.S. Rosen, J. 

23 Sobrinho, and M.M. Frey. 2002. Source Water Assessment: Variability of Pathogen 

24 Concentrations. AwwaRF Report 90906. Project #488. 

25 Logsdon, G.S. et al. 2002. Filter Maintenance and Operations Guidance Manual. 

26 AWWARF Report 90908. Project #2511. 

27 McGuire, M.J., J.L. McLain, and A. Obolensky. 2002. Information Collection Rule Data 

28 Analysis. AWWARF Report 90947. Project #2799. 

29 McMeen. 2001. Alternate Filtration: Placing New Technology in an Old Regulatory Box. 

30 American Water Works Association, Membrane Conference Proceedings. 
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REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-4 UNE 2006 

1 Mullenger, J., G. Ryan, and J. Hearn. 2002. A Water Authority's Experience with 

2 HACCP. Water Supply. 2(5-6): 149-155. 

3 Mysore, C. et al. 2003. Impact of Water Quality on the Inactivation of Bacterial and Viral 

4 Pathogens. AwwaRF Report 90972F. Project #2592. 

5 NSF International. 1996. NSF International Environmental Management System 

6 Demonstration Project - Final Report. 

7 Pennsylvania’s Multi State Working Group Pilot. The Effects of ISO 14001 

8 Environmental Management Systems on the Environmental and Economic Performance 

9 of Organizations. March 27, 1999. 

10 Prévost, M.(editor) et al. 2005. Biodegradable Organic Matter in Drinking Water 

11 Treatment and Distribution. AWWA. 

12 Redaud, J.L. 2005. ISO/TC 224 “Service Activities Relating to Drinking Water Supply 

13 Systems and Wastewater Systems - Quality Criteria of the Service and Performance 

14 Indicators". ISO. March 31, 2005. 

15 Renner, R. 2004. Plumbing the Depths of D.C.’s Drinking Water Crisis. Environmental 

16 Science and Technology. 38(12): 224-227. 

17 Roig, R. and A. Saponara. 2003. ISO 14001 Environmental Management Systems: A 

18 Complete Implementation Guide. ISO. 

19 Sorg, T.J. 1988. Methods for Removing Uranium from Drinking Water. Journal of the 

20 American Water Works Association, 80(7) 

21 Texas Natural Resource Conservation Commission (TNRCC). 2005. Texas Optimization 

22 Program (TOP). http://www.tceq.state.tx.us/permitting/water_supply/pdw/swmor/top/ 

23 U.S. EPA. 1989. National Primary Drinking Water Regulations; Giardia lamblia, Viruses, 

24 and Legionella, Maximum Contaminant Levels, and Turbidity, and Heterotrophic 

25 Bacteria. (Surface Water Treatment Rule), Final Rule. 43 FR 27486. June 29, 1989. 

26 U.S. EPA. 1991. Guidance Manual for Compliance with the Filtration and Disinfection 

27 Requirements for Public Water Systems Using Surface Water Sources. Developed by 

28 Malcolm Pirnie and HDR. USEPA, Washington, DC. 568 pp. 

29 U.S. EPA. 1994. National Primary Drinking Water Regulations: Disinfection and 

30 Disinfection Byproducts; Proposed Rule. 59 FR 38668. July 29, 1994. 
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REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-5 UNE 2006 

1 U.S. EPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the 

2 Composite Correction Program. EPA 625/6-91/027. 

3 U.S. EPA. 1998b. National Primary Drinking Water Regulations: Interim Enhanced 

4 Surface Water Treatment Rule; Final Rule. 63 FR 69477. December 16, 1998 

5 http://www.epa.gov/safewater/mdbp/ieswtrfr.html 

6 U.S. EPA. 1998c. National Primary Drinking Water Regulations: Disinfectants and 

7 Disinfection By Products; Final Rule. 63 FR 69389. December 16, 1998. 

8 http://www.epa.gov/safewater/mdbp/dbpfr.html 

9 U.S. EPA. 1999a. Disinfection Profiling and Benchmarking Guidance Manual. EPA 815-

10 R-99-013. 

11 U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R12 99-014. 

13 U.S. EPA. 1999c. Uncovered Finished Water Reservoirs Guidance Manual. EPA 815-R14 99-011. 

15 U.S. EPA. 1999d. Guidance Manual for Compliance with the Interim Enhanced Surface 

16 Water Treatment Rule: Turbidity Provisions. EPA 815-R-99-010. 

17 U.S. EPA. 1999e. Unfiltered Systems Guidance Manual. 

18 U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance 

19 Guidance Manual. EPA 815-R-99-011. August 1999. 

20 U.S. EPA. 1999g. Guidance Manual for Conducting Sanitary Surveys of Public Water 

21 Systems; Surface Water and Ground Water Under the Direct Influence (GWUDI). EPA 

22 815-R-99-016. 

23 U.S. EPA. 1999i. Lead and Copper Rule Minor Revision Fact Sheet. EPA 815-F-99-010. 

24 U.S. EPA. 2000a. National Primary Drinking Water Regulations: Radionuclides Rule; 

25 Final Rule. 65 FR 76707. December 7, 2000. 

26 http://www.epa.gov/safewater/rads/radfr.html 

27 U.S. EPA. 2000b. National Primary Drinking Water Regulations for Lead and Copper. 65 

28 FR 1949. January 12, 2000. http://www.epa.gov/fedrgstr/EPA29 WATER/2000/January/Day-12/w3.htm 

30 U.S. EPA. 2000c. Lead and Copper Rule: Summary of Revisions. Office of Water. EPA 

31 815-R-99-020. 
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REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-6 UNE 2006 

1 U.S. EPA. 2001a. Implementation Guidance for the Stage 1 Disinfectants/Disinfection 

2 Byproducts Rule. Office of Water. EPA 816-R-01-012. 

3 U.S. EPA. 2001b. State Implementation Guidance for the Lead and Copper Rule Minor 

4 Revisions. Office of Water. EPA 816-R-01-021. 

5 U.S. EPA. 2001d. National Primary Drinking Water Regulations: Filter Backwash 

6 Recycling Rule; Final Rule. 66 FR 31085. June 8, 2001. 

7 http://www.epa.gov/safewater/mdbp/fr-fbr.html 

8 U.S. EPA. 2001e. National Primary Drinking Water Regulations: Arsenic and 

9 Clarifications to Compliance and New Source Contaminants Monitoring . 66 FR 6975. 

10 January 22, 2001. http://www.epa.gov/fedrgstr/EPA-WATER/2001/January/Day11 22/w1668.htm 

12 U.S. EPA. 2001f. Total Coliform Rule: A Quick Reference Guide. EPA 816-F-01-035. 

13 November, 2001. http://www.epa.gov/safewater/tcr/pdf/qrg_tcr_v10.pdf 

14 U.S. EPA. 2001g. A Small System Guide to the Total Coliform Rule. Office of Water. 

15 EPA 816-R-01-017A. http://www.epa.gov/safewater/smallsys/small-tcr.pdf 

16 U.S. EPA. 2001k. Stage 1 Disinfectants and Disinfection Byproducts Rule: A Quick 

17 Reference Guide. Office of Water. EPA 816-F-01-010. May, 2001. 

18 http://www.epa.gov/safewater/mdbp/qrg_st1.pdf 

19 U.S. EPA. 2001l. Interim Enhanced Surface Water Treatment Rule: A Quick Reference 

20 Guide. Office of Water. EPA 816-F-01-011. May, 2001. 

21 http://www.epa.gov/safewater/mdbp/qrg_ieswtr.pdf 

22 U.S. EPA. 2001m. Filter Backwash Recycling Rule: A Quick Reference Guide. Office of 

23 Water. EPA 816-F-01-019. June 2001. http://www.epa.gov/safewater/mdbp/fbrr_qrg.pdf 

24 U.S. EPA. 2001n. Arsenic and Clarifications to Compliance and New Source Monitoring 

25 Rule: A Quick Reference Guide. Office of Water. EPA 816-F-01-004. January, 2001. 

26 http://www.epa.gov/safewater/arsenic/pdfs/quickguide.pdf 

27 U.S. EPA. 2002a. National Primary Drinking Water Regulations: Long Term 1 Enhanced 

28 Surface Water Treatment Rule. 67 FR 1811. January 14, 2002. 

29 http://www.epa.gov/fedrgstr/EPA-WATER/2002/January/Day-14/w409.htm 

30 U.S. EPA. 2002c. Long Term 1 Enhanced Surface Water Treatment Rule: A Quick 

31 Reference Guide. Office of Water. EPA 816-F-02-001. January, 2002. 

32 http://www.epa.gov/safewater/mdbp/lt1eswtr-quick-ref.pdf 
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REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-7 UNE 2006 

1 U.S. EPA. 2003c. Draft Significant Excursion Guidance Manual. Office of Water. EPA 

2 815-D-03-004. July, 2003. 

3 U.S. EPA. 2004a. Draft Filter Surveillance Manual (June 2004). 

4 U.S. EPA. 2004c. Draft Process Monitoring Manual (July 2004). 

5 U.S. EPA. 2004d. National Primary Drinking Water Regulations; Minor Corrections and 

6 Clarification to Drinking Water Regulations; National Primary Drinking Water 

7 Regulations for Lead and Copper. 69 FR 38850. June 29, 2004. 

8 http://www.epa.gov/fedrgstr/EPA-WATER/2004/June/Day-29/w14604.htm 

9 U.S. EPA. 2004e. Guidance Manual for Compliance with the Long Term 1 Enhanced 

10 Surface Water Treatment Rule: Turbidity Provisions. EPA 816-F-02-001. 

11 U.S. EPA. 2004f. The Long Term 1 Enhanced Surface Water Treatment Rule 

12 Implementation Guidance. EPA 816-R-04-008. 

13 U.S. EPA. 2004g. Lead and Copper Rule: A Quick Reference Guide. Office of Water. 

14 EPA 816-F-04-009. March, 2004. 

15 U.S. EPA. 2005a. Occurrence Assessment for the Final Stage 2 Disinfectants and 

16 Disinfection Byproducts Rule. Prepared by The Cadmus Group, Inc. Contract 68-C-99-

17 206. 

18 U.S. EPA. 2005d. Technologies and Costs for the Final Long Term 2 Enhanced Surface 

19 Water Treatment Rule and Final Stage 2 Disinfectants and Disinfection Byproducts Rule. 

20 EPA 815-R-05-012. December, 2005. 

21 U.S. EPA. 2005e. Occurrence and Exposure Assessment for the Long Term 2 Enhanced 

22 Surface Water Treatment Rule. EPA-821-R-06-002. 

23 U.S. EPA. 2006a. Initial Distribution System Evaluation Guidance Manual for the Final 

24 Stage 2 DBPR. Office of Water. EPA 815-B-06-002. 

25 U.S. EPA. 2006b. Draft Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 

26 DBPR) Implementation Guidance. Office of Water. EPA 816-R-06-002. June, 2006. 

27 U.S. EPA. 2006c. Draft Long Term 2 Enhanced Surface Water Treatment Rule 

28 (LT2ESWTR) Implementation Guidance. EPA 816-R-06-006. June, 2006. 

29 U.S. EPA. 2006d. Source Water Monitoring Guidance Manual for Public Water Systems 

30 for the Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA 

31 815-R-06-005. February, 2006. 
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REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-8 UNE 2006 

1 Urfer, D., P.M. Huck, S.D.J. Booth, and B.M. Coffey. 1997. Biological Filtration for 

2 BOM and Particle Removal: A Critical Review. Journal of American Water Works 

3 Association. 89(12):83-98. 

4 Volk, C.J. and M.W. LeChevallier. 2002. Effects of Conventional Treatment on AOC 

5 and BDOC Levels. Journal of American Water Works Association. 94(6):112-123. 

6 Westerhoff, G.P., et al. 1998a. The Changing Water Utility: Creative Approaches to 

7 Effectiveness and Efficiency. AWWA. 

8 White, G.C. 1992. Handbook of Chlorination and Alternative Disinfectants. Third ed. 

9 Van Nostrand Reinhold Co., New York, NY. 

10 White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. Fourth ed. 

11 Van Nostrand Reinhold Co., New York, NY. 

12 World Health Organization. 2004a. Guidelines for Drinking Water Quality, 3rd Edition. 

13 Geneva, Switzerland. World Health Organization. 

14 World Health Organization. 2004b. Water Treatment and Pathogen Control: Process 

15 Efficiency in Achieving Safe Drinking Water. Edited by M.W. LeChevallier and K.K. 

16 Au. ISBN: 1 84339 069 8. Published by IWA Publishing, London, UK. 

17 Wubbena, R.L. 2002a. Strategic Business Planning as a Water Resource Management 

18 Tool. AWWARF Report 90905. Project # 2698. 

19 

20 7.1.2 Formation and Control of Chlorinated DBPs 

21 

22 Choi, J. and R. Valentine. 2002. Formation of N-nitrosodimethylamine (NDMA) from 

23 reaction of monochloramine: a new disinfection by-product. Water Research. 36: 817-

24 824. 

25 Cowman, G.A., and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid 

26 Speciation Resulting from Chlorination and Chloramination of Humic Extracts. 

27 Conference proceedings, AWWA Annual Conference, New York, NY. 

28 George, D.B. et al. 1990. Case Studies of Modified Disinfection Practices for 

29 Trihalomethane Control. AWWARF Report 90574. Project #201. 

30 Krasner, S.W. et al. 2003. Case Studies of Modified Treatment Practices for Disinfection 

31 By-Product Control. AWWARF Report 90946F. Project #369. 

32 Krasner, S.W., K.M. Reagan, J.G. Jacangelo, N.L. Patania, E.M. Aieta, and K.M. 

33 Gramith. 1990. Relationships Between Disinfection By-products and Water Quality 
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DRAFT - DO NOT CITE OR QUOTE J 7-9 UNE 2006 

1 Parameters: Implications for Formation and Control. In Proc. AWWA Annual 

2 Conference. Denver, Colo.: American Water Works Association. 

3 Mitch, W.A., and D.L. Sedlak. 2002. Factors Controlling Nitrosoamine Formation 

4 During Wastewater Chlorination. Water Supply. 2(3): 191-198. 

5 Najm, I. and R. Rhodes Trussell. 2001. NDMA formation in water and wastewater. 

6 Journal of American Water Works Association. 93(2): 92-99. 

7 Reckhow, D.A. and P.C. Singer. 1985. Mechanisms of Organic Halide Formation During 

8 Fulvic Acid Chlorination and Implications with Respect to Pre-ozonation. Water 

9 Chlorination: Environmental Impact and Health Effects. 5: 1229-1257 (Lewis Publishers, 

10 Inc., Chelsea, MI, 1985). 

11 Routt, J.C. 2004. Lowering DBPs in Combined Systems. Opflow. 30(4): 1-7. 

12 Routt, J.C. and N.G. Pizzi 2000. Kentucky-American Water’s Cooperative, Step-wise 

13 Process of Assisting Two Small Contiguous Systems in Complying with Pending D/DBP 

14 Requirements. Proceedings of AWWA Water Quality Technology Conference. 

15 Singer, P.C. (Ed.). 1999. Formation and Control of Disinfection By-Products in Drinking 

16 Water. AWWA. Denver, CO. 424 pp. 

17 Singer, P.C. 1992. Formation and Characterization of Disinfection Byproducts. Presented 

18 at the First International Conference on the Safety of Water Disinfection: Balancing 

19 Chemical and Microbial Risks. 

20 Singer, P.C. and S.D. Chang. 1989. Correlations between trihalomethanes and total 

21 organic halides formed during water treatment. Journal of American Water Works 

22 Association. 81(8): 61-65. 

23 Singer, P.C. et al. 2002. Relative Dominance of HAAs and THMs in Treated Drinking 

24 Water. AWWARF Report 90844. Project #339. 

25 Speitel, G.E. Jr. and J.M. Symons.1998. Advanced Oxidation/Biodegradation Processes 

26 for the Destruction of TOC and Disinfection By-Product Precursors. AWWARF Report 

27 #90758. Project #289. 

28 Stevens, A.A., C.J. Slocum, D.R. Seeger, and G.G. Robeck. 1976. Chlorination of 

29 Organics in Drinking Water. Journal of American Water Works Association. 68(11):615. 

30 Stevens, A.A., L.A. Moore. and R.J. Miltner. 1989. Formation and Control of Non31 Trihalomethane Byproducts. Journal of American Water Works Association. 81(8): 54. 
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1 Summers, R.S., S.M. Hooper, H.M. Shukairy, G. Solarik, and D. Owen. 1996. Assessing 

2 DBP yield: uniform formation conditions. Journal of American Water Works 

3 Association. 88(6): 80–93. 

4 U.S. EPA. 2001c. Controlling Disinfection By-Products and Microbial Contaminants in 

5 Drinking Water. Office of Research and Development. EPA/600/R-01/110. 

6 

7 7.1.3 Corrosion 

8 

9 AWWA. 1993. Initial Monitoring Experiences of Large Water Utilities Under USEPA’s 

10 Lead and Copper Rule. Sponsored by the WITAF. Denver Colorado. 

11 AWWA. 2004d. Proceedings of Getting the Lead Out: Analysis & Treatment of Elevated 

12 Lead Levels in DC’s Drinking Water. WQTC. 

13 AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

14 Rule Corrosion Control Treatment 

15 AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

16 Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

17 Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data. 

18 Opflow. 30(6):16-19. 

19 Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy: 

20 Electrochemical Impedance and Noise. National Association of Corrosion Engineers. 

21 Houston, TX. 

22 Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in 

23 Distribution Systems. AWWARF Report 90983. Project #2648. 

24 Edwards, M., and S. Reiber. 1997. A General Framework for Corrosion Control Based on 

25 Utility Experience. AWWARF Report 90712. Project #910. 

26 Edwards, M., and T. Holm. 2001. Role of Phosphate Inhibitors in Mitigating Lead and 

27 Copper Corrosion. AWWARF Report 90823 Project #2587. 

28 Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole 

29 leaks in residential plumbing. Water Science and Technology. 49(2): 83-90. 

30 Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of 

31 American Water Works Association. 86(7): 74-91. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-11 UNE 2006 

1 Edwards, M., S. Jacobs and D. Dodrill 1999. “Desktop Guidance for Mitigating Pb and 

2 Cu Corrosion Byproducts,” Journal of the American Water Works Association, 91:5:66-

3 77. 

4 Edwards, M., T.E. Meyer, J. Rehring, J. Ferguson, G. Korshin, and S. Perry. 1996. Role 

5 of Inorganic Anions, NOM, and Water Treatment Process in Copper Corrosion. 

6 AWWARF Project 90687 Project #831. 

7 Kirmeyer, G.J. 1990. Lead Control Strategies. AWWARF 

8 Kirmeyer, G.J. et al. 2000a. Distribution System Water Quality Changes Following 

9 Implementation of Corrosion Control Strategies. AWWARF Report 90764. Project 

10 #157. 

11 Kirmeyer, G.J., A.M. Sandvig, G.L. Pierson, and C.H. Neff. 1994. Development of a 

12 Pipe Loop Protocol for Lead Control. AWWARF Report 90650 Project #604 

13 Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G. 

14 Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring 

15 Strategies. AWWARF Report 90996F Project #2679 

16 Korshin, G.V. and J.F. Ferguson. 1999. Corrosion and Metal Release for Lead 

17 Containing Materials: Influence of NOM. AWWARF Report 90759 Project #182. 

18 Lytle, D.A. & Schock, M.R., 2005. The Formation of Pb(IV) Oxides in Chlorinated 

19 Water. Journal of the American Water Works Association, 97:11:102. 

20 Maas, R.P., J.C. Pitch, and A.M. Smith. 2005. Effects of Fluorides and Chloramines on 

21 Lead Leaching from Leaded-Brass Surfaces. Asheville Environmental Quality Institute 

22 Technical Report #04-137 

23 Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids 

24 and chlorine in copper pitting corrosion. In Proceedings of AWWA Annual Conference. 

25 Denver CO. 

26 Rushing, J.C., and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold 

27 water pitting of copper. Proceedings of AWWA Water Quality Technology Conference. 

28 Sarin, P., et al. 2003. Iron Release from Corroded, Unlined Cast-Iron Pipes. Journal of 

29 American Water Works Association. 95(11): 85-96. 

30 Sarin, P., V.L. Snoeyink, J. Bebee, K.K. Jim, M.A. Beckett, W.M. Kriven, J.A. Clement. 

31 2004. Iron Release from Corroded Iron Pipes in Drinking Water Distribution Systems: 

32 Effect of Dissolved Oxygen. Water Research. 38: 1259-1269. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-12 UNE 2006 

1 Schock, M.R., Wagner, I. & Oliphant, R., 1996 (Second ed.) The Corrosion and 

2 Solubility of Lead in Drinking Water. Internal Corrosion of Water Distribution Systems, 

3 pp. 131-230. AWWA Research Foundation/TZW, Denver, CO. 

4 Schock, Michael. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment: 

5 Conforming to the Lead and Copper Rule. Presented at NACE Corrosion 1996 

6 Conference. 

7 Schock, M.R., 2001. Tetravalent Lead: A Hitherto Unrecognized Control of Tap Water 

8 Lead Contamination. In Proc. of the AWWA Water Quality Technology Conference. 

9 Denver, Colo.: AWWA. 

10 Schock, M.R. & Giani, R., 2004. Oxidant/Disinfectant Chemistry and Impacts on Lead 

11 Corrosion. In Proc. Of the AWWA Water Quality Technology Conference. 

12 Schock, M.R., Scheckel, K.G., DeSantis, M., and Gerke, T.L., 2005. Mode of 

13 Occurrence, Treatment and Monitoring Significance of Tetravalent Lead, In Proc. Of the 

14 AWWA Water Quality Technology Conference. 

15 U.S. EPA 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water 

16 Systems. Office of Water. EPA 816-R-02-009. 

17 U.S. EPA. 2003d. Revised Guidance Manual for Selecting Lead and Copper Control 

18 Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 

19 Veazey, M.V. 2004. New Research May Explain Pinholes in Copper Tubing. Materials 

20 Performance. 43(5): 18-22 

21 

22 7.1.4 Source Management 

23 

24 Cooke, G.D. and R.H. Kennedy. 2001. Managing drinking water supplies. Lake and 

25 Reservoir Management. 17(3): 157-174. 

26 Cooke, G.D., and R.E. Carlson. 1989. Reservoir Management for Water Quality and 

27 THM Precursor Control. AWWARF Report 90569. Project #308. 

28 Effler, S.W. et al. 2005. Origins, Behavior, and a Mechanistic Model for THM Precursors 

29 in Lakes and Reservoirs. AWWARF Report 91057F. Project #557. 

30 Knappe, D.R.U. et al. 2004. Algae Detection and Removal Strategies for Drinking Water 

31 Treatment Plants. AwwaRF Report 90971. Project #360. 

32 Kornegay, B.H. 2000c. Natural Organic Matter in Drinking Water: Recommendations to 

33 Water Utilities. AWWARF Report 90802. Project #2543. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-13 UNE 2006 

1 

2 7.1.5 Distribution System Management 

3 

4 AWWA. 1998. Distribution System Requirements for Fire Protection. 3rd edition. 

5 AWWA Manual M31. 63 pp. 

6 AWWA. 2001b. Elevated Water Storage Tanks: Maintenance. VHS Video. Denver, CO. 

7 AWWA. 2002b. Unidirectional Flushing. DVD. Denver, CO. 

8 AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

9 Transmission and Distribution, Third Edition. 553 pp. 

10 AWWA. 2003b. Sizing Water Service Lines and Meters. Second Edition. AWWA 

11 Manual M22. 112 pp. 

12 AWWA. 2004a. Computer Modeling of Water Distribution Systems. AWWA Manual 

13 M32. 160 pp. 

14 AWWA. 2004e. G200-04: Distribution Systems Operation and Management. 16 pp. 

15 AWWA. 2005. Biodegradable Organic Matter in Drinking Water Treatment and 

16 Distribution. M. Prevost et al. (editor). 

17 AWWA. 2005b. Distribution System Water Quality Challenges in the 21st Century – A 

18 Strategic Guide. MacPhee, M.J. (Editor) 190 pp. 

19 Camper, A.K. and W.L. Jones. 2000. Factors Affecting Microbial Growth in Model 

20 Distribution Systems. AWWARF Report 90785. Project #183. 

21 Cesario, A. L. 1995. Modeling, Analysis, and Design of Water Distribution Systems. 

22 AWWA. Denver, CO. 

23 Clark, R.M., and W.M. Grayman. 1998. Modeling Water Quality in Drinking Water 

24 Distribution Systems. AWWA. Denver, CO. 231 pp. 

25 Escobar, I.C., A.A. Randall, and J. S. Taylor. 2001. Bacterial Growth in Distribution 

26 Systems: Effect of Assimilable Organic Carbon and Biodegradable Dissolved Organic 

27 Carbon. Environmental Science and Technology. 35(17): 3442-3447. 

28 Grayman, W.M. et al. 2000. Water Quality Modeling of Distribution System Storage 

29 Facilities. AWWARF Report 90774. Projct #260. 

30 Haestad Methods. WaterCAD. Water Distribution Modeling & Management Software. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

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DRAFT - DO NOT CITE OR QUOTE J 7-14 UNE 2006 

1 Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water 

2 Quality. AWWARF Report 90798. Project #357. 

3 Lauer, William C. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

4 1,083 pp. 

5 LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988b. Inactivation of Biofilm 

6 Bacteria. Applied and Environmental Microbiology. 54(10):2492-2499. 

7 LeChevallier, M.W., C.D. Lowry, and R.G. Lee. 1990. Disinfection of Biofilms in a 

8 Model Distribution System. Journal of American Water Works Association. 82(7): 87-99. 

9 LeChevallier, M.W., C.D. Lowry, R.G. Lee, and D.L. Gibbon. 1993. Examining the 

10 Relationship Between Iron Corrosion and the Disinfection of Biofilm Bacteria. Journal 

11 of the American Water Works Association, 85(7) 

12 LeChevallier, M.W., N.J. Welch, and D.B. Smith. 1996. Full scale studies of factors 

13 related to coliform regrowth in drinking water. Applied and Environmental 

14 Microbiology. 62: 2201-2211. 

15 Liu, W., H. Wu, Z. Wang, S.L. Ong, J.Y. Hu and W.J. Ng. 2002. Investigation of 

16 Assimilable Organic Carbon (AOC) and Bacterial Regrowth in Drinking Water 

17 Distribution System. Water Research 36: 891-898. 

18 Lowther, E.D. and R.H. Mosher. 1984. Detecting and Eliminating Coliform Regrowth. 

19 Proceedings of the AWWA Water Quality Technology Conference, Denver, CO. 

20 AWWA. Denver, CO. 

21 Martel, Kathy, Gregory Kirmeyer, Amie Hanson, Melita Stevens, Joanne Mullenger, and 

22 Daniel Deere. 2006. Application of HACCP for Distribution System Protection. 

23 AWWARF Report 91131. Project #2856. Denver, CO. 

24 Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 900 pp. 

25 Najm, I. 2000. Case Studies of the Impacts of Treatment Changes on Biostability in Full26 Scale Distribution Systems. AWWARF Report 90816. Project #361. 

27 Powell, J. et al. 2004. Predictive Models for Water Quality in Distribution Systems. 

28 AWWARF Report 91023F. Project #2865. Denver, CO. 

29 Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. 

30 Denver, CO. 85 pp. 

31 Snyder, J.K., and AK. Deb. 2002. Impacts of Fireflow on Distribution System Water 

32 Quality, Design, and Operation. AWWARF Report 90913. Project #2554. 
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DRAFT - DO NOT CITE OR QUOTE J 7-15 UNE 2006 

1 Taylor, J.S. et al. 2005. Effects of Blending on Distribution System Water Quality. 

2 AWWARF Report 91065F. Project #2702. 

3 Tikkanen, M. et al. 2001. Guidance Manual for Disposal of Chlorinated Water. 

4 AWWARF Report 90863. Project #2513. 

5 U.S. EPA. 1992. Control of Biofilm Growth in Drinking Water Distribution Systems. 

6 Office of Research and Development, EPA 625/R-92/001. 

7 Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. 

8 AWWA. Denver, CO. 278 pp. 

9 7.1.6 Problem Organisms in Water Treatment 

10 AWWA. 2003c. Problem Organisms in Water: Identification and Treatment (M7), 3rd 

11 edition. American Water Works Association. 155 pages 

12 Belanger, Scott E., D.S. Cherry, J.L. Farris, K.G. Sappington, and J. Cairns, Jr. 1991. 

13 Sensitivity of the Asiatic Clam to Various Biocidal Control Agents. Journal American 

14 Water Works Association. 83(10). 

15 Britton, J.C. and B. Morton. 1982. A dissection guide, field and laboratory manual for the 

16 introduced bivalve Corbicula fluminea. Malacological Review. Suppl. 3:1-82. 

17 Cameron, G.N., J.M. Symons, S.R. Spencer, and J.Y. Ma. 1989. Minimizing THM 

18 Formation During Control of the Asiatic Clam: A Comparison of Biocides. Journal of 

19 American Water Works Association. 81(10):53-62. 

20 Counts, C. L., III. 1986. The zoogeography and history of the invasion of the United 

21 States by Corbicula fluminea (Bivalvia: Corbiculidae). American Malacological Bulletin, 

22 Special Edition No. 2, Proceedings of the Second International Corbicula Symposium. 

23 pp. 7-39. 

24 Lange, C. L., T. M. Short, E. Blake. 1994. Development of Zebra Mussel Control 

25 Strategies for a Coalition of Vermont Water Suppliers on Lake Champlain. Proceedings 

26 of The Fourth International Zebra Mussel Conference, Madison, Wisconsin, March 1994. 

27 Stevenson, B. 1997. Controlling Zebra Mussels at Water Treatment Plant Intakes. 

28 AWWARF Report 90612. Project #614. 

29 Stevenson, B. 1999. Controlling Zebra Mussels at Water Treatment Plant Intakes Part II. 

30 AWWARF Report. Project #821. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

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DRAFT - DO NOT CITE OR QUOTE J 7-16 UNE 2006 

1 7.1.7 Presedimentation 

2 U.S. EPA. 2003a. Draft LT2ESWTR Toolbox Guidance Manual. Office of Water. EPA 

3 815-D-03-009. June, 2003. 

4 7.1.8 Enhanced Coagulation and Enhanced Softening 

5 Bell, K. et al. 2001. Enhanced and Optimized Coagulation for Particulate and Microbial 

6 Removal. AWWARF Report. Project #155. 

7 Carlson, K.H., S. Via, B. Bellamy, and M. Carlson. 2000. Secondary Effects of Enhanced 

8 Coagulation and Softening. Journal of American Water Works Association. 92(6): 63-75. 

9 Chowdhury, Z.K., J.A. Roberson, and D.M. Owen, 1997. “A National Evaluation of 

10 Enhanced Coagulation and Enhanced Softening.” Proc. AWWA Annual Conference, 

11 Atlanta, GA, June 1997. 

12 Edwards, M. 1997. Predicting DOC Removal During Enhanced Coagulation. Journal of 

13 American Water Works Association. 89(5): 78-89. 

14 Hering, J.G., P.Y. Chen, J.A. Wilkie, M. Elimelech, and S. Liang. 1996. Arsenic removal 

15 by ferric chloride. Journal of American Water Works Association. 88(4): 155-167. 

16 Krasner, S.W. and G. Amy, 1995. Jar-test evaluations of enhanced coagulation. Journal 

17 of American Water Works Association. 87(10): 93-107. 

18 Lovins, W.A., III, S.J. Duranceau, R.M. Gonzalez, and J.S. Taylor. 2003. Optimized 

19 Coagulation Assessment for a Highly Organic Surface Water Supply. Journal of 

20 American Water Works Association. 95(10): 94-108. 

21 Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water 

22 Treatment Plant No. 3 Membrane Softening Facility Operations Manual Final Report. 

23 Pages 4-19 to 4-20. 

24 Randtke, S.J., and R.C. Hoehn. 1999. Removal of DBP precursors by Enhanced 

25 Coagulation and Lime Softening. AWWARF Report 90783. Project #814. 

26 Randtke, S.J., C.E. Thiel, M.Y. Liao, and C.N. Yamaya. 1982. Removing Soluble 

27 Organic Contaminants by Lime-Softening. Journal of American Water Works 

28 Association. 74(4): 192. 

29 Scott, K.N., J.F. Green, H.D. Do, and S.J. McLean. 1995. Arsenic Removal by 

30 Enhanced Coagulation. Journal of the American Water Works Association 87(4) 
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DRAFT - DO NOT CITE OR QUOTE J 7-17 UNE 2006 

1 Shorney, H.L., and S.J. Randtke. 1994. Enhanced Lime Softening for the Removal of 

2 Disinfection By-Product Precursors. In Proceedings of the 1994 Annual AWWA 

3 Conference. Denver CO. 

4 States, S., R. Tomko, M. Scheuring, and L. Casson. 2002. Enhanced coagulation and 

5 removal of Cryptosporidium. Journal of American Water Works Association. 94(11): 67-

6 77. 

7 Thompson, P.L., and W.L. Paulson 1998. Dewaterability of Alum and Ferric Coagulation 

8 Sludges. Journal of American Water Works Association. 90(4): 164-170. 

9 U.S. EPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening Guidance 

10 Manual. EPA 815-R-99-012. 

11 U.S. EPA. 2004b. Draft Coagulation Control Manual (July 2004). 

12 U.S. EPA. 2005c. A Regulator’s Guide to the Management of Radioactive Residuals 

13 from Drinking Water Treatment Technologies. USEPA 816-R-05-004. 

14 7.1.9 GAC 

15 American Chemical Society. 1983. Treatment of Water by Granular Activated Carbon. 

16 M.J. McGuire and I.H. Suffet (eds). Washington, D.C. 

17 Crittenden, J.C. 1989. Prediction of GAC Performance Using Rapid Small-Scale Column 

18 Tests. AWWARF Report 90549. Project #230. 

19 Klotz, M., P. Werner, and R. Schweisfurth. 1976. Investigations concerning the 

20 microbiology of activated carbon filters. Pp. 312-330 in H. Sontheimer, ed. Translation of 

21 Reports on Special Problems of Water Technology. Volume 9 Adsorption. Conference 

22 held in Karlsruhe, Federal Republic of Germany, 1975. U.S. Environmental Protection 

23 Agency, Municipal Environmental Research Laboratory, Cincinnati, Ohio. Report No. 

24 EPA 600/9-76-030. 

25 Leung, K.S., and R.L. Segar. 2000. Adsorption Interactions of S-Triazine Herbicide with 

26 Trace Organics in a GAC Filter-Absorber. Presented at the AWWA Conference 

27 December, 2000. 

28 McTigue, N. and D. Cornwell. 1994. The Hazardous Potential of Activated Carbons 

29 Used in Water Treatment. AWWARF Report 90640. Project #620. 

30 Najm, I., M. Kennedy, and W. Naylor. 2005. Lignite versus Bituminous GAC for 

31 Biofiltration - A Case Study. Journal of American Water Works Association. 97(1): 94-

32 101. 
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DRAFT - DO NOT CITE OR QUOTE J 7-18 UNE 2006 

1 Owen, D.M. 1998. Removal of DBP Precursors by GAC Adsorption. AWWARF Report 

2 90744. Project #816. 

3 Xie, Y., et al. 2004. Haloacetic Acid Removal Using Granular Activated Carbon. 

4 AWWARF Report 91041F. Project #2825. 

5 7.1.10 Membranes 

6 Adham, S., et al. 2005. Development of a Microfiltration and Ultrafiltration Knowledge 

7 Base. AWWARF Report 91059. Project #2763. 

8 Amy, G., M. Clark, and J. Pellegrino. 2001. NOM Rejection by, and Fouling of, NF and 

9 UF Membranes. AWWARF Report 90837. Project #390. 

10 AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. 

11 Brown, J. and and D. Hugaboom. 2004. Integrating Membrane Treatment in Large Water 

12 Utilities. AWWARF Report 91045F. Project #2876. 

13 Duranceau, S.J. 2001. Membrane Practices for Water Treatment. AWWA. Denver, CO. 

14 Glucina, K., A. Alvarez, and J.M. Laine. 2000. Assessment of an integrated membrane 

15 system for surface water treatment. Proceeding of the conference in drinking and 

16 industrial water production. 2: 113-122. Italy, October 2000. 

17 Laine, J.M., J.G. Jacangelo, E.W. Cummings, K.E. Carns, J. Mallevialle. 1993. Influence 

18 of Bromide on Low Pressure Membrane Filtration for Controlling DBPs in Surface 

19 Waters. Journal of American Water Works Association. 85(6). 

20 Mallevialle, J. et al. 1996. Water Treatment Membrane Processes. AWWARF Report 

21 90716. Project #826. 

22 Panayides, N. 1999. Operational Procedures of a New 27 MGD Nanofiltration Membrane 

23 Water Treatment Plant (WTP No. 9) in South Florida. Palm Beach County Water 

24 Utilities Department. 

25 Schippers, J.C. et al. 2004. Integrated Membrane Systems. AWWARF Report 90899. 

26 Project #264. 

27 U.S. Bureau of Reclamation. 1998. The Desalting and Water Treatment Membrane 

28 Manual: A Guide to Membranes for Municipal Water Treatment (2nd Edition). Technical 

29 Service Center, Water Treatment Engineering and Research, Denver, CO. 

30 U.S. EPA. 2005b. Membrane Filtration Guidance Manual. Office of Water. EPA 815-R31 06-009. November, 2005. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-19 UNE 2006 

1 7.1.11 Riverbank Filtration 

2 Gollnitz, W.D., J.L.Clancy, J. B. McEwen, and S. C. Garner. 2005. Riverbank Filtration 

3 for IESWTR Compliance. 2005. Journal of American Water Works Association. 

4 97(12):64-76. 

5 Julich, W. and J. Schubert (eds.). Proceedings of International Riverbank Filtration 

6 Conference, Nov. 2-4, Duesseldorf. International Arbeitgemeinschaft der Wasserwerke 

7 im Rheineinzugsgebiet, Amsterdam. 

8 Ray, C. (ed.). 2001. Riverbank Filtration: Understanding Contaminant Biogeochemistry 

9 and Pathogen Removal.NATO Science Series IV. Earth and Environmental Sciences - 

10 Vol. 14. Kluwer Academic Publishers. 

11 Wang, J., S. Hubbs, and R. Song. 2002. Evaluation of Riverbank Filtration as a Drinking 

12 Water Treatment Process. AWWARF Report 90922. Project #2622. 

13 7.1.12 Chloramines 

14 Arber, R., M.A. Speed, and F. Scully. 1985. Significant Findings Related to Formation of 

15 Chlrinated Organics, in the Presence of Chloramines. In: Water Chlorination: 

16 Environmental Impact and Health Effects, Vol. 7. Edited by R.L. Jolley, R.J. Bull, W.P. 

17 Davis, S. Katz, M.H. Roberts, and V.A. Jacobs. Chelsea, MI: Lewis Publishers. 

18 AWWA. 2004b. Converting Distribution Systems from Chlorine to Chloramines. DVD. 

19 Denver, CO. 

20 Bonds, R.W. 2004. Effect of Chloramines on Ductile-Iron Pipe Gaskets of Various 

21 Eslastomer Compounds. Journal of American Water Works Association. 96(4): 153-160. 

22 Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage 

23 Disinfection By-Products. New York State Section AWWA. September 2003. Published 

24 by O’Brien and Gere. 

25 Gianatasio, J.M. 1985. Experience at Tampa, Florida, Using Combined Chlorine to 

26 Control THM Production. Paper presented at the North Carolina AWWA/WPLC Joint 

27 Technical Conference, November 13, at Charlotte NC. 

28 Harms, L.L. and C. Owen. 2004. Draft. A Guide for the Implementation and Use of 

29 Chloramines. AWWARF Report 91018F. Project #2847. 

30 Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan, 

31 and D. Van Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution 

32 System Nitrification. AWWARF Report 90949. Project #553. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-20 UNE 2006 

1 Jacangelo, J.G., V.P. Olivieri, and K. Kawata. 1987. Mechanism of Inactivation of 

2 Microorganisms by Combined Chlorine. AWWA, Denver, CO. 

3 Kirmeyer, G.J. et al. 1995. Nitrification Occurrence and Control in Chloraminated Water 

4 Systems. AWWARF Report 90669. Project #710. 

5 Kirmeyer, G.J. et al. 2004a. Update of Optimizing Chloramine Treatment. AWWARF 

6 Report 90993. Project #2760. 

7 Krasner, S.W., and S.E. Barrett. 1985. Aroma and Flavor Characteristics of Free Chlorine 

8 and Chloramines. In Proc. Of the Twelfth Annual AWWA Water Quality Technology 

9 Conference. AWWA Denver, CO. 

10 McGuire, M.J., M.S. Pearthree, N.K. Blute, K.F. Arnold, and T. Hoogerwerf. 2006. 

11 Nitrification Control by Chlorite Ion at Pilot Scale. Journal of the American Water 

12 Works Association, 98(1):95-105 

13 McGuire, M.J., N.I. Lieu, and M.S. Pearthree. 1999. Using chlorite ion to control 

14 nitrification. Journal of American Water Works Association. 91(10): 52-61. 

15 Means, E.G., K.N. Scott, M.L. Lee, and R.W. Wolfe. 1986. Effects of Chlorine and 

16 Ammonia Application Points on Bactericidal Efficiency. Journal of American Water 

17 Works Association. 78(1): 62-69. 

18 Ollos, P.J., P.M. Huck, R.M. Slawson. 2003. Factors Affecting Biofilm Accumulation in 

19 Model Distribution Systems. Journal of American Water Works Association. 94(1). 

20 Reiber, S. 1991. Corrosion Effects by Chloramines. AWWARF Denver, CO. 

21 Reiber, S. 1993. Chloramine Effects on Distribution System Materials. AWWARF 

22 Report 90624. Project #508. 

23 Skadsen, J. 1993. Nitrification in a Distribution System. Journal of American Water 

24 Works Association. 85(7): 95-103. 

25 Speitel, G.E. Jr. et al. 2004. Disinfection By-Product Formation and Control During 

26 Chloramination. AWWARF Report 91040F. Project #2677. 

27 Symons, J.M. et al. 1998. Factors Affecting DBP Formation During Chloramination. 

28 AWWARF Report 90728. Project #803. 

29 Tokuno, S. 1999. Granulated Activated Carbon Filtration and Chloramine. Water 

30 Engineering Management, 146(1):16-21 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-21 UNE 2006 

1 Uchida, M. and A. Okuwaki. 1999. Dissolution Behavior of Lead Plates in Aqueous 

2 Nitrate Solutions. Corrosion Science. 41:1977 

3 Valentine, R.L. 1998. Chloramine Decomposition in Distribution System and Model 

4 Waters. AWWARF Report 90721. Project #937. 

5 Wilczak, A. L. Hoover, and H.H. Lai. 2003. Effects of Treatment Changes on 

6 Chloramine Demand and Decay. Journal of the American Water Works Association. 

7 95(7):94-107 

8 Wilczak, A., J.G. Jacangelo, J.P. Marcinko, L.H. Odell, G.J. Kirmeyer, and R.L. Wolfe. 

9 1996. Occurrence of Nitrification in Chloraminated Distribution Systems. Journal of 

10 American Water Works Association. 88(7): 74-85. 

11 Wolfe, R.L. 1990. Ammonia-Oxidizing Bacteria in a Chloraminated Distribution System: 

12 Seasonal Occurrence, Distribution, and Disinfection Resistance. Applied and 

13 Environmental Microbiology. 56: 541. 

14 Wolfe. R.L., E.G. Means, M.K. Davis, and S.E. Barrett. 1988. Biological Nitrification in 

15 Covered Reservoirs Containing Chloraminated Water. Journal of American Water Works 

16 Association. 80(9): 109-114. 

17 7.1.13 Ozone 

18 AWWARF and Compagnie Generale des Eaux. 1992. Ozone in Water Treatment: 

19 Application and Engineering. AWWARF Report. Project #421. 

20 Becker, W.C. et al. 1996. Optimizing Ozonation for Turbidity and Organics (TOC) 

21 Removal by Coagulation and Filtration. AWWARF Report 90703. Project #934. 

22 Carlson, K.H. and G.L. Amy. 2001. Ozone and biofiltration optimization for multiple 

23 objectives. Journal of American Water Works Association. 93(1): 88-98. 

24 Escobar, I.C. and A.A. Randall. 2001. Case study: Ozonation and distribution system 

25 biostability. Journal of American Water Works Association. 93(10): 77-89. 

26 Galey, C. et al. 2001. Controlling bromate formation. Journal of American Water Works 

27 Association. 93(8): 105-115. 

28 Kennedy, R.M. and M.E. Richardson. 2004. Ozone and Biofiltration, An Improved Water 

29 Quality at Wilmington. PowerPoint Presentation. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-22 UNE 2006 

1 LeChevallier, M.W., W.C. Becker, P. Schorr, and R.G. Lee. 1992. Evaluating the 

2 Performance of Biologically Active Rapid Sand Filters. Journal of American Water 

3 Works Association. 84(4): 136. 

4 National Research Council. 2000. Identifying Future Drinking Water Contaminants. 

5 National Academy Press. Washington, D.C. 

6 Price, M.L. et al. 1994. Ozone and Biological Treatment for DBP Control and Biological 

7 Stability. AWWARF Report 90649. Project #504. 

8 Reckhow, D.A. 1999. Control of Disinfection Byproduct Formation Using Ozone. In 

9 Singer, P.C. (Ed) Formation and Control of Disinfection By-Products in Drinking Water. 

10 pp. 179-204 AWWA, Denver, CO. 

11 Reckhow, D.A. J.K. Edzwald, and J.E. Tobiason. 1993. Ozone as an Aid to Coagulation 

12 and Filtration. AWWARF Report 90643. Project #403. 

13 Stolarik, G., and J.D. Christie. 1997. A Decade of Ozonation in Los Angeles. Conference 

14 proceedings, IOA Pan American Group Annual Conference, Lake Tahoe, NV. 

15 Urfer, D. et al. 1999. Modeling enhanced coagulation to improve ozone disinfection. 

16 Journal of American Water Works Association. 91(3): 59-73. 

17 Van der Kooij, D. 1997. Bacterial Nutrients and Biofilm Formation Potential within 

18 Drinking Water Distribution Systems. Conference Proceedings, AWWA Water Quality 

19 Technology Conference. 

20 Westerhoff, G.P., et al. 1998b. NOM's role in bromine and bromate formation during 

21 ozonation. Journal of American Water Works Association. 90(2): 82-94. 

22 Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia 

23 for Controlling Bromate During Cryptosporidium Disinfection. Journal of American 

24 Water Works Association. 95(10): 82-93. 

25 Zhou, P. and J. Neemann. 2005. Use of Chlorine Dioxide and Ozone for Control of 

26 Disinfection By-Products. AWWARF Report 90981F. Project #2742. 

27 7.1.14 Ultraviolet Light 

28 Ballester, N.A. and J.P. Malley, Jr. 2004. Sequential Disinfection of Adenovirus Type 2 

29 with UV-Chlorine-Chloramine. Journal of American Water Works Association. 

30 96(10):97-103. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-23 UNE 2006 

1 Bukhari, Z., T.M. Hargy, J.R. Bolton, B. Dussert, and J.L. Clancy. 1999. Medium2 Pressure UV for Oocyst Inactivation. Journal of American Water Works Association. 

3 91(3): 86-94. 

4 Clancy, J.L. et al. 2000. Using UV to inactivate Cryptosporidium. Journal of American 

5 Water Works Association. 92(9): 97-104. 

6 Cotton, C. et al. 2006. Integrating UV Disinfection Into Existing Water Treatment Plants. 

7 AWWARF Report 91086. Project #2861. 

8 Cotton, C.A., D.M. Owen, G.C. Cline, and T.P. Brodeur. 2001. UV disinfection costs for 

9 inactivating Cryptosporidium. Journal of American Water Works Association. 93(6): 82-

10 94. 

11 Crozes, G. 2001. Practical Aspects of UV Disinfection. AWWARF Report 90875. Project 

12 #2623. 

13 Gagnon, G.A., T.S. Dykstra, K.C. O’Leary, R.C. Andrews, C. Chauret and C. Volk. 

14 2004. Impact of UV Disinfection on Biological Stability. AWWARF Report 90999F. 

15 Project #2723. 

16 Mackey, E.D., J. Malley, Jr., R.S. Cushing, M. Janex-Habibi, N. Picard, and J. Laine, 

17 2001. Bridging Pilot-Scale Testing to Full-Scale Design of UV Disinfection Systems. 

18 AWWARF Report 90991. Project #2593. 

19 Malley, J.P. et al. 2001. Full Scale Implimentation of UV in Groundwater Disinfection 

20 Systems. AWWARF Report 90860. Project #474. 

21 Malley, J.P. Jr. et al. 2004. Inactivation of Pathogens with Innovative UV Technologies. 

22 AWWARF Report 91024. Project #2593. 

23 Mofidi, A.A. et al. 2001. Disinfection of Cryptosporidium parvum with polychromatic 

24 UV light. Journal of American Water Works Association. 93(6): 95-109. 

25 NWRI and AWWARF. 2000. Ultraviolet Disinfection Guidelines for Drinking Water and 

26 Water Reuse. AWWARF Report. Project #2674. 

27 Shaw, J.P., J.P. Malley Jr., and S. Willoughby. 2000. Effects of UV irradiation on organic 

28 matter. Journal of American Water Works Association. 92(4): 157-167. 

29 U.S. EPA. 2003b. Draft Ultraviolet Disinfection Guidance Manual. Office of Water. EPA 

30 815-D-03-007. June, 2003. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-24 UNE 2006 

1 7.1.15 Chlorine Dioxide 

2 Andrews, R.C. et al. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and 

3 Distribution System Performance. AWWARF Report 91082. Project #2843. 

4 Dietrich, A.M. and R.C. Hoehn. 1991. Taste-and-Odor Problems Associated with 

5 Chlorine Dioxide. AWWARF Report 90589. Project #405. 

6 Gallagher, D.L., R.C. Hoehn, and A.M. Dietrich. 1994. Sources, Occurrence, and Control 

7 of Chlorine Dioxide By-Product Residuals in Drinking Water. AWWARF Report 90656. 

8 Project #611. 

9 Gates, D. 1997. The Chlorine Dioxide Handbook. AWWA. Denver, CO. 177 pp. 

10 Gordon, G. 2001. Is all chlorine dioxide created equal? Journal of American Water 

11 Works Association. 93(4): 163-174. 

12 Hoehn, R.C. 1993. Chlorine Dioxide Use in Water Treatment: Key Issues Proceedings, 

13 2nd International Symposium, Chlorine Dioxide and Drinking Water Issues. Houston, 

14 TX. pp. 1-14. 

15 Hoehn, R.C., A.M. Dietrich, W.S., Farmer, M.P. Orr, R.G. Lee, E.M. Aieta, D.W. Wood 

16 III, and G. Gordon. 1990. Household Odors Associated with the Use of Chlorine Dioxide. 

17 Journal of American Water Works Association. 82(4):166-172. 

18 Volk, C.J., R. Hofmann, C. Chauret, G.A. Gagnon, G. Ranger, and R.C. Andrews. 2002. 

19 Implementation of chlorine dioxide disinfection: Effects of the treatment change on 

20 drinking water quality in a full-scale distribution system. Journal of Environmental 

21 Engineering and Science. 1: 323-330. 

22 Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia 

23 for Controlling Bromate During Cryptosporidium Disinfection. Journal of American 

24 Water Works Association. 95(10): 82-93. 

25 Zhou, P. and J. Neemann. 2005. Use of Chlorine Dioxide and Ozone for Control of 

26 Disinfection By-Products. AWWARF Report 90981F. Project #2742. 

27 7.1.16 Tools for Gathering More Information 

28 Advantica. SynerGEE Water. Advanced water distribution analysis. 

29 http://www.advantica.biz/Default.aspx?page=321 

30 American Public Heath Association (APHA), AWWA, and Water Environment 

31 Federation (WEF). 1998. Standard Methods for the Examination of Water and 

32 Wastewater, 20th Edition. 220 pp. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-25 UNE 2006 

1 ASTM D2688-83 Method B. 1983a. Standard Test Methods for the Corrosivity of 

2 Water in the Absence of Heat Transfer (Weight Loss Protocol). American Society for 

3 Testing and Materials. Philadelphia, PA. 

4 ASTM D2688-83 Method C. 1983b. Standard Test Methods for the Corrosivity of 

5 Water in the Absence of Heat Transfer (Machined Nipple Test). American Society for 

6 Testing and Materials. Philadelphia, PA. 

7 ASTM D934-80(2003). 2003. Standard Practices for Identification of Crystalline 

8 Compounds in Water Formed Deposits by X-Ray Diffraction. American Society for 

9 Testing and Materials. Philadelphia, PA. 

10 ASTM G1-81. 1981. Recommended Practise for Preparing, Cleaning and Evaluating 

11 Corrosion Test Specimens. American Society for Testing and Materials. Philadelphia, 

12 PA. 

13 ASTM G46-76. 1976. Recommended Practise for the Examination and Evaluation of 

14 Pitting Type Corrosion. American Society for Testing and Materials. Philadelphia, PA. 

15 AWWA. 2001a. The Rothberg, Tamburini & Winsor Blending Application Package 4.0. 

16 AWWA Catalog Number 53042. 

17 AWWARF. 2000. Consumer Attitude Survey Update. AWWARF Report 394. Project 

18 #394. 

19 AWWARF. 2003. Public Involvement Strategies on the Web. Interactive tool that builds 

20 on AWWARF Report. 

21 http://www.awwarf.org/research/TopicsAndProjects/Resources/webTools/ch2m/default.h

22 tml. 

23 Brereton, J.A. and D.S. Mavinic. 2002. Field and material-specific simulated distribution 

24 system testing as aids to understanding trihalomethane formation in distribution systems. 

25 Canadian Journal of Civil Engineering. 29(1): 17-26. 

26 Burlingame, G.A., J.J. Muldowney, R.E. Maddrey. 1992. Cucumber Flavor in 

27 Philadelphia’s Drinking Water. Journal of American Water Works Association. 84(8). 

28 CH2M Hill. 1995. Public Involvement Strategies: A Manager’s Handbook. AWWARF 

29 Report 90694. Project # 918. 

30 Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions. 

31 AWWARF Report 90856. Project #466. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-26 UNE 2006 

1 Crittenden, J.C., J.K. Berrigan, and D.W. Hand. 1986. Design of Rapid Small-Scale 

2 Adsorption Tests for a Constant Diffusivity. Journal Water Pollution Control Federation. 

3 Vol. 58, No. 4, pp. 312-319. 

4 Dentel, S.K. et al. 1989. Procedures Manual for Polymer Selection in Water Treatment 

5 Plants. AWWARF Report 90553. Project #209. 

6 Dietrich, A.M. 2004. Practical Taste-and-Odor Methods for Routine Operations: 

7 Decision Tree. AWWARF Report 91019. Project #467. 

8 Edwards, M., S.H. Reiber. 1997. Predicting Pb and Cu corrosion by-product release using 

9 CORRODE software. AWWARF Report 90712. 

10 Emmert, G. et al. 2004. Methods for Real-Time Measurement of THMs and HAAs in 

11 Distribution Systems. AWWARF Report 91003F. Project #2873. 

12 Giani, R., M. Edwards, C. Chung, and J. Wujek. 2004. Lead Profiling Methodologies 

13 and Results. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

14 Levels in DC’s Drinking Water at the 2004 AWWA WQTC. 

15 Grayman, W.M., R.A. Deininger, and R.M. Males. 2001. Design of Early Warning and 

16 Predictive Source-Water Monitoring Systems. AWWARF Report 90878. Project #2527. 

17 Hecht, P.M., and E.A. Turner. 2004. Washington Aqueduct Desktop & Flow-Through 

18 Study. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

19 Levels in DC’s Drinking Water at the 2004 AWWA WQTC. 

20 Khiari, D., S. Barrett, R. Chinn, A. Bruchet, P. Piriou, L. Matia, F. Ventura, I. Suffet, T. 

21 Gittelman, and P. Luitweiler. 2002. Distribution Generated Taste-and-Odor Phenomena. 

22 AwwaRF Report 90897. Project # 365. 

23 Kirmeyer, G. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

24 AWWARF Report 90882. Project #2522. 

25 Koch, B., S.W. Krasner, M.J. Sclimenti, and W.K. Schimpff. 1991. Predicting the 

26 formation of DBPs by the simulated distribution system. Journal of American Water 

27 Works Association. 83(10): 62–70. 

28 Lauer, B. 2001. Self-Assessment for Treatment Plant Optimization, International Edition. 

29 AWWA Publication. 256 pp. 

30 McGuire, M., et al. 2004. Water Utility Self-Assessment for the Management of 

31 Aesthetic Issues. AWWARF Report 90978F. Project #2777. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-27 UNE 2006 

1 Nero, W. et al. 2001. Public Involvement . . . Making It Work. AWWARF Report 90865. 

2 Project #2526. 

3 Olstein, M.A. 2001. Best Practices for a Continually Improving Customer Responsive 

4 Organization. AWWARF Report 90868. Project #2525. 

5 Raucher, R. et al. 2005. The Value of Water: Concepts, Estimates, and Applications for 

6 Water Managers. AwwaRF Report 91068F. Project #2855. 

7 Renner, R.C. and B.A. Hegg. 1997. Self-Assessment Guide for Surface Water Treatment 

8 Plant Optimization. AWWARF Report 90736. Project #274. 

9 Rettie, M. et al. 2005. Effective Practices to Select, Acquire, and Implement a Utility 

10 CIS. AWWARF Report 91071. Project # 3007. 

11 Tatham, C., E. Tatham, and J. Mobley. 2004. Customer Attitudes, Behavior and the 

12 Impact of Communications Efforts. AWWARF Report 90975. Project #2613. 

13 U.S. Bureau of Reclamation and I. Moch & Associates. 2003. WTCost©. Development 

14 of program sponsored by the American Membrane Technology Association. 

15 U.S. EPA. 2001h. Water Treatment Plant Model (Version 2.0). 

16 U.S. EPA. 2001i. The Surface Water Analytical Tool (Version 1.1). March 20, 2001. 

17 U.S. EPA. 2001j. 1999 Drinking Water Infrastructure Needs Survey: Modeling the Cost 

18 of Infrastructure. Office of Water. EPA 816-R-01-005. 

19 U.S. EPA. 2002b. EPANET 2.0. http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html 

20 Wesner, G.M. Copyright 1994-2000. W/W Costs, Windows Version 3.0. 

21 

22 7.2 References Organized Alphabetically 

23 Adham, S., et al. 2005. Development of a Microfiltration and Ultrafiltration Knowledge 

24 Base. AWWARF Report 91059. Project #2763. 

25 Advantica. SynerGEE Water. Advanced water distribution analysis. 

26 http://www.advantica.biz/Default.aspx?page=321 

27 American Chemical Society. 1983. Treatment of Water by Granular Activated Carbon. 

28 M.J. McGuire and I.H. Suffet (eds). Washington, D.C. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-28 UNE 2006 

1 American Public Heath Association (APHA), AWWA, and Water Environment 

2 Federation (WEF). 1998. Standard Methods for the Examination of Water and 

3 Wastewater, 20th Edition. 220 pp. 

4 Amy, G., M. Clark, and J. Pellegrino. 2001. NOM Rejection by, and Fouling of, NF and 

5 UF Membranes. AWWARF Report 90837. Project #390. 

6 Andrews, R.C. et al. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and 

7 Distribution System Performance. AWWARF Report 91082. Project #2843. 

8 Angers, J. 2001. Question of the Month: Which Disinfectant Will Work Best for Us? 

9 Opflow. 27(5): 6-7, 22. 

10 Arber, R., M.A. Speed, and F. Scully. 1985. Significant Findings Related to Formation of 

11 Chlrinated Organics, in the Presence of Chloramines. In: Water Chlorination: 

12 Environmental Impact and Health Effects, Vol. 7. Edited by R.L. Jolley, R.J. Bull, W.P. 

13 Davis, S. Katz, M.H. Roberts, and V.A. Jacobs. Chelsea, MI: Lewis Publishers. 

14 ASTM D2688-83 Method B. 1983a. Standard Test Methods for the Corrosivity of 

15 Water in the Absence of Heat Transfer (Weight Loss Protocol). American Society for 

16 Testing and Materials. Philadelphia, PA. 

17 ASTM D2688-83 Method C. 1983b. Standard Test Methods for the Corrosivity of 

18 Water in the Absence of Heat Transfer (Machined Nipple Test). American Society for 

19 Testing and Materials. Philadelphia, PA. 

20 ASTM D934-80(2003). 2003. Standard Practices for Identification of Crystalline 

21 Compounds in Water Formed Deposits by X-Ray Diffraction. American Society for 

22 Testing and Materials. Philadelphia, PA. 

23 ASTM G1-81. 1981. Recommended Practise for Preparing, Cleaning and Evaluating 

24 Corrosion Test Specimens. American Society for Testing and Materials. Philadelphia, 

25 PA. 

26 ASTM G46-76. 1976. Recommended Practise for the Examination and Evaluation of 

27 Pitting Type Corrosion. American Society for Testing and Materials. Philadelphia, PA. 

28 AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). McGraw-Hill, New 

29 York, NY. 

30 AWWA 1993. Initial Monitoring Experiences of Large Water Utilities Under USEPA’s 

31 Lead and Copper Rule. Sponsored by the WITAF. Denver Colorado. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-29 UNE 2006 

1 AWWA. 1998. Distribution System Requirements for Fire Protection. 3rd edition. 

2 AWWA Manual M31. 63 pp. 

3 AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. 

4 AWWA. 1999c. Water Quality and Treatment: A Handbook of Community Water 

5 Supplies. Fifth Edition. Letterman, R.D. (editor). McGraw-Hill 

6 AWWA. 1999d. Design and Construction of Small Water Systems, Second Edition. 228 

7 pp. 

8 AWWA. 1999e. Hydraulic Design Handbook. Mays, L.W.(editor). McGraw-Hill. 

9 AWWA. 2000. Operational Control of Coagulation and Filtration Processes. 2nd Edition. 

10 AWWA Manual M37. pp. 1-34. 

11 AWWA. 2001a. The Rothberg, Tamburini & Winsor Blending Application Package 4.0. 

12 AWWA Catalog Number 53042. 

13 AWWA. 2001b. Elevated Water Storage Tanks: Maintenance. VHS Video. Denver, CO. 

14 AWWA. 2002b. Unidirectional Flushing. DVD. Denver, CO. 

15 AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

16 Transmission and Distribution, Third Edition. 553 pp. 

17 AWWA. 2003b. Sizing Water Service Lines and Meters. Second Edition. AWWA 

18 Manual M22. 112 pp. 

19 AWWA. 2003c. Problem Organisms in Water: Identification and Treatment (M7), 3rd 

20 edition. American Water Works Association. 155 pages 

21 AWWA. 2004a. Computer Modeling of Water Distribution Systems. AWWA Manual 

22 M32. 160 pp. 

23 AWWA. 2004b. Converting Distribution Systems from Chlorine to Chloramines. DVD. 

24 Denver, CO. 

25 AWWA. 2004d. Proceedings of Getting the Lead Out: Analysis & Treatment of Elevated 

26 Lead Levels in DC’s Drinking Water. WQTC. 

27 AWWA. 2004e. G200-04: Distribution Systems Operation and Management. 16 pp. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-30 UNE 2006 

1 AWWA. 2005. Biodegradable Organic Matter in Drinking Water Treatment and 

2 Distribution. M. Prevost et al. (editor). 

3 AWWA. 2005a. Managing Change and Unintended Consequences: Lead and Copper 

4 Rule Corrosion Control Treatment 

5 AWWA. 2005b. Distribution System Water Quality Challenges in the 21st Century – A 

6 Strategic Guide. MacPhee, M.J. (Editor) 190 pp. 

7 AWWARF and Compagnie Generale des Eaux. 1992. Ozone in Water Treatment: 

8 Application and Engineering. AWWARF Report. Project #421. 

9 AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

10 Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

11 AWWARF and Lyonnaise des Eaux. 1995. Advances in Taste and Odor Treatment and 

12 Control. AWWARF Report 90610. Project #629. 

13 AWWARF. 2000. Consumer Attitude Survey Update. AWWARF Report 394. Project 

14 #394. 

15 AWWARF. 2003. Public Involvement Strategies on the Web. Interactive tool that builds 

16 on AWWARF Report. 

17 http://www.awwarf.org/research/TopicsAndProjects/Resources/webTools/ch2m/default.h

18 tml. 

19 Ballester, N.A. and J.P. Malley, Jr. 2004. Sequential Disinfection of Adenovirus Type 2 

20 with UV-Chlorine-Chloramine. Journal of American Water Works Association. 

21 96(10):97-103. 

22 Becker, W.C. et al. 1996. Optimizing Ozonation for Turbidity and Organics (TOC) 

23 Removal by Coagulation and Filtration. AWWARF Report 90703. Project #934. 

24 Becker, W.C., K. Au, C.R. O'Melia, and J.S. Young, Jr. 2004. Using Oxidants to 

25 Enhance Filter Performance. AWWARF Report 90998. Project #2725. 

26 Belanger, Scott E., D.S. Cherry, J.L. Farris, K.G. Sappington, and J. Cairns, Jr. 1991. 

27 Sensitivity of the Asiatic Clam to Various Biocidal Control Agents. Journal American 

28 Water Works Association. 83(10). 

29 Bell, K. et al. 2001. Enhanced and Optimized Coagulation for Particulate and Microbial 

30 Removal. AWWARF Report. Project #155. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-31 UNE 2006 

1 Bonds, R.W. 2004. Effect of Chloramines on Ductile-Iron Pipe Gaskets of Various 

2 Eslastomer Compounds. Journal of American Water Works Association. 96(4): 153-160. 

3 Brereton, J.A. and D.S. Mavinic. 2002. Field and material-specific simulated distribution 

4 system testing as aids to understanding trihalomethane formation in distribution systems. 

5 Canadian Journal of Civil Engineering. 29(1): 17-26. 

6 Britton, J.C. and B. Morton. 1982. A dissection guide, field and laboratory manual for the 

7 introduced bivalve Corbicula fluminea. Malacological Review. Suppl. 3:1-82. 

8 Brown, J. and and D. Hugaboom. 2004. Integrating Membrane Treatment in Large Water 

9 Utilities. AWWARF Report 91045F. Project #2876. 

10 Bukhari, Z., T.M. Hargy, J.R. Bolton, B. Dussert, and J.L. Clancy. 1999. Medium11 Pressure UV for Oocyst Inactivation. Journal of American Water Works Association. 

12 91(3): 86-94. 

13 Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data. 

14 Opflow. 30(6):16-19. 

15 Burlingame, G.A., J.J. Muldowney, R.E. Maddrey. 1992. Cucumber Flavor in 

16 Philadelphia’s Drinking Water. Journal of American Water Works Association. 84(8). 

17 Cameron, G.N., J.M. Symons, S.R. Spencer, and J.Y. Ma. 1989. Minimizing THM 

18 Formation During Control of the Asiatic Clam: A Comparison of Biocides. Journal of 

19 American Water Works Association. 81(10):53-62. 

20 Camper, A.K. and W.L. Jones. 2000. Factors Affecting Microbial Growth in Model 

21 Distribution Systems. AWWARF Report 90785. Project #183. 

22 Carlson, K.H. and G.L. Amy. 2001. Ozone and biofiltration optimization for multiple 

23 objectives. Journal of American Water Works Association. 93(1): 88-98. 

24 Carlson, K.H., S. Via, B. Bellamy, and M. Carlson. 2000. Secondary Effects of Enhanced 

25 Coagulation and Softening. Journal of American Water Works Association. 92(6): 63-75. 

26 Cesario, A. L. 1995. Modeling, Analysis, and Design of Water Distribution Systems. 

27 AWWA. Denver, CO. 

28 CH2M Hill. 1995. Public Involvement Strategies: A Manager’s Handbook. AWWARF 

29 Report 90694. Project # 918. 
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1 Choi, J. and R. Valentine. 2002. Formation of N-nitrosodimethylamine (NDMA) from 

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3 824. 

4 Chowdhury, Z.K., J.A. Roberson, and D.M. Owen, 1997. “A National Evaluation of 

5 Enhanced Coagulation and Enhanced Softening.” Proc. AWWA Annual Conference, 

6 Atlanta, GA, June 1997. 

7 Clancy, J.L. et al. 2000. Using UV to inactivate Cryptosporidium. Journal of American 

8 Water Works Association. 92(9): 97-104. 

9 Clark, R.M., and W.M. Grayman. 1998. Modeling Water Quality in Drinking Water 

10 Distribution Systems. AWWA. Denver, CO. 231 pp. 

11 Colbourne, J. 2001. Tools and Methods to Effectively Measure Customer Perceptions. 

12 AWWARF Report 90856. Project #466. 

13 Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 

14 174 pp. 

15 Cooke, G.D. and R.H. Kennedy. 2001. Managing drinking water supplies. Lake and 

16 Reservoir Management. 17(3): 157-174. 

17 Cooke, G.D., and R.E. Carlson. 1989. Reservoir Management for Water Quality and 

18 THM Precursor Control. AWWARF Report 90569. Project #308. 

19 Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy: 

20 Electrochemical Impedance and Noise. National Association of Corrosion Engineers. 

21 Houston, TX. 

22 Cotton, C. et al. 2006. Integrating UV Disinfection Into Existing Water Treatment Plants. 

23 AWWARF Report 91086. Project #2861. 

24 Cotton, C.A., D.M. Owen, G.C. Cline, and T.P. Brodeur. 2001. UV disinfection costs for 

25 inactivating Cryptosporidium. Journal of American Water Works Association. 93(6): 82-

26 94. 

27 Counts, C. L., III. 1986. The zoogeography and history of the invasion of the United 

28 States by Corbicula fluminea (Bivalvia: Corbiculidae). American Malacological Bulletin, 

29 Special Edition No. 2, Proceedings of the Second International Corbicula Symposium. 

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1 Cowman, G.A., and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid 

2 Speciation Resulting from Chlorination and Chloramination of Humic Extracts. 

3 Conference proceedings, AWWA Annual Conference, New York, NY. 

4 Crittenden, J.C. 1989. Prediction of GAC Performance Using Rapid Small-Scale Column 

5 Tests. AWWARF Report 90549. Project #230. 

6 Crittenden, J.C., J.K. Berrigan, and D.W. Hand. 1986. Design of Rapid Small-Scale 

7 Adsorption Tests for a Constant Diffusivity. Journal Water Pollution Control Federation. 

8 Vol. 58, No. 4, pp. 312-319. 

9 Crozes, G. 2001. Practical Aspects of UV Disinfection. AWWARF Report 90875. Project 

10 #2623. 

11 Culp, G.L. and R.L. Culp. 1974. New Concepts in Water Purification. Van Norstrand 

12 Reinhold Co., New York. 

13 DeMers, L.D. and R.C. Renner. 1993. Alternative Disinfection Technologies for Small 

14 Drinking Water Systems. AWWARF Report 90619. Project #621. 

15 Dentel, S.K. et al. 1989. Procedures Manual for Polymer Selection in Water Treatment 

16 Plants. AWWARF Report 90553. Project #209. 

17 Dewettinck T., E. Van Houtte, D. Geenens, K. Van Hege, and W. Verstraete. 2001. 

18 HACCP (Hazard Analysis and Critical Control Points) to Guarantee Safe Water Reuse 

19 and Drinking Water Production--a Case Study. Water Science and Technology. 43(12): 

20 31-8. 

21 DeWolfe, J. et al. Guidance Manual for Coagulant Changeover. AWWARF Report 

22 90958. Project #2512. 

23 Dietrich, A.M. 2004. Practical Taste-and-Odor Methods for Routine Operations: 

24 Decision Tree. AWWARF Report 91019. Project #467. 

25 Dietrich, A.M. and R.C. Hoehn. 1991. Taste-and-Odor Problems Associated with 

26 Chlorine Dioxide. AWWARF Report 90589. Project #405. 

27 Duranceau, S.J. 2001. Membrane Practices for Water Treatment. AWWA. Denver, CO. 

28 Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in 

29 Distribution Systems. AWWARF Report 90983. Project #2648. 

30 Edwards, M. 1997. Predicting DOC Removal During Enhanced Coagulation. Journal of 

31 American Water Works Association. 89(5): 78-89. 
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1 Edwards, M., and S. Reiber. 1997. A General Framework for Corrosion Control Based on 

2 Utility Experience. AWWARF Report 90712. Project #910. 

3 Edwards, M., and T. Holm. 2001. Role of Phosphate Inhibitors in Mitigating Lead and 

4 Copper Corrosion. AWWARF Report 90823 Project #2587. 

5 Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole 

6 leaks in residential plumbing. Water Science and Technology. 49(2): 83-90. 

7 Edwards, M., J.F. Ferguson, S. Reiber. 1994. The Pitting Corrosion of Copper. Journal of 

8 American Water Works Association. 86(7): 74-91. 

9 Edwards, M., S. Jacobs and D. Dodrill 1999. “Desktop Guidance for Mitigating Pb and 

10 Cu Corrosion Byproducts,” Journal of the American Water Works Association, 91:5:66-

11 77. 

12 Edwards, M., S.H. Reiber. 1997. Predicting Pb and Cu corrosion by-product release using 

13 CORRODE software. AWWARF Report 90712. 

14 Edwards, M., T.E. Meyer, J. Rehring, J. Ferguson, G. Korshin, and S. Perry. 1996. Role 

15 of Inorganic Anions, NOM, and Water Treatment Process in Copper Corrosion. 

16 AWWARF Project 90687 Project #831. 

17 Effler, S.W. et al. 2005. Origins, Behavior, and a Mechanistic Model for THM Precursors 

18 in Lakes and Reservoirs. AWWARF Report 91057F. Project #557. 

19 Emmert, G. et al. 2004. Methods for Real-Time Measurement of THMs and HAAs in 

20 Distribution Systems. AWWARF Report 91003F. Project #2873. 

21 Escobar, I.C. and A.A. Randall. 2001. Case study: Ozonation and distribution system 

22 biostability. Journal of American Water Works Association. 93(10): 77-89. 

23 Escobar, I.C., A.A. Randall, and J. S. Taylor. 2001. Bacterial Growth in Distribution 

24 Systems: Effect of Assimilable Organic Carbon and Biodegradable Dissolved Organic 

25 Carbon. Environmental Science and Technology. 35(17): 3442-3447. 

26 Faust, S. and O. Aly. 1998. Chemistry of Water Treatment. Second Edition. Lewis 

27 Publishers. New York. 

28 Finch, G.R., D.W. Smith, and M. Belosevic. 2001. Sequential Disinfection Design 

29 Criteria for Inactivation of Cryptosporidium Oocysts in Drinking Water. AWWARF 

30 Report 90831. Project #348. 
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1 Friedman, M. and G. Hamilton. 1997. Enhancing CTs, Coagulation, and Corrosion 

2 Control through Carbon Dioxide Injection. Proceedings 1996 Water Quality Technology 

3 Conference, Part II. American Water Works Association. 

4 Gagnon, G.A., T.S. Dykstra, K.C. O’Leary, R.C. Andrews, C. Chauret and C. Volk. 

5 2004. Impact of UV Disinfection on Biological Stability. AWWARF Report 90999F. 

6 Project #2723. 

7 Galey, C. et al. 2001. Controlling bromate formation. Journal of American Water Works 

8 Association. 93(8): 105-115. 

9 Gallagher, D.L., R.C. Hoehn, and A.M. Dietrich. 1994. Sources, Occurrence, and Control 

10 of Chlorine Dioxide By-Product Residuals in Drinking Water. AWWARF Report 90656. 

11 Project #611. 

12 Gates, D. 1997. The Chlorine Dioxide Handbook. AWWA. Denver, CO. 177 pp. 

13 Gell, R. and J. Bromka. 2003. Successful Application of Chloramines to Manage 

14 Disinfection By-Products. New York State Section AWWA. September 2003. Published 

15 by O’Brien and Gere. 

16 George, D.B. et al. 1990. Case Studies of Modified Disinfection Practices for 

17 Trihalomethane Control. AWWARF Report 90574. Project #201. 

18 Gianatasio, J.M. 1985. Experience at Tampa, Florida, Using Combined Chlorine to 

19 Control THM Production. Paper presented at the North Carolina AWWA/WPLC Joint 

20 Technical Conference, November 13, at Charlotte NC. 

21 Giani, R., M. Edwards, C. Chung, and J. Wujek. 2004. Lead Profiling Methodologies 

22 and Results. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

23 Levels in DC’s Drinking Water at the 2004 AWWA WQTC. 

24 Global Environment & Technology Foundation. 2000. Final Report: The US EPA 

25 Environmental Management System Pilot Program for Local Government. 

26 Global Environment & Technology Foundation. 2002. Final Report: Second EMS 

27 Initiative for Government Entities (2000-2002). 

28 Glucina, K., A. Alvarez, and J.M. Laine. 2000. Assessment of an integrated membrane 

29 system for surface water treatment. Proceeding of the conference in drinking and 

30 industrial water production. 2: 113-122. Italy, October 2000. 
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1 Gollnitz, W.D., J.L.Clancy, J. B. McEwen, and S. C. Garner. 2005. Riverbank Filtration 

2 for IESWTR Compliance. 2005. Journal of American Water Works Association. 

3 97(12):64-76. 

4 Gordon, G. 2001. Is all chlorine dioxide created equal? Journal of American Water 

5 Works Association. 93(4): 163-174. 

6 Grant, G.B. Sc., CEA, EMS(LA), CEAS. 2004. ISO 14001 and Drinking Water Quality. 

7 Environmental Science and Engineering. January, 2004. 

8 Grayman, W.M. et al. 2000. Water Quality Modeling of Distribution System Storage 

9 Facilities. AWWARF Report 90774. Projct #260. 

10 Grayman, W.M., R.A. Deininger, and R.M. Males. 2001. Design of Early Warning and 

11 Predictive Source-Water Monitoring Systems. AWWARF Report 90878. Project #2527. 

12 Haestad Methods. WaterCAD. Water Distribution Modeling & Management Software. 

13 Harms, L.L. and C. Owen. 2004. Draft. A Guide for the Implementation and Use of 

14 Chloramines. AWWARF Report 91018F. Project #2847. 

15 Harrington, G.W., D.R. Noguera, C.C. Bone, A.I. Kandou, P.S. Oldenburg, J.M. Regan, 

16 and D. Van Hoven. 2003. Ammonia from Chloramine Decay: Effects on Distribution 

17 System Nitrification. AWWARF Report 90949. Project #553. 

18 HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd ed. 

19 Hecht, P.M., and E.A. Turner. 2004. Washington Aqueduct Desktop & Flow-Through 

20 Study. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

21 Levels in DC’s Drinking Water at the 2004 AWWA WQTC. 

22 Hering, J.G., P.Y. Chen, J.A. Wilkie, M. Elimelech, and S. Liang. 1996. Arsenic removal 

23 by ferric chloride. Journal of American Water Works Association. 88(4): 155-167. 

24 Hoehn, R.C. 1993. Chlorine Dioxide Use in Water Treatment: Key Issues Proceedings, 

25 2nd International Symposium, Chlorine Dioxide and Drinking Water Issues. Houston, 

26 TX. pp. 1-14. 

27 Hoehn, R.C., A.M. Dietrich, W.S., Farmer, M.P. Orr, R.G. Lee, E.M. Aieta, D.W. Wood 

28 III, and G. Gordon. 1990. Household Odors Associated with the Use of Chlorine Dioxide. 

29 Journal of American Water Works Association. 82(4):166-172. 

30 Huck, P.M., B.M. Coffey, A. Amirtharajah, and E.J. Bouwer. 2000. Optimizing Filtration 

31 in Biological Filters. AWWARF Report 90793. Project #252. 
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1 Hulsey, R.A. et al. 2004. Evaluation of Ozone and Ultraviolet Light. AWWARF Report 

2 91046F. Project #2749. 

3 Jacangelo, J.G., C. Gerba, and C.N. Haas. 2002. Inactivation of Waterborne Emerging 

4 Pathogens by Selected Disinfectants. AWWARF Report 90886. Project #442. Denver, 

5 CO. 

6 Jacangelo, J.G., V.P. Olivieri, and K. Kawata. 1987. Mechanism of Inactivation of 

7 Microorganisms by Combined Chlorine. AWWA, Denver, CO. 

8 Julich, W. and J. Schubert (eds.). Proceedings of International Riverbank Filtration 

9 Conference, Nov. 2-4, Duesseldorf. International Arbeitgemeinschaft der Wasserwerke 

10 im Rheineinzugsgebiet, Amsterdam. 

11 Kawamura, Susumu. 2000. Integrated Design and Operation of Water Treatment 

12 Facilities. 2nd ed. John Wiley & Sons, Inc. 

13 Kennedy, R.M. and M.E. Richardson. 2004. Ozone and Biofiltration, An Improved Water 

14 Quality at Wilmington. PowerPoint Presentation. 

15 Khiari, D., S. Barrett, R. Chinn, A. Bruchet, P. Piriou, L. Matia, F. Ventura, I. Suffet, T. 

16 Gittelman, and P. Luitweiler. 2002. Distribution Generated Taste-and-Odor Phenomena. 

17 AwwaRF Report 90897. Project # 365. 

18 Kim, Y., Y. Lee, C.S. Gee, and E. Choi. 1997. Treatment of Taste and Odor Causing 

19 Substances in Drinking Water. Water Science and Technology. 35(8): 29-36. 

20 Kirmeyer, G. 2002. Guidance Manual for Monitoring Distribution System Water Quality. 

21 AWWARF Report 90882. Project #2522. 

22 Kirmeyer, G.J. 1990. Lead Control Strategies. AWWARF 

23 Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water 

24 Quality. AWWARF Report 90798. Project #357. 

25 Kirmeyer, G.J. et al. 1995. Nitrification Occurrence and Control in Chloraminated Water 

26 Systems. AWWARF Report 90669. Project #710. 

27 Kirmeyer, G.J. et al. 2000a. Distribution System Water Quality Changes Following 

28 Implementation of Corrosion Control Strategies. AWWARF Report 90764. Project 

29 #157. 

30 Kirmeyer, G.J. et al. 2004a. Update of Optimizing Chloramine Treatment. AWWARF 

31 Report 90993. Project #2760. 
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3 Kirmeyer, G.J., B.M. Murphy, A. Sandvig, G. Korshin, B. Shaha, M. Fabbricino, and G. 

4 Burlingame. 2004b. Post Optimization of Lead and Copper Control Monitoring 

5 Strategies. AWWARF Report 90996F Project #2679 

6 Klotz, M., P. Werner, and R. Schweisfurth. 1976. Investigations concerning the 

7 microbiology of activated carbon filters. Pp. 312-330 in H. Sontheimer, ed. Translation of 

8 Reports on Special Problems of Water Technology. Volume 9 Adsorption. Conference 

9 held in Karlsruhe, Federal Republic of Germany, 1975. U.S. Environmental Protection 

10 Agency, Municipal Environmental Research Laboratory, Cincinnati, Ohio. Report No. 

11 EPA 600/9-76-030. 

12 Knappe, D.R.U. et al. 2004. Algae Detection and Removal Strategies for Drinking Water 

13 Treatment Plants. AwwaRF Report 90971. Project #360. 

14 Koch, B., S.W. Krasner, M.J. Sclimenti, and W.K. Schimpff. 1991. Predicting the 

15 formation of DBPs by the simulated distribution system. Journal of American Water 

16 Works Association. 83(10): 62–70. 

17 Kornegay, B.H. 2000c. Natural Organic Matter in Drinking Water: Recommendations to 

18 Water Utilities. AWWARF Report 90802. Project #2543. 

19 Korshin, G.V. and J.F. Ferguson. 1999. Corrosion and Metal Release for Lead 

20 Containing Materials: Influence of NOM. AWWARF Report 90759 Project #182. 

21 Krasner, S.W. and G. Amy, 1995. Jar-test evaluations of enhanced coagulation. Journal 

22 of American Water Works Association. 87(10): 93-107. 

23 Krasner, S.W. et al. 2003. Case Studies of Modified Treatment Practices for Disinfection 

24 By-Product Control. AWWARF Report 90946F. Project #369. 

25 Krasner, S.W., and S.E. Barrett. 1985. Aroma and Flavor Characteristics of Free Chlorine 

26 and Chloramines. In Proc. Of the Twelfth Annual AWWA Water Quality Technology 

27 Conference. AWWA Denver, CO. 

28 Krasner, S.W., K.M. Reagan, J.G. Jacangelo, N.L. Patania, E.M. Aieta, and K.M. 

29 Gramith. 1990. Relationships Between Disinfection By-products and Water Quality 

30 Parameters: Implications for Formation and Control. In Proc. AWWA Annual 

31 Conference. Denver, Colo.: American Water Works Association. 
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3 Waters. Journal of American Water Works Association. 85(6). 

4 Lange, C. L., T. M. Short, E. Blake. 1994. Development of Zebra Mussel Control 

5 Strategies for a Coalition of Vermont Water Suppliers on Lake Champlain. Proceedings 

6 of The Fourth International Zebra Mussel Conference, Madison, Wisconsin, March 1994. 

7 Lauer, B. 2001. Self-Assessment for Treatment Plant Optimization, International Edition. 

8 AWWA Publication. 256 pp. 

9 Lauer, William C. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

10 1,083 pp. 

11 LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988a. Factors Promoting Survival 

12 of Bacteria in Chlorinated Water Supplies. Applied and Environmental Microbiology. 

13 54(3): 649-654. 

14 LeChevallier, M.W., C.D. Cawthorn, and R.G. Lee. 1988b. Inactivation of Biofilm 

15 Bacteria. Applied and Environmental Microbiology. 54(10):2492-2499. 

16 LeChevallier, M.W., C.D. Lowry, and R.G. Lee. 1990. Disinfection of Biofilms in a 

17 Model Distribution System. Journal of American Water Works Association. 82(7): 87-99. 

18 LeChevallier, M.W., C.D. Lowry, R.G. Lee, and D.L. Gibbon. 1993. Examining the 

19 Relationship Between Iron Corrosion and the Disinfection of Biofilm Bacteria. Journal 

20 of the American Water Works Association, 85(7) 

21 LeChevallier, M.W., G. Di Giovanni, J.L. Clancy, Z. Bukhari, S. Bukhari, J.S. Rosen, J. 

22 Sobrinho, and M.M. Frey. 2002. Source Water Assessment: Variability of Pathogen 

23 Concentrations. AwwaRF Report 90906. Project #488. 

24 LeChevallier, M.W., N.J. Welch, and D.B. Smith. 1996. Full scale studies of factors 

25 related to coliform regrowth in drinking water. Applied and Environmental 

26 Microbiology. 62: 2201-2211. 

27 LeChevallier, M.W., W.C. Becker, P. Schorr, and R.G. Lee. 1992. Evaluating the 

28 Performance of Biologically Active Rapid Sand Filters. Journal of American Water 

29 Works Association. 84(4): 136. 

30 Leung, K.S., and R.L. Segar. 2000. Adsorption Interactions of S-Triazine Herbicide with 

31 Trace Organics in a GAC Filter-Absorber. Presented at the AWWA Conference 

32 December, 2000. 
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1 Liu, W., H. Wu, Z. Wang, S.L. Ong, J.Y. Hu and W.J. Ng. 2002. Investigation of 

2 Assimilable Organic Carbon (AOC) and Bacterial Regrowth in Drinking Water 

3 Distribution System. Water Research 36: 891-898. 

4 Logsdon, G.S. et al. 2002. Filter Maintenance and Operations Guidance Manual. 

5 AWWARF Report 90908. Project #2511. 

6 Lovins, W.A., III, S.J. Duranceau, R.M. Gonzalez, and J.S. Taylor. 2003. Optimized 

7 Coagulation Assessment for a Highly Organic Surface Water Supply. Journal of 

8 American Water Works Association. 95(10): 94-108. 

9 Lowther, E.D. and R.H. Mosher. 1984. Detecting and Eliminating Coliform Regrowth. 

10 Proceedings of the AWWA Water Quality Technology Conference, Denver, CO. 

11 AWWA. Denver, CO. 

12 Lytle, D.A. & Schock, M.R., 2005. The Formation of Pb(IV) Oxides in Chlorinated 

13 Water. Journal of the American Water Works Association, 97:11:102. 

14 Maas, R.P., J.C. Pitch, and A.M. Smith. 2005. Effects of Fluorides and Chloramines on 

15 Lead Leaching from Leaded-Brass Surfaces. Asheville Environmental Quality Institute 

16 Technical Report #04-137 

17 Mackey, E.D., J. Malley, Jr., R.S. Cushing, M. Janex-Habibi, N. Picard, and J. Laine, 

18 2001. Bridging Pilot-Scale Testing to Full-Scale Design of UV Disinfection Systems. 

19 AWWARF Report 90991. Project #2593. 

20 Mallevialle, J. et al. 1996. Water Treatment Membrane Processes. AWWARF Report 

21 90716. Project #826. 

22 Malley, J.P. et al. 2001. Full Scale Implimentation of UV in Groundwater Disinfection 

23 Systems. AWWARF Report 90860. Project #474. 

24 Malley, J.P. Jr. et al. 2004. Inactivation of Pathogens with Innovative UV Technologies. 

25 AWWARF Report 91024. Project #2593. 

26 Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids 

27 and chlorine in copper pitting corrosion. In Proceedings of AWWA Annual Conference. 

28 Denver CO. 

29 Martel, Kathy, Gregory Kirmeyer, Amie Hanson, Melita Stevens, Joanne Mullenger, and 

30 Daniel Deere. 2006. Application of HACCP for Distribution System Protection. 

31 AWWARF Report 91131. Project #2856. Denver, CO. 

32 Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 900 pp. 
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1 McGuire, M., et al. 2004. Water Utility Self-Assessment for the Management of 

2 Aesthetic Issues. AWWARF Report 90978F. Project #2777. 

3 McGuire, M.J., J.L. McLain, and A. Obolensky. 2002. Information Collection Rule Data 

4 Analysis. AWWARF Report 90947. Project #2799. 

5 McGuire, M.J., M.S. Pearthree, N.K. Blute, K.F. Arnold, and T. Hoogerwerf. 2006. 

6 Nitrification Control by Chlorite Ion at Pilot Scale. Journal of the American Water 

7 Works Association, 98(1):95-105 

8 McGuire, M.J., N.I. Lieu, and M.S. Pearthree. 1999. Using chlorite ion to control 

9 nitrification. Journal of American Water Works Association. 91(10): 52-61. 

10 McMeen. 2001. Alternate Filtration: Placing New Technology in an Old Regulatory Box. 

11 American Water Works Association, Membrane Conference Proceedings. 

12 McTigue, N. and D. Cornwell. 1994. The Hazardous Potential of Activated Carbons 

13 Used in Water Treatment. AWWARF Report 90640. Project #620. 

14 Means, E.G., K.N. Scott, M.L. Lee, and R.W. Wolfe. 1986. Effects of Chlorine and 

15 Ammonia Application Points on Bactericidal Efficiency. Journal of American Water 

16 Works Association. 78(1): 62-69. 

17 Mitch, W.A., and D.L. Sedlak. 2002. Factors Controlling Nitrosoamine Formation 

18 During Wastewater Chlorination. Water Supply. 2(3): 191-198. 

19 Mofidi, A.A. et al. 2001. Disinfection of Cryptosporidium parvum with polychromatic 

20 UV light. Journal of American Water Works Association. 93(6): 95-109. 

21 Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water 

22 Treatment Plant No. 3 Membrane Softening Facility Operations Manual Final Report. 

23 Pages 4-19 to 4-20. 

24 Mullenger, J., G. Ryan, and J. Hearn. 2002. A Water Authority's Experience with 

25 HACCP. Water Supply. 2(5-6): 149-155. 

26 Mysore, C. et al. 2003. Impact of Water Quality on the Inactivation of Bacterial and Viral 

27 Pathogens. AwwaRF Report 90972F. Project #2592. 

28 Najm, I. 2000. Case Studies of the Impacts of Treatment Changes on Biostability in Full29 Scale Distribution Systems. AWWARF Report 90816. Project #361. 

30 Najm, I. and R. Rhodes Trussell. 2001. NDMA formation in water and wastewater. 

31 Journal of American Water Works Association. 93(2): 92-99. 
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4 National Research Council. 2000. Identifying Future Drinking Water Contaminants. 

5 National Academy Press. Washington, D.C. 

6 Nero, W. et al. 2001. Public Involvement . . . Making It Work. AWWARF Report 90865. 

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8 NSF International. 1996. NSF International Environmental Management System 

9 Demonstration Project - Final Report. 

10 NWRI and AWWARF. 2000. Ultraviolet Disinfection Guidelines for Drinking Water and 

11 Water Reuse. AWWARF Report. Project #2674. 

12 Ollos, P.J., P.M. Huck, R.M. Slawson. 2003. Factors Affecting Biofilm Accumulation in 

13 Model Distribution Systems. Journal of American Water Works Association. 94(1). 

14 Olstein, M.A. 2001. Best Practices for a Continually Improving Customer Responsive 

15 Organization. AWWARF Report 90868. Project #2525. 

16 Owen, D.M. 1998. Removal of DBP Precursors by GAC Adsorption. AWWARF Report 

17 90744. Project #816. 

18 Panayides, N. 1999. Operational Procedures of a New 27 MGD Nanofiltration Membrane 

19 Water Treatment Plant (WTP No. 9) in South Florida. Palm Beach County Water 

20 Utilities Department. 

21 Pennsylvania’s Multi State Working Group Pilot. The Effects of ISO 14001 

22 Environmental Management Systems on the Environmental and Economic Performance 

23 of Organizations. March 27, 1999. 

24 Powell, J. et al. 2004. Predictive Models for Water Quality in Distribution Systems. 

25 AWWARF Report 91023F. Project #2865. 

26 Prévost, M.(editor) et al. 2005. Biodegradable Organic Matter in Drinking Water 

27 Treatment and Distribution. AWWA. 

28 Price, M.L. et al. 1994. Ozone and Biological Treatment for DBP Control and Biological 

29 Stability. AWWARF Report 90649. Project #504. 

30 Randtke, S.J., and R.C. Hoehn. 1999. Removal of DBP precursors by Enhanced 

31 Coagulation and Lime Softening. AWWARF Report 90783. Project #814. 
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1 Randtke, S.J., C.E. Thiel, M.Y. Liao, and C.N. Yamaya. 1982. Removing Soluble 

2 Organic Contaminants by Lime-Softening. Journal of American Water Works 

3 Association. 74(4): 192. 

4 Raucher, R. et al. 2005. The Value of Water: Concepts, Estimates, and Applications for 

5 Water Managers. AwwaRF Report 91068F. Project #2855. 

6 Ray, C. (ed.). 2001. Riverbank Filtration: Understanding Contaminant Biogeochemistry 

7 and Pathogen Removal.NATO Science Series IV. Earth and Environmental Sciences - 

8 Vol. 14. Kluwer Academic Publishers. 

9 Reckhow, D.A. 1999. Control of Disinfection Byproduct Formation Using Ozone. In 

10 Singer, P.C. (Ed) Formation and Control of Disinfection By-Products in Drinking Water. 

11 pp. 179-204 AWWA, Denver, CO. 

12 Reckhow, D.A. and P.C. Singer. 1985. Mechanisms of Organic Halide Formation During 

13 Fulvic Acid Chlorination and Implications with Respect to Pre-ozonation. Water 

14 Chlorination: Environmental Impact and Health Effects. 5: 1229-1257 (Lewis Publishers, 

15 Inc., Chelsea, MI, 1985). 

16 Reckhow, D.A. J.K. Edzwald, and J.E. Tobiason. 1993. Ozone as an Aid to Coagulation 

17 and Filtration. AWWARF Report 90643. Project #403. 

18 Redaud, J.L. 2005. ISO/TC 224 “Service Activities Relating to Drinking Water Supply 

19 Systems and Wastewater Systems - Quality Criteria of the Service and Performance 

20 Indicators". ISO. March 31, 2005. 

21 Reiber, S. 1991. Corrosion Effects by Chloramines. AWWARF Denver, CO. 

22 Reiber, S. 1993. Chloramine Effects on Distribution System Materials. AWWARF 

23 Report 90624. Project #508. 

24 Renner, R. 2004. Plumbing the Depths of D.C.’s Drinking Water Crisis. Environmental 

25 Science and Technology. 38(12): 224-227. 

26 Renner, R.C. and B.A. Hegg. 1997. Self-Assessment Guide for Surface Water Treatment 

27 Plant Optimization. AWWARF Report 90736. Project #274. 

28 Rettie, M. et al. 2005. Effective Practices to Select, Acquire, and Implement a Utility 

29 CIS. AWWARF Report 91071. Project # 3007. 

30 Roig, R. and A. Saponara. 2003. ISO 14001 Environmental Management Systems: A 

31 Complete Implementation Guide. ISO. 
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REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-44 UNE 2006 

1 Routt, J.C. 2004. Lowering DBPs in Combined Systems. Opflow. 30(4): 1-7. 

2 Routt, J.C. and N.G. Pizzi 2000. Kentucky-American Water’s Cooperative, Step-wise 

3 Process of Assisting Two Small Contiguous Systems in Complying with Pending D/DBP 

4 Requirements. Proceedings of AWWA Water Quality Technology Conference. 

5 Rushing, J.C., and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold 

6 water pitting of copper. Proceedings of AWWA Water Quality Technology Conference. 

7 Sarin, P., et al. 2003. Iron Release from Corroded, Unlined Cast-Iron Pipes. Journal of 

8 American Water Works Association. 95(11): 85-96. 

9 Sarin, P., V.L. Snoeyink, J. Bebee, K.K. Jim, M.A. Beckett, W.M. Kriven, J.A. Clement. 

10 2004. Iron Release from Corroded Iron Pipes in Drinking Water Distribution Systems: 

11 Effect of Dissolved Oxygen. Water Research. 38: 1259-1269. 

12 Schippers, J.C. et al. 2004. Integrated Membrane Systems. AWWARF Report 90899. 

13 Project #264. 

14 Schock, M.R., Wagner, I. & Oliphant, R., 1996 (Second ed.) The Corrosion and 

15 Solubility of Lead in Drinking Water. Internal Corrosion of Water Distribution Systems, 

16 pp. 131-230. AWWA Research Foundation/TZW, Denver, CO. 

17 Schock, Michael. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment: 

18 Conforming to the Lead and Copper Rule. Presented at NACE Corrosion 1996 

19 Conference. 

20 Schock, M.R., 2001. Tetravalent Lead: A Hitherto Unrecognized Control of Tap Water 

21 Lead Contamination. In Proc. of the AWWA Water Quality Technology Conference. 

22 Denver, Colo.: AWWA. 

23 Schock, M.R. & Giani, R., 2004. Oxidant/Disinfectant Chemistry and Impacts on Lead 

24 Corrosion. In Proc. Of the AWWA Water Quality Technology Conference. 

25 Schock, M.R., Scheckel, K.G., DeSantis, M., and Gerke, T.L., 2005. Mode of 

26 Occurrence, Treatment and Monitoring Significance of Tetravalent Lead, In Proc. Of the 

27 AWWA Water Quality Technology Conference. 

28 Scott, K.N., J.F. Green, H.D. Do, and S.J. McLean. 1995. Arsenic Removal by 

29 Enhanced Coagulation. Journal of the American Water Works Association 87(4) 

30 Shaw, J.P., J.P. Malley Jr., and S. Willoughby. 2000. Effects of UV irradiation on organic 

31 matter. Journal of American Water Works Association. 92(4): 157-167. 
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1 Shorney, H.L., and S.J. Randtke. 1994. Enhanced Lime Softening for the Removal of 

2 Disinfection By-Product Precursors. In Proceedings of the 1994 Annual AWWA 

3 Conference. Denver CO. 

4 Singer, P.C. (Ed.). 1999. Formation and Control of Disinfection By-Products in Drinking 

5 Water. AWWA. Denver, CO. 424 pp. 

6 Singer, P.C. 1992. Formation and Characterization of Disinfection Byproducts. Presented 

7 at the First International Conference on the Safety of Water Disinfection: Balancing 

8 Chemical and Microbial Risks. 

9 Singer, P.C. and S.D. Chang. 1989. Correlations between trihalomethanes and total 

10 organic halides formed during water treatment. Journal of American Water Works 

11 Association. 81(8): 61-65. 

12 Singer, P.C. et al. 2002. Relative Dominance of HAAs and THMs in Treated Drinking 

13 Water. AWWARF Report 90844. Project #339. 

14 Skadsen, J. 1993. Nitrification in a Distribution System. Journal of American Water 

15 Works Association. 85(7): 95-103. 

16 Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. 

17 Denver, CO. 85 pp. 

18 Snyder, J.K., and AK. Deb. 2002. Impacts of Fireflow on Distribution System Water 

19 Quality, Design, and Operation. AWWARF Report 90913. Project #2554. 

20 Sorg, T.J. 1988. Methods for Removing Uranium from Drinking Water. Journal of the 

21 American Water Works Association, 80(7) 

22 Speitel, G.E. Jr. and J.M. Symons.1998. Advanced Oxidation/Biodegradation Processes 

23 for the Destruction of TOC and Disinfection By-Product Precursors. AWWARF Report 

24 #90758. Project #289. 

25 Speitel, G.E. Jr. et al. 2004. Disinfection By-Product Formation and Control During 

26 Chloramination. AWWARF Report 91040F. Project #2677. 

27 States, S., R. Tomko, M. Scheuring, and L. Casson. 2002. Enhanced coagulation and 

28 removal of Cryptosporidium. Journal of American Water Works Association. 94(11): 67-

29 77. 

30 Stevens, A.A., C.J. Slocum, D.R. Seeger, and G.G. Robeck. 1976. Chlorination of 

31 Organics in Drinking Water. Journal of American Water Works Association. 68(11):615. 
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1 Stevens, A.A., L.A. Moore. and R.J. Miltner. 1989. Formation and Control of Non2 Trihalomethane Byproducts. Journal of American Water Works Association. 81(8): 54. 

3 Stevenson, B. 1997. Controlling Zebra Mussels at Water Treatment Plant Intakes. 

4 AWWARF Report 90612. Project #614. 

5 Stevenson, B. 1999. Controlling Zebra Mussels at Water Treatment Plant Intakes Part II. 

6 AWWARF Report. Project #821. 

7 Stolarik, G., and J.D. Christie. 1997. A Decade of Ozonation in Los Angeles. Conference 

8 proceedings, IOA Pan American Group Annual Conference, Lake Tahoe, NV. 

9 Summers, R.S., S.M. Hooper, H.M. Shukairy, G. Solarik, and D. Owen. 1996. Assessing 

10 DBP yield: uniform formation conditions. Journal of American Water Works 

11 Association. 88(6): 80–93. 

12 Symons, J.M. et al. 1998. Factors Affecting DBP Formation During Chloramination. 

13 AWWARF Report 90728. Project #803. 

14 Tatham, C., E. Tatham, and J. Mobley. 2004. Customer Attitudes, Behavior and the 

15 Impact of Communications Efforts. AWWARF Report 90975. Project #2613. 

16 Taylor, J.S. et al. 2005. Effects of Blending on Distribution System Water Quality. 

17 AWWARF Report 91065F. Project #2702. 

18 Texas Natural Resource Conservation Commission (TNRCC). 2005. Texas Optimization 

19 Program (TOP). http://www.tceq.state.tx.us/permitting/water_supply/pdw/swmor/top/ 

20 Thompson, P.L., and W.L. Paulson 1998. Dewaterability of Alum and Ferric Coagulation 

21 Sludges. Journal of American Water Works Association. 90(4): 164-170. 

22 Tikkanen, M. et al. 2001. Guidance Manual for Disposal of Chlorinated Water. 

23 AWWARF Report 90863. Project #2513. 

24 Tokuno, S. 1999. Granulated Activated Carbon Filtration and Chloramine. Water 

25 Engineering Management, 146(1):16-21 

26 U.S. Bureau of Reclamation and I. Moch & Associates. 2003. WTCost©. Development 

27 of program sponsored by the American Membrane Technology Association. 

28 U.S. Bureau of Reclamation. 1998. The Desalting and Water Treatment Membrane 

29 Manual: A Guide to Membranes for Municipal Water Treatment (2nd Edition). Technical 

30 Service Center, Water Treatment Engineering and Research, Denver, CO. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-47 UNE 2006 

1 U.S. EPA 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water 

2 Systems. Office of Water. EPA 816-R-02-009. 

3 U.S. EPA. 1989. National Primary Drinking Water Regulations; Giardia lamblia, Viruses, 

4 and Legionella, Maximum Contaminant Levels, and Turbidity, and Heterotrophic 

5 Bacteria. (Surface Water Treatment Rule), Final Rule. 43 FR 27486. June 29, 1989. 

6 U.S. EPA. 1991. Guidance Manual for Compliance with the Filtration and Disinfection 

7 Requirements for Public Water Systems Using Surface Water Sources. Developed by 

8 Malcolm Pirnie and HDR. USEPA, Washington, DC. 568 pp. 

9 U.S. EPA. 1992. Control of Biofilm Growth in Drinking Water Distribution Systems. 

10 Office of Research and Development, EPA 625/R-92/001. 

11 U.S. EPA. 1994. National Primary Drinking Water Regulations: Disinfection and 

12 Disinfection Byproducts; Proposed Rule. 59 FR 38668. July 29, 1994. 

13 U.S. EPA. 1998a. Handbook: Optimizing Water Treatment Plant Performance Using the 

14 Composite Correction Program. EPA 625/6-91/027. 

15 U.S. EPA. 1998b. National Primary Drinking Water Regulations: Interim Enhanced 

16 Surface Water Treatment Rule; Final Rule. 63 FR 69477. December 16, 1998 

17 http://www.epa.gov/safewater/mdbp/ieswtrfr.html 

18 U.S. EPA. 1998c. National Primary Drinking Water Regulations: Disinfectants and 

19 Disinfection By Products; Final Rule. 63 FR 69389. December 16, 1998. 

20 http://www.epa.gov/safewater/mdbp/dbpfr.html 

21 U.S. EPA. 1999a. Disinfection Profiling and Benchmarking Guidance Manual. EPA 815-

22 R-99-013. 

23 U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R24 99-014. 

25 U.S. EPA. 1999c. Uncovered Finished Water Reservoirs Guidance Manual. EPA 815-R26 99-011. 

27 U.S. EPA. 1999d. Guidance Manual for Compliance with the Interim Enhanced Surface 

28 Water Treatment Rule: Turbidity Provisions. EPA 815-R-99-010. 

29 U.S. EPA. 1999e. Unfiltered Systems Guidance Manual. 

30 U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance 

31 Guidance Manual. EPA 815-R-99-011. August 1999. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-48 UNE 2006 

1 U.S. EPA. 1999g. Guidance Manual for Conducting Sanitary Surveys of Public Water 

2 Systems; Surface Water and Ground Water Under the Direct Influence (GWUDI). EPA 

3 815-R-99-016. 

4 U.S. EPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening Guidance 

5 Manual. EPA 815-R-99-012. 

6 U.S. EPA. 1999i. Lead and Copper Rule Minor Revision Fact Sheet. EPA 815-F-99-010. 

7 U.S. EPA. 2000a. National Primary Drinking Water Regulations: Radionuclides Rule; 

8 Final Rule. 65 FR 76707. December 7, 2000. 

9 http://www.epa.gov/safewater/rads/radfr.html 

10 U.S. EPA. 2000b. National Primary Drinking Water Regulations for Lead and Copper. 65 

11 FR 1949. January 12, 2000. http://www.epa.gov/fedrgstr/EPA12 WATER/2000/January/Day-12/w3.htm 

13 U.S. EPA. 2000c. Lead and Copper Rule: Summary of Revisions. Office of Water. EPA 

14 815-R-99-020. 

15 U.S. EPA. 2001a. Implementation Guidance for the Stage 1 Disinfectants/Disinfection 

16 Byproducts Rule. Office of Water. EPA 816-R-01-012. 

17 U.S. EPA. 2001b. State Implementation Guidance for the Lead and Copper Rule Minor 

18 Revisions. Office of Water. EPA 816-R-01-021. 

19 U.S. EPA. 2001c. Controlling Disinfection By-Products and Microbial Contaminants in 

20 Drinking Water. Office of Research and Development. EPA/600/R-01/110. 

21 U.S. EPA. 2001d. National Primary Drinking Water Regulations: Filter Backwash 

22 Recycling Rule; Final Rule. 66 FR 31085. June 8, 2001. 

23 http://www.epa.gov/safewater/mdbp/fr-fbr.html 

24 U.S. EPA. 2001e. National Primary Drinking Water Regulations: Arsenic and 

25 Clarifications to Compliance and New Source Contaminants Monitoring . 66 FR 6975. 

26 January 22, 2001. http://www.epa.gov/fedrgstr/EPA-WATER/2001/January/Day27 22/w1668.htm 

28 U.S. EPA. 2001f. Total Coliform Rule: A Quick Reference Guide. EPA 816-F-01-035. 

29 November, 2001. http://www.epa.gov/safewater/tcr/pdf/qrg_tcr_v10.pdf 

30 U.S. EPA. 2001g. A Small System Guide to the Total Coliform Rule. Office of Water. 

31 EPA 816-R-01-017A. http://www.epa.gov/safewater/smallsys/small-tcr.pdf 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

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1 U.S. EPA. 2001h. Water Treatment Plant Model (Version 2.0). 

2 U.S. EPA. 2001i. The Surface Water Analytical Tool (Version 1.1). March 20, 2001. 

3 U.S. EPA. 2001j. 1999 Drinking Water Infrastructure Needs Survey: Modeling the Cost 

4 of Infrastructure. Office of Water. EPA 816-R-01-005. 

5 U.S. EPA. 2001k. Stage 1 Disinfectants and Disinfection Byproducts Rule: A Quick 

6 Reference Guide. Office of Water. EPA 816-F-01-010. May, 2001. 

7 http://www.epa.gov/safewater/mdbp/qrg_st1.pdf 

8 U.S. EPA. 2001l. Interim Enhanced Surface Water Treatment Rule: A Quick Reference 

9 Guide. Office of Water. EPA 816-F-01-011. May, 2001. 

10 http://www.epa.gov/safewater/mdbp/qrg_ieswtr.pdf 

11 U.S. EPA. 2001m. Filter Backwash Recycling Rule: A Quick Reference Guide. Office of 

12 Water. EPA 816-F-01-019. June 2001. http://www.epa.gov/safewater/mdbp/fbrr_qrg.pdf 

13 U.S. EPA. 2001n. Arsenic and Clarifications to Compliance and New Source Monitoring 

14 Rule: A Quick Reference Guide. Office of Water. EPA 816-F-01-004. January, 2001. 

15 http://www.epa.gov/safewater/arsenic/pdfs/quickguide.pdf 

16 U.S. EPA. 2002a. National Primary Drinking Water Regulations: Long Term 1 Enhanced 

17 Surface Water Treatment Rule. 67 FR 1811. January 14, 2002. 

18 http://www.epa.gov/fedrgstr/EPA-WATER/2002/January/Day-14/w409.htm 

19 U.S. EPA. 2002b. EPANET 2.0. http://www.epa.gov/ORD/NRMRL/wswrd/epanet.html 

20 U.S. EPA. 2002c. Long Term 1 Enhanced Surface Water Treatment Rule: A Quick 

21 Reference Guide. Office of Water. EPA 816-F-02-001. January, 2002. 

22 http://www.epa.gov/safewater/mdbp/lt1eswtr-quick-ref.pdf 

23 U.S. EPA. 2003a. Draft LT2ESWTR Toolbox Guidance Manual. Office of Water. EPA 

24 815-D-03-009. June, 2003. 

25 U.S. EPA. 2003b. Draft Ultraviolet Disinfection Guidance Manual. Office of Water. EPA 

26 815-D-03-007. June, 2003. 

27 U.S. EPA. 2003c. Draft Significant Excursion Guidance Manual. Office of Water. EPA 

28 815-D-03-004. July, 2003. 

29 U.S. EPA. 2003d. Revised Guidance Manual for Selecting Lead and Copper Control 

30 Strategies. Office of Water. EPA 816-R-03-001. March, 2003. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-50 UNE 2006 

1 U.S. EPA. 2004a. Draft Filter Surveillance Manual (June 2004). 

2 U.S. EPA. 2004b. Draft Coagulation Control Manual (July 2004). 

3 U.S. EPA. 2004c. Draft Process Monitoring Manual (July 2004). 

4 U.S. EPA. 2004d. National Primary Drinking Water Regulations; Minor Corrections and 

5 Clarification to Drinking Water Regulations; National Primary Drinking Water 

6 Regulations for Lead and Copper. 69 FR 38850. June 29, 2004. 

7 http://www.epa.gov/fedrgstr/EPA-WATER/2004/June/Day-29/w14604.htm 

8 U.S. EPA. 2004e. Guidance Manual for Compliance with the Long Term 1 Enhanced 

9 Surface Water Treatment Rule: Turbidity Provisions. EPA 816-F-02-001. 

10 U.S. EPA. 2004f. The Long Term 1 Enhanced Surface Water Treatment Rule 

11 Implementation Guidance. EPA 816-R-04-008. 

12 U.S. EPA. 2004g. Lead and Copper Rule: A Quick Reference Guide. Office of Water. 

13 EPA 816-F-04-009. March, 2004. 

14 U.S. EPA. 2005a. Occurrence Assessment for the Final Stage 2 Disinfectants and 

15 Disinfection Byproducts Rule. EPA 815-R-05-011. December, 2005. 

16 U.S. EPA. 2005b. Membrane Filtration Guidance Manual. Office of Water. EPA 815-R17 06-009. November, 2005. 

18 U.S. EPA. 2005c. A Regulator’s Guide to the Management of Radioactive Residuals 

19 from Drinking Water Treatment Technologies. USEPA 816-R-05-004. 

20 U.S. EPA. 2005d. Technologies and Costs for the Final Long Term 2 Enhanced Surface 

21 Water Treatment Rule and Final Stage 2 Disinfectants and Disinfection Byproducts Rule. 

22 EPA 815-R-05-012. December, 2005. 

23 U.S. EPA. 2005e. Occurrence and Exposure Assessment for the Long Term 2 Enhanced 

24 Surface Water Treatment Rule. EPA-821-R-06-002. 

25 U.S. EPA. 2006a. Initial Distribution System Evaluation Guidance Manual for the Final 

26 Stage 2 DBPR. Office of Water. EPA 815-B-06-002. 

27 U.S. EPA. 2006b. Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 

28 DBPR) Implementation Guidance. Office of Water. EPA 816-R-06-002. June, 2006. 

29 U.S. EPA. 2006c. Draft Long Term 2 Enhanced Surface Water Treatment Rule 

30 (LT2ESWTR) Implementation Guidance. EPA 816-R-06-006. June, 2006. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-51 UNE 2006 

1 U.S. EPA. 2006d. Source Water Monitoring Guidance Manual for Public Water Systems 

2 for the Long Term 2 Enhanced Surface Water Treatment Rule. Office of Water. EPA 

3 815-R-06-005. February, 2006. 

4 Uchida, M. and A. Okuwaki. 1999. Dissolution Behavior of Lead Plates in Aqueous 

5 Nitrate Solutions. Corrosion Science. 41:1977 

6 Urfer, D. et al. 1999. Modeling enhanced coagulation to improve ozone disinfection. 

7 Journal of American Water Works Association. 91(3): 59-73. 

8 Urfer, D., P.M. Huck, S.D.J. Booth, and B.M. Coffey. 1997. Biological Filtration for 

9 BOM and Particle Removal: A Critical Review. Journal of American Water Works 

10 Association. 89(12):83-98. 

11 Valentine, R.L. 1998. Chloramine Decomposition in Distribution System and Model 

12 Waters. AWWARF Report 90721. Project #937. 

13 Van der Kooij, D. 1997. Bacterial Nutrients and Biofilm Formation Potential within 

14 Drinking Water Distribution Systems. Conference Proceedings, AWWA Water Quality 

15 Technology Conference. 

16 Veazey, M.V. 2004. New Research May Explain Pinholes in Copper Tubing. Materials 

17 Performance. 43(5): 18-22 

18 Volk, C.J. and M.W. LeChevallier. 2002. Effects of Conventional Treatment on AOC 

19 and BDOC Levels. Journal of American Water Works Association. 94(6):112-123. 

20 Volk, C.J., R. Hofmann, C. Chauret, G.A. Gagnon, G. Ranger, and R.C. Andrews. 2002. 

21 Implementation of chlorine dioxide disinfection: Effects of the treatment change on 

22 drinking water quality in a full-scale distribution system. Journal of Environmental 

23 Engineering and Science. 1: 323-330. 

24 Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. 

25 AWWA. Denver, CO. 278 pp. 

26 Wang, J., S. Hubbs, and R. Song. 2002. Evaluation of Riverbank Filtration as a Drinking 

27 Water Treatment Process. AWWARF Report 90922. Project #2622. 

28 Wesner, G.M. Copyright 1994-2000. W/W Costs, Windows Version 3.0. 

29 Westerhoff, G.P., et al. 1998a. The Changing Water Utility: Creative Approaches to 

30 Effectiveness and Efficiency. AWWA. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 7 

REFERENCES 

 

DRAFT - DO NOT CITE OR QUOTE J 7-52 UNE 2006 

1 Westerhoff, G.P., et al. 1998b. NOM's role in bromine and bromate formation during 

2 ozonation. Journal of American Water Works Association. 90(2): 82-94. 

3 White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. Fourth ed. 

4 Van Nostrand Reinhold Co., New York, NY. 

5 Wilczak, A. L. Hoover, and H.H. Lai. 2003. Effects of Treatment Changes on 

6 Chloramine Demand and Decay. Journal of the American Water Works Association. 

7 95(7):94-107 

8 Wilczak, A., J.G. Jacangelo, J.P. Marcinko, L.H. Odell, G.J. Kirmeyer, and R.L. Wolfe. 

9 1996. Occurrence of Nitrification in Chloraminated Distribution Systems. Journal of 

10 American Water Works Association. 88(7): 74-85. 

11 Williams, M.D., B.M. Coffey, and S.W. Krasner, 2003. Evaluation of pH and Ammonia 

12 for Controlling Bromate During Cryptosporidium Disinfection. Journal of American 

13 Water Works Association. 95(10): 82-93. 

14 Wolfe, R.L. 1990. Ammonia-Oxidizing Bacteria in a Chloraminated Distribution System: 

15 Seasonal Occurrence, Distribution, and Disinfection Resistance. Applied and 

16 Environmental Microbiology. 56: 541. 

17 Wolfe. R.L., E.G. Means, M.K. Davis, and S.E. Barrett. 1988. Biological Nitrification in 

18 Covered Reservoirs Containing Chloraminated Water. Journal of American Water Works 

19 Association. 80(9): 109-114. 

20 World Health Organization. 2004a. Guidelines for Drinking Water Quality, 3rd Edition. 

21 Geneva, Switzerland. World Health Organization. 

22 World Health Organization. 2004b. Water Treatment and Pathogen Control: Process 

23 Efficiency in Achieving Safe Drinking Water. Edited by M.W. LeChevallier and K.K. 

24 Au. ISBN: 1 84339 069 8. Published by IWA Publishing, London, UK. 

25 Wubbena, R.L. 2002a. Strategic Business Planning as a Water Resource Management 

26 Tool. AWWARF Report 90905. Project # 2698. 

27 Xie, Y., et al. 2004. Haloacetic Acid Removal Using Granular Activated Carbon. 

28 AWWARF Report 91041F. Project #2825. 

29 Zhou, P. and J. Neemann. 2005. Use of Chlorine Dioxide and Ozone for Control of 

30 Disinfection By-Products. AWWARF Report 90981F. Project #2742. 

31 
 

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1 

1 

2 

3 

4 

5 

6 Alkalinity, 2-2, 2-3, 3-3, 3-5, 3-8, 3-10, 3- 6 

7 33, 3-34, 3-45, 3-47, 3-51, 3-53, 3-54, 3-

8 55, 4-15, 4-18, 5-5, 5-7, 5-27, 5-40, 6-3, 

9 6-4, 6-5, 6-13, 6-16 

10 Alum, 3-7, 3-19, 3-32, 3-34, 3-44, 3-45, 3-

11 47, 3-49, 3-50, 3-51, 6-21 

12 Aluminum, 2-2, 2-8, 3-8, 3-32, 3-34, 3-47, 

13 3-48, 3-49, 3-50, 3-51, 5-26, 5-32 

14 Ammonia, 2-8, 3-14, 3-23, 4-3, 4-5, 4-6, 5-

15 1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 5-8, 5-9, 5-

16 10, 5-12, 5-17, 5-18, 5-20, 5-30, 5-44, 5-

17 45, 5-47 

18 AOC, 2-3, 2-8, 2-9, 2-10, 4-2, 4-3, 5-10, 5-

19 18, 5-19, 5-20, 5-22, 5-44, 5-45, 5-46, 5-

20 47 

21 Arsenic, 1-3, 2-7, 3-6, 3-7, 3-44, 3-45, 3-50, 

22 4-8, 4-13, 5-15, 5-35 

23 Bank filtration, 4-20, 4-21, 4-22, 4-23, 4-24, 

24 6-20 

25 BDOC, 5-19, 5-22 

26 Benchmark, 3-1, 3-23, 5-9, 5-15, 5-24, 5-25, 

27 5-28, 5-29, 5-35, 5-37, 6-22 

28 Biological filter, 2-8, 5-22 

29 BMP, 1-7, 3-11, 3-12, 3-13, 3-14, 3-17 

30 Carryover, 2-8, 3-32, 3-51 

31 Chloramines, 1-6, 1-7, 2-8, 2-10, 2-12, 2-15, 

32 2-16, 3-14, 3-23, 3-56, 3-58, 4-5, 4-6, 4-

33 8, 4-13, 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-7, 

34 5-8, 5-9, 5-10, 5-11, 5-12, 5-13, 5-20, 5-

35 24, 5-30, 5-39, 5-41, 5-42, 5-44, 5-45, 5-

36 46, 5-47, 5-48, 6-5, 6-6 

37 Chlorination, iii, 1-7, 2-3, 2-6, 2-12, 2-13, 2-

38 16, 3-18, 3-19, 3-20, 3-21, 3-22, 3-23, 3-

39 24, 3-25, 3-26, 3-27, 3-30, 3-31, 3-34, 3-

40 35, 3-39, 3-57, 4-4, 5-8, 5-28, 6-15 

41 Chlorine Dioxide, vii, 1-7, 2-5, 2-11, 2-12, 

42 2-15, 2-16, 3-22, 3-23, 3-24, 3-44, 3-56, 

43 3-58, 4-3, 4-5, 4-8, 4-13, 5-1, 5-9, 5-11, 

44 5-15, 5-24, 5-26, 5-27, 5-28, 5-29, 5-30, 

45 5-34, 5-35, 5-36, 5-37, 5-38, 5-39, 5-40, 

46 5-41, 5-42, 5-43, 5-44, 5-45, 5-46, 5-47, 

47 5-48, 6-14 

48 Coagulation, 1-11, 2-2, 2-6, 2-10, 3-5, 3-6, 

49 3-7, 3-8, 3-18, 3-19, 3-20, 3-22, 3-24, 3-

50 26, 3-32, 3-34, 3-40, 3-43, 3-44, 3-45, 3-

51 46, 3-47, 3-49, 3-51, 3-52, 3-53, 3-54, 3-

52 60, 4-4, 4-9, 4-15, 5-14, 5-15, 5-16, 5-

53 18, 5-25, 5-36, 5-39, 5-40, 6-3, 6-13, 6-

54 16, 6-21 

55 Coliform, 2-7, 3-17, 3-35, 3-38, 3-39, 5-5, 5-

56 6, 5-11, 5-12 

57 Contact time, 3-6, 3-7, 3-21, 3-25, 3-28, 3-

58 45, 3-56, 3-57, 4-1, 4-2, 5-9, 5-10, 5-18, 

59 5-30, 5-40 

60 Copper, 1-3, 2-13, 3-15, 3-23, 3-30, 3-32, 3-

61 47, 3-48, 3-51, 3-55, 5-5, 5-6, 6-10, 6-17 

62 Corrosion, 1-6, 1-8, 2-4, 2-6, 2-7, 2-8, 2-10, 

63 2-16, 3-8, 3-13, 3-14, 3-17, 3-25, 3-26, 

64 3-27, 3-30, 3-31, 3-32, 3-33, 3-34, 3-35, 

65 3-46, 3-47, 3-48, 3-49, 3-51, 3-52, 3-54, 

66 3-55, 3-58, 3-60, 4-15, 4-18, 5-3, 5-5, 5-

67 6, 5-7, 5-11, 5-13, 5-16, 5-17, 5-18, 5-

68 19, 5-20, 5-21, 5-22, 5-23, 5-26, 5-27, 5-

69 30, 5-36, 5-37, 5-43, 5-45, 5-46, 5-47, 6-

70 3, 6-5, 6-6, 6-10, 6-12, 6-13, 6-14, 6-17, 

71 6-18 

72 DBP, 1-1, 1-6, 1-7, 1-8, 1-9, 2-6, 2-7, 2-8, 2-

73 9, 2-16, 3-2, 3-3, 3-4, 3-5, 3-6, 3-7, 3-8, 

74 3-12, 3-13, 3-14, 3-17, 3-18, 3-19, 3-22, 

75 3-27, 3-29, 3-33, 3-34, 3-35, 3-36, 3-40, 

76 3-41, 3-42, 3-43, 3-44, 3-45, 3-48, 3-53, 

77 3-57, 3-58, 4-1, 4-2, 4-4, 4-5, 4-6, 4-8, 4-

78 12, 4-13, 4-14, 4-18, 4-21, 4-22, 4-24, 4-

79 25, 5-2, 5-8, 5-9, 5-11, 5-14, 5-15, 5-16, 

80 5-17, 5-18, 5-20, 5-22, 5-26, 5-27, 5-30, 

81 5-32, 5-34, 5-35, 5-36, 5-39, 5-42, 5-48, 

82 6-3, 6-13, 6-14, 6-15, 6-19, 6-20 

Index 
 

1 DBP precursors, 2-6, 2-7, 2-8, 2-9, 3-4, 3-5, 

2 3-6, 3-7, 3-8, 3-18, 3-22, 3-34, 3-40, 3-

3 41, 3-43, 3-45, 3-53, 4-2, 4-12, 4-13, 4-

4 18, 4-21, 4-22, 4-25, 5-16, 5-20, 6-19, 6-

5 20 

6 Disinfection profile, 3-1 

7 Distribution system, 1-7, 1-8, 2-3, 2-5, 2-6, 

8 2-7, 2-8, 2-10, 2-12, 2-16, 3-1, 3-3, 3-8, 

9 3-11, 3-12, 3-13, 3-14, 3-15, 3-16, 3-17, 

10 3-18, 3-25, 3-26, 3-27, 3-30, 3-31, 3-32, 

11 3-33, 3-34, 3-35, 3-36, 3-37, 3-38, 3-39, 

12 3-40, 3-43, 3-47, 3-48, 3-49, 3-52, 3-55, 

13 3-58, 3-59, 3-60, 4-1, 4-3, 4-6, 4-8, 4-13, 

14 4-15, 5-1, 5-2, 5-3, 5-4, 5-5, 5-6, 5-8, 5-

15 9, 5-10, 5-11, 5-12, 5-13, 5-14, 5-18, 5-

16 19, 5-20, 5-22, 5-23, 5-25, 5-27, 5-28, 5-

17 30, 5-31, 5-37, 5-38, 5-39, 5-42, 5-43, 5-

18 44, 5-47, 6-3, 6-5, 6-7, 6-8, 6-9, 6-10, 6-

19 11, 6-12, 6-13, 6-14, 6-15, 6-17, 6-18, 6-

20 20, 6-21 

21 E. coli, 3-38, 3-39 

22 Enhanced Coagulation, 1-7, 1-10, 2-2, 2-3, 

23 2-7, 2-12, 2-13, 2-14, 2-16, 3-5, 3-19, 3-

24 25, 3-26, 3-43, 3-44, 3-45, 3-46, 3-47, 3-

25 48, 3-49, 3-50, 3-51, 3-52, 3-55, 3-60, 4-

26 2, 4-9, 4-15, 4-24, 5-36, 6-16 

27 Enhanced Softening, 1-7, 2-4, 2-8, 2-12, 2-

28 16, 3-53, 3-54, 3-55, 3-56, 3-57, 3-58, 3-

29 59, 3-60, 4-2, 5-36, 5-37 

30 Ferric chloride, 3-49, 6-21 

31 Filtration, 1-11, 2-4, 2-5, 2-9, 2-10, 2-12, 2-

32 14, 2-16, 3-8, 3-20, 3-21, 3-22, 3-24, 3-

33 26, 3-32, 3-34, 3-42, 3-44, 3-46, 3-49, 4-

34 1, 4-2, 4-3, 4-5, 4-9, 4-10, 4-12, 4-13, 4-

35 14, 4-16, 4-20, 4-21, 4-22, 4-23, 4-24, 4-

36 25, 5-18, 5-19, 5-20, 5-21, 5-22, 5-27, 5-

37 40, 5-47, 6-1, 6-3, 6-16, 6-17, 6-20, 6-21 

38 Flash mixer, 3-18 

39 GAC, 2-4, 2-8, 2-10, 2-14, 2-16, 4-1, 4-2, 4-

40 3, 4-4, 4-5, 4-6, 4-7, 4-9, 4-21, 4-22, 4-

41 25, 5-3, 5-10, 5-19, 5-21, 5-40, 6-16, 6-

42 19, 6-21 

43 HAA5, 2-3, 2-4, 2-5, 2-7, 2-8, 2-10, 2-11, 3-

44 12, 3-19, 3-22, 3-23, 3-25, 3-27, 3-30, 3-

45 31, 3-36, 3-37, 3-38, 3-41, 3-45, 5-2, 5-

46 6, 5-17, 5-18, 5-34, 5-35, 5-36, 5-39, 5-

47 45, 5-46, 6-10 

48 Heterotrophic plate count, 3-17, 3-35, 3-39, 

49 4-7, 4-11, 4-18, 5-4, 5-12, 5-22 

50 IESWTR, 1-3, 1-9, 1-10, 2-2, 2-6, 2-7, 2-8, 

51 2-10, 2-11, 3-46, 3-51, 4-20, 5-24, 5-37, 

52 5-45 

53 Langelier Saturation Index, 3-58, 5-31, 6-13 

54 Lead, 1-3, 1-8, 2-10, 3-2, 3-8, 3-13, 3-14, 3-

55 15, 3-16, 3-17, 3-30, 3-31, 3-32, 3-39, 3-

56 46, 3-47, 3-48, 3-49, 3-54, 3-58, 4-3, 4-

57 4, 4-15, 5-1, 5-3, 5-5, 5-6, 5-7, 5-8, 5-10, 

58 5-16, 5-17, 5-18, 5-19, 5-37, 5-47, 6-8, 

59 6-10 

60 Lead and Copper Rule, 1-3, 1-8, 3-14, 3-31, 

61 4-15, 5-19, 6-8, 6-10 

62 LT1ESWTR, 1-3, 1-10, 2-2, 2-6, 2-7, 2-8, 2-

63 10, 2-11, 3-46, 5-37, 5-45 

64 LT2ESWTR, 1-1, 1-2, 1-3, 1-6, 1-9, 1-10, 1-

65 11, 2-1, 2-2, 2-5, 2-6, 2-7, 2-8, 2-9, 2-10, 

66 2-11, 3-1, 3-41, 3-43, 3-54, 4-1, 4-2, 4-8, 

67 4-12, 4-13, 4-20, 5-1, 5-18, 5-24, 5-25, 

68 5-28, 5-29, 5-32, 5-35, 5-38, 5-42, 5-45, 

69 5-46, 6-1, 6-2, 6-3, 6-8, 6-10, 6-11, 6-12, 

70 6-16, 6-17, 6-18 

71 Membrane, 1-11, 2-14, 3-58, 4-5, 4-8, 4-9, 

72 4-10, 4-11, 4-12, 4-13, 4-14, 4-15, 4-16, 

73 4-17, 4-18, 4-19, 6-3, 6-17, 6-18, 6-19, 

74 6-20, 6-21 

75 MF/UF, 1-7, 2-4, 2-8, 2-12, 2-16, 3-58, 4-8, 

76 4-9, 4-10, 4-11, 4-12, 4-13, 6-20, 6-21 

77 Nanofiltration, 1-7, 2-4, 2-9, 2-12, 2-14, 2-

78 16, 4-13, 4-14, 4-15, 4-17, 6-20 

79 Nitrification, 2-8, 2-10, 2-14, 3-12, 3-13, 3-

80 14, 4-3, 4-5, 4-6, 5-1, 5-3, 5-4, 5-5, 5-6, 

81 5-7, 5-8, 5-10, 5-11, 5-12, 5-18, 5-30, 5-

82 42, 5-44, 5-45, 5-46, 5-47, 6-5 

83 NOM, 2-3, 2-5, 3-1, 3-3, 3-5, 3-10, 3-12, 3-

84 27, 3-42, 3-43, 3-44, 3-45, 3-47, 3-57, 4-

85 18, 5-37, 6-20 

86 Orthophosphate, 3-51, 5-6 

87 Ozone, 1-7, 2-8, 2-10, 2-12, 2-16, 3-23, 3-

88 24, 3-32, 3-44, 3-45, 3-56, 3-57, 3-58, 4-

89 2, 4-3, 5-1, 5-3, 5-9, 5-10, 5-14, 5-15, 5-

90 16, 5-17, 5-18, 5-19, 5-20, 5-21, 5-22, 5-
 

1 23, 5-24, 5-26, 5-27, 5-28, 5-29, 5-30, 5-

2 32, 5-34, 5-35, 5-44, 5-45, 5-46, 5-47, 5-

3 48, 6-14, 6-21 

4 Pinhole Leaks, 3-51 

5 Residuals, 2-1, 2-2, 2-7, 2-8, 2-9, 2-10, 2-14, 

6 3-11, 3-14, 3-25, 3-39, 3-46, 3-50, 3-51, 

7 3-59, 4-10, 4-16, 4-22, 4-23, 5-1, 5-2, 5-

8 4, 5-5, 5-7, 5-8, 5-12, 5-30, 5-39, 5-40, 

9 5-42, 5-43, 6-4, 6-7 

10 Scale, 1-7, 2-16, 3-13, 3-26, 3-31, 3-33, 3-

11 35, 3-40, 3-45, 3-47, 3-49, 3-52, 3-55, 3-

12 58, 3-59, 3-60, 4-7, 5-6, 5-13, 5-16, 5-

13 23, 5-29, 5-31, 5-33, 5-39, 5-43, 5-47, 6-

14 1, 6-5, 6-6, 6-8, 6-9, 6-14, 6-16, 6-17, 6-

15 18, 6-19, 6-22 

16 Second Stage Filtration, 2-4, 2-9, 2-12, 4-21, 

17 4-22 

18 Secondary disinfection, 3-30, 3-40, 5-30 

19 Softening, 1-10, 2-4, 2-8, 2-12, 2-16, 3-9, 3-

20 25, 3-44, 3-47, 3-52, 3-53, 3-54, 3-55, 3-

21 56, 3-57, 3-58, 3-59, 3-60, 4-24, 6-16, 6-

22 21 

23 Source Management, 1-7, 2-3, 2-5, 2-6, 2-

24 12, 2-16, 3-1, 3-2, 3-4, 3-5, 3-6, 3-7, 3-8, 

25 3-9, 3-10 

26 Stage 1 D/DBPR, 1-3, 1-9, 1-10, 2-6, 2-7, 2-

27 8, 2-10, 2-11, 3-20, 3-25, 3-26, 3-45, 3-

28 50, 3-53, 3-54, 4-5, 5-12, 5-14, 5-15, 5-

29 17, 5-27, 5-36, 5-38, 5-39, 5-45, 5-46 

30 Stage 2 DBPR, 1-1, 1-2, 1-3, 1-6, 1-9, 1-10, 

31 1-11, 2-1, 2-2, 2-5, 2-6, 2-7, 2-8, 2-9, 2-

32 10, 2-11, 3-1, 3-17, 3-26, 3-27, 3-35, 3-

33 40, 3-52, 3-54, 3-57, 3-60, 4-1, 4-2, 4-7, 

34 4-9, 4-12, 4-18, 4-19, 4-25, 5-1, 5-2, 5-

35 13, 5-15, 5-16, 5-23, 5-24, 5-30, 5-33, 5-

36 36, 5-39, 5-42, 5-45, 5-46, 6-1, 6-2, 6-3, 

37 6-8, 6-10, 6-12, 6-13, 6-16 

38 SUVA, 3-5, 3-10 

39 TOC, 2-6, 2-8, 2-14, 3-5, 3-9, 3-10, 3-19, 3-

40 20, 3-45, 3-47, 3-50, 3-52, 3-53, 3-54, 3-

41 55, 3-57, 3-58, 3-60, 4-2, 4-6, 4-9, 4-11, 

42 4-17, 4-18, 5-9, 5-22, 6-16 

43 Total Coliform Rule, 1-3, 2-2, 2-6, 2-7, 2-8, 

44 2-10, 3-14, 3-32, 3-37, 3-38, 3-48, 4-3, 

45 5-4, 5-8, 5-19, 5-20, 5-25, 5-45, 5-46, 5-

46 47, 6-8, 6-9, 6-16 

47 TTHM, 2-3, 2-4, 2-5, 2-7, 2-8, 2-10, 2-11, 3-

48 19, 3-22, 3-23, 3-25, 3-27, 3-29, 3-30, 3-

49 31, 3-36, 3-37, 3-38, 3-41, 3-45, 3-56, 3-

50 57, 3-58, 4-6, 5-2, 5-6, 5-9, 5-15, 5-17, 

51 5-18, 5-34, 5-35, 5-36, 5-39, 5-45, 5-46, 

52 6-7, 6-10, 6-14 

53 Turbidity, 1-10, 3-10, 3-43, 3-46, 4-7, 4-20, 

54 4-24 

55 UV, 1-7, 1-10, 2-1, 2-5, 2-10, 2-11, 2-12, 2-

56 15, 2-16, 3-5, 3-42, 3-58, 4-5, 5-1, 5-9, 

57 5-14, 5-16, 5-24, 5-25, 5-26, 5-27, 5-28, 

58 5-29, 5-30, 5-31, 5-32, 5-33, 5-36, 5-40, 

59 5-46, 5-48, 6-17, 6-18, 6-19, 6-21 

60 Watershed Control, 2-5, 2-9, 3-1 

61 

62 
 

Appendix A

Summary of Pertinent Drinking Water Regulations
 

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M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX A - QUICK REFERENCE GUIDES 

 

DRAFT - DO NOT CITE OR QUOTE M A-1 ARCH 2006 

Appendix A 

Summary of Pertinent Drinking Water Regulations

 This appendix contains quick reference guides for the major rules discussed in this 

guidance manual. The 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 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

Long Term 2 Enhanced Surface Water 

Treatment Rule (LT2ESWTR) 

December 2005 Microbial Pathogens Fact Sheet 

Stage 2 Disinfectants and Disinfection 

Byproducts Rule (Stage 2 DBPR) 

December 2005 Disinfectants and 

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 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 Microbial Pathogens Quick Reference 

Guide 

Long Term 1 Enhanced Surface Water 

Treatment Rule (LT1ESWTR) 

January 2002 Microbial Pathogens Quick Reference 

Guide 

Filter Backwash Recycling Rule 

(FBRR) 

June 2001 Filter Backwash 

(Microbial Pathogens) 

Quick Reference 

Guide 
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: 

• Source Water Monitoring Guidance

• Microbial Laboratory Guidance

• Small Entity Compliance Guidance

• Microbial Toolbox Guidance Manual

• Ultraviolet Disinfection Guidance Manual

• Membrane Filtration Guidance Manual

• Simultaneous Compliance Guidance Manual

• 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.

1

The 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







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 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 3 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 3 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 3 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%

1 Systems meeting at least one of the alternative compliance criteria in the rule are not required to meet the

 removals in this table.

2 Systems 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.
1 Appendix B

2 Case Studies 
1 

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M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 

 

DRAFT – DO NOT CITE OR QUOTE B-1 

1 Case Studies in this Guidance Manual and Issues they Address 2 

Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

1 Moving the Point of 

Chlorination Downstream 

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) 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 

 

DRAFT – DO NOT CITE OR QUOTE B-2 

Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

6 Enhanced 

Coagulation - Managing Radioactive Residuals 

Allen Water Filtration Plant 

Englewood, Colorado 48,000 8.5 Surface Wate

(river, creek, diversions) 

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 Surface 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) 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 

 

DRAFT – DO NOT CITE OR QUOTE B-3 

Case 

Study 

No. 

Treatment/Issue 

Addressed 

Utility Name Case Study 

Location 

Population 

Served 

Average 

Annual 

Treatment 

Plant (MGD) 

Production 

Source 

Water 

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) 

14 Chlorine Dioxide for 

Primary Disinfection and Chloramines for Residual Disinfection 

Village of Waterloo Water Treatment Plant 

Waterloo, New York <10,000 2 Surface Wate

(lake) 

1 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

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1 This page intentionally left blank. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE J B-5 UNE 2006

1 Case Study #1 

2 Moving the Point of Chlorination

3 Owenton Water Works and Kentucky American TriVillage 

4 Owenton, Kentucky

5 

6 

7 This case study provides an example of how two small PWSs, both using water treated by 

8 the same conventional filtration plant, worked together to change chlorination practices to their 

9 existing treatment and operations to reduce TTHM. Reducing TTHM was the primary objective, 

10 due to the timing of this work beginning in late 1999 prior to regulatory limits for these systems 

11 serving a combined population under 10,000. 

12 

13 Changes described here took place primarily over the first 6 months of 2000 and were 

14 made in a series of carefully planned and monitored steps in close consultation with the state 

15 regulatory officials and with knowledge of available EPA regulations and guidance. This work 

16 has also been successful in reducing HAA5s as these systems completed the first year (2004) in 

17 compliance with the 80/60 THM/HAA limits. 

18 

19 Prior to moving the point of chlorination, the following steps were carried out: 

20 

21 1) Enhanced coagulation was initiated at lower pH to improve TOC removal and sodium 

22 hydroxide (caustic soda) was added to maintain distribution corrosion control. 

23 

24 2) Potassium permanganate feed to the raw water was optimized to control source water 

25 manganese and to provide reliable pre-oxidation in anticipation of moving the 

26 chlorine application point. 

27 

28 3) In-plant chlorine disinfection contact time was assessed and operations revised to 

29 increase chlorine retention time in the plant clearwell. This step included trending 12 

30 months of disinfection data in the plant and consultation with the state. The state 

31 provided a list of additional source monitoring (microbiological and other related 

32 water quality parameters from source through distribution) to be conducted prior to 

33 and following the change in chlorine application point. 

34 

35 The point of chlorination was then moved by turning off the chlorine feed to the rapid 

36 mix portion of plant treatment and increasing chlorine at the application points just before and 

37 after the filters to provide the required residuals in the plant clearwell and through distribution. 

38 

39 This case study is documented in Routt (2004) and Routt and Pizzi (2000). Readers may 

40 refer to those references for more details. Updates were also provided for this case study by J. 

41 Routt in January 2005. 

42 
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1 Introduction

2 

3 The Owenton City Water Works operates a conventional 1 million gallons per day 

4 treatment plant that uses water from an algae-rich reservoir. Approximately half of the water 

5 that is produced by the Owenton facility is sold to Kentucky American Water Northern Division 

6 (TriVillage), a privately owned water system. Owenton delivers the remainder of the water in its 

7 own distribution network. Together, the two systems serve fewer than 10,000 people. However, 

8 for several years prior to this work (which began in late 1999), both systems had been regularly 

9 issuing state-required health-based public notices due to elevated TTHM. 

10 

11 To define the factors contributing to the elevated DBPs, Kentucky American Water, in 

12 cooperation with the City of Owenton, collected water quality data from both systems. These 

13 data showed that the most effective solution to the elevated DBPs would be to switch to a source 

14 water of higher quality. Switching source waters, however, was understood to be a long-term, 

15 expensive project that would require designing and building new intake and transmission 

16 facilities. In the meantime, the systems decided to make operational changes to improve water 

17 quality before the completion of the new intake and transmission lines. 

18 

19 The Original Treatment Process at the Owenton WTP

20 

21 The system used a high TOC, high alkalinity source water prone to fluctuating 

22 manganese levels. Before treatment changes were made, chlorine was being added at the rapid 

23 mix and again at booster stations to provide required free chlorine residuals through the 

24 distribution system. The treatment plant was using alum-lime coagulation with a pH of 

25 approximately 7.8, and was achieving less than 28 percent TOC removal. This TOC removal 

26 efficiency would not meet the Step 1 requirements of the Stage 1 D/ DBPR for the system. In 

27 addition, monitoring showed that TTHM levels were elevated leaving the treatment plant and 

28 increased substantially with retention time and re- chlorination through the distribution network. 

29 

30 Simultaneous Compliance Issues Faced by the Utilities

31 

32 The combined systems had high TTHM concentrations and were faced with the challenge 

33 of complying with upcoming Stage 1 D/DBPR and Stage 2 DBPR requirements. Priorities and 

34 plans had to be clearly set to help ensure ongoing compliance with other regulations that stood to 

35 be impacted by treatment changes to reduce DBPs–such as SWTR disinfection and filtered 

36 turbidity requirements, LCR corrosion control requirements and TCR microbiological control 

37 requirements. To that end, the systems embarked upon a cooperative effort to proceed through 

38 steps to improve DBPs for the short term–using existing source water and treatment and 

39 distribution facilities–while keeping the multiple regulatory requirements in mind. 

40 
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1 Steps Taken by the Utilities

2 

3 Profiles of TOC removal, TTHM formation, and disinfection were collected through the 

4 plant and distribution system. These process profiles showed that TOC was not being effectively 

5 removed, and that high levels of TTHM and HAA5 were being formed in the treatment plant. 

6 

7 Treatment changes, therefore, consisted of maximizing TOC removal and optimizing 

8 chlorine disinfectant application. Operational changes were made in a phased process over 

9 several months, with state approval granted for each step. The results of each step were 

10 evaluated before the systems proceeded to the next phase. 

11 

12 Enhancing Coagulation

13 

14 The removal of TOC was increased by making several relatively simple changes to the 

15 coagulation process in the Owenton treatment plant. Coagulation and TOC removal were 

16 enhanced by ceasing pre-lime application, and approximately doubling the alum dose to lower 

17 the treated water pH to 6.9. The change in coagulation chemicals required addition of a 

18 postfiltration caustic feed (sodium hydroxide) to adjust the finished water's pH to 7.6-7.8 for 

19 distribution system corrosion control. 

20 

21 In addition, a switch from alum to ferric chloride was made in order to improve the solids 

22 handling in the plant's solids-contact upflow clarifier. Ferric chloride was expected to produce 

23 good TOC removal with less chemical, and to produce a more stable floc, less prone to upset and 

24 carry-over onto filters. These expectations were met. 

25 

26 Changes to the coagulation process roughly doubled the TOC removal and decreased 

27 chlorine demand. Chlorine residuals persisted noticeably longer in the distribution system, 

28 which allowed the systems to reduce their re- chlorination doses at the master metering points in 

29 the distribution system. Levels of TTHM, however, were decreased by only 15 percent. The 

30 next step was to evaluate plant disinfection and seek state approval to move the point of 

31 chlorination to later in the treatment process. 

32 

33 Converting to Top-of-Filter Chlorination

34 

35 Prior to moving the chlorination point, the Owenton plant was thoroughly assessed for 

36 adequate disinfection contact time. Tracer studies were conducted of the clearwell, which is 

37 well-baffled, and operational guidelines were changed to increase the minimum water level in 

38 the clearwell which effectively increased the chlorine disinfection contact time with filtered 

39 water. This was to offset contact time that would be lost when chlorine application was moved 

40 from rapid mix to the top of the filters. Potassium permanganate pretreatment procedures were 

41 revised to incorporate regular demand tests to improve dosing accuracy and to reduce chlorine 

42 oxidant demand. It was emphasized that, once the point of chlorination was moved to the top of 

43 the filter, permanganate would be the only pre-oxidant. Therefore, optimization would be 
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1 critical to good coagulation of natural organics and to prevent manganese carryover when 

2 treating the fluctuating dissolved manganese in the source water. 

3 

4 The state approved the system's proposal to switch to ferric chloride coagulant, followed 

5 by post-caustic for corrosion control, and moving the point of chlorination to the top of the 

6 filters. The changes were made in sequence and with close supervision and monitoring. The 

7 change in point of chlorination was approved with the contingency that additional testing would 

8 be conducted before and after the change, in order to verify adequate disinfection and good 

9 overall water quality. This additional testing included TOC and organic nitrogen source water 

10 monitoring, as well as heterotrophic and total coliform bacteria monitoring through the treatment 

11 plant and distribution network. 

12 

13 Optimization of Booster Chlorination

14 

15 In addition to the changes made at the Owenton treatment plant, both water systems have 

16 worked to optimize their distribution systems, and the purchaser, TriVillage, has optimized 

17 chlorine doses at the booster stations. The reduction in finished water TOC leaving the Owenton 

18 plant has allowed for a reduction in the amount of booster chlorine needed to maintain a residual 

19 throughout the distribution system. Both systems have conducted additional flushing and have 

20 cleaned and inspected their storage tanks. Since the changes, lead and copper action levels and 

21 TCR standards have been met in both distribution systems. The systems continued to conduct 

22 extra testing for TOC, DBPs, chlorine residual, and HPCs to track distribution system water 

23 quality. In 2004, the TOC and DBP “compliance” testing has replaced the earlier special testing. 

24 

25 Implementation and Operational Issues Faced by the Utilities 

26 

27 Overall, operational changes have gone smoothly. The greatest ongoing operational 

28 impacts have been related to enhanced coagulation: an increase in (approximate doubling of) 

29 chemical treatment costs, along with a need for increased attention to solids removal from the 

30 upflow clarifier and filter backwash settling basins. 

31 

32 Post-filter caustic feed has necessitated cleaning of deposits from filtered water transfer 

33 pumps just downstream of the application point. This caustic buildup did not become 

34 problematic until 2004 - 4 years after the initiation of caustic feed. However, utilities are advised 

35 to watch for caustic clogging in mechanical devises located immediately downstream of caustic 

36 application points. 

37 

38 In the summer of 2001, source water dissolved manganese temporarily increased to levels 

39 that could not be treated by potassium permanganate alone. The resulting discolored water 

40 forced the system to return to minimal prechlorination and, then, to switch briefly to 

41 polyaluminum chloride as coagulant. The polyaluminum chloride coagulated well at a higher pH 

42 (8.0), which improved potassium permanganate removal of the dissolved manganese and 

43 eliminated the need for pre-chlorine. Within a few weeks, the source water manganese levels 
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1 dropped, and the system returned to ferric chloride coagulation at lower pH. This scenario has 

2 not recurred since. 

3 

4 Systems should be extremely careful when switching coagulants to ensure that they 

5 maintain consistent particle and pathogen removal. The dosage of new coagulant needed should 

6 be carefully calculated and confirmed with up-to-date jar testing using the water to be treated. 

7 

8 Results of the Steps Taken

9 

10 Since changes were made in May 2000, filtered and distributed water quality compliance 

11 has been maintained. TTHM levels have dropped below the 0.080 mg/L standard. Testing has 

12 shown that HAA5 levels have been reduced by more than half as well. As of 2004, the first year 

13 of compliance TOC testing showed monthly removal ratios ranging from 1.96-2.35 and 

14 averaging 2.19 for the year, and the RAAs for THM and HAA5 levels were 74 and 47 ug/L, 

15 respectively. 

16 

17 Overall, customers have noticed that their water has improved in clarity and taste of their 

18 water, possibly due to the enhanced coagulation, and decreased chlorine demand combined with 

19 diligent attention to water quality throughout the system. 

20 

21 Lessons Learned From this Case Study

22 

23 • Source water testing and the development of treatment plant and distribution system 

24 profiles helped the systems identify the factors that were causing DBP formation. 

25 

26 • By adjusting coagulation methods and the point of chlorination, while optimizing 

27 distribution operations to optimize booster chlorine use, these small surface water 

28 systems succeeded at reducing TTHM and HAA5 in the combined system, even when 

29 using a challenging source water. 

30 

31 • Compliance with TTHM and HAA5 standards can be achieved, without negatively 

32 impacting other regulatory programs, by implementing a combination of several 

33 carefully planned and monitored operational changes. 

34 

35 • Water quality improvements can be realized with short-term operational changes, and 

36 provide information useful in decision-making, pending completion of more costly, 

37 time-intensive, long-term modifications. 

38 

39 
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1 Further Reading

2 

3 Readers can find more information about this case study in the following publications: 

4 

5 Routt, J.C. 2004. Lowering DBPs in Combined Systems. Opflow. 30(4): 1-7. 

6 

7 Routt, J.C. and N.G. Pizzi 2000. Kentucky-American Water’s Cooperative, Step-wise Process of 

8 Assisting Two Small Contiguous Systems in Complying with Pending D/DBP Requirements. 

9 Proceedings of AWWA Water Quality Technology Conference. 

10 

11 
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DRAFT- DO NOT CITE OR QUOTE J B-11 UNE 2006

1 Case Study #2 

2 Modifying pH During Chlorination

3 Public Utility District #1 

4 Skagit County, Washington 

5 

6 

7 This case study provides an example of how a PWS used pH depression to reduce DBPs. 

8 The depression of pH via carbon dioxide (CO2) injection ahead of the flocculation basins also 

9 produced the following results: 

10 

11 1) Increased coagulation efficiency and removal of DBP precursors; 

12 2) Increased CT throughout the treatment plant, allowing for reduced chlorine injection; 

13 and 

14 3) Increased and stabilized pH levels in the distribution system by increasing the 

15 buffering capacity following caustic soda addition. 

16 

17 The information for this case study came from Friedman and Hamilton (1997). Readers 

18 should refer to that reference for further information. 

19 

20 Introduction

21 

22 Public Utility District #1 of Skagit County (the District) is located in the northwest sector 

23 of Washington State, approximately 70 miles south of the Canadian border and 70 miles north of 

24 Seattle. The District's source of supply is Judy Reservoir, which is fed by several streams 

25 originating in the Cultus Mountain watershed in Sedro-Woolley, WA. The District operates a 

26 water filtration plant (WFP) designed to provide an original nominal/hydraulic flow of 12/18 

27 million gallons per day (MGD) with an ultimate capacity of 21/36 MGD. Exhibit B.1 provides a 

28 summary of typical water quality parameters. 

29 

30 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 

31 
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1 In the late 1980s, the District faced several source water quality issues. The TOC in the 

2 Judy Reservoir supply ranged from 3 to 7 mg/L, leading to high formation of DBPs upon 

3 chlorination. The District was having difficulty meeting CTs year-round, especially during the 

4 colder months. The Judy Reservoir supply is soft and poorly buffered, with alkalinity levels 

5 between 14-16 mg/L as CaCO3, and the District exceeded the lead action level under the LCR. 

6 

7 The Original Treatment Process at Judy Reservoir

8 

9 Before changes were made, initial oxidation/ disinfection was provided by chlorine 

10 dioxide, primarily to oxidize manganese which is present in the 0.2-0.3 mg/L range. Coagulants 

11 consisting of hybrid aluminum salts and a polyquaternaryamine were used. Direct filtration was 

12 conducted with a slight addition of a mild anionic filter aid. The filter media consisted of one 

13 foot of silica sand and two feet of anthracite coal. Typical flows were 6000 gpm (8.6 mgd) in 

14 the winter and 11,800 gpm (17 mgd) in the summer with 2000 square feet of available filter 

15 surface area. Chloramination was used for secondary disinfection. 

16 

17 Simultaneous Compliance Issues Faced by the Utility

18 

19 The District was having difficulty meeting CTs required by the SWTR. To address this 

20 problem, free chlorine was historically applied ahead of the flocculation basins to increase CTs. 

21 However, TOC levels in the Judy Reservoir led to high formation levels of DBPs upon 

22 chlorination. This situation created difficulty for the District in complying with the Stage 1 

23 D/DBPR. Exhibit B.2 shows the historical relationship between inactivation ratio (calculated CT 

24 divided by required CT) and TTHM formation. 

25 
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1 

2 Exhibit B.2 Inactivation Ratio vs. TTHM Plant Effluent 

3 

4 Using existing treatment methods, CTs could not be met consistently without 

5 significantly increasing DBPs. Thus, a method other than increasing chlorine and contact time 

6 was needed to achieve higher inactivation ratios. Methods of decreasing pH levels throughout 

7 the treatment train were therefore considered. Because the District used direct filtration (rather 

8 than conventional filtration), they were not required to meet TOC removal criteria under the 

9 Stage 1 D/DBPR. However, lowering the pH at the beginning of the treatment train would have 

10 the added benefit of enhancing coagulation, increasing the removal of DBP precursor materials. 

11 

12 Simultaneously, the District was having difficulty complying with the LCR; the 90th 

13 percentile lead level was 0.049 mg/L at a finished water pH of approximately 7.3. The pH was 

14 raised to 8.0 but the lead action level was still exceeded. Electrochemical corrosion testing was 

15 conducted to compare the corrosion control effectiveness of pH adjustment and orthophosphate 

16 addition for lead containing surfaces. The greatest reductions in corrosion rate were observed 

17 when the pH was raised to 8.5, or when the pH was raised to 8.0 and 4 mg/L (as PO4) were 

18 added. Due to a number of functional constraints, the District did not want to add phosphates to 

19 the water supply. Thus, the decision was made to increase pH to the range of 8.5 to 9.0. 

20 
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1 Like most surface water supplies in the Pacific Northwest, the District's Judy Reservoir 

2 supply is very soft and poorly buffered. Alkalinity levels are between 14-16 mg/L as CaCO3. 

3 To maintain the desired pH range of 8.5 to 9.0 throughout the distribution system, alkalinity 

4 increases would also be required. 

5 

6 Steps Taken by the Utility

7 

8 The District injected CO2 prior to the flocculation basins in addition to at the end of the 

9 treatment train where caustic soda is added. The advantages of adding carbon dioxide ahead of 

10 the flocculation basins were three-fold: 

11 

12 1) The associated pH depression increased coagulation efficiency to remove DBP 

13 precursors; 

14 2) The associated pH depression increased CTs throughout the treatment plant, allowing 

15 chlorine injection to be reduced; and 

16 3) Subsequent pH increases using caustic soda provided finished water with increased 

17 alkalinity levels and, increased buffering capacity. 

18 

19 The chemistry of CO2 is well understood and is used extensively throughout the water 

20 and wastewater industry. However, use of CO2 for WTP process control in the Pacific 

21 Northwest was fairly uncommon. The stoichiometry of CO2 addition in the pH range of 6.0 to 

22 10.0 is outlined below. 

23 

24 CO2 + H2O —> H2CO3 (carbonic acid) 

H2CO3 —> H+

 + HCO3

- 25 (bicarbonate) 

26 

27 Over the pH range of 6.0-10.0, the dissociation of carbonic acid in water depresses the pH and 

28 adds bicarbonate, which is the primary contributor to alkalinity. 

29 

30 CO2 feed was set up at two locations within the District's treatment facility: 1) ahead of 

31 the flocculation basins and 2) at the plant effluent. CO2 injection began on a trial basis during 

32 March, 1995. 24-144 lb/d (2 mg/L) were injected ahead of the flocculation basins (depending on 

33 plant flow), and 192 lb/d (3 mg/L) were injected after filtration. The target pH level ahead of the 

34 flocculation basin was less than 6.5. Additional CO2 was required prior to caustic soda addition 

35 to raise the alkalinity of the finished water to 25 mg/L as CaCO3. 

36 

37 Results of the Steps Taken

38 

39 Effects on DBP Formation

40 

41 With the depression of pH and resulting increased coagulation efficiency, the percent of 

42 TOC removal increased from an average of 25 percent to approximately 40 percent. The mass of 

43 TOC removed nearly tripled from 1 mg/L to 2.5-3 mg/L. The percent and mass of TOC 
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DRAFT- DO NOT CITE OR QUOTE J B-15 UNE 2006

1 removed before and after CO2 injection are shown in Exhibit B.3. Thus, even a small decrease in 

2 pH (from 6.9 to 6.6) during coagulation and flocculation has significantly enhanced coagulation. 

3 

4 Exhibit B.3 shows the percent and max of TOC removed after CO2 injection was 

5 initiated in March 1995. During the first few months, CO2 was fed on a trial basis using a 

6 temporary feed system that restricted the amount of CO2 that could be added. Thus, initial 

7 decreases in TOC removal were observed until the system stabilized. 

8 

9 TTHM formation within the treatment train was reduced by approximately 33 percent. 

10 Observed decreases in TTHM formation can be attributed to enhanced TOC removal, reduced 

11 chlorine levels, and to the fact that less TTHMs are formed at lower pH levels. Prior to CO2

12 addition, HAA5 levels in the plant effluent ranged between 40-60 μg/L when TOC levels were 

13 between 3-5 mg/L. After CO2 addition, HAA5 levels in the plant effluent decreased to the range 

14 of 35-45 μg/L even though raw water TOC levels were in the range of 5-7 mg/L. 

15 

16 

17 Exhibit B.3 TOC Removal vs. Time 

18 

19 Effects on CT Compliance

20 

21 CT credit decreases as temperature, disinfectant concentration, and contact time decrease. 

22 CT credit using chlorine increases as pH decreases. Since DBP formation was a concern for the 
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1 District, the best way to increase CT credit without forming additional DBPs was to lower the 

2 pH. 

3 

4 It is difficult to show actual improvements in the District's CT compliance as a result of 

5 CO2 addition since disinfectant dosages, plant throughput (i.e., contact time) and temperature 

6 vary from month to month. However, the impacts of depressing the pH by 0.5 units are outlined 

7 in terms of required chlorine dose and required contact time in Exhibit B.4. 

8 

9 

10 Exhibit B.4 Impacts of CO2 Injection on CTs 

11 

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 

12 

13 

14 Thus, the same CT can be achieved with less chlorine. Alternatively, higher flows can be 

15 accommodated without increasing chlorine dosages. It should be noted that in addition to 

16 considering impacts of reduced chlorine dosages on CT, utilities must consider other drivers for 

17 determining chlorine dose, such as the ability to maintain a disinfectant residual throughout the 

18 distribution system. Because Skagit PUD#1 chloraminates, they are able to maintain a stable 

19 residual despite fluctuations in chlorine dosage at the head of the treatment plant. 

20 

21 Effects on Corrosion Control Treatment

22 

23 Distribution system water quality sampling suggested that pH and alkalinity levels are 

24 more uniform throughout the system. Alkalinity levels have nearly doubled (from 14 mg/L as 

25 CaCO3 to 25 mg/L as CaCO3), resulting in more stable water with respect to pH and corrosion 

26 control. Prior to CO2 injection, the District would raise the pH of the finished water to 8.0, but it 

27 would decrease to 7.4 at many locations within the distribution system. Follow-up LCR 

28 monitoring conducted by utilities across the U.S. has shown that providing consistent and stable 

29 pH/ alkalinity levels can be essential to controlling lead levels at the tap. The District found that 

30 nearly a year of CO2 injection has to pass before pH levels stabilized within the distribution 

31 system. 

32 
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1 Lead levels at the tap decreased substantially at most of the "high lead" homes in the 

2 District. The 90th percentile lead level was 0.004 mg/L during the last round of monitoring 

3 conducted in 2003. It is likely that increased alkalinity helped to decrease lead levels by two 

4 different mechanisms: 1) providing stabilized pH levels at the tap; and 2) increasing carbonate 

5 levels to aid in the formation of more stable lead carbonate passivating films. 

6 

7 A study was undertaken by the District to determine whether elevated lead levels 

8 measured at the tap were in the soluble or particulate form. It was found the lead was primarily 

9 in the particulate form. When the pH was adjusted to 8.0 without alkalinity adjustment, elevated 

10 lead levels were mostly due to particulate lead (particulate being the difference between total and 

11 soluble lead), suggesting that stable lead carbonate films were not forming. After the pH was 

12 further increased and the alkalinity was doubled, total lead concentrations decreased as shown 

13 for three sampling locations in Exhibit B.5. Although lead solubility theoretically decreases as 

14 pH increases to a maximum of 9.5, alkalinity adjustment may also be necessary to address the 

15 particulate lead fraction. 

16 

17 

18 Exhibit B.5 Total vs. Soluble Lead 

20 

22 

24 

26 

28 

30 

32 

34 

36 

38 

40 

42 

44 

46 

48 

50 

52 

54 

56 

58 

59 
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1 Implementation and Operational Issues Faced by the Utility

2 

3 CO2 does not solubilize instantaneously, and therefore a pressurized solution feed system 

4 was required. In this system, the CO2 is injected to a pressurized side stream forming carbonic 

5 acid. The carbonic acid solution is readily solubilized by the receiving water and is injected 

6 directly into the pipeline. 

7 

8 Chemical costs for caustic soda doubled once CO2 was injected since twice as much 

9 caustic was required to raise the pH to 8.5-9.0. Considering the multiple benefits the District is 

10 experiencing, a chemical cost increase of $30,000 per year or $10 per million gallons treated was 

11 relatively inexpensive. The capital cost of the permanent CO2 system was $15,000 (1996 

12 dollars). 

13 

14 Lessons Learned From this Case Study

15 

16 • It is possible to achieving both greater Ct and TOC removal by reducing pH during 

17 treatment. 

18 • pH reduction can in some cases be achieved through CO2 injection. 

19 • CO2 injection at multiple locations during treatment may enhance benefits compared to 

20 injection at the end of treatment only for pH control purposes. 
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DRAFT- DO NOT CITE OR QUOTE J B-19 UNE 2006

1 Case Study #3 

2 Presedimentation

3 Kansas City Water Services 

4 Kansas City, Missouri

5 

6 This case study provides an example of how Kansas City’s existing pre-sedimentation basins 

7 may help to achieve compliance with the upcoming regulations. 

8 

9 Kansas City’s presedimentation basins were constructed prior to development of the 

10 DBPRs and ESWTRs, but still provided a benefit with respect to regulatory compliance. These 

11 pre-sedimentation basins have the potential to assist in providing the following benefits: 

12 

13 T TOC reduction required under the Stage 1 D/DBPR due to coagulation in the basins; 

14 T Turbidity reduction necessary for compliance with the ESWTR; and 

15 T Lower Cryptosporidium levels for purposes of bin classification. 

16 

17 Systems with presedimentation in place at the time they begin LT2ESWTR 

18 Cryptosporidium monitoring are not eligible for the 0.5 log presumptive credit and must sample 

19 after the basin when in use for the purpose of determining their bin classification for 

20 LT2ESWTR. Because Kansas City’s pre-sedimentation basins were built decades before 

21 promulgation of the LT2ESWTR, Kansas City cannot receive a credit for Cryptosporidium 

22 removal for the basins under the LT2ESWTR. However, this may result in a lower bin 

23 classification due to reduced particle concentrations in the basin effluent. 

24 

25 Simultaneous compliance issues associated with presedimentation basins may also 

26 include the potential for algae blooms, which can increase disinfection by-product formation at 

27 the plant effluent. Additionally, simultaneous compliance with the provisions of the 

28 LT2ESWTR and the Stage 1D/ DBPR necessitates designating two different existing locations as 

29 the treatment plant point of entry. For LT2ESWTR bin classification, the treatment plant point 

30 of entry is considered to be the effluent of the pre-sedimentation basins. For the Stage 1 

31 D/DBPR, the treatment plant point of entry is the influent to the pre-sedimentation basins. 

32 

33 This case study was developed using information available from staff at Kansas City 

34 Water Services. 

35 

36 Introduction

37 

38 The Kansas City, Missouri drinking WTP, which was originally constructed in the 1920s, 

39 is rated for 240 MGD. The source water comes from the Missouri River and wells under the 

40 influence of the Missouri River. The treatment process involves pre-sedimentation, excess lime 

41 softening, recarbonation, filtration, and stabilization. 

42 
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1 Due to the turbidity levels of the Missouri River, the pre-sedimentation basins are a 

2 critical step in the City’s WTP processes. The turbidity of the untreated source water is quite 

3 variable, averaging 114 nephelometric turbidity units (NTU) in 2002, 185 NTU in 2003, and 318 

4 NTU in 2004. The untreated water turbidity can exceed 5,000 NTU. The turbidity of the 

5 untreated source water was even higher and more variable when the plant was built. However, 

6 the construction of several upstream dams during the 1960’s resulted in lower turbidity levels at 

7 the City’s intake. In addition, the pre-sedimentation basins serve to reduce the amount of solids 

8 entering the softening process. 

9 

10 The plant was constructed well before the Safe Drinking Water Act (SDWA) and 

11 subsequent drinking water regulations came into effect. Therefore, the pre-sedimentation basins 

12 were not designed to meet compliance issues as much as they were needed as part of the water 

13 treatment process. However, as the treatment regulations evolved, the pre-sedimentation basins 

14 helped the plant meet new regulations. 

15 

16 The Treatment Process at the Kansas City, Missouri WTP

17 

18 Today there are 6 presedimentation basins, each with a detention time of about 4 hours at 

19 40 MGD. Each pre-sedimentation basin is approximately 200 feet in diameter and has an 80-

20 foot diameter fiberglass ring installed that is approximately half the height of the basin. This 

21 fiberglass ring serves as a mixing area for the coagulation chemicals to react. There are four 

22 mixers in each pre-sedimentation basin. These mixers and the capability for chemical injection 

23 were added to the pre-sedimentation basins in the 1970s. Lower source water turbidity levels 

24 resulted in reduced solids loading to the pre-sedimentation basins and increased colloidal 

25 materials, impacting the efficiency of the pre-sedimentation basins for removing turbidity. 

26 Therefore, the mixing areas and chemical feed capabilities were added. However, the solids 

27 removal capacity of the basins remained the same. 

28 

29 Role of Presedimentation Basins in Regulatory Compliance 

30 

31 Kansas City’s presedimentation basins could be used to lower turbidity as part of 

32 compliance with the Surface Water Treatment Rules (SWTRs). Additionally, compliance with 

33 the Stage 1 D/DBPR requires removal of TOC from source water to reduce the formation of 

34 DBPs. Presedimentation basins may serve to remove a portion of the TOC. Finally, although 

35 Kansas City can not receive a 0.5-log Cryptosporidium reduction credit for the pre-existing 

36 presedimentation basins, the basins may assist in removing Cryptosporidium from the source 

37 water. Kansas City is required to monitor the effluent from their presedimentation basins to 

38 determine their Cryptosporidium bin classification. Since presedimentation basin effluent levels 

39 are lower than source water Cryptosporidium levels, this will likely result in a lower bin 

40 classification, thereby reducing Kansas City’s treatment requirements. 

41 
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1 Simultaneous Compliance Issues Faced by the Utility and Steps Taken

2 

3 Algae may grow in the presedimentation basins, which could contribute additional NOM 

4 and result in the formation of DBPs, affecting compliance with the DBP Rules. Kansas City has 

5 managed to avoid this simultaneous compliance issue by minimizing algae blooms through 

6 potassium permanganate addition in the presedimentation basins. Additionally, the velocity of 

7 the water in the presedimentation basins is kept high by the mixers. In the rare instance that 

8 algae is observed, it is minimal and typically resides around the sides of the presedimentation 

9 basins. Additionally, the presedimentation basins are followed by an excess lime softening step, 

10 during which pH levels are raised above 10 units, reducing the potential for algae growth in this 

11 step. 

12 

13 Kansas City must also now designate two different existing locations as treatment plant 

14 entry points for regulatory compliance monitoring. For compliance with the Stage 1 D/DBPR 

15 TOC removal requirements, Kansas City monitors the influent to their pre-sedimentation basins 

16 for the purposes of comparing source water TOC with TOC removed during treatment. 

17 However, for compliance with the LT2ESWTR, Kansas City must conduct source water 

18 monitoring at the effluent from the pre-sedimentation basins (USEPA 2003g). 

19 

20 Implementation and Operational Issues Faced by the Utility

21 

22 The presedimentation basin improvements allow the plant to add a variety of treatment 

23 chemicals to control turbidity of the pre-sedimentation basin effluent. The water plant has the 

24 capability of feeding ferric sulfate, polymer, and potassium permanganate to these basins. The 

25 turbidity of the pre-sedimentation basin effluent is controlled based on the economics of the 

26 treatment plant operations. By adding different coagulation chemical concentrations and 

27 combinations, the turbidity exiting the pre-sedimentation basis can be reduced to below 10 NTU. 

28 The plant uses factors such as lime dose requirements to determine the optimal treatment in the 

29 pre-sedimentation basins. This is because higher turbidity water entering the softening basins 

30 usually has more colloidal material, which in turn requires more lime to provide the desired 

31 softening because of the competing reactions between the charges stabilizing the colloids and the 

32 calcium carbonate precipitation process. Thus, the cost of the coagulant dosage to obtain a 

33 certain turbidity from the basins is compared to the cost of the lime required to provide the 

34 desired softening and an economic balance is found. 

35 

36 The plant reports that 80-90 percent of the time, potassium permanganate is sufficient for 

37 addressing operational issues such as taste and odor control and turbidity control. The remainder 

38 of the time, ferric sulfate is able to maintain the plant’s operation. 

39 

40 Lessons Learned From this Case Study

41 

42 The following lessons were learned from Kansas City’s experience with presedimentation 

43 basins: 
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1 

2 • The pre-sedimentation basins reduce the effects of large and variable turbidity 

3 episodes. 

4 

5 • Improving the pre-sedimentation basins to incorporate chemical treatment and mixing 

6 allowed the presedimentation basins to become more useful in water treatment 

7 operations by allowing the plant to control turbidity entering the softening basins as 

8 well as assisting in removing TOC and DBP precursors. 

9 

10 • The potential drawbacks of pre-sedimentation basins such as increased NOM from 

11 algae are minimized through operations. 

12 

13 • Utilities with existing presedimentation basins will need to designate a different 

14 location as the treatment plant point of entry if they want to realize any benefit of the 

15 pre-sedimentation basins with regard to Cryptosporidium removal. This location will 

16 be different from the point of entry already used for compliance with other 

17 regulations. 
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1 Case Study #4 

2 Switching Coagulants

3 Hillsborough River Water Treatment Plant 

4 Tampa, Florida

5 

6 This case study describes how a system could simultaneously comply with the TOC removal 

7 requirements of the Stage 1 D/DBPR and the turbidity removal requirements of the IESWTR. 

8 Enhanced coagulation is a best available technology (BAT) for TTHM precursor removal for the 

9 Stage 1 D/DBPR. This case study shows how a system implementing enhanced coagulation for 

10 the Stage 1 D/DBPR simultaneously complied with requirements of the Stage 2 DBPR. 

11 

12 Introduction

13 

14 The City of Tampa, Florida, operates a 100 MGD conventional treatment plant (the 

15 Hillsborough River Water Treatment Plant, HRWTP). The HRWTP uses the Hillsborough River 

16 as its source water. The plant, built in 1924, currently serves over 450,000 people. In 1991, it 

17 switched from enhanced coagulation with alum to enhanced coagulation with ferric sulfate. The 

18 influent surface water has high TOC and is subject to large seasonal variations. By switching 

19 coagulant, the HRWTP’s operators expected to satisfy requirements of the Stage 1 D/DBPR. 

20 They had investigated the feasibility of enhanced coagulation with ferric sulfate before the Stage 

21 1 D/DBPR became a regulatory requirement. They found that enhanced coagulation with ferric 

22 sulfate not only increased TOC removal significantly, but also reduced turbidity levels in the 

23 finished water. 

24 

25 A summary of the influent water quality is provided in Exhibit B.6. 

26 
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1 

2 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 

3 Notes: 1. Data from an Information Collection Rule (ICR) sample collection from July 1997 - 

4 December 1998 

5 

6 

7 The Original Treatment Process at HRWTP

8 

9 Exhibit B.7 shows a schematic of the treatment process at HRWTP prior to converting to 

10 ferric sulfate. Raw water was treated with potassium permanganate for taste and odor control. 

11 Enhanced coagulation was implemented using alum (range of alum dose = 50 - 200 mg/L, 

12 average dose = 120 mg/L), at an average pH of 5.7 (range 4.9 - 6.6). An organic polymer was 

13 added to enhance the flocculation process. Primary disinfection was attained by applying 

14 chlorine just prior to the filters. After filtration, more chlorine and ammonia were added to form 

15 chloramines for residual disinfection. The pH of the finished water was increased to around 7.6 

16 with caustic soda and soda ash in the blending chamber, to meet a Langelier Index goal of +/-0.2. 

17 

18 
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1 

2 Exhibit B.7 Treatment at the HRWTP Prior to Implementing Enhanced Coagulation 

3 

4 

5 Simultaneous Compliance Issues Faced by the Utility

6 

7 In order to reduce DBP precursors and TTHM and HAA5 concentrations, the City of 

8 Tampa decided to switch to enhanced coagulation with ferric sulfate, enhancing TOC removal 

9 and consequently lowering the DBP formation potential. 

10 

11 Successfully enhancing coagulation to improve TOC removal can affect particle and 

12 pathogen removal effectiveness. The system was concerned that, at lower pH, the higher 

13 coagulant dose conditions for enhanced coagulation could result in particle re-stabilization and 

14 an increase in settled water turbidity, leading to non-compliance with the IESWTR. Increased 

15 settled water turbidity could also impact the system’s ability to receive Cryptosporidium removal 

16 credit for enhanced filter performance. Variability in source water quality presented a further 

17 challenge to the operators who were attempting to optimize particle and TOC removal with a 

18 new coagulant. 

19 

20 Steps Taken by the Utility

21 

22 Tampa implemented enhanced coagulation with ferric sulfate to improve TOC removal. 

23 At the same time, it applied BMPs to ensure that filter effluent turbidity would not be adversely 

24 affected. These included flow-pacing the coagulant feed and conducting additional jar tests to 

25 ensure that coagulant overdosing did not occur. 

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
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1 

2 Exhibit B.8 shows a schematic of the treatment process at HRWTP after the system 

3 changed to enhanced coagulation with ferric sulfate. Raw water continues to be treated with 

4 potassium permanganate for taste and odor control. Enhanced coagulation uses ferric sulfate 

5 (range dose = 40 - 300 mg/L, average dose = 140 mg/L), at an average pH of 4.0 (range 3.5 - 

6 4.8). The low coagulation pH is attained by adding sulfuric acid. An organic polymer is added 

7 to enhance the flocculation process. The settled water is treated with lime for partial pH 

8 adjustment. The residuals are thickened and then pumped to a residuals processing facility for 

9 further dewatering, processing, and disposal. Primary disinfection is attained by adding chlorine 

10 to the settled water to produce a free residual of 1-2 mg/L just prior to the filters. After filtration, 

11 ammonia and chlorine are added to form chloramines. The finished water combined disinfectant 

12 residual ranges from 3 - 4.5 mg/L of monochloramine. The pH of the finished water is adjusted 

13 to around 7.6 with caustic soda and soda ash in the blending chamber, to meet a Langelier Index 

14 goal of +/-0.2. 

15 

16 

17 Exhibit B.8 Treatment at the HRWTP After Implementing Enhanced Coagulation 

18 

19 

20 To ensure that excessive coagulant dosing doesn’t occur, the operators check the 

21 coagulant dose regularly with jar tests. The operators also ensure that coagulant feed is flow 

22 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
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1 

2 Results of the Steps Taken 

3 

4 • TOC removal - Finished water TOC removal with enhanced alum coagulation ranged 

5 from 21 to 50 percent. For enhanced coagulation with ferric sulfate, TOC removal 

6 ranges from 70 to 88 percent, with an average of 81 percent. This is well beyond the 

7 minimum TOC removal requirements of the Stage 1 D/DBPR (based on the source 

8 water TOC and alkalinity concentrations). Influent and effluent water quality is 

9 shown in Exhibit B.9. Thus, enhanced coagulation with ferric sulfate is much more 

10 effective than enhanced coagulation with alum for removing DBP precursors. 

11 

12 • TTHM reduction - Before the changes in the coagulation practice, the finished water 

13 TTHM ranged from 27 - 111 Fg/L, with an average of 59 Fg/L (Exhibit 4). After the 

14 treatment modifications (from July 1997 through December 1998), the finished water 

15 TTHM ranged from 47 - 67 Fg/L, with an average of 60 Fg/L. Enhanced coagulation 

16 with ferric sulfate seems more effective than coagulation with alum at removing DBP 

17 precursors (i.e., TOC), when the raw water is high in TOC. This is reflected by the 

18 lower maximum level of TTHM measured after treatment modifications (i.e., the 

19 maximum trihalomethane (THM) concentration was reduced from 111 to 67 Fg/L). 

20 The new treatment approach reduced THMs by increasing TOC removal and 

21 chlorinating at a lower pH. Implementing enhanced coagulation with ferric sulfate 

22 has enabled HRWTP to achieve compliance with the Stage 1 TTHM MCL of 80 

23 Fg/L. 

24 

25 • Turbidity - As can be seen clearly from Exhibit B.9, enhanced coagulation with ferric 

26 sulfate was more effective than alum coagulation at reducing turbidity in the finished 

27 water. Enhanced coagulation with ferric sulfate was able to achieve the IESWTR 

28 turbidity requirements more easily and consistently. 

29 
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1 Exhibit B.9 Finished Water Quality Before and After Implementing Enhanced 

2 Coagulation with Ferric Sulfate 

3 

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 (Fg/L)

Minimum 

Average 

Maximum 

NA 27 

59 

111 

47 

60 

66 

HAA5 (Fg/L)

Minimum 

Average 

Maximum 

NA NDC 32 

47 

66 

4 Notes: 

5 1. Data from ICR sample collection from July 1997 - December 1998 

6 2. Data collected for calendar year 1990. 

7 3. Data collected for calendar year 1997; ICR data from July 1997 - December 1998 was used for organic 

8 analysis. 

9 4. NDC = No Data Collected 

10 5. NA = Not Applicable

11 

12 
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1 Implementation and Operational Issues Faced by the Utility 

2 

3 • Operator training and start-up - It took around 6 months for the operational staff to 

4 be comfortable with implementing enhanced coagulation, and nearly a year for the 

5 treatment plant to operate like an integral unit. The treatment strategy did not 

6 significantly change the operational needs of the plant and no additional staff were 

7 added. 

8 

9 • Controlling manganese - The only major problem experienced in implementing the 

10 treatment modification was the control of manganese. The lower pH required for 

11 enhanced coagulation with ferric sulfate, relative to alum coagulation, allowed 

12 dissolved manganese to pass through the filters. The issue was resolved by 

13 maintaining the pH on top of the filters at greater than 6.0. 

14 

15 Corrosion due to acid addition - The addition of sulfuric acid promoted corrosion in the rapid16 mix chamber at the feed diffuser. The problem was resolved when the utility found a suitable 

17 coating for their rapid-mix chamber. The coating used was a two-part commercial membrane 

18 applied at 60 wet mils, using an air-supplied mastic air gun. After application, the coating 

19 required a 7-day curing period before the basin could be put back into service. The settling 

20 basins were epoxy-coated and did not experience any corrosion. 

21 

22 Lessons Learned From this Case Study

23 

24 • Enhanced coagulation with ferric sulfate can achieve the multiple objectives of 

25 increased TOC removal and improving reductions in finished water turbidity without 

26 significantly changing the operational needs of the plant. 

27 

28 • One key to successfully implementing enhanced coagulation is to ensure that 

29 excessive coagulant dosing does not occur. This results in turbidity breakthrough at 

30 the filters, resulting in potential non-compliance with the IESWTR. One way to 

31 achieve this is by conducting additional jar tests and flow-pacing the coagulant feed 

32 when plant water flows are variable. 
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2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

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1 Case Study #5 

2 Enhanced Coagulation - Problems with Copper Pitting

3 Washington Suburban Sanitary Commission 

4 Montgomery and Prince Georges County, Maryland

5 

6 

7 This case study provides an example of negative effects that could possibly be caused by 

8 enhanced coagulation. Washington Suburban Sanitary Commission (WSSC) changed their 

9 coagulation process to reduce filtered water turbidity. This was implemented prior to 

10 development of the Stage 1 D/DBPR and, therefore, not optimized to meet associated 

11 requirements. However, WSSC's experience indicates that coagulation improvements might 

12 have had unintended results in the distribution system. After alterations were made to WSSC's 

13 coagulation process, WSSC customers began reporting pinhole leaks in their copper piping, 

14 possibly caused by a combination of factors. The utility has been unable to determine the exact 

15 cause of the pinhole leaks. In this case study, the primary concerns relate to compliance with: 

16 

17 • LCR, and 

18 • DBP Rules. 

19 

20 While this treatment was implemented prior to the DBP Rules, it does indicate a potential 

21 problem associated with implementing the Stage 1 D/DBPR's required treatment technique using 

22 enhanced coagulation. 

23 

24 This case study was developed using information available from staff at the WSSC and from 

25 their customer care Web site detailing this issue 

26 (http://www.wsscwater.com/cfdocs/ copperpipe/pinholescroll.cfm). The cause of pinhole leaks 

27 in WSSC’s system continues to be under investigation. 

28 

29 Introduction

30 

31 The WSSC provides drinking water to 1.6 million people in suburban Maryland. WSSC 

32 relies on two rivers, the Potomac and Patuxent, to supply an average of 167 MG per day. Both 

33 river supplies are treated at separate filtration plants. The Potomac plant treats river supply while 

34 the Patuxent plant treats water from a reservoir system. In the mid-1990s, WSSC made 

35 treatment changes at the Potomac plant to enhance filtration performance, including changing 

36 filtration media and changing coagulant, from ferric chloride to polyaluminum chloride. During 

37 the 1990s, coagulant doses were increased slightly at the Patuxent plant, which used alum most 

38 of the time, occasionally switching to ferric chloride during the winter. 

39 
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1 The primary reasons WSSC made these treatment changes were: 

2 

3 $ Prevention of waterborne pathogen outbreaks - A large-scale cryptosporidiosis 

4 outbreak occurred in Milwaukee, Wisconsin in 1993. The outbreak coincided with 

5 elevated effluent turbidity levels. Studies of the causes and prevention methods 

6 indicated that coagulation and filtration performance are critical in preventing the 

7 entry of Cryptosporidium to the distribution system. 

8 

9 $ Partnership for Safe Water - This is an industry program, supported by EPA and the 

10 American Water Works Association (AWWA), that focuses on protecting drinking 

11 water customers from microbial contaminants. WSSC has participated in this 

12 program that includes meeting stringent criteria for turbidity in filtered drinking 

13 water. 

14 

15 While WSSC's coagulation changes were not optimized for compliance with the Stage 1 

16 D/DBPR, WSSC did observe lower TOC levels in effluent at the Potomac WTP. 

17 

18 The Original Treatment Process at WSSC's WTPs

19 

20 Both the Potomac and Patuxent Treatment Plants include similar treatment processes: 

21 

22 • Coagulation and flocculation 

23 • Sedimentation 

24 • Filtration 

25 • Fluoridation 

26 • Lime addition for corrosion control 

27 • Chlorination 

28 

29 Simultaneous Compliance Issues Faced by the Utility

30 

31 In 1998, WSSC began receiving complaints from customers that pinhole leaks were 

32 developing in their copper piping. As of December 2004, almost 5,500 customers have reported 

33 this problem. Pinhole leaks have occurred in areas served by both drinking water supply 

34 sources. WSSC has collected data on pinhole leaks from customers and these trends have been 

35 apparent: 

36 

37 • Many pinhole leaks are in cold water horizontal copper piping 

38 • Many leaks are located in older portions of service area 

39 • Almost 80 percent of leaks have occurred in homes built before 1970 

40 

41 In 2000, WSSC formed a task force to study the pinhole leaks and possible causes. The 

42 task force included WSSC staff, copper and plumbing industry experts, and corrosion experts. 
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1 The researchers conducted bench-scale experiments with copper piping and simulated drinking 

2 water and determined that a combination of high pH, aluminum solids, and chlorine levels, and 

3 no remaining NOM caused significant pitting on copper piping in about one month (Marshall, 

4 Rushing and Edwards 2003). 

5 

6 NOM present in drinking water supplies is a DBP precursor and is typically removed 

7 through filtration or coagulation. TOC levels usually correspond to the presence of NOM in 

8 drinking water. The presence of NOM in the distribution system was previously thought to 

9 prevent, to some extent, corrosion of piping materials, such as cement, iron, and copper. The 

10 research by Marshall, Rushing and Edwards (2003) contradicts previous understanding of 

11 NOM’s role in copper corrosion. 

12 

13 Water quality conditions in WSSC's distribution system that may have contributed to pinhole 

14 leaks in copper piping include: 

15 

16 • Aluminum - Since 1995, both treatment plants have used an aluminum-based 

17 coagulant. Finished water aluminum levels are relatively low. The average Potomac 

18 WTP residual levels range from 0.046 mg/L to 0.060 mg/L, and at Patuxent WTP, 

19 which recently switched from alum to polyaluminum chloride, average effluent 

20 aluminum levels are 0.030 mg/L (Edwards et al. 2004). In comparison, the national 

21 average for effluent aluminum levels is 0.090 mg/L. Sampling in WSSC's 

22 distribution system indicated that aluminum levels increased after treatment to levels 

23 higher than 0.065 mg/L total aluminum. Researchers indicate that high aluminum 

24 samples were collected in areas near recently cleaned or re-lined piping (Edwards et 

25 al. 2004). A forensic analysis of WSSC failed copper piping showed that aluminum 

26 deposits were frequently present (Marshall, Rushing and Edwards 2003). 

27 • Chlorine - WSSC, like the majority of utilities, uses chlorine to provide a disinfectant 

28 residual in the distribution system. 

29 • pH - WSSC increases the pH of water entering their system during the treatment 

30 process for corrosion control. Water from the Potomac WTP has a pH of about 7.5 in 

31 the distribution system. Until recently, the Patuxent WTP had a pH of about 8.2 in 

32 the distribution system (now adjusted to about 7.5 since orthophosphate addition 

33 began). 

34 TOC - The Potomac WTP achieves approximately 40 percent TOC removal, which is a slight 

35 increase since the coagulant and filter media change. Patuxent reservoir water has a lower level 

36 of NOM, with treated water TOC levels below 2 mg/L. TOC removal at the Patuxent WTP has 

37 not changed. 

38 

39 StepsTaken by the Utility

40 

41 In late 2003, WSSC implemented orthophosphate addition to both treatment plants. 

42 Addition was phased in slowly with the dose reaching a level of 1 mg/L (as PO4) after 4 to 5 
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1 months. This gradual increase was recommended by WSSC's operations staff to limit the 

2 potential for discolored water problems caused by phosphates forming comples with iron, 

3 making it more soluble. In pilot-testing, orthophosphate effectively reduced pinhole leak 

4 activity. WSSC participated in a state-wide task force that surveyed utilities regarding pinhole 

5 leaks. WSSC also contacted the USEPA regarding the pinhole leak issue and research findings 

6 that removal of NOM, as required in the DBP Rules, may promote pinhole leaks in certain 

7 waters. Finally, WSSC has worked to educate the public on this topic. 

8 

9 Results of the Steps Taken

10 

11 Overall, the utility is receiving fewer pinhole leak reports from their customers and area 

12 plumbers have indicated that they are seeing fewer pinhole leaks. It will take more time before 

13 WSSC can conclusively determine whether orthophosphate has addressed the problem. 

14 

15 Implementation and Operational Issues Faced by the Utility

16 

17 WSSC experienced the following issues when implementing orthophosphate addition: 

18 

19 • Increased wastewater phosphorus resulted in increasing cost for wastewater 

20 treatment. 

21 • WSSC investigated the potential for orthophosphate addition to increase discolored 

22 water complaints due to iron release from unlined cast iron mains. 

23 • During summer conditions, turbidity of finished water (i.e., following post-filter lime 

24 addition) has increased occasionally after orthophosphate addition. WSSC is still 

25 investigating the cause. 

26 

27 Lessons Learned From this Case Study

28 

29 • Switching coagulant may have unintended consequences on water quality. 

30 

31 • The role of NOM in copper corrosion control needs to be better understood by the 

32 drinking water industry. 

33 

34 • The synergistic effects of chlorine and aluminum at pHs that have been optimized for 

35 corrosion control also need to be better understood by the drinking water industry. 

36 These interactions can be exacerbated for utilities that use free chlorine. 

37 

38 • Pilot-scale and/or electro-chemical testing for determining the impacts of chemicals 

39 on corrosion control were useful in identifying an appropriate solution. 

40 

41 References

42 
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DRAFT- DO NOT CITE OR QUOTE J B-35 UNE 2006

1 Edwards, M., J.C. Rushing, S. Kvech, and S. Reiber. 2004. Assessing copper pinhole 

2 leaks in residential plumbing. Water Science and Technology. 49(2): 83-90. 

3 

4 Marshall, B., J. Rushing, and M. Edwards. 2003. Confirming the role of aluminum solids 

5 and chlorine in copper pitting corrosion. In Proceedings of AWWA Annual Conference. 

6 Denver CO. 

7 

8 Rushing, J.C. and M. Edwards. 2002. Effect of aluminum solids and chlorine on cold 

9 water pitting of copper. In Proceedings of AWWA Water Quality Technology Conference. 
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1 Case Study #6 

2 Enhanced Coagulation - Managing Radioactive Residuals 

3 Allen Water Filtration Plant 

4 Englewood, CO 

5 

6 This case study presents a discussion of a system's options for disposing of 

7 radioactive residuals resulting from enhanced coagulation. Enhanced coagulation is 

8 practiced at the system to meet the requirements of the Stage 1 D/DBPR. Uranium is 

9 naturally occurring in the City's source water, but radionuclide levels in the raw water do 

10 not warrant treatment for removal. The radionuclides become concentrated in the residuals 

11 as a result of the enhanced coagulation process at levels that require special considerations 

12 for regulatory approval of sludge disposal. 

13 

14 Introduction

15 

16 The City of Englewood Allen WFP is a conventional treatment plant with an average 

17 treated flow of 8.5 mgd (design flow of 28 mgd) to serve a population of 48,000 people. The 

18 primary raw water supply comes from surface sources, including the South Platte River, Bear 

19 Creek, and water sources diverted from the Western Slope of Colorado. The plant treatment 

20 processes include addition of potassium permanganate, coagulant, and coagulant aid to the 

21 pipeline ahead of the rapid mix. Mixing is followed by three-stage tapered flocculation and 

22 settling using lamella inclined plates. The water passes through GAC filters prior to chlorine 

23 addition. Chlorine contact time is obtained in the clearwell and ammonia is added after the 

24 clearwell for chloramine disinfectant residual in the distribution system. Sedimentation sludge 

25 and filter backwash water are dewatered by belt press and the filtrate is sent to the backwash 

26 settling lagoon along with the waste backwash water. Decant from the backwash settling lagoon 

27 is returned to the North Reservoir to be recycled to the head of the plant. Recycle goes into the 

28 washwater lagoon (aka backwash settling lagoon) which overflows to an 80 million gallon 

29 reservoir that is used sparingly as source water as it is blended with raw water drawn from other 

30 sources. The approximate recycle return flow is 1.5%. Treatment includes settling of solids in 

31 the lagoon and in the reservoir. 

32 

33 Exhibit B.10 presents source water and finished water quality details. A process 

34 schematic is shown in Exhibit B.11. 

35 
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DRAFT- DO NOT CITE OR QUOTE J B-38 UNE 2006

1 

2 Exhibit B.10 Typical Water Quality Parameters at Allen WFP 

3 

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 

4 * If available, levels present in raw water will be added to next draft. 

5 

6 

7 The Allen WFP practices enhanced coagulation to comply with the Stage 1 

8 D/DBPR by the addition of alum with typical doses of 40 - 60 mg/L of alum. Based on the 

9 average plant flow, the production rate of residuals would be expected to be 1632 lb/day or 

10 302 cy/yr. Recently (2002-2004), residuals production from the backwash pond is 

11 approximately 1600 cy/yr. The current large volume may be a result of catching up on 

12 previous years' storage. City employees are processing residuals from March to November 

13 to make sure the backwash pond does not exceed its capacity. 

14 

15 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE J B-39 UNE 2006

1 Exhibit B.11 Allen Water Filtration Plant Schematic 

2 

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

3 

4 

5 Residuals Management Prior to Enhanced Coagulation 

6 

7 The City of Englewood has historically disposed of water treatment residuals by 

8 land applying dried residuals at the City golf course. These residuals were mixed with fill 

9 dirt (2:1 ratio fill to residuals) for berm construction with grass cover. This procedure met 

10 the requirements of the Colorado Department of Health and Environment (CDPHE) with 

11 respect to the state's solid waste regulations and the hazardous/radioactive material 

12 regulations. Residuals disposal facilities in Colorado must comply with all Colorado 

13 health laws and with CDPHE regulations and standards. Acceptance criteria for solid 

14 waste disposal include: 

15 

16 • WFP residuals containing any free liquid cannot be accepted for disposal 

17 • WFP residuals with a pH less than 6.0 cannot be accepted for disposal 

18 • WFP residuals with a total alpha activity value exceeding 40 pCi/g of dry solids 

19 require additional CDPHE guidance prior to disposal. The residuals generator 

20 must contact the CDPHE's Radiation Control Division and the Solid Waste 

21 Division for guidance 

22 

23 Colorado drinking water utilities with residuals that have total alpha activity values 

24 exceeding 40 pCi/g have disposed of residuals using landfill disposal, sanitary sewer 

25 discharge, monofill disposal, and compost amendment with and without approval from 

26 CDPHE. 

27 
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DRAFT- DO NOT CITE OR QUOTE J B-40 UNE 2006

1 Liquid residuals discharged to sanitary sewers are not regulated for water treatment 

2 residuals disposal by CDPHE. Acceptance of water treatment residuals is approved by the 

3 sanitary district authority based on impacts to the treatment process from additional flow 

4 and solids loading. 

5 

6 Simultaneous Compliance Issue Faced by the Utility

7 

8 Since the inception of enhanced coagulation at the Allen WFP, analysis of the 

9 residuals has shown that the total alpha activity exceeds 40 pCi/g, resulting in the 

10 requirement that the City of Englewood must notify CDPHE of disposal plans for the 

11 residuals to comply with state regulations. The City can no longer dispose of residuals as 

12 has been done in the past because CDPHE no longer allows land application at the golf 

13 course. The concentrated residuals are considered technologically enhanced naturally 

14 occurring radioactive materials (TENORM). Regulation of TENORM in drinking water 

15 residuals is not clearly spelled out in Federal or state regulations. 

16 

17 Steps Taken by the Utility

18 

19 The City undertook a study to develop a long-term residuals disposal plan. Six 

20 disposal alternatives were evaluated using three criteria: compliance with residuals 

21 disposal regulations, cost of disposal, and ease of implementation. The six alternatives 

22 considered were as follows: 

23 

24 • Discharge to the sanitary sewer is not regulated by the state, however the waste 

25 water treatment plant (WWTP) has a limit of 30 pCi/g for biosolids. Because 

26 liquid residuals samples from the Allen WFP holding pond have an average 

27 gross alpha level of 5,880 pCi/L, the allowable discharge rate would be limited 

28 to a total flow well below the average daily production rate. This option is 

29 therefore not operationally sound. 

30 • Disposal at an approved landfill requires loading and trucking residuals to one 

31 of two landfills at a distances of 44 miles or 100 miles from the plant site. The 

32 landfills are approved for disposal of Resource Conservation and Recovery Act 

33 (RCRA) wastes by the State of Colorado and all material disposed is 

34 manifested and final disposal location within the landfill is documented. The 

35 minimum operating cost of this option is $66,000 per year. 

36 • Compost/topsoil amendment recycling requires the City to take responsibility 

37 for loading dry residuals onto City trucks to transport to the facility. The 

38 compost facility can mix residuals immediately upon delivery to avoid 

39 stockpiling of residuals only material. The expected annual operating cost for 

40 this option is $19,900. 

41 • Disposal at a new City monofill requires the development, operation, and 

42 eventual closing of a landfill operation used solely for Allen WFP residuals. In 
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DRAFT- DO NOT CITE OR QUOTE J B-41 UNE 2006

1 addition, trucking of the residuals to the landfill site would be required. This 

2 option requires a capital investment of approximately $1.4 million and annual 

3 operating costs of $233,000. 

4 • On-site mixing with fill material provides material ready for compost or topsoil 

5 application. A portion of residuals is mixed with fill material with low 

6 background gross alpha levels. City monitoring for gross alpha will be required 

7 to ensure levels below 40 pCi/g. Expected annual operating cost for this option 

8 is $68,100. 

9 • Disposal at out-of-state approved landfill assumes transport of residuals by 

10 truck or rail cars to the nearest landfill (600 miles away) that accepts TENORM 

11 waste similar to the Allen WFP residuals. Material at this facility is manifested 

12 and final disposal location in the landfill is documented. The expected annual 

13 operational cost is a minimum of $202,500. 

14 

15 In addition to evaluating these six options, the City contracted for a human health 

16 risk assessment to be done to determine possible radiation exposure to City and landfill 

17 employees from managing the residuals, as well as the public exposure arising from 

18 possible future property uses. The risk assessment utilized RESRAD Version 6.21 

19 modeling software to assess the dose to workers and residents from contact with 

20 radioactive material in the treatment plant residuals, either directly or indirectly. Included 

21 were the possible radiation exposures for a landfill worker, a composting facility worker, 

22 and a hypothetical future resident farmer living and farming the area above a closed 

23 landfill. The risk assessment indicated that neither the landfill or compost worker would 

24 be subject to significant radiation exposure resulting from the residuals handling. In 

25 addition, the hypothetical future farmer is unlikely to experience exposures above typical 

26 background levels in Colorado. Thus, the risk assessment supported the disposal of 

27 residuals in a local landfill and at the compost recycling facility. 

28 

29 As of March 2006, the sludge is being disposed of at a licensed industrial landfill 

30 within the state. 

31 

32 The City is assessing coagulation schemes that use less alum and produce less 

33 residuals. One such possibility is using a 15 mg/L dose of polyaluminum chloride (PACl) 

34 with a small supplemental dose of 8 mg/L of alum. Essential to making this change will 

35 be the ability to remove sufficient TOC to meet the Stage 1 D/DBPR. 

36 

37 Since there is currently no state or Federal guidance for disposal of radioactive 

38 water treatment residuals, the City has undertaken an effort with other local utilities to 

39 assist the State CDPHE in development of guidance for the disposal of TENORM in 

40 drinking water residuals. 

41 
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DRAFT- DO NOT CITE OR QUOTE J B-42 UNE 2006

1 Results of the Steps Taken

2 

3 The long-term recommendation to the City is that residuals be transported to the 

4 compost/topsoil amendment recycling center. In addition the City is expected to obtain 

5 approval for both onsite mixing and in-state landfill disposal. Approval for all three 

6 disposal methods has been requested from CDPHE. 

7 

8 The State CDPHE has begun a stakeholder process that will ultimately result in 

9 guidance for utilities in disposing of TENORM. 

10 

11 Implementation and Operational Issues Faced by the Utility

12 

13 The fact that appropriate Federal and state guidance does not yet exist to provide utilities 

14 with an understanding of requirements has made managing residuals much more complex. 

15 Approval from CDPHE must be obtained as soon as possible as residuals are currently stockpiled 

16 on the plant site at near capacity. If residuals handling operations are impacted with respect to 

17 volume, the drinking water treatment process may also be impacted with respect to production. 

18 

19 Lessons Learned From this Case Study

20 

21 • The levels of radioactivity in sludge may be significantly higher than expected based 

22 on the background levels in the raw water when the treatment process produces 

23 residuals that concentrate contaminants. These residuals can be liquid and/or solid. 

24 

25 • Disposal to the sanitary sewer is likely to be a problem for almost any concentrated 

26 contaminant that is regulated in biosolids. 

27 

28 • No regulatory guidance is available to utilities to assist in developing disposal options 

29 for residuals that qualify as TENORM. 

30 

31 State regulatory agency groups that have responsibility for radioactive waste products are 

32 generally different from the group responsible for drinking water compliance. This can result in 

33 some complex interactions with regulators as the utility may find themselves in the role of 

34 initiating internal interactions within state agencies. In Colorado, the Hazardous Materials and 

35 Waste Management Division is the licensing group for disposal at hazardous waste disposal 

36 facilities or licensed radioactive waste facilities. Discharge permits, if the liquid waste meets 

37 water quality standards, are issued by the Water Quality Control Division's Colorado Discharge 

38 Permit System. Drinking water is regulated through the Water Quality Control Division 

39 Drinking Water Program. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE J B-43 UNE 2006

1 Case Study #7 

Granular Activated Carbon Filtration for TOC Removal1 2 

3 Higginsville Water Treatment Plant 

4 Higginsville, Missouri

5 

6 

7 Introduction

8 

9 This case study provides an example of how a utility used GAC to address high 

10 levels of atrazine in its source water and high TTHM levels in its finished water. Most of 

11 the information for this case study came from Leung and Segar (2000). Interested readers 

12 are referred to that reference for more information. 

13 

14 The Higginsville, Missouri Water Treatment Plant is a 2 million gallons per day 

15 (MGD) treatment plant that draws water from a small surface water impoundment in 

16 Missouri. The plant operates 12 hours a day and employs a two stage settling process with 

17 conventional filtration. In 1994, the plant experienced a violation of the atrazine maximum 

18 contaminant level (MCL). The system eventually switched to GAC caps on their filters to 

19 counter the problem. 

20 

21 The source for the Higginsville plant is an impoundment that collects surface 

22 runoff from nearby agricultural areas. It has high hardness and TOC. The average source 

23 water quality is described in Exhibit B.12. 

24 

25 

26 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 

27 

28 

 

1

For an example of GAC used as a biological filter after ozonation, see Case Studies 9 and 10. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE J B-44 UNE 2006

1 The Original Treatment Process at the Higginsville WTP 

2 

3 Exhibit B.13 displays a schematic of the treatment scheme at the Higginsville plant. 

4 The plant adds chlorine dioxide to the raw water to control taste and odor problems. 

5 Copper sulfate is also added occasionally to control biological blooms that lead to taste and 

6 odor problems. The water is then pumped to a first set of coagulation and settling basins. 

7 An average of approximately 40 mg/L of alum and 1.7 mg/L of cationic polymer are 

8 added. Lime and fluoride are added to a second flash mix prior to the water passing 

9 through a second set of coagulation and sedimentation basins. The water is then filtered 

10 through dual media filters. Chlorine is added both prior to the filters and to a 0.5 million 

11 gallon clearwell after the filters. 

12 

13 When the utility first experienced violations of the atrazine MCL in 1994, it added 

14 powdered activated carbon (PAC) in the first flash mixer to combat the problem. Although 

15 PAC did lower atrazine concentrations below the MCL, it was limited in removal 

16 capabilities because of the short contact time. 

17 

18 Exhibit B.13 Higginsville Water Treatment Plant 

19 

20 

21 Simultaneous Compliance Issue Faced by the Utility

22 

23 The utility was in violation of the atrazine MCL. In addition, high TOC levels 

24 were contributing to total trihalomethane (TTHM) levels which averaged around 80 mg/L, 

25 which could cause problems with Stage 1 and Stage 2 DBPR compliance. Although PAC 

26 provided a temporary solution to the atrazine problem, it was not desirable as a long term 

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
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE J B-45 UNE 2006

1 treatment method because of high amounts of sludge. The system also faced periodic taste 

2 and odor episodes. 

3 

4 Steps Taken by the Utility 

5 

6 The utility replaced the anthracite in its dual media filters with GAC in an attempt 

7 to reduce atrazine concentrations and lower TOC and DBPs. The pre-chlorination residual 

8 was also reduced to 0.1 mg/L to prevent degradation of the GAC. Twenty four inches of 

9 GAC were placed on top of the sand and gravel base of the filters. The total EBCT was 

10 7.5 minutes. 

11 

12 Results of the Steps Taken

13 

14 When the GAC caps were first installed, atrazine levels dropped to below detection 

15 and DBP precursors as measured by ultraviolet light adsorption at 254 nm (UV254) dropped 

16 by 50 percent. After about 3 months of operation the removal rates dropped. Removal 

17 rates eventually settled at 30 to 60 percent atrazine removal and 20 percent UV254 removal 

18 after about 6 months of operation. The atrazine concentrations were always below the 

19 MCL of 3 mg/L, averaging between 1 and 2 mg/L. The hydraulic performance of the filter 

20 was unaffected by the change to the GAC cap. Turbidity values leaving the filters were 

21 comparable to values produced previously with the anthracite filters. 

22 

23 Implementation and Operational Issues Faced by the Utility

24 

25 Adsorption of atrazine and other organics onto the GAC gradually decreased 

26 removal rates over time. A build up of inorganic precipitates, largely calcium, was seen on 

27 the GAC, which also contributed to decreased removal rates. The removal rates can be 

28 restored by regenerating or replacing the GAC, though this can be expensive. 

29 

30 It is possible that initial removal was due to adsorption and biological activity was 

31 later established. If this were the case, subsequent removal resulted from a combination of 

32 adsorption and biological degradation. If biological activity is suspected, care should be 

33 taken not to change the operational characteristics (e.g., fluidized bed heights, backflow 

34 rates) since changes in these operational parameters might impact removal performance. 

35 

36 There was a trade-off between removal of atrazine and removal of UV254. Lower 

37 pH favored UV254 removal at the expense of atrazine removal, while high pH had the 

38 opposite effects. 

39 

40 The system still experiences occasional taste and odor episodes. This is most likely 

41 caused by taste and odor causing compounds passing through the filters because GAC 

42 contact time and design are not optimal for taste and odor control. These episodes have 

43 been dealt with by adding PAC prior to the filters. 
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DRAFT- DO NOT CITE OR QUOTE J B-46 UNE 2006

1 

2 Lessons Learned From this Case Study

3 

4 • GAC caps can be used effectively to reduce pesticide and TOC concentrations. 

5 

6 • Adsorption of organic compounds by GAC is complicated and depends on the 

7 concentrations of other adsorbing compounds present in the source water. Bench 

8 scale tests should be done on the specific source water to determine if GAC itself, as 

9 well as different brands of GAC, will be effective with that water. 

10 

11 • The pH of the water can impact GAC removal rates for different organic compounds.
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE J B-47 UNE 2006

1 Case Study # 8 

2 Nanofiltration Membrane Technology for TOC Removal 

3 PBCWUD Water Treatment Plant #9 

4 West Palm Beach, Florida

5 

6 

7 The Palm Beach County Water Utilities Department (PBCWUD) Water Treatment 

8 Plant # 9 (WTP #9) was originally constructed in 1971 by private developers and was 

9 acquired by the County in 1983. The original plant utilized lime softening, rapid sand 

10 filtration, short-term free chlorination for biological growth control in the filters and 

11 chloramination as the secondary disinfection process. The facility had a maximum day 

12 flow capacity of 13.45 MGD, and was comprised of three treatment trains with capacities 

13 of 1 MGD, 3 MGD and 10 MGD. 

14 

15 Initially, the plant provided water service to the local area, but it was later 

16 incorporated into the regional water distribution system to provide potable water for the 

17 southern portion of the PBCWUD Service Area. Recognizing the growing demands for 

18 water in the area and the implementation of new drinking water standards, PBCWUD 

19 administered a construction contract for a new 27 MGD nanofiltration plant that was 

20 awarded in 1999. Nanofiltration will be used for removal of hardness, color, TOC, and its 

21 related chlorinated DBPs, which are commonly found in South Florida ground water. The 

22 plant started operational testing in November 2001. 

23 

24 This case study provides an example of the following simultaneous compliance 

25 issues that can be associated with nanofiltration membrane technology: 

26 

27 • DBP Rules - ability to remove DBP precursors 

28 • LCR - ability to provide a non-corrosive water in the PBCWUD distribution 

29 system 

30 • Secondary Drinking Water Standards - ability to provide an aesthetically 

31 pleasing water to PBCWUD customers 

32 

33 Introduction

34 

35 The mission of PBCWUD is to provide the highest quality drinking water service 

36 in a fiscally and environmentally sound manner. In the last decade, with the enforcement 

37 of the Secondary Drinking Water Standards and the Stage 1 D/DBPR in the State of 

38 Florida, PBCWUD's capital improvement strategy for new water treatment plants has been 

39 focused on nanofiltration membrane technology. Membrane water treatment technology is 

40 cost competitive with traditional conventional treatment methods while producing higher 

41 quality potable water; consequently, becoming the dominant water treatment technology in 

42 South Florida. 
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DRAFT- DO NOT CITE OR QUOTE J B-48 UNE 2006

1 

2 In May of 2003, PBCWUD completed Phase I construction of a new, and one of 

3 the largest in the world, nanofiltration membrane treatment plant (WTP #9) with a 

4 maximum capacity of 27 million gallons per day (MGD) finished water, including 23 

5 MGD of membrane permeate and 4 MGD of raw blend water. As stated previously, the 

6 primary reason for the membrane softening is for removal of hardness, color, TOC, and its 

7 related chlorinated DBPs. 

8 

9 The raw water supply for WTP #9 is water from the local surficial Biscayne 

10 Aquifer. The surficial aquifer system provides the water source for most public water 

11 supply wellfields in southeastern Florida. The aquifer system is generally unconfined and 

12 extends from land surface to a depth of approximately 330 feet below land surface (bls). 

13 The ground water is generally colored due to organics, hard and alkaline with varying 

14 amounts of dissolved iron and hydrogen sulfide. Typical ranges of water quality found in 

15 the Biscayne Aquifer are shown in Exhibit B.14. 

16 

17 

18 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 

19 

20 

21 The New Treatment Process at Water Treatment Plant #9

22 

23 The treatment train for WTP #9 is shown in Exhibit B.15. The raw water supplied 

24 to WTP #9 is taken from the shallow surficial aquifer through a series of 24 wells. 

25 Pretreatment includes a sand strainer which removes bulk sand from the raw water stream, 

26 acid injection to control pH to 5.0-5.9, and 5-micron cartridge filters to remove particulates 

27 greater than 5 microns. Six membrane feed pumps located after the micron filters boost 

28 the feed water pressure to 125-132 psi. The nanofiltration membrane building includes 

29 eight membrane treatment trains where each one has two stages with 47 and 22 pressure 

30 vessels, respectively. The degasifier/odor control system functions to remove hydrogen 

31 sulfide and carbon dioxide from the permeate water (product water from the membranes) 

32 and to prevent the emission of odors into the atmosphere. A sodium hypochlorite system 
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DRAFT- DO NOT CITE OR QUOTE J B-49 UNE 2006

1 supplies dilute liquid chlorine for disinfection. Six high service pumps supply water to the 

2 distribution system. Post-storage chemical injection points for ammonia, chlorine and 

3 caustic soda are included in the system to allow final disinfection and/or pH adjustment 

4 before the finished water enters the distribution system. The water entering the 

5 distribution system is monitored for chlorine residual, pH, pressure, and flow. The 

6 impurities removed by the membrane softening trains are consolidated into a concentrate 

7 stream and discharged through three-concentrate booster pumps into one deep injection 

8 well. 

9 

10 Treatment Steps Taken by Palm Beach County 

11 

12 • Pretreatment of sand strainer, acid injection, cartridge filtering 

13 

14 • Eight nanofiltration membrane treatment trains 

15 

16 • Degasification and odor control 

17 

18 • Dilute chlorine disinfection 

19 

20 • Post-storage final disinfection and/or pH adjustment and control 

21 

22 • Distribution system monitoring 

23 

24 Simultaneous Compliance Issues Faced by the Utility

25 

26 Nanofiltration membranes remove organic compounds in a molecular weight range of 

27 200 to 20,000 Daltons and reject selected salts (typically divalent). Nanofiltration economically 

28 softens water without the use of salt-regenerated systems and provides unique organic removal 

29 capabilities. While effective in removing organic constituents or DBP precursors, the 

30 nanofiltration membrane rejects selected salts, producing treated water with low total dissolved 

31 solids (TDS). Low TDS water has poor buffering capacity and can lead to low pH water, which 

32 is corrosive to metal pipes. Generally, an alkalinity below 25 mg/L as CaCO3 (0.5 meq/l) can be 

33 problematic for corrosion of piping (AWWARF and DVGW-Technologiezentrum Wasser 1996). 

34 This chemically unstable water can result in compliance issues with the Secondary Drinking 

35 Water Standards and the LCR.

36 .
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL 

 DRAFT- DO NOT CITE OR QUOTE B-50 

1 Exhibit B.15 Water Treatment Plant #9 Treatment Train 3 5 7 9 

11 13 15 
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DRAFT- DO NOT CITE OR QUOTE B-51 JUNE 2006

1 Steps Taken by the Utility

2 

3 Steps taken by the utility to overcome the potential simultaneous compliance issues 

4 discussed above occur primarily in the post-treatment process. The post-treatment process 

5 is mainly taking place in the clearwell complex area as shown in Exhibit B.16. The 

6 clearwell complex consists four major processes: 1) de-gasification process for de7 gasification of hydrogen sulfide and carbon dioxide from the permeate solution, 2) odor 

8 control process to remove hydrogen sulfide from the air, 3) clearwell disinfection process 

9 to create free and combined chlorine, and 4) transfer pump process to discharge the post10 treated water to the storage tanks. 

11 

12 Prior to the de-gasification process, approximately 4 MGD of raw water is 

13 introduced into the treatment train to blend with the 23 MGD of treated water. Blending of 

14 this raw water introduces some of the divalent salts back into the water that had been 

15 previously rejected by the membrane. This provides a more chemically-stable finished 

16 water. 

17 

18 Permeate water from the nanofiltration trains contains excessive amounts of carbon 

19 dioxide and hydrogen sulfide; therefore, 4 identical de-gasifier towers with air blowers in 

20 the clearwell complex function to remove carbon dioxide (CO2) and hydrogen sulfide 

21 (H2S) from the permeate water with the air stripping process. Sodium hypochlorite is 

22 injected into the permeate water before entering into the de-gasifiers for disinfection. The 

23 towers are of the forced draft, randomly packed bed, counter flow type. 

24 

25 The de-gasifiers are designed for maximum influent pH of 6 std. units; influent H2S 

26 with concentration of 1.3 mg/L and removal efficiency of 92 percent; and influent CO2

27 with concentration of 77 mg/L and with removal efficiency of 93.5 percent. 

28 

29 The stripped permeate is treated with a chlorine solution and ammonia for 

30 secondary disinfection and caustic soda for pH adjustment. 

31 

32 Results of the Steps Taken

33 

34 The resulting finished water quality is listed in Exhibit B.16. 

35 
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DRAFT- DO NOT CITE OR QUOTE B-52 JUNE 2006

1 Exhibit B.16 Typical ranges of distribution system water quality 

2 

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 

3 

4 As shown in Exhibit B.16, all Secondary Drinking Water Standards, DBP Rule MCLs, 

5 and LCR Action Levels are met. 

6 

7 Implementation and Operational Issues Faced by the Utility

8 

9 The utility experienced two serious problems in bringing the nanofiltration membrane 

10 treatment plant online. The most serious problem involved numerous leaks in the acid feed 

11 system. As a result of the leaks, the acid system had to be completely rebuilt during the first year 

12 of operation. 

13 

14 The other problem involved the micron cartridge filter housings and the string wound 

15 filter. The filter housings use a single open end cartridge with a stainless steel spring on the 

16 other end to keep tension on the cartridge, holding it in place. In this case, the filters sagged in 

17 the middle causing them to pull out of the socket. With the filter out of place, sand and debris 

18 accumulated on the membranes. This problem was eliminated by modifying the cartridge 

19 housings with a center bracket to support the filters. With these two modifications, the treatment 

20 plant has worked very well and continues to produce very high quality water. 

21 

22 Lessons Learned From This Case Study 

23 

24 • Nanofiltration economically softens water without the use of salt-regenerated systems 

25 and provides unique organic removal capabilities thereby removing disinfection 

26 byproduct precursors. 

27 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

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1 • Blending a portion of the raw water with treated water and the de-gasification process 

2 significantly enhances the aesthetic qualities of the finished water and results in a 

3 more chemically stable water. This enables PBCWUD to provide their customers 

4 with water that complies with both the LCR and the Secondary Drinking Water 

5 Standards. 

6 

7 References

8 

9 AWWA. 1999. Reverse Osmosis and Nanofiltration. AWWA Manual M46. 

10 

11 Glucina, K., A. Alvarez, and J.M. Laine. 2000. Assessment of an integrated membrane 

12 system for surface water treatment. Proceeding of the conference in drinking and 

13 industrial water production. 2: 113-122. Italy, October 2000. 

14 

HDR Engineering, Inc. 2001. Handbook of Public Water Systems. 2nd 15 ed. Pages 509-510. 

16 

17 Montgomery Watson Inc. 1998. Palm Beach County Water Utilities Department Water 

18 Treatment Plant No. 3 Membrane Softening Facility Operations Manual Final Report. 

19 Pages 4-19 to 4-20. 

20 

21 Panayides, N., Operational Procedures of a New 27 MGD Nanofiltration Membrane 

22 Water Treatment Plant (WTP No. 9) in South Florida. Palm Beach County Water 

23 Utilities Department.
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4 

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6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 This page intentionally left blank. 
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1 Case Study #9 

2 Modifying Chloramination Practices to Address Nitrification Issues

Ann Arbor Utilities2 3 

4 Ann Arbor, Michigan 

5 

6 

7 This case study demonstrates how a utility modified chloramination practices to address 

8 nitrification problems in the distribution system to be in compliance with the Stage 1 DBPR and 

9 the TCR. 

10 

11 Introduction 

12 

13 The City of Ann Arbor operates a two-stage lime softening plant (50 million gallons per 

14 day (MGD) design flow) that treats a blend of surface water and ground water. It serves 

15 approximately 115,000 people. The influent to the plant consists of a blend of Huron River 

16 water (approximately 85 percent) and well water (approximately 15 percent). Typical water 

17 quality parameters for raw river water and well water, prior to any treatment modifications, are 

18 presented in Exhibit B.17. The water entering the plant has high alkalinity (average alkalinity of 

19 314 mg/L as CaCO3), with high TOC levels (average 6 mg/L). 

20 

 

2

 this system is also used in Case Study #10 Ozonation
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE B-56 JUNE 2006

1 

2 Exhibit B.17 Summary of Relevant Water Quality Parameters at Ann Arbor Before 

3 Treatment Modifications 

4 

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 

5 Notes:

6 1. Data collected between July 1994 and June 1995; based on monthly (average) data. 

7 2. Minimum or maximum values (in parentheses) represent minimum or maximum of all measurements, not 

8 limited to monthly average data.

9 3. ND = Non Detectable

10 

11 

12 The Treatment Process at the Ann Arbor WTP 

13 

14 The treatment plant is a 50 MGD two-stage lime softening plant that uses chloramines for 

15 primary disinfection. The average operating flow is 20 MGD. Exhibit B.18 shows a schematic 

16 of the treatment plant. Raw river water is disinfected with chlorine, then chlorine is added again 

17 with ammonia after filtration to form chloramines. The free chlorine contact time is minimal. 

18 The water is softened with lime (average dose = 187 mg/L as CaCO3), at a pH slightly above 11. 
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1 From April through November well water is blended with softened water from the first stage 

2 clarifier effluent and recarbonated (i.e., addition of CO2) to bring the pH down to around 10. It 

3 then enters the second-stage clarifier. A cationic polymer is added at this point (average dose 

4 0.62 mg/L) to enhance settling. The water is then recarbonated (i.e., CO2 is added) down to a pH 

5 slightly greater than 9, and sodium hexametaphosphate is added to facilitate corrosion control. 

6 The water is then filtered (granular activated carbon (GAC)/sand dual-media filters). After 

7 filtration, sodium hypochlorite and ammonia are added to form chloramines and the finished 

8 water is distributed at an average pH of 9.4. 

9 

10 From December through March the chemical application points are similar to those 

11 during the summer months. However, the well water is blended with the river water prior to the 

12 first stage of the lime softening process to raise the water temperature and improve sludge 

13 dewatering. 

14 

15 The chloramines dose ranged from 4.1-6.2 mg/L and Giardia log inactivation by 

16 chloramination ranged from 0.5 to1.0 logs. 

17 

18 

19 Exhibit B.18 Ann Arbor Water Treatment Plant 

20 

21 

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
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

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1 

2 Simultaneous Compliance Issue Faced by the Utility

3 

4 The system switched to chloramines to reduce TTHM formation and to be in compliance 

5 with the Stage 1 Disinfectants/Disinfection Byproducts Rule (D/DBPR). However, the use of 

6 chloramines can result in the presence of ammonia in the distribution system if the proper 

7 chlorine to ammonia (as nitrogen) ratio is not maintained. This increases the potential for 

8 biological nitrification. Nitrification can result in a loss of combined chlorine residual, and result 

9 in sharp increases in HPC bacteria. This increases the chances of a TCR violation.

10 

11 Steps Taken by the Utility

12 

13 To cope with the nitrification problem, Ann Arbor expanded its monitoring program and 

14 made several operational and facility adjustments to improve ammonia feed rate control. The 

15 chlorine to ammonia (as nitrogen) ratio was maintained at 4.75:1, with a target level for free 

16 ammonia entering the distribution system of 0.15 mg/L. Warning and action levels for nitrite in 

17 the system were set at 0.025 and 0.050 mg/L, respectively. 

18 

19 As soon as the utility became aware of its nitrification problem, it attempted to control it 

20 by controlling the concentration of free ammonia reaching the filters. No changes were made to 

21 the existing treatment configuration. However, the system made several operational changes. 

22 Ammonia dosage at the headworks was reduced so that less than 0.15 mg/L of free ammonia 

23 remained in the water when it entered the filters. Along with this, distribution lines were flushed 

24 at low velocity until an average combined chlorine residual of approximately 3 mg/L was 

25 achieved. The Stage 1 DBPR specifies a running annual average maximum residual disinfectant 

26 level (MRDL) for chlorine of 4.0 mg/L (as Cl2). 

27 

28 During the summer months (i.e., June to September), the system switched back to 

29 chlorination. This was achieved by simply shutting down ammonia addition after filtration and 

30 adjusting the chlorine feed rate. This would ensure that nutrient levels (i.e., ammonia) in the 

31 distribution system were low during the warmer months, when the temperature was most 

32 conducive to the rapid growth of nitrifying organisms. This would decrease biological activity in 

33 the distribution system. 

34 

35 Results of the Steps Taken

36 

37 As a result of these steps, nitrite concentrations in the distribution system were below 

38 detection level. Also, HPC levels dropped significantly in five of the six locations where 

39 nitrification had previously been found. The system did see an increase in TTHM formation 

40 during the summer months. However, careful monitoring, dosing, and complementary hydrant 

41 flushing (see next paragraph for details) resulted in compliance with the Stage 1 DBPR. The 

42 average and maximum TTHM in the finished water were 24 and 39 Fg/L, respectively (based on 

43 the monthly TTHM data collected between July 1994 and June 1995). 
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DRAFT- DO NOT CITE OR QUOTE B-59 JUNE 2006

1 

2 Implementation and Operational Issues Faced by the Utility

3 

4 Although switching to free chlorine during the summer was effective for controlling 

5 nitrification, it appeared to result in higher levels of heterotrophic and coliform bacteria than 

6 when the water was chloraminated. At the same time, increasing the chlorine dose during the 

7 summer months increased TTHM concentrations. As a result, the system decided to continue 

8 disinfecting with chloramines and pursue a more aggressive hydrant flushing program to control 

9 bacterial re-growth in the distribution system. 

10 

11 Analysis revealed that one of the prime causes of nitrification could have been the switch 

12 to a GAC/sand dual-media filter from a pure sand filter. The ammonia added before the water 

13 reached the filters could have provided a nutrient source sufficient for nitrifying bacteria to 

14 attach, establish, and proliferate within the GAC media. Such a condition could have allowed 

15 the nitrifying organisms to pass through the filter and seed the distribution system if they 

16 survived the chloramine disinfection. 

17 

18 

19 Lessons Learned From this Case Study

20 

21 • Controlling nitrification in the distribution can be a challenge for utilities switching to 

22 chloramines. 

23 

24 • Carrying a chloramine residual through the treatment plant might increase distribution 

25 system problems with biological nitrification. 

26 

27 • The most common strategies for controlling nitrification are listed below. 

28 

29 o Improving ammonia feed rate control to limit the free ammonia levels entering the 

30 distribution system. 

31 o Implementing a comprehensive distribution system flushing and monitoring 

32 program. 

33 o Having an alternative disinfection strategy for the warmer months of the year. 

34 

35 • Systems adding ammonia prior to a GAC filter may be more likely to face 

36 nitrification in the distribution system. 
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2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 This page intentionally left blank. 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

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1 Case Study #10 

2 Ozonation

Ann Arbor Utilities3 3 

4 Ann Arbor, Michigan

5 

6 

7 This case study demonstrates how a utility switched to ozonation to meet the Interim 

8 Enhanced Surface Water Treatment Rule (IESWTR) and the Stage 1 and 2 DBPR regulations, 

9 and simultaneously controlled microbial regrowth potential in the distribution system to be in 

10 compliance with the TCR. 

11 

12 Introduction 

13 

14 The City of Ann Arbor serves approximately 115,000 people, and operates a two-stage 

15 lime softening plant (50 MGD design flow) that treats a blend of surface water and ground water. 

16 In 1990, for the reasons outlined below, the Ann Arbor plant decided to switch from 

17 chloramines to ozonation for primary disinfection. 

18 

19 • Ozonation would meet IESWTR CT requirements for viruses at low temperatures. 

20 

21 • In addition to complying with the IESWTR, ozonation was expected to allow the 

22 plant to comply with Stage 1 and 2 DBPRs. 

23 

24 • Ozonation was also expected to improve taste and odor. 

25 

26 The influent to the plant consists of a blend of Huron River water (approximately 85 

27 percent) and well water (approximately 15 percent). Typical water quality parameters for raw 

28 river water and well water, prior to any treatment modifications, are presented below in Exhibit 

29 B.19. The water entering the plant has high alkalinity (average influent alkalinity of 314 mg/L as 

30 CaCO3), with high TOC levels (average 6 mg/L). 

31 

 

3

 this system is also used in Case Study #9 Modifying Chloramination Practices to Address Nitrification 

Issues.
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE B-62 JUNE 2006

1 

2 Exhibit B.19 Summary of Relevant Water Quality Parameters at Ann Arbor Before 

3 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 (Fg/L)

Minimum 

Average 

Maximum 

 

14 

24 

39 

HAA54 (Fg/L)

Minimum 

Average 

Maximum 

 

4.2 

16 

21 

4 Notes:

5 Data collected between July 1994 and June 1995; based on monthly (average) data. 

6 Minimum or maximum values (in parentheses) represent minimum or maximum of all measurements, not limited 

7 to monthly average data.

8 ND = Non Detectable

9 Data collected quarterly between October 1995 and May 1996.

10 
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DRAFT- DO NOT CITE OR QUOTE B-63 JUNE 2006

1 

2 The Original Treatment Process at the Ann Arbor WTP 

3 

4 The original treatment plant was a 50 MGD two-stage lime softening plant that used 

5 chloramines for primary and secondary disinfection. The average operating flow was 20 MGD. 

6 Exhibit B.20 shows a schematic of the treatment plant, prior to the modifications. Raw river 

7 water was disinfected with chlorine, followed by ammonia addition to form chloramines. The 

8 free chlorine contact time was minimal. The water was softened with lime (average dose = 187 

9 mg/L as CaCO3), at a pH slightly above 11. From April through November, well water was 

10 blended with softened water from the first stage clarifier effluent and recarbonated (i.e., addition 

11 of CO2) to bring the pH down to around 10. It then entered the second-stage clarifier. A cationic 

12 polymer was added at this point (average dose 0.62 mg/L) to enhance settling. The water was 

13 then recarbonated down to a pH slightly greater than 9 and sodium hexametaphosphate added, to 

14 facilitate corrosion control. It was then filtered (GAC/sand dual media filters). After filtration, 

15 sodium hypochlorite and ammonia were added to boost the level of chloramines. The finished 

16 water was distributed at an average pH of 9.4. 

17 

18 From December through March the chemical application points were similar to those 

19 during the summer months. However, the well water was blended with the river water prior to 

20 the first stage of the lime softening process to raise the water temperature and improve sludge 

21 dewatering.
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE B-64 JUNE 2006

1 Exhibit B.20 Ann Arbor Water Treatment Plant Before Treatment Modifications 

2 

3 

4 Simultaneous Compliance Issue Faced by the Utility

5 

6 Application of ozone would lower the formation of TTHM and HAA5s and enhance the 

7 ability to meet minimum virus and Giardia inactivation levels (to be in compliance with the 

8 IESWTR). However, ozonation could lead to an increase in the AOC levels in the finished water, 

9 resulting in potential microbial regrowth in the distribution system and non-compliance with the 

10 TCR. 

11 

12 Steps Taken by the Utility

13 

14 The utility switched to ozonation, followed by biofiltration, in order to address the 

15 simultaneous compliance issue. They no longer pre-chlorinate or pre-chloraminate. 

16 

17 Before switching to ozone, the operators of Ann Arbor’s system contacted known ozone 

18 facilities and talked with their engineers and operators to learn what features, in retrospect, they 

19 wish they had installed when they installed the ozone. Based on these discussions, some features 

20 missing from previous plant designs were incorporated into the Ann Arbor system’s design. One 

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
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1 example of such as a feature is the addition of waterproof hatches for direct access to the contact 

2 chambers. This eliminated the need for roof entry, which is an important consideration for 

3 system operators. 

4 

5 Overall process – Exhibit B.21 shows a schematic of the treatment plant after the 

6 modifications. Changes made to the original treatment train are outlined below. 

7 

8 • Ozonation is now the primary disinfection step. The pre-chlorination step was 

9 eliminated. 

10 

11 • The first point of disinfectant addition (i.e., ozonation) is after the secondary clarifier, 

12 and recarbonation. The ozonation pH is 8.0. 

13 

14 • After ozonation, sodium hydroxide is added to raise the pH of the water to 9.4 prior to 

15 adding sodium hexametaphosphate as a corrosion inhibitor. 

16 

17 • The original dual media (GAC/sand) filters are now operated as biofilters. To help 

18 inactivate HPC bacteria shed from the filters, filter effluent is disinfected with an 

19 average chloramine dose of 3.5 mg/L, and held for approximately 3 hours in the 

20 covered reservoir. 

21 

22 Ozonation Details

23 

24 There are 8 ozone contact cells with an overall contact time of 16.8 minutes. The system 

25 is operated at a 6 to 10 percent gas concentration. An off-gas recycle system applies ozone to the 

26 first cell, which reduces demand in subsequent cells but does not produce an ozone residual. The 

27 goal is to achieve a residual of 0.1 mg/L or greater in the first cell, and to maintain sufficient 

28 residuals in subsequent cells, to meet the target CT.

29 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

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1 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

2 

3 

4 Biofiltration Operations 

5 

6 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 7 . The empty bed contact time (EBCT) of the GAC is 3.7 minutes at 

8 design flow and 7.4 minutes at typical flow. Filter backwash frequency is governed by: (a) 

9 effluent turbidity exceeding 0.2 nephelometric turbidity units (NTU), (b) number of hours in 

10 service (usually 80 hours is the cut-off point), and (c) acceptable headloss limits (which is 

11 usually not a controlling criterion). The backwash is performed using finished chloraminated 

12 water.

13 

14 Results of the Steps Taken 

15 

16 • DBP reductions - Exhibit B.22 shows the TTHM and HAA5 concentrations before 

17 and after the modifications at the Ann Arbor plant. Clearly, ozonation resulted in a 

18 significant drop in TTHM and HAA5 concentrations, resulting in no compliance 

19 problems with the Stage 1 and Stage 2 DBPRs. 

20 

21 • Bromate formation - Ozonation can oxidize bromide to bromate, which is regulated 

22 by the Stage 1 DBPR at an MCL of 10 Fg/L. Influent bromide concentrations at the 
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1 ozonation plant ranged from 27 to 80 Fg/L, with an average of 67 Fg/L. The well 

2 contributes more to the bromide levels than the river water. The average bromide 

3 concentration in the ground water is 100 Fg/L, and the Huron River water has an 

4 average bromide concentration of 59 Fg/L. The bromate levels in the finished water 

5 ranged from 2 to 8 Fg/L, with an average of 3 Fg/L. At its current level of bromate 

6 formation, Ann Arbor meets the bromate MCL. 

7 

8 • TOC removal - The average influent TOC to the plant after the modifications was 5.5 

9 mg/L (with a range of 4.5-7.0 mg/L). The average effluent TOC was 2.7 mg/L (with 

10 a range of 2.1-3.4 mg/L). Therefore, TOC removal ranged from 40 to 59 percent with 

11 an average of 51 percent, which is quite similar to the TOC removals achieved before 

12 implementing ozonation. The Stage 1 D/DBPR TOC removal requirements for 

13 softening plants with an influent TOC >4.0-8.0 or >8.0 mg/L are 25 and 30 percent, 

14 respectively (USEPA 1998a). The Ann Arbor plant exceeds these requirements. 

15 Higher TOC removal has the advantage of lowering the ozone dose requirements 

16 because the ozone applied is not used up by reactions with TOC. 

17 

18 Exhibit B.22 DBP Formation Before and After Ozonation at Ann Arbor 

19 

DBPs Before Modification1 After Modifications2

TTHM (Fg/L)

Minimum 

Average 

Maximum 

14 

24 

39 

1.4 

7.2 

13 

HAA5 (Fg/L)

Minimum 

Average 

Maximum 

4.2 

16 

21 

1.5 

5.0 

15 

Bromate 

(Fg/L)

Minimum 

Average 

Maximum 

2 

3 or 43

8 

20 Notes:

21 1. Monthly TTHM data collected between July 1994 and June 1995; other DBP data collected quarterly between 

22 October 1995 and May 1996. 

23 2. Data collected in calendar year 1997; based on monthly or quarterly data. 

24 3. Depending on whether the non-detects were set to zero or half the minimum detection level.

25 

26 

27 Implementation and Operational Issues Faced by the Utility 

28 

29 • Operator training and start-up - It took about 2 to 3 months for the operational staff to 

30 be at ease with the new technology, and about 3 to 5 months for the plant to operate 
M-DBP SIMULTANEOUS COMPLIANCE GUIDANCE MANUAL APPENDIX B - CASE STUDIES

 

DRAFT- DO NOT CITE OR QUOTE B-68 JUNE 2006

1 optimally and smoothly. The change in treatment also changed the operational needs 

2 of the plant; additional mechanics and instrumentation technicians were needed. 

3 Additional resources had to be allocated to treatment operation and maintenance. 

4 

5 • Sludge accumulation over diffusers - This caused fluctuating ozone residuals, 

6 resulting in difficulty obtaining the required CT. The plant has been testing various 

7 chemicals to improve secondary settling to reduce the impact of the sludge on the 

8 ozone system. 

9 

10 • Liquid Oxygen (LOX) vaporizers did not defrost well in winters, causing the system 

11 to shut down due to low gas flow. 

12 

13 • Optimizing biofiltration during winters - Extremely large seasonal fluctuations in 

14 temperature have strongly governed treatment strategy at the Ann Arbor plant. 

Average monthly river water temperature in 1997 ranged from 7.9 to 22o 15 C, with an 

average of 14o 16 C. The lowest temperature in winter during the sampling period was 

3oC. Well water temperatures are fairly constant at 14o 17 C. After ozonation and 

18 biofiltration, AOC content ranged from 40 to 210 Fg C/L (average = 129 Fg C/L). 

19 During the summer, approximately 40 percent of AOC produced by ozonation was 

20 removed during biofiltration, whereas in winter there was practically no removal. 

21 This suggests poor biological activity on the filters in winter months. Ann Arbor 

22 raises the temperature of the influent water in winter by mixing in a larger proportion 

23 of ground water (24-29 percent versus 10-20 percent in the summer). It also 

24 introduces well water at the head of the plant in winter to increase the water 

25 temperature so that treatment processes like biofiltration are more effective. 

26 

27 Lessons Learned From this Case Study

28 

29 • Ozonation requires a high degree of operational expertise. The key to running a 

30 successful ozonation treatment unit depends greatly on the operator being 

31 comfortable with the new instrumentation and controls. 

32 

33 • Ozonation may not be suitable for influent waters with high bromide concentrations. 

34 

35 • Ozonation increases the AOC concentration in finished water. As a result, 

36 biofiltration is required downstream of ozonation to ensure AOC removal and reduce 

37 the opportunity for microbial regrowth in the distribution system. Failure to do so 

38 may result in TCR violations. Biofiltration needs careful monitoring and 

39 optimization, especially during winter when microbial activity is greatly reduced. 

40 One operational strategy is to increase the proportion of ground water in the influent 

41 surface/ground water blend during winter to ensure that treated water has a higher 

42 temperature. 
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1 Case Study #11 

2 Ozonation and Biological Filtration

3 Sweeney Water Treatment Plant 

4 Wilmington, North Carolina

5 

6 

7 This case study provides an example of a water system that upgraded its treatment plant 

8 by expanding its capacity from 15 MGD to 25 MGD and installing ozonation and biological 

9 filtration to improve compliance with IESWTR and LT2ESWTR regulations and to increase 

10 aesthetics and customer confidence. 

11 

12 The majority of the information for this case study was found in Najm et al., (2004). For 

13 more information on the Sweeney Water Treatment Plant, please refer to Kennedy et al. (2004). 

14 

15 Introduction

16 

17 Sweeney Water Treatment Plant (SWTP) is owned and operated by the City of 

18 Wilmington, NC. SWTP uses the Cape Fear River water as its source water, which has high 

19 organic content, high color, and low turbidity. The source water also contains iron and 

20 manganese that can cause aesthetic issues in the finished water. A summary of the source water 

21 quality as received at the SWTP is provided in Exhibit B.23. 

22 

23 
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1 Exhibit B.23 Cape Fear River Water Quality 

2 (as received at the SWTP)

3 

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 

4 Source: Adapted from Najm, et al., 2004 

5 Note: Data collected between Oct. 2001 - July 2002

6 

7 The treatment train for the SWTP is shown schematically in Exhibit B.24 below. The 

8 capacity of the SWTP is 25 MGD, and consists of the following two treatment trains: 

9 

10 South Plant (15 MGD) 

11 • coagulation 

12 • flocculation 

13 • sedimentation train 

14 • intermediate ozonation 

15 • dual-media GAC/sand filtration 

16 North Plant (10 MGD) 

17 • coagulation 

18 • high rate clarification (SuperPulsator) 

19 • intermediate ozonation 

20 • dual-media GAC/sand filtration 

21 

22 Source water first undergoes pre-ozonation and is then split between the North and South 

23 Plants, where the alkalinity is raised by adding caustic and/or lime. During the rapid mix step of 

24 each treatment train, alum and cationic polymer are added. Primary disinfection requirements of 

25 0.5-log Giardia removal and 2-log virus inactivation are satisfied via the intermediate ozonation 

26 step. After undergoing filtration, the treated waters from the South Plant and North Plant are 
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1 joined and caustic and/or lime, chlorine, phosphate, and fluoride are added to the combined filter 

2 effluent (CFE) before the water enters the clearwell. Finally, the effluent of the SWTP’s 

3 clearwell receives additional chlorination prior to entering the distribution system. 

4 

5 

6 Exhibit B.24 Schematic of SWTP 

7 Source: Najm, et al., 2004

8 

9 

10 Simultaneous Compliance Issue Faced by the Utility

11 

12 The City of Wilmington upgraded its facility for the following reasons: 

13 

14 • to better accommodate future population growth, 

15 • to comply with LT2ESWTR regulations by providing Cryptosporidium inactivation, 

16 and 

17 • to improve aesthetics and customer confidence. 

18 

19 Application of ozone also lowers the formation of TTHM and HAA5. However, 

20 ozonation could lead to an increase in the AOC levels in the finished water, resulting in potential 

21 microbial regrowth in the distribution system and non-compliance with the TCR. Biofiltration 

22 was used to remove AOC before the water entered the distribution system. 

23 
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1 Steps Taken by the Utility

2 

3 Changes made to the original treatment train of the SWTP are outlined below. 

4 

5 • The North Plant (10 MGD facility) was constructed to be operated simultaneously 

6 with the existing South Plant (15 MGD). 

7 • An ozone generation and dissolution facility was constructed. 

8 • New pretreatment facilities were built for coagulation. 

9 • 12 sand/anthracite filters were converted to biofilters by the use of deep bed dual 

10 media with gravel support and GAC. 

11 • A SCADA system to monitor/control all processes and equipment in the facility was 

12 installed. 

13 

14 Ozonation and biological filtration began at the SWTP in March, 1998. Details of the 

15 two processes are provided below. 

16 

17 Ozonation Details

18 

19 SWTP has two application points for ozone. First, in pre-ozonation, ozone is applied 

20 prior to coagulation, at doses between 3-7 mg/L. In intermediate ozonation, ozone is applied 

21 again to settled water at doses between 0.75 - 4.0 mg/L before the water undergoes biological 

22 filtration. The ozonation system at the SWTP uses a maximum of 1380 lbs ozone/day. 

23 

24 Biofiltration Details

25 

26 Specifications for the four new biological filters in the North Plant are as follows: 

27 

28 • Support Gravel - 3" 

29 • Silica Sand - 15" 

30 • GAC - 48" 

31 

32 Specifications for the 12 existing filters in the South Plant which were converted to 

33 biological filtration are as follows: 

34 

35 • Support Gravel - 12" 

36 • Silica Sand - 6" 

37 • GAC - 21" 

38 

39 Finished water from the SWTP’s storage reservoir is used to backwash the biological 

40 filters at both the North and South Plants. At the North Plant, the filters undergo air scouring 

41 prior to backwash, and at the South Plant, the filters use surface sweeps prior to backwash. 

42 
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1 Results of the Steps Taken

2 

3 After the upgrades made at the SWTP, the following water quality improvements have 

4 been observed. 

5 

6 • TOC reduction from raw water to settled water has been observed, and additional 

7 TOC reduction has been observed as result of the biological filtration. Finished water 

8 TOC levels have been reduced to 2.0 - 2.5 mg/L. 

9 

10 • TTHM levels have decreased to 60 μg/L (typical level). 

11 

12 • HAA5 levels have decreased from 48.5 μg/L (based on 1997 values) to 21.37 μg/L 

13 (based on 1999 values). 

14 

15 • Iron levels have been reduced from 0.9 mg/L (maximum level in source water) to less 

16 than 0.020 mg/L (finished water). 

17 

18 • Manganese levels have been reduced from 0.06 - 4.0 mg/L (range of typical to 

19 maximum levels in source water) to less than 0.01 mg/L (finished water). 

20 

21 Implementation and Operational Issues Faced by the Utility

22 

23 The SWTP switched from disinfection with chlorine/chlorine dioxide to ozone. Although 

24 no specific issues were described for the SWTP, the following general issues are relevant to 

25 switching to disinfection with ozone. 

26 

27 • Increased costs (due to liquid oxygen, electricity, and higher O&M costs). 

28 • Use of ozone requires a higher level of technical skill from the operators; therefore, 

29 increased training may be required. 

30 • Since ozonation could lead to an increase in the AOC levels in the finished water, 

31 biofiltration should be implemented to remove the additional AOC. 
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1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 This page intentionally left blank. 
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1 Case Study #12 

2 Ultraviolet Disinfection

3 Poughkeepsie Water Treatment Facility 

4 Poughkeepsie, New York 

5 

6 

7 This case study provides an example of a water system that installed ultraviolet light 

8 (UV) to meet DBP requirements while maintaining compliance with SWTR and IESWTR 

9 requirements. By switching to UV, the system also facilitated compliance with the LT2ESWTR 

10 requirements for Cryptosporidium inactivation. 

11 

12 The information for this case study comes from interviews with water treatment plant 

13 staff (Alstadt 2005, Lill 2005) and from the plant's Web site at http://www.pokwater.com. 

14 Readers are also encouraged to refer to the Draft Ultraviolet Light Disinfection Guidance 

15 Manual (U.S. EPA 2003b) for information on UV sensor calibration procedures and practices. 

16 

17 Introduction

18 

19 Poughkeepsie's Water Treatment Facility (PWTF) is a surface water treatment plant 

20 located in Poughkeepsie, New York. The plant uses the Hudson River as a source and has a 

21 capacity of 16 MGD. In March 2002 the system began a series of improvements to the plant to 

22 increase its rated capacity, ensure continued compliance with existing regulations, and prepare 

23 for expected future regulations. In the second quarter of 2003 (May 1 through July 31) the 

24 PWTF incurred a violation for exceeding the MCL for HAA5. The system has been in 

25 compliance with the MCLs for both HAA5 and TTHM since that date and is completing 

26 modifications, including installing UV, to prevent another exceedance. 

27 

28 PWTF is a conventional surface water treatment plant with rapid mix, followed by three 

29 parallel trains, each with a solids contact tank and sedimentation followed by filtration. The 

30 plant has a total of six filters. An equalization basin succeeds the filters with orthophosphoric 

31 acid added in the first half and sodium hydroxide added in the second half. Chlorine is added in 

32 the sedimentation basins and again just before the water leaves the treatment plant to maintain a 

33 residual in the distribution system. 

34 

35 Simultaneous Compliance Issues Faced by the Utility

36 

37 The primary issue faced by the system was the need to reduce DBPs. However, in doing 

38 so, the system needed to ensure that it could maintain a high enough CT to ensure compliance 

39 with the requirements for Giardia and viruses. In addition, the LT2ESWTR was expected to 

40 contain new requirements for Cryptosporidium inactivation. The system needed to consider how 

41 any modifications made to address DBPs could impact the system's ability to meet these other 

42 requirements.
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1 

2 Steps Taken by the Utility

3 

4 In order to reduce DBPs, the system proposed moving the point of disinfection from the 

5 sedimentation basins to just prior to the filters, after more DBP precursors have been removed. 

6 However, in doing so, the system would lose some disinfection contact time. In order to 

7 maintain the necessary CT, the system needed to add an additional contact basin after the filters. 

8 Due to space limitations, constructing a contact basin large enough to maintain CT was not 

9 feasible. Therefore, the system chose to install UV after each filter to provide additional CT and 

10 meet space requirements. In addition, UV does not produce any DBPs, so installing UV rather 

11 than additional chlorine contact time after the filters would further reduce the system's TTHM 

12 and HAA5 levels. The UV installation and all associated modifications have been completed. 

13 

14 An additional benefit of installing UV at the PWTF is that UV has been shown to be an 

15 effective technology for inactivating Cryptosporidium at a low dose. The use of UV at PWTF 

16 should enable the system to meet the Cryptosporidium inactivation requirements under the 

17 LT2ESWTR. 

18 

19 PWTF is now planning to switch from chlorine to chloramines for secondary disinfection 

20 to further reduce DBPs in the distribution system. The system will continue to use chlorine and 

21 UV as primary disinfectants, but will begin adding ammonia after the equalization basin to form 

22 chloramines. The system expects to begin using chloramines in 2006 after a new flushing 

23 program has been implemented. 

24 

25 Expected Results of the Steps Taken

26 

27 Bench-scale pilot testing indicated that installing UV would reduce TTHM and HAA5 by 

28 20 percent. Pilot testing also showed that addition of chloramines will reduce DBPs by another 

29 80 percent. The UV installation is expected to provide 3-log inactivation of Giardia and 

30 Cryptosporidium, which will ensure that the system maintains compliance with the Giardia 

31 inactivation requirements under the IESWTR. In addition, the system should be able to meet the 

32 requirements for Cryptosporidium under the LT2ESWTR. Because UV is less effective against 

33 some kinds of viruses, the system expects that it will need to achieve 1 log of virus inactivation 

34 through chlorination after the UV units. The system will meet this requirement with the existing 

35 equalization basin. 

36 

37 Implementation and Operational Issues Faced by the Utility

38 

39 One of the biggest issues for the PWTF staff during the modifications was learning to 

40 operate and maintain the UV system. PWTF found that operating a UV system is very different 

41 from operating a chemical disinfection system. It is a fairly simple process to determine when a 

42 chemical disinfection system is operating properly because the residual can be easily measured 

43 with a grab sample. Determining how effectively a UV unit is working is much more complex 
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1 because there is no measurable residual in the water. In order to determine the UV dose received 

2 by organisms in the water, the operator needs to know the intensity delivered by the UV bulbs 

3 and the transmittance of the water. The UV reactor contains an array of sensors that are used to 

4 determine the intensity and the readings among the sensors can vary significantly, making it 

5 difficult to determine which are correct. PWTF staff had problems with many of the intensity 

6 sensors in their UV chambers and had to have them replaced. They also had problems with the 

7 transmittance meter. These problems had not been resolved as of Fall 2005. 

8 

9 Obtaining appropriate training was also an issue for the system. Although the 

10 manufacturer provided some training, the water treatment plant staff had not yet worked with the 

11 UV system and were unable to communicate specific training needs to the manufacturer. 

12 Therefore, the plant staff found that many operational and maintenance issues arose during 

13 installation and testing that were not addressed during training. 

14 

15 Programming the UV system and integrating it into plant controls was difficult. The 

16 water treatment plant would have to be shut down if the UV system failed and the control system 

17 would need to be programmed to do so. In addition, the UV units require 10 minutes to cool 

18 down before shutdown to avoid damage to the UV units. Therefore, PWTF had to install a UPS 

19 to hold the power for the UV units for 10 minutes in the event of a power failure. Trying to 

20 consider all possible scenarios and how to react to and program them was a complicated process. 

21 

22 Large UV systems require a significant amount of power, particularly at high doses. The 

23 UV units at PWTF have all been successfully started up and the system is receiving one (1) log 

24 inactivation credit for the UV although the primary disinfectant application point has not yet 

25 been moved. With all UV units running, PWTF observed a 20 percent increase in power 

26 utilization, which significantly increased the plant's power costs. The new UV system also led to 

27 increased maintenance time and costs. The UV system has many components, such as sensors 

28 and bulbs, which require periodic replacement. In addition, the monitoring equipment must be 

29 calibrated regularly. 

30 

31 Lessons Learned From this Case Study

32 

33 • UV disinfection is very different from chemical disinfection. It is important that 

34 operators undergo training and have continued access to knowledgeable 

35 representatives from the manufacturer during installation and start-up of this 

36 technology to allow them to become comfortable with the new instrumentation and 

37 controls. 

38 

39 • UV is an effective technology both for reducing DBPs and inactivating Giardia and 

40 Cryptosporidium. However, it also consumes much more electricity than chlorination 

41 or chloramination. Therefore, it is important to consider the availability of electricity 

42 and the financial impact of increased power usage before installing UV. 
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1 References

2 

3 Alstadt, R. 2005. Personal Communication. 

4 

5 Lill, P. 2005. Personal Communication. 
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1 Case Study #13 

2 Chlorine Dioxide for Primary Disinfection and Chloramines for Secondary 

3 Disinfection

4 Gulf Coast Water Authority 

5 Texas City, TX 

6 

7 

8 This case study provides an example of a water treatment plant with high influent TOC, 

9 high bromide, warm water temperatures, and long residence times in the distribution system that 

10 converted to chlorine dioxide as a primary disinfectant and chloramines as a secondary disinfect 

11 to reduce the formation of chlorinated DBPs. 

12 

13 The information for this case study was obtained primarily from Krasner et al. (2003). 

14 Readers should refer to that text for more detailed information. 

15 

16 Introduction

17 

18 The Gulf Coast Water Authority (GCWA), which has been operating since 1981, 

19 operates the Thomas S. Mackey WTP from which treated water is wholesaled to seven 

20 municipalities between Houston and Galveston, TX. All of the systems served by GCWA 

21 conduct their own distribution system monitoring for regulatory compliance. Approximately 

22 92,000 people are served by the GCWA in the seven municipalities. Additionally, raw water is 

23 pumped to industry and treated water is provided to the City of Houston via pipeline between 

24 Houston and Galveston. 

25 

26 The current rated capacity of the Thomas S. Mackey WTP is 25 MGD, with approximate 

27 average and maximum flows of 12 and 20 MGD, respectively. 

28 

29 GCWA uses the Brazos River as their source water, which has moderate to high levels of 

30 TOC, hardness, alkalinity, and bromide. 

31 

32 A summary of the influent water quality to the GCWA is provided in Exhibit B.25. 
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1 

2 Exhibit B.25 Water Quality at GCWA 

3 

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 

4 

5 

6 The Original Treatment Process at the Gulf Coast Water Authority

7 

8 Before treatment changes were made at the Thomas S. Mackey WTP, free chlorine was 

9 used as a primary disinfectant. The treatment train consisted of the following: 

10 

11 • raw water pumping 

12 • chemical addition (including lime softening) 

13 • upflow solids contact/clarification 

14 • recarbonation 

15 • filtration 

16 • disinfection (with free chlorine) 

17 • finished water pumping 

18 

19 The Brazos River has moderate to high concentrations of TOC, as well as high bromide 

20 concentrations. The Thomas S. Mackey WTP was using chlorine as a disinfectant; therefore, 

21 GCWA was facing the challenge of controlling formation of chlorinated and brominated DBPs. 

22 Under these conditions, TTHM formation was ranging up to 350 μg/L, and TTHM formation 

23 potential (TTHMFP) concentrations were ranging between 800 and 1000 μg/L. These concerns 

24 were the main reasons that GCWA changed their disinfection strategy from chlorine to chlorine 

25 dioxide. 

26 

27 Simultaneous Compliance Issues Faced by the Utility

28 

29 Disinfection with chlorine dioxide raised the following compliance issues for GCWA: 

30 

31 • Ensuring that the system was in compliance with SWTR and IESWTR under all 

32 operating conditions 
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1 • Ensuring that the Stage 1 DBPR TTHM MCL of 80 μg/L and HAA5 MCL of 60 

2 μg/L were not exceeded 

3 • Ensuring that the Stage 1 DBPR chlorine dioxide MRDL of 0.8 mg/L and the chlorite 

4 MCL of 1.0 mg/L were not exceeded 

5 

6 Note, at the time of the treatment train modifications, the plant was initially operating to 

7 comply with a TTHM MCL of 100 μg/L and limiting the use of chlorine dioxide to make sure 

8 the sum of chlorine dioxide, chlorite, and chlorate did not exceed 1 mg/L. 

9 

10 Steps Taken by the Utility

11 

12 GCWA conducted eight phases of research before a final decision was made to use 

13 chlorine dioxide as both a primary and secondary disinfectant. Exhibit B.26 show the various 

14 disinfection strategies implemented at GCWA during the eight phases. 

15 

16 Exhibit B.26 Disinfection Strategies implemented at GCWA 

17 

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 

18 Source: Adapted from Krasner et al., 2003. 

19 Notes: 

1 20 Disinfection scheme changed after SWTR promulgation 

2 21 Chlorine dioxide used intermittently as a pre-oxidant in raw water 

3 22 Chlorine dioxide used as primary disinfectant following filtration 

4 23 Breakpoint chlorination used to achieve free chlorine residual in distribution system 

24 

25 

26 As shown in Exhibit B.26, the eight phases span more than 20 years. Following 

27 promulgation of SWTR, chlorine dioxide was used as a primary disinfectant, which was applied 

28 after filtration. Chloramines were used for secondary disinfection. Additionally, chlorine 

29 dioxide was also intermittently used as pre-oxidant, which was applied to the raw water. 
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1 

2 A process schematic of the treatment train at the Thomas S. Mackey WTP after changes 

3 were made is provided in Exhibit B.27. 
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1 Exhibit B.27 Schematic of Thomas S. Mackey WTP Treatment TrainAfter Changes 

2 Were Made

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 Source: Krasner et al., 2003.

46 

47 Results of the Steps Taken

48 

49 During the disinfection scheme used in phase 8, TTHM concentrations decreased 

50 significantly from above 300 μg/L when free chlorine was used as the disinfectant. Disinfection 

51 with chlorine dioxide, followed by residual disinfection with chloramines, decreased TTHM 

52 concentrations in the GCWA system by approximately 80 percent, to 50 - 70 μg/L. 

53 
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1 Stage 1 DBPR set a chlorine dioxide MRDL of 0.8 mg/L and a chlorite MCL of 1.0 

2 mg/L. GCWA is in compliance with these requirements. GCWA applies a chlorine dioxide 

3 dose of 0.75 mg/L and, as shown in Exhibit B.28, the chlorite concentration in the treated water 

4 is 0.5 mg/L. However, the chlorine dioxide dose applied is not high enough to obtain any CT log 

5 removal credit under LT2ESWTR. 

6 

7 The GCWA treated water quality after modifications were made to disinfection is 

8 summarized in Exhibit B.28. 

9 

10 Exhibit B.28 Treated Water Quality at GCWA 

11 

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) 

12 Note: Based on data collected between January 1996 - November 1997. Partial lime softening was discontinued in 

13 1994.

14 

15 
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1 Implementation and Operational Issues Faced by the Utility

2 

3 Because chlorine dioxide was a new technology at the time GCWA was considering 

4 switching disinfectants, they were faced with some technical questions and challenges in the 

5 implementation of chlorine dioxide as their primary disinfectant. Most of the technical issues 

6 concerned distribution system water quality, and therefore there was need for a full-scale plant 

7 study. The main technical issues faced by GCWA are summarized below: 

8 

9 • Effectiveness of disinfection with chlorine dioxide 

10 • Microbial side effects in distribution system 

11 • Production of chlorite as a byproduct of chlorine dioxide generation 

12 • Taste and odor issues related to disinfection with chlorine dioxide 

13 

14 

15 Lessons Learned From this Case Study

16 

17 • Use of chlorine dioxide can help a system comply with TTHM and HAA5 MCLs. 

18 

19 • Systems may have trouble providing sufficient Cryptosporidium inactivation to 

20 satisfy LT2ESWTR toolbox requirements and still meet the chlorine dioxide MRDL 

21 and chlorite MCL. 
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1 

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4 

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9 

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1 Case Study #14 

2 Chlorine Dioxide for Primary Disinfection and Chloramines 

3 for Residual Disinfection 

4 Village of Waterloo Water Treatment Plant 

5 Waterloo, New York

6 

7 

8 This case study provides an example of a small surface water system that successfully 

9 converted from using chlorine as its primary and residual disinfectant to using chlorine dioxide 

10 for primary disinfection and chloramines for residual disinfection. By switching disinfectants, 

11 the Village of Waterloo improved its ability to comply with Stage 1 DBPR and Stage 2 DBPR 

12 requirements, added protection against Cryptosporidium, and improved the system’s ability to 

13 maintain a disinfectant residual throughout its distribution system. The narrative for this case 

14 study borrows from Gell and Bromka (2003). Readers should refer to this paper for more 

15 information about the changes made to Waterloo’s system. 

16 

17 Introduction

18 

19 The Village of Waterloo operates a diatomaceous earth (DE) filtration plant that draws 

20 water from Seneca Lake in central New York. The original treatment plant design provides a 

21 nominal capacity of 2 million gallons per day (MGD), but the system plans to expand its service 

22 to neighboring areas. The system currently serves fewer than 10,000 people, but covers a large 

23 geographical area. 

24 

25 The DE filtration produces a low turbidity finished water (usually <0.2 NTU) but does 

26 not significantly reduce concentrations of DBP precursors. When chlorine was used, DBPs 

27 leaving the plant were generally low but increased to levels close to or above the TTHM MCL. 

28 The high DBP levels resulted because the distribution system is sufficiently large and retention 

29 time sufficiently long that chlorine, NOM, and bromide in the water had several days to react 

30 with each other and form high TTHM concentrations. 

31 

32 A summary of Seneca Lake raw water quality is provided in Exhibit B.29. 

33 
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1 

2 Exhibit B.29 Seneca Lake Raw Water Quality 

3 

4 

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 

5 Adapted from Gell, R. and Bromka, 2003.

1 6 Timeframe for the chlorine demand is 1.5 to 2 hours, depending on how much water is being pumped by the 

7 system.

8 

9 

10 Moderate bromide concentrations in the raw water were causing predominantly 

11 brominated THMs to be formed in the finished water. A 1998 survey of distribution system 

12 samples showed an average TTHM concentration of 79 Fg/L and an average HAA5 

13 concentration of 21 Fg/L. TTHM concentrations ranged from 48 to 150 Fg/L, with 

14 approximately 75 percent of the TTHM being brominated compounds. 

15 

16 At the same time when the Waterloo system was considering treatment modifications to 

17 improve water quality, the system was receiving requests from neighboring areas to expand its 

18 service area. As a result, modifications made at the treatment plant included upgrades to 

19 increase capacity as well as improve water quality. 

20 

21 The Original Treatment Process at the Waterloo WTP

22 

23 The Village had added potassium permanganate consistently, and PAC/permanganate 

24 seasonally, to control zebra mussel growth and taste and odor problems. These were fairly 

25 effective at controlling seasonal taste and odor problems, but the Village operators were 

26 interested in improving taste and odor treatment for more consistent control. 

27 
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1 Chlorine had previously been added after the DE filters and before water entered the 

2 clearwell in order to achieve sufficient Giardia and virus CT. Chlorine was added again at 

3 booster stations in order to maintain a sufficient disinfectant residual throughout 

4 the distribution system. 

5 

6 Simultaneous Compliance Issues Faced by the Utility

7 

8 The Village of Waterloo faced problems complying with both the Stage 1 D/DBPR and 

9 the Stage 2 DBPR due to high TTHM concentrations in its distribution system. It was having 

10 trouble maintaining a disinfectant residual throughout the distribution system, which is a 

11 requirement of the SWTR. 

12 

13 At the same time that the Stage 1 DBPR requirements were introduced, the IESWTR and 

14 the LT1ESWTR introduced requirements for the removal of Cryptosporidium. Although DE 

15 filtration is not effective at removing DBP precursors, the Village of Waterloo wanted to keep its 

16 DE filters in use because of their simplicity and performance for Cryptosporidium removal. The 

17 Village has been monitoring their raw water for Cryptosporidium for several years, and no 

18 oocysts have been detected. 

19 

20 Steps Taken by the Utility

21 

22 A pilot study helped the Village realize that installing treatment to remove DBP 

23 precursors would not be efficient, because of the low SUVA concentrations in Seneca Lake’s 

24 water. Since the system uses DE for its filtration step, enhanced coagulation would have 

25 required significant modifications to the current filtration process. Moreover, the Waterloo 

26 treatment plant’s lakefront location limited options for the disposal of waste streams that would 

27 have been generated by many of the DBP precursor removal options. 

28 

29 Simulated distribution system testing showed that TTHM and HAA5 concentrations 

30 could be lowered significantly if the system changed its residual disinfectant from chlorine to 

31 chloramines. This discovery enabled the system to keep its existing DE filtration process by 

32 opting for an alternative disinfection strategy. 

33 

34 In addition, by changing its primary disinfectant from chlorine to chlorine dioxide, the 

35 Village could simplify its operations by eliminating the use of potassium permanganate for zebra 

36 mussel and taste and odor control. Chlorine dioxide is now injected at the intake structure. 

37 Furthermore, changing primary disinfectant from chlorine to chlorine dioxide has enabled a 

38 smaller clearwell expansion, which has reduced the amount of expensive lakefront real estate 

39 needed by the treatment plant. 

40 

41 Chlorine dioxide is added to the intake and maintains a residual throughout the clearwell. 

42 Anhydrous ammonia is added immediately after the clearwell into the discharge pipe before 

43 water is pumped into the distribution system. A few yards downstream of the ammonia addition 
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1 point, chlorine gas is injected. Bench scale tests determined the optimum ammonia and chlorine 

2 dosages to maintain a total chlorine residual of 2.0 mg/L over several days. 

3 

4 Before converting from free chlorine to chloramines, the Village, with assistance from its 

5 consultants, conducted a thorough and successful public notification campaign to inform users of 

6 the potential adverse impact of chloramines consumption (primarily for dialysis patients and fish 

7 owners). The Village hosted public meetings, placed newspaper articles, and issued notifications 

8 that provided the important information. 

9 

10 Results of the Steps Taken

11 

12 The reductions in TTHM and HAA5 concentrations after the system switched to chlorine 

13 dioxide and chloramines exceeded the Water Manager’s expectations. In 2002, THM levels 

14 were mostly below their detection levels, with one TTHM measurement of 2.1 Fg/L in August at 

15 the farthest sampling location. HAA5 concentrations in 2002 averaged 8 Fg/L. The total 

16 chlorine residual has been maintained throughout the distribution system without the use of re17 chlorination stations. 

18 

19 The chlorine dioxide dosage ranges from 0.4 to 1.00 mg/L, depending on water 

20 temperature. Distribution system chlorite concentrations range from 0.25 to 0.45 mg/L. 

21 

22 The Village has not experienced any uncontrollable re-growth episodes, but uses a 

23 carefully monitored program to address the potential for nitrification and biological re-growth. 

24 As part of this effort, the Village adheres to the following guidelines: 

25 

26  Maintain a high chlorine to ammonia weight ratio (5:1) at the time when the 

27 chloramines are formed. 

28  Maintain a finished water total chlorine residual of 2 mg/L and a residual of at least 

29 1.0 mg/L throughout the distribution system. 

30  Take advantage of the possibility that chlorite, a byproduct of chlorine dioxide 

31 disinfection, may be toxic to nitrifying bacteria. 

32  Monitor monthly for HPC, nitrite, chlorite, free and total ammonia at each storage 

33 tank and at key points in the distribution system. 

34  Routinely check the percentage of monochloramine in the total chlorine present. Aim 

35 to have at least 95 percent monochloramine leaving the treatment plant. 

36 

37 Since switching disinfectants, the Village has observed two occasions when HPC 

38 numbers increased, and traced the cause of these events to stagnation in a remote storage tank. 

39 Sodium hypochlorite was added to the tank and HPC levels returned to normal. Plans are being 

40 developed to improve mixing in the tanks. 

41 

42 The Water Director believes that previously bothersome taste and odor problems are 

43 being controlled more effectively by using chlorine dioxide. He also believes that the use of 
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1 chloramines following chlorine dioxide has prevented the development of nuisance odors 

2 associated with chlorine dioxide in households (see Hoehn et al., 1990). 

3 

4 Implementation and Operational Issues Faced by the Utility

5 

6 The Village encountered an operational problem when it first converted to chloramines. 

7 Ammonia reacts with calcium and magnesium hardness in the water and produces a scale, even 

8 when hardness values are as low as 35 mg/L as CaCO3. As a result, scaling was clogging the 

9 injector throat of the ammonia feed system. Since a water softening unit was installed to treat 

10 the water that is used for injection, the ammonia feed system has functioned reliably. 

11 

12 The Village has a service contract with the company that provided the chlorine dioxide 

13 equipment to supply sodium chlorite and monitor and verify the performance of the generator. 

14 This contract has provided the Village with sufficient time to educate its staff on proper 

15 equipment operation. 

16 

17 Further Reading

18 

19 Readers who are interested in learning more about the Village of Waterloo system should refer to 

20 the following paper: 

21 

22 Gell, Richard and Bromka, James. 2003. Successful Application of Chloramines to Manage 

23 Disinfection By-Products. New York State Section AWWA. September 2003. Published by 

24 O’Brien and Gere. 
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1 Appendix C 

2 Guidelines for Evaluating Potential Impacts of Treatment Changes on 

3 Distribution Systems
 

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2 
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1 Appendix C Guidelines for Evaluating Potential Impacts of Treatment 

2 Changes on Distribution Systems 

3 

4 This appendix is designed to accompany the guidance manual and act as a tool for examining 

5 issues that might arise in the distribution system as a result of changes made during treatment. 

6 The table below lists treatment changes that could potentially impact the distribution system and 

7 page numbers in this appendix where the potential impacts of particular treatment changes are 

8 discussed. A list of references is also included for each distribution system impact. 

9 

Treatment Change See Appendix Page

Modifying pH C-2 

Change in finished water alkalinity C-6 

Change in finished water oxidation/reduction potential C-9 

Switching from chlorine to chloramines C-10 

Switching coagulant C-14 

Modifying chlorine dose with warmer water temperatures C-16 

Adding/discontinuing softening C-17 

Adding ozone C-21 

Adding chlorine dioxide C-24 

Enhanced coagulation C-27 

Installing nanofiltration C-30 

Installing granular activated carbon C-33 

Installing ozone without subsequent biological filtration C-34 
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1 MODIFYING pH 

2 

3 The following impacts to your distribution system may result from modifying pH: 

4 

5 • Increased lead and copper in tap water 

6 • Change/disruption of scale 

7 • Colored water 

8 • High iron 

9 • Increased heterotrophic bacteria 

10 • Nitrite/nitrate formation 

11 12 • Change in DBP concentration/composition 

13 

14 References, along with brief descriptions of treatment impacts, are provided below. Refer to 

15 Section 3.4 for additional information on modifying pH during chlorination. 

16 

17 

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. 18 

Further Reading

• U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• U.S. EPA. 2000c. Lead and Copper Rule: Summary of Revisions. Office of Water. EPA 815-R-99-

020. 

• U.S. EPA. 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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 
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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. Fifth 

Edition. Letterman, R.D. (editor). McGraw-Hill. 1,233 pp. 

• U.S. EPA. 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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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

• U.S. EPA. 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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 
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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

• U.S. EPA. 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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, William C. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 
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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. 

• Kirmeyer, G.J. et al. 2004. Update of Optimizing Chloramine Treatment. AWWARF Report 90993. 

Project #2760. 

• Kirmeyer, G.J. et al. 1995. Nitrification Occurrence and Control in Chloraminated Water Systems. 

AWWARF Report 90669. Project #710. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Cowman, G.A., and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation 

Resulting from Chlorination and Chloramination of Humic Extracts. Conference proceedings, 

AWWA Annual Conference, New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, William C. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 
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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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, William C. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

1 
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1 CHANGE IN FINISHED WATER ALKALINITY

2 

3 The following impacts to your distribution system may result from changes in finished water 

4 alkalinity: 

5 

6 • Increased lead and copper in tap water 

7 • Change/disruption of scale 

8 • Colored water 

9 • High iron 

10 • Pinhole leaks 

11 

12 The following reference can provide further information about how to address most of these 

13 impacts. Additional references and brief descriptions are listed by impact in the table below. 

14 

15 • AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of 

16 Water Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

17 

18 Refer to Sections 3.4 and 3.7 for additional information on changes in finished water alkalinity. 

19 

20 

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. Fifth 

Edition. Letterman, R.D. (editor). McGraw-Hill. 1,233 pp. 

• AWWA. 2004c. Draft. Managing Lead and Copper Rule Corrosion Control Practices to Avoid 

Unintended Consequences. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 
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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). McGraw-Hill, New York, NY. 

• U.S. EPA. 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. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

• Douglas, B.D., and D.T. Merrill. 1991. Control of Water Quality Deterioration Caused by 

Corrosion of Cement-Mortar Pipe Linings. 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). McGraw-Hill, New York, NY. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 
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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). McGraw-Hill, New York, NY. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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. 

1 
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1 CHANGE IN FINISHED WATER OXIDATION/REDUCTION POTENTIAL

2 

3 Oxidation/reduction (redox) potential is the ability of the water to oxidize or reduce compounds 

4 it comes into contact with, and is measured electrochemically. The following impacts to your 

5 distribution system may result from if a treatment change causes a change in finished water 

6 oxidation/reduction potential: 

7 

8 • Increased lead in tap water 

9 • Change/disruption of scale 

10 

11 The following references can provide further information about how to address both of these 

12 impacts. Additional references and brief descriptions are listed by impact in the table below. 

13 

14 • AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of 

15 Water Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

16 • Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control 

17 in Distribution Systems. AWWARF. Denver, CO. 

18 

19 Refer to Section 5.1 for additional information on changes to finished water oxidation/reduction 

20 potential. 

21 

Increased lead in tap water

Description 

Raising or lowering the oxidation/reduction potential 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. 22 

Further Reading

• AWWA. 2004d. Proceedings of Getting the Lead Out: Analysis & Treatment of Elevated Lead 

Levels in DC’s Drinking Water. WQTC. 

Change/disruption of scale

Description

Changing the oxidation/reduction potential 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. 
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Further Reading

• AWWA. 2004c. Draft. Managing Lead and Copper Rule Corrosion Control Practices to Avoid 

Unintended Consequences. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 
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1 SWITCHING FROM CHLORINE TO CHLORAMINES

2 

3 The following impacts to your distribution system may result from switching from chlorine to 

4 chloramines: 

5 

6 • Increased lead in tap water 

7 • Change/disruption of scale 

8 • Taste and odor 

9 • Increased coliform bacteria 

10 • Increased heterotrophic bacteria 

11 • Nitrite/nitrate formation 

12 • Change in DBP concentration/composition 

13 

14 The following references can provide further information about how to address most of these 

15 impacts. Additional references and brief descriptions are listed by impact in the table below. 

16 

17 • Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second 

18 Edition. AWWA. Denver, CO. 278 pp. 

19 • U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 

20 815-R-99-014. 

21 

22 Refer to Section 5.1 for additional information on switching from chlorine to chloramines. 

23 

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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 
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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

• U.S. EPA. 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). McGraw-Hill, New York, NY. 

• AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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 not to exceed 

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. 1999. Formation and Control of Disinfection By-Products in Drinking Water. AWWA. 

Denver, CO. 424 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 
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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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Kirmeyer, G.J. et al. 1995. Nitrification Occurrence and Control in Chloraminated Water Systems. 

AWWARF Report 90669. Project #710. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Cowman, G.A., and P.C. Singer. 1994. Effect of Bromide Ion on Haloacetic Acid Speciation 

Resulting from Chlorination and Chloramination of Humic Extracts. Conference proceedings, 

AWWA Annual Conference, New York, NY. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 
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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. et al. 1995. Nitrification Occurrence and Control in Chloraminated Water Systems. 

AWWARF Report 90669. Project #710. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, CO. 174 pp. 

• AWWARF. 2004b. Update of Optimizing Chloramine Treatment Project #2760. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, 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. Conference 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. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

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

• U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous Compliance Guidance 

Manual. EPA 815-R-99-011. August 1999. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

• Valentine, R. 2001. Mechanisms and Kinetics of Chloramine Loss and By-Product Formation in 

the Presence of Reactive Drinking Water Distribution System Constituents. USEPA. 
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1 SWITCHING COAGULANT

2 

3 The following impacts to your distribution system may result from switching your coagulant: 4 

5 • Change in finished water pH 

6 • Increased lead and copper in tap water 

7 • Change/disruption of scale 

8 • Change in finished water NOM 

9 • Change in chloride:sulfate ratio 10 

11 The following references can provide further information about how to address most of these 

12 impacts. Additional references and brief descriptions are listed by impact in the table below. 13 

14 • U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

15 Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

16 • U.S. EPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening 

17 Guidance Manual. Office of Water. EPA 815-R-99-012. 

18 

19 Refer to Sections 3.3 and 3.7 for additional information on switching coagulants. 

20 

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. 21 

Further Reading

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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

• U.S. EPA. 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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 
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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. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

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., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 
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1 MODIFYING CHLORINE DOSE WITH WARMER WATER TEMPERATURES

2 

3 The following impacts to your distribution system may result from reducing chlorine dose during 

4 warmer water temperatures in order to reduce DBP formation: 5 

6 • Increased coliform and heterotrophic bacteria 

7 • Increased loss of chlorine residual in the distribution system 8 

9 The following references can provide further information about how to address this distribution 

10 system impact: 11 

12 • White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. Fourth 

13 ed. Van Nostrand Reinhold Co., New York, NY. 

14 • Connell, G. 1996. The Chlorination/Chloramination Handbook. AWWA. Denver, 

15 CO. 174 pp. 

16 • Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second 

17 Edition. AWWA. Denver, CO. 278 pp. 

18 • AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

19 Transmission and Distribution, Third Edition. 553 pp. 

20 • Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water 

21 Quality. AWWARF Report 90798. Project #357. 

22 • Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, 

23 CO. 

24 • Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

25 • Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. 

26 Denver, CO. 85 pp. 

27 • U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 

28 815-R-99-014. 

29 

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. 
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1 ADDING/DISCONTINUING SOFTENING

2 

3 The following impacts to your distribution system may result from adding or discontinuing 

4 softening: 

5 

6 • Change in finished water pH 

7 • Increased lead and copper in tap water 

8 • Change/disruption of scale 

9 • Taste and color problems 

10 • Change in finished water NOM 

11 • High iron 

12 • Change in DBP concentration/composition 

13 • Pinhole leaks 

14 

15 The following reference can provide further information about how to address all of these 

16 impacts. Additional references and brief descriptions are listed by impact in the table below. 

17 

18 • U.S. EPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening 

19 Guidance Manual. Office of Water. EPA 815-R-99-012. 

20 

21 Refer to Section 3.8 for additional information on adding or discontinuing softening. 

22 

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. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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. 
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Further Reading

• AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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, Third Edition. 553 pp. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 
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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). McGraw-Hill, New York, NY. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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. 
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Further Reading

• AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). McGraw-Hill, New York, NY. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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. 

1 
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1 ADDING OZONE

2 

3 The following impacts to your distribution system may result from adding ozone: 

4 

5 • Increased lead and copper in tap water 

6 • Taste and odor 

7 • Change in finished water NOM 

8 • Colored water 

9 • High iron 

10 • Change in DBP concentration/composition 

11 

12 The following references can provide further information about how to address most of these 

13 impacts. Additional references and brief descriptions are listed by impact in the table below. 

14 

15 • U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 

16 815-R-99-014. 

17 • U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

18 Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

19 

20 Refer to Section 5.2 for additional information on adding ozone. 

21 

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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 
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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. 

• Singer, P.C. 1999. Formation and Control of Disinfection By-Products in Drinking Water. AWWA. 

Denver, CO. 424 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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. 1999. Formation and Control of Disinfection By-Products in Drinking Water. AWWA. 

Denver, CO. 424 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

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. 
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Further Reading

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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

• U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• U.S. EPA. 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. Fourth ed. Van 

Nostrand Reinhold Co., New York, NY. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 
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1 ADDING CHLORINE DIOXIDE

2 

3 The following impacts to your distribution system may result from adding chlorine dioxide: 

4 

5 • Increased lead and copper in tap water 

6 • Taste and odor 

7 • Change in finished water NOM 

8 • Colored water 

9 • High iron 

10 • Change in DBP concentration/composition 

11 

12 References, along with brief descriptions, that are specific to individual issues are listed by 

13 impact in the table below. Refer to Sections 5.4 and 5.5 for additional information on adding 

14 chlorine dioxide. 

15 

Increased lead and copper in tap water

Description

Changing to chlorine dioxide from another oxidant can change the oxidation/reduction potential of the tap water. 

Changes in oxidation/reduction potential 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. 2004c. Draft. Managing Lead and Copper Rule Corrosion Control Practices to Avoid 

Unintended Consequences. 

• AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water Distribution 

Systems. 2nd edition. AWWARF Report 90508. Project #725. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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). 
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Further Reading

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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

• U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Andrews, R.C. et al. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and Distribution 

System Performance. AWWARF Report 91082. Project #2843. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

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 oxidation/reduction potential can also destabilize some already formed layers of corrosion products, 

leading to colored water. 

Further Reading

• U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Andrews, R.C. et al. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and Distribution 

System Performance. AWWARF Report 91082. Project #2843. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 
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High iron

Description

Chlorine dioxide can react with organic matter to form AOC which can cause microbial-induced corrosion. 

Changes in water oxidation/reduction potential resulting from chlorine dioxide use may also allow dissolution of 

existing scales. 

Further Reading

• U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• Andrews, R.C. et al. 2005. Impact of Chlorine Dioxide on Transmission, Treatment, and Distribution 

System Performance. AWWARF Report 91082. Project #2843. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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

• U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 815-R-99-014. 

• White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants. Fourth ed. Van Nostrand 

Reinhold Co., New York, NY. 

• Gates, D. 1997. The Chlorine Dioxide Handbook. AWWA. Denver, CO. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

1 
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1 ENHANCED COAGULATION

2 

3 The following impacts to your distribution system may result from using enhanced coagulation: 

4 

5 • Reduction in finished water pH 

6 • Increased lead and copper in tap water 

7 • Change/disruption of scale 

8 • Change in finished water NOM 

9 • Change in DBP concentration/composition 

10 • Change in chloride:sulfate ratio 

11 

12 The following references can provide further information about how to address most of these 

13 impacts. Additional references and brief descriptions are listed by impact in the table below. 

14 

15 • U.S. EPA. 1999h. Enhanced Coagulation and Enhanced Precipitative Softening 

16 Guidance Manual. Office of Water. EPA 815-R-99-012. 

17 • U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

18 Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

19 

20 Refer to Section 3.7 for additional information on using enhanced coagulation. 

21 

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. 22 

Further Reading

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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. 
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Further Reading

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

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, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 
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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., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

1 
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1 INSTALLING NANOFILTRATION

2 

3 The following impacts to your distribution system may result from installing nanofiltration: 

4 

5 • Change in finished water pH 

6 • Increased lead and copper in tap water 

7 • Change/disruption of scale 

8 • Change in finished water NOM 

9 • Colored water 

10 • High iron 

11 • Change in DBP concentration/composition 

12 • Pinhole leaks 

13 

14 The following reference can provide further information about how to address most of these 

15 impacts. Additional references and brief descriptions are listed by impact in the table below. 

16 

17 • AWWA. 1999b. Reverse Osmosis and Nanofiltration. AWWA Manual M46. 178 pp. 

18 

19 Refer to Section 4.3 for additional information on installing nanofiltration. 

20 

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. 2004. Integrated Membrane Systems. AWWARF Report 90899. Project #264. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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. 
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Further Reading

• AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

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. 
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Further Reading

• AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

• Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• AWWA. 2003a. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. 553 pp. 

• Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water Quality. 

AWWARF Report 90798. Project #357. 

• Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

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. 

• Duranceau, S.J., D. Townley, and G.E.C. Bell. 2004. Optimizing Corrosion Control in Distribution 

Systems. AWWARF Report 90983. Project #2648. 

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, Second Edition. AWWA. 

Denver, CO. 278 pp. 

• Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 85 

pp. 

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. 
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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. 
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1 INSTALLING GRANULAR ACTIVATED CARBON

2 

3 The following impacts to your distribution system may result from installing granulated activated 

4 carbon (GAC): 

5 

6 • Increased coliform and heterotrophic bacteria 

7 

8 The following references can provide further information about how to address this impact. A 

9 brief description of the distribution system impact is provided in the table below. 

10 

11 • AWWA. 1990. Water Quality and Treatment. F.W. Pontius (editor). McGraw-Hill, 

12 New York, NY. 

13 • American Chemical Society. 1983. Treatment of Water by Granular Activated 

14 Carbon. M.J. McGuire and I.H. Suffet (eds). ACS, Washington, D.C. 

15 • Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second 

16 Edition. AWWA. Denver, CO. 278 pp. 

17 • AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

18 Transmission and Distribution, Third Edition. 553 pp. 

19 • Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water 

20 Quality. AWWARF Report 90798. Project #357. 

21 • Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, 

22 CO. 

23 • Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

24 • Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. 

25 Denver, CO. 85 pp. 

26 

27 Refer to Section 4.1 for additional information on installing GAC. 

28 

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. 

29 
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1 INSTALLING OZONE WITHOUT SUBSEQUENT BIOLOGICAL FILTRATION

2 

3 The following impact to your distribution system may result from installing ozone without 

4 subsequent biological filtration: 

5 

6 • Increased coliform and heterotrophic bacteria 

7 

8 The following references can provide information about how to address this impact. A brief 

9 description of the distribution system impact is provided in the table below. 

10 

11 • Singer, P.C. 1999. Formation and Control of Disinfection By-Products in Drinking 

12 Water. AWWA. Denver, CO. 424 pp. 

13 • U.S. EPA. 1999b. Alternative Disinfectants and Oxidants Guidance Manual. EPA 

14 815-R-99-014. 

15 • U.S. EPA. 1999f. Microbial and Disinfection Byproduct Rules Simultaneous 

16 Compliance Guidance Manual. EPA 815-R-99-011. August 1999. 

17 • Von Huben, H. 1999. Water Distribution Operator Training Handbook, Second 

18 Edition. AWWA. Denver, CO. 278 pp. 

19 • AWWA. 2003a. Principles and Practices of Water Supply Operations: Water 

20 Transmission and Distribution, Third Edition. 553 pp. 

21 • Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water 

22 Quality. AWWARF Report 90798. Project #357. 

23 • Lauer, W.C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, 

24 CO. 

25 • Mays, L.W. 1999. Water Distribution Systems Handbook. AWWA. Denver, CO. 

26 • Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. 

27 Denver, CO. 85 pp. 

28 

29 Refer to Section 5.2 for additional information on installing ozone without subsequent biological 

30 filtration. 

31 

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. 

32 
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1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 This page intentionally left blank. 
 

1 Appendix D 

2 Tools for Evaluating Impacts of Treatment Changes on 

3 Lead and Copper Rule Compliance 
 

1 

2 

3 This page intentionally left blank. 

4 
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1 Appendix D Tools for Evaluating Impacts of Treatment Changes on Lead and 

2 Copper Rule Compliance 

3 

4 Many things can cause corrosion of piping and appurtenances in the distribution system. 

5 Changes in pH, alkalinity, microbiological growth, oxidation reduction potential of the water, 

6 and electric currents passing through the piping can increase corrosion rates. While corrosion is 

7 always a concern, if it occurs in distribution system elements containing lead or copper, it can 

8 result in an exceedence of Lead and Copper Rule (LCR) action levels. 

9 

10 Because corrosion can lead to increased levels of lead and copper at the tap, prevention 

11 and quick responses are important. Corrosion assessment tools can be valuable for preventing 

12 corrosion and responding to it when it occurs. This appendix gives brief descriptions of tools 

13 that can be used to examine impacts of water quality change on corrosion, and to identify and 

14 locate existing corrosion problems. It also provides references where more in-depth information 

15 can be found. 

16 

17 Corrosion assessment tools can be used in several different ways. In cases where 

18 corrosion has already become a problem, they can be used to determine where and why it is 

19 occurring and to test alternative corrosion control strategies. If used prior to a treatment change, 

20 they can be used to assess the potential impact of the treatment change on corrosion. They can 

21 also be used to select appropriate materials that will perform the best for a given water quality. 

22 

23 D.1 Desktop Studies

24 

25 Description of Method

26 

27 A desktop evaluation should aim to document the extent, magnitude and possible causes 

28 of a potential problem by developing and assessing options, identifying constraints on the system 

29 and recommending actions for systems to implement. Desktop studies can include: 

30 

31 32 • literature reviews 

33 

34 • mathematical modeling 

35 

36 • review of past findings 

37 

38 • review of standards and guidance documents 

39 

40 • expert opinion, and 

41 
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1 • consultation with other systems with similar water quality and distribution systems 

2 Desktop studies typically examine the literature to find information. Case studies of systems 

3 with similar problems can be helpful. For example, AWWA’s Water Industry Technical Action 

4 Fund conducted a survey of lead and copper leaching in 400 US water systems. The survey 

gives 90th 5 percentile lead and copper values for each of the 400 systems along with other water 

6 quality data such as pH, alkalinity, calcium, and the any corrosion inhibitor used. Systems could 

7 use such data to discern general trends in corrosion with changes in water quality programs, or 

8 they could look specifically for systems with similar water quality to their own and find what 

9 was worked for those systems. 

10 

11 Literature reviews of laboratory studies may help reveal mechanisms and possible corrosion 

12 prevention strategies. Contacting consultants or researchers familiar with the problem or 

13 systems that have encountered similar problems can also aid in finding a solution. Computer 

14 models can be helpful for predicting potential corrosion problems. Chemical solubility models 

15 can predict the thermodynamic stability of a given metal in a specific water quality. These 

16 solubility models may be especially useful for lead corrosion. Blending analysis programs can 

17 predict the water quality of multiple sources blended in a distribution system and help determine 

18 if and where corrosive conditions might result. In cases where models may not be sufficient, jar 

19 testing can help show how treatment changes can change finished water quality. 

20 

21 Uses and Limitations

22 

23 Desktop studies can be useful prior to changes to determine potential corrosion problems. 

24 They can also be used to find solutions to existing corrosion problems. They are a relatively 

25 inexpensive ways to narrow down the number of potential solutions to a corrosion problem. 

26 They can draw off other’s expertise and minimize time spent on testing ineffectual techniques. 

27 

28 Desktop studies, however, are limited in that they do not apply exactly to a specific 

29 system’s water quality and configuration. For this reason, they can rarely be used alone but are 

30 often used in combination with other methods. 

31 

32 References 

33 

34 Hecht, P.M., and E.A. Turner. 2004. Washington Aqueduct Desktop & Flow-Through 

35 Study. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

36 Levels in DC’s Drinking Water at the 2004 AWWA WQTC. 

37 

38 AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

39 Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

40 

41 AWWA 1993. Initial Monitoring Experiences of Large Water Utilities Under USEPA’s 

42 Lead and Copper Rule. Sponsored by the WITAF. Denver Colorado. 
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1 

2 

3 D.2 Expanded Baseline Monitoring

4 

5 Description of Method

6 

7 The LCR requires systems to measure water quality parameters in the distribution 

8 system. These parameters include: pH, alkalinity, calcium, conductivity, temperature, and the 

9 concentration of any corrosion inhibitors, as determined by the primacy agency and the corrosion 

10 control permit. Samples give useful information on the state of corrosion within the distribution 

11 system. By expanding this monitoring throughout the system and performing it at more frequent 

12 intervals, better information on potential trouble spots within the system can be determined. For 

13 example, bacteriological data from TCR compliance monitoring can help systems identify areas 

14 likely to suffer from biologically enhanced corrosion. Water quality parameteter monitoring 

15 conducted at TCR sample sites can help systems identify LCR compliance issues. 

16 

17 Usefulness and Limitations

18 

19 Monitoring can provide systems with a good sense of areas of the system that have 

20 potentially corrosive waters or may be experiencing biologically induced corrosion. It can also 

21 show how effective a corrosion inhibitor is performing. It cannot predict corrosion rates or 

22 predict successful corrosion control strategies. Burlingame and Sandvig (2004) provides an 

23 example of how one system used evaluate lead and copper data to determine if changes in 

24 operations, treatment, or source were impacting lead and copper corrosion rates. 

25 

26 References 

27 

28 U.S. EPA 2002c. Lead and Copper Monitoring and Reporting Guidance for Public Water 

29 Systems. Office of Water. EPA 816-R-02-009. 

30 

31 Kirmeyer, G.J. 2000b. Guidance Manual for Maintaining Distribution System Water 

32 Quality. AWWARF Report 90798. Project #357. 

33 

34 Burlingame, G.A. and A. Sandvig. 2004. How to Mine Your Lead and Copper Data. 

35 Opflow. 30(6):16-19. 

36 

37 

38 D.3 Coupon Techniques

39 

40 Description of Method

41 
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1 Coupon techniques are a commonly used technique to evaluate the corrosion of a given 

2 distribution system metal for a given water quality. Coupon techniques place a small sample or 

3 coupon of metal in flowing water that is the same as, or closely replicates, the water that will be 

4 used in the distribution system. Flow conditions also replicate those that will be experienced in 

5 the system as closely as possible. 

6 

7 Traditional coupon techniques have involved flat metal coupons mounted in a flow 

8 stream. These include methods ASTM D2688-83 method B, ASTM G1-81, ASTM G46-76, and 

9 the Water Research Center Coupon Rig. Other techniques have been developed that use actual 

10 pipe lengths. These include ASTM D2688-83 method C, Modified ISWS Coupon sleeve tester, 

11 Corps of Engineers Research Lab tester, Ringsaulen protocol, and the TZW Karlsruhe protocol. 

12 

13 Coupon preparation is important in order to obtain consistent corrosion rates, since the 

14 corrosion rate is highly dependent on the properties of the corroding surface. There are several 

15 different coupon preparation techniques, which include a variety of steps. Steps can include: 

16 

17 • machining, 

18 • deburring, 

19 • degreasing, 

20 • paint removal, 

21 • acid wash, 

22 • application of exterior epoxy, 

23 • drying, and 

24 • weighing. 

25 

26 Once the coupons are prepared, they are placed in the flow stream. Coupons are sacrificed 

27 periodically and the total weight loss is measured. It is necessary to ensure that enough coupons 

28 are used to obtain a statistically valid corrosion rate. Because corrosion rates vary over time as 

29 passivating layers form, coupon experiments must be done over a relatively long time span. Test 

30 periods can range from 1 month to 2 years. In addition, rates must also be reported over a 

31 standardized time frame to be comparable to other measured corrosion rates. 

32 

33 If pitting corrosion occurs, weight measurements can be combined with other visual 

34 inspection techniques to better determine potential useful life of the material. These visual 

35 techniques are described in ASTM G46-76. 

36 

37 Usefulness and Limitations

38 

39 Coupon techniques are best suited for determining likely corrosion rates that can be 

40 expected for given water quality conditions and a given metal. They are well suited for trending 

41 corrosion rates because actual water quality conditions and the actual metal are used. They can 

42 also be very useful in selecting new materials to be used for distribution system expansion or 
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1 rehabilitation. When combined with visual inspection techniques, coupon methods can give a 

2 good prediction of the expected service length of a given material in given water quality 

3 conditions. 

4 

5 Because coupon techniques take a long time, they are not usually appropriate for 

6 determining an early warning to a new problem. Coupon methods also measure weight loss and 

7 this has not always correlated well with measurements of metal in water samples (Schock 1996). 

8 In addition, coupon rates only measure total weight loss, so they may not be adequate for 

9 predicting material life of materials that undergo pitting corrosion. For these materials, coupon 

10 methods can be combined with inspection and analysis techniques to obtain estimates of material 

11 life. The number of coupons, the time involved, and the procedures needed to obtain some 

12 precision also make coupon testing a fairly labor intensive method. 

13 

14 References 

15 

16 ASTM D2688-83 Method B. 1983a. Standard Test Methods for the Corrosivity of Water 

17 in the Absence of Heat Transfer (Weight Loss Protocol). American Society for Testing 

18 and Materials. Philadelphia, PA. 

19 

20 ASTM D2688-83 Method C. 1983b. Standard Test Methods for the Corrosivity of Water 

21 in the Absence of Heat Transfer (Machined Nipple Test). American Society for Testing 

22 and Materials. Philadelphia, PA. 

23 

24 AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

25 Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

26 

27 ASTM G46-76. 1976. Recommended Practice for the Examination and Evaluation of 

28 Pitting Type Corrosion. American Society for Testing and Materials. Philadelphia, PA. 

29 

30 ASTM G1-81. 1981. Recommended Practice for Preparing, Cleaning and Evaluating 

31 Corrosion Test Specimens. American Society for Testing and Materials. Philadelphia, 

32 PA. 

33 

34 Schock, Michael. 1996. Corrosion Inhibitor Applications in Drinking Water Treatment: 

35 Conforming to the Lead and Copper Rule. Presented at NACE Corrosion 1996 

36 Conference. 

37 

38 D.4 Pipe Loops 

39 

40 Description of Method

41 
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1 Pipe loops use actual pipes to test corrosion rates of water of a given water quality. Pipe 

2 loops are most often made up of small diameter piping and are intended to simulate corrosion in 

3 the consumer’s plumbing. 

4 

5 Water is circulated through the pipe loop for an extended period of time. There are two 

6 types of pipe loops, flow through and recirculating. In flow through pipe loops, water flows 

7 through the pipe a single time as in a real system and is discharged to waste. Recirculating pipe 

8 loops recirculate the same water through the pipes continuously. In both types of pipe loops 

9 water can be stagnant in the pipes for periods of time to represent water use patterns. The water 

10 is collected and analyzed for corrosion products. Pipes must be conditioned for a period of time 

11 to achieve a stable rate of corrosion. 

12 

13 Corrosion can be measured in pipe loops using several different methods. These methods 

14 include: 

15 

16 • potentiodynamic scans, 

17 • electrochemical impedance spectroscopy, 

18 • metals release, and 

19 • oxygen uptake. 

20 

21 The first two methods are electrochemical techniques. They operate on the principal that 

22 corrosion reactions are electrochemical reactions which involve the transfer of electrons and 

23 therefore generation of current. Although the corrosion current is very localized and transient, 

24 the electrochemical techniques use electrical measurements and corrosion theory to obtain 

25 corrosion rates. 

26 

27 Potentiodynamic scans are a fundamental electrochemical technique, where the surface 

28 potential of the pipe specimen is forced continuously from a high potential to a low potential. 

29 The potential versus current relationship is recorded. Then using electrokinetic models, the data 

30 are used to calculate the corrosion potential of the metal. 

31 

32 Electrochemical impedance spectroscopy is a relatively new technique that is well suited 

33 for drinking water applications. It works similar to other techniques in that an impressed current 

34 is applied to the surface and the resulting potential is measured. It differs from techniques in that 

35 the current is an alternating current (AC) instead of a direct current (DC). The results are 

36 analyzed to create a model of the corrosion surface. This can give a picture of all the 

37 components of a corroding surface such as the polarization resistance of the surface and the 

38 presence of a passivating layer. 

39 

40 Metals release measures the concentration of metal released to the water after some 

41 stagnation or recirculation period. Both particulate and dissolved forms of the metal can be 

42 measured. 
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1 

2 Oxygen uptake measures the rate of oxygen consumption from the circulating water. 

3 This is assumed to be an indication of the corrosion rate. For it to be effective the corrosion rate 

4 must be large enough to cause a significant decrease in dissolved oxygen levels. 

5 

6 Uses and Limitations 

7 

8 Pipe loops are best suited to examine how distribution or plumbing materials will respond 

9 to treatment changes or other changes in water quality or to evaluate potential corrosion control 

10 strategies. One advantage is that they closely simulate actual distribution systems and the 

11 conditions under which corrosion occurs. Their disadvantage is that they can take a relatively 

12 long time to conduct and are relatively expensive. 

13 

14 Potentiodynamic scans are best suited for determining corrosion rates, although they are 

15 less effective at evaluating pitting corrosion. As with most electrochemical techniques they 

16 experience some imprecision from the high internal resistance of the material compared to the 

17 low conductivity of water. They also may alter the surface in unknown ways through application 

18 of a current and require very careful sample preparation to achieve reproducible results. 

19 

20 Electrochemical impedance spectroscopy is advantageous because it performs well for 

21 the low corrosion rates found in water systems. It can also reveal more in-depth information 

22 about the nature of the corrosion such as the existence of passivating layers and the other 

23 physical components of the corrosion system. Its disadvantage is that it is relatively new and 

24 interpretation of results is complex and requires considerable expertise in the area. 

25 

26 Measuring metals release gives a good indication of dissolved metals concentrations that 

27 will be seen in the consumer’s taps. Measuring metals release alone, however, can lead to an 

28 inaccurate total corrosion rate as some metal can be retained on the surface in corrosion scales. 

29 Oxygen uptake measurements may miss some corrosion that occurs by mechanisms other than 

30 oxidation and is limited to relatively rapidly corroding metals. 

31 

32 References 

33 

34 AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

35 Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

36 

37 Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy: 

38 Electrochemical Impedance and Noise. National Association of Corrosion Engineers. 

39 Houston, TX. 

40 

41 Kirmeyer, G.J., A.M. Sandvig, G.L. Pierson, and C.H. Neff. 1994. Development of a 

42 Pipe Loop Protocol for Lead Control. AWWARF Report 90650 Project #604. 
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1 

2 D.5 Partial System Testing

3 

4 Description of Method

5 

6 In partial system testing, a corrosion control method is tested on a small part of the 

7 distribution system which has been hydraulically isolated from the rest of the system. An 

8 outreach program should be in place to the customers in that section of the distribution system 

9 informing them of the test and any changes which they might see. 

10 

11 Uses and Limitations

12 

13 A partial system test can be very useful in examining system specific issues which might 

14 not be obvious from pipe loop tests or other laboratory techniques. For example, partial system 

15 tests can help determine whether a given water quality change might lead to red water incidents 

16 within the system. 

17 

18 A partial system test, however, does not guarantee that problems will not occur in the rest 

19 of the system as there can still be differences in piping material, temperatures, soil conditions, 

20 pipe age and other variables. A partial system test will also require isolating that part of the 

21 system and communicating closely with customers in that portion of the system. It may also 

22 require setting up temporary chemical feed facilities, which can be expensive. 

23 References 

24 

25 Kirmeyer, G.J. et al. 2000a. Distribution System Water Quality Changes Following 

26 Implementation of Corrosion Control Strategies. AWWARF Report 90764. Project 

27 #157. 

28 

29 D.6 Water Line Profiling

30 

31 Description of Method

32 

33 Elevated lead and copper levels in tap water could originate from a number of locations 

34 in the home plumbing system, such as meters, welded joints, service lines, and plumbing 

35 fixtures. Water line profiling is a method that can be used to determine from where elevated lead 

36 or copper levels are originating. The procedure for performing the profiling is as follows: 

37 

38 • Collect data on the diameter and length of the various portions of the plumbing 

39 system from the water main to the tap that will be sampled. Determine the volume of 

40 water in each section. 

41 • Let the water stagnate for at least 6 hours prior to beginning the test. This can be 

42 done while the customer is away from home. 
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1 • Draw consecutive samples from the tap in 1-liter sample bottles. Samples should be 

2 collected at a flow rate of about 2 liters/min. 

3 • Measure each sample for lead and copper. It is helpful to measure both dissolved and 

4 particulate forms of the metals. 

5 • Consider analyzing samples for pH, temperature, and chlorine residual. Other 

6 variables such as iron, aluminum, zinc, copper, chlorine residual, nitrite, nitrate, free 

7 ammonia and corrosion inhibitors can also be measured. 

8 

9 Examining the metal concentration across the samples will show where the peak 

10 corrosion is occurring in the plumbing system relative to the tap. For example, if the first sample 

11 is the highest then the corrosion is likely occurring in the customer’s plumbing, a slightly later 

12 peak may indicate corrosion of the service line, while an even later peak would point to problems 

13 in the water mains. 

14 

15 Uses and limitations

16 

17 Profiling is advantageous in that it can give a quick assessment of the source of elevated 

18 metals concentration in a customer’s tap water. It requires close coordination with the customer, 

19 including filtration of the samples in their home if they are to be analyzed for dissolved 

20 constituents. In addition, the method only gives a snapshot picture of a single system at a single 

21 point in time which may not correspond to corrosion in other areas of the system. This can be 

22 alleviated to some degree by sampling in several homes throughout the distribution system. 

23 References 

24 

25 Giani, R., M. Edwards, C. Chung, and J. Wujek. 2004. Lead Profiling Methodologies 

26 and Results. Presented at Getting the Lead Out: Analysis & Treatment of Elevated Lead 

27 Levels in DC’s Drinking Water at the 2004 AWWA WQTC. 

28 

29 D.7 Laboratory Analysis of Corrosion Products

30 

31 Description of Method

32 

33 Once corrosion has occurred, the corrosion products can be analyzed using several 

34 advanced techniques which can reveal detailed information about the composition and form of 

35 the corrosion products. This information may help determine the likely mechanisms of corrosion 

36 and the elements involved. These techniques include: 

37 

38 • X-ray emission spectroscopy, 

39 

40 • X-ray diffraction, and 

41 

42 • Auger electron microscopy. 
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1 

2 X-ray emission spectroscopy can give a semi-quantitative analysis of the elemental composition 

3 of corrosion products. X-ray diffraction provides a quantitative analysis of the composition of 

4 crystalline compounds. It can identify the mineral composition of corrosion scale. Auger 

5 electron microscopy can give a depth profile of corrosion scales. 

6 

7 Uses and Limitations

8 

9 Surface analyses using the techniques described above can be very useful for determining 

10 the composition of corrosion scale and corrosion products, and are therefore useful for systems 

11 where corrosion has already occurred. This information can help determine the corrosion 

12 mechanism, and therefore the cause of the corrosion, such as oxidation of the pipe, biologically 

13 induced corrosion, or reaction with other contaminants. These techniques can also give 

14 information on any passivating or barrier layers that can protect pipes from further corrosion. 

15 These techniques cannot be used to give quantitative assessments of corrosion rates and metals 

16 release. Other methods must be used to obtain that information. 

17 

18 References 

19 

20 ASTM D934-80. 2003. Standard Practices for Identification of Crystalline Compounds 

21 in Water Formed Deposits by X-Ray Diffraction. American Society for Testing and 

22 Materials. Philadelphia, PA. 

23 

24 D.8 Electrochemical Methods

25 

26 Description of Method

27 

28 The electrochemical methods of potentiodynamic scans and electrochemical impedance 

29 spectroscopy were described in the section on pipe loops. Several other electrochemical 

30 techniques that may be more useful for online monitoring of corrosion include: 

31 

32 • electrical resistance, 

33 • linear polarization, and 

34 • electrochemical noise. 

35 

36 Electrical resistance is a method where the electrical resistance change is measured in a 

37 corroding wire. The resistance of the wire changes as it corrodes, and the change in resistance is 

38 then correlated to the corrosion rate. 

39 

40 Linear polarization is a technique that is frequently used for online, continuous 

41 measurements. It relies on the fact that near the freely corroding surface potential, the slope of 

42 the current versus potential curve is linear. The linear polarization, then, involves a short 
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1 duration polarization offset within the linear range. The polarization resistance is then converted 

2 to a corrosion rate by application of a constant. The constant is highly dependent on water 

3 quality and must be evaluated for specific conditions. Generally because of the uncertainty 

4 surrounding the constant, this technique is best for determining relative corrosion rates rather 

5 than actual corrosion rates. 

6 

7 Electrochemical noise monitors low frequency changes in the freely corroding surface 

8 potential. This is a relatively new technology which is just beginning to find applications in 

9 water distribution systems. It is mostly useful for online monitoring. 

10 

11 Uses and Limitations

12 

13 These electrochemical techniques are generally imprecise and do not reproduce easily 

14 across different conditions. For this reason they are best suited for determining relative 

15 corrosion rates within a single system. This makes them best suited for online monitoring to 

16 determine real time corrosion rates. 

17 

18 Electrical resistance is a simple and relatively inexpensive method of online corrosion 

19 monitoring. It is relatively imprecise, though, and cannot provide absolute corrosion rates thus 

20 the data are not easily applied to situations other than in which it was taken. 

21 

22 Linear polarization is most useful for online corrosion monitoring and is relatively simple 

23 and inexpensive. It is highly site specific, and therefore the data collected cannot be applied to 

24 situations other than that in which it was recorded. 

25 

26 The main advantage of electrochemical noise is that it does not perturb the corroding 

27 surface and therefore more closely measures actual corrosion rates. It is also good for online 

28 corrosion monitoring. Its disadvantage is that it is relatively expensive and its use is still not 

29 standardized in the water industry. 

30 

31 References 

32 

33 AWWARF and DVGW-Technologiezentrum Wasser. 1996. Internal Corrosion of Water 

34 Distribution Systems. 2nd edition. AWWARF Report 90508. Project #725. 

35 

36 Cottis, R.A., S. Turgoose, and R. Newman. 1999. Corrosion Testing Made Easy: 

37 Electrochemical Impedance and Noise. National Association of Corrosion Engineers. 

38 Houston, TX.
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2 
 

1 Appendix E 

2 Innovative Management Tools for Achieving Simultaneous Compliance
 

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2 
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1 Appendix E Innovative Management Tools for Achieving Simultaneous 

2 Compliance 

3 

4 

5 Systems simultaneously complying with the Long Term 2 Enhanced Surface Water 

6 Treatment Rule (LT2ESWTR), Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR), 

7 and other drinking water regulations may benefit from a broader, more holistic approach to water 

8 system management. Therefore, EPA and other organizations are developing integrated, source9 to-tap management programs to assist water systems. These programs can provide a framework 

10 within which water systems can identify simultaneous compliance concerns, prioritize them, and 

11 adopt approaches to ensure that they will be in compliance with numerous regulations at the 

12 same time. 

13 

14 This appendix identifies existing and developing programs that can help water systems 

15 comply with regulations and produce consistently high quality water. These programs include 

16 performance-driven and integrated management approaches that consider treatment processes 

17 and operating practices throughout the entire water system. Systems are encouraged to consult 

18 with primacy agencies and other systems with similar treatment facilities and water quality to aid 

19 in carrying out these programs. 

20 

21 Performance-Driven Optimization Programs

22 

23 Several programs have been developed for water systems to optimize treatment plant 

24 performance. The Partnership for Safe Water (http://www.awwa.org/science/partnership/), for 

25 example, has provided a successful approach for systems to improve turbidity removal in their 

26 treatment plants and reduce microbial risks as addressed in the surface water treatment rules. 

27 This section briefly describes an additional complementary approach to evaluating water 

28 systems, identifying performance limitations, and establishing performance goals and standards 

29 that guide water system operation. 

30 

31 Microbial and DBP Comprehensive Performance Evaluations

32 

33 A comprehensive performance evaluation (CPE) is the evaluation phase of EPA’s 

34 Composite Correction Program. A Composite Correction Program is a systematic, 

35 comprehensive procedure that identifies and corrects a unique combination of factors to improve 

36 performance at filtration plants using existing facilities. CPEs are designed to identify and 

37 correct limiting factors in the design, operation, maintenance, and administration of public water 

38 systems that prevent compliance with drinking water regulations and optimized water system 

39 operation. CPEs help systems prioritize ways to improve water system operation, and often 

40 provide options without significant capital improvements as the highest priority option. CPEs 

41 are designed to ensure that water systems consistently produce high quality drinking water. 

42 
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1 While CPEs have primarily addressed pathogen control, efforts are underway to develop 

2 a CPE methodology that addresses DBP control. A CPE for microbes or disinfection byproducts 

3 (DBPs) consists of three components: performance assessment, major unit process evaluation, 

4 and identification of factors that are limiting performance. The performance assessment 

5 component determines a facility’s status in achieving compliance for microbial and DBP 

6 compliance requirements and performance goals and verifies the extent of any performance 

7 problems at the plant. The major unit process evaluation determines if the various key existing 

8 treatment processes in the plant, if properly operated, are of sufficient size to meet microbial and 

9 DBP performance goals at the plant’s current peak instantaneous operating flows. The last and 

10 most significant component of a CPE is the identification of factors that limit the plant’s 

11 performance. CPEs are often conducted with the aid of primacy agency personnel or 

12 consultants. 
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1 

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://asdwa.citysoft.com/awop

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

U.S. EPA. 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

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

USEPA. 2004f. 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. 

U.S. EPA. 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. 

US EPA. Area Wide Optimization Program. http://www.epa.gov/reg3wapd/drinkingwater/optimization/
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1 Integrated Management Approaches

2 

3 It can be challenging for water systems to consider the impacts of specific management 

4 or operations decisions on their entire water system. Efforts have been made to develop or adopt 

5 management programs that consider the entire water system. Most of these programs are 

6 frameworks that managers can use to tailor a source-to-tap management program addressing 

7 issues and concerns specific to their water system. Because this approach is holistic (source-to8 tap), such programs can serve as effective ways to consider simultaneous compliance issues. 

9 This section briefly describes a few source-to-tap integrated management approaches that, if 

10 used properly, could help a system achieve simultaneous compliance. 

11 

12 Hazard Analysis and Critical Control Point

13 

14 The Hazard Analysis and Critical Control Point (HACCP) program has been used by the 

15 U.S. Food and Drug Administration for years, and has become an accepted management practice 

16 internationally to ensure the safety of food across the world. Recent research indicates that 

17 HACCP principles may be successfully applied to drinking water systems (Martel et al., 2006). 

18 HACCP is an integrated risk management approach that examines and assesses risks of drinking 

19 water contamination from the source to the tap. This information may then be used by drinking 

20 water systems to reduce the risk of contamination to the general public. An HACCP can be 

21 created and implemented by system management or with the help of expert consultants. 

22 

23 Seven basic principles are employed: hazard analysis; critical control point identification; 

24 establishing critical limits; monitoring procedures; corrective actions; verification procedures; 

25 and record-keeping and documentation. If a deviation occurs that indicates a loss of control, the 

26 water system detects the deviation and takes the appropriate, defined steps to reestablish control 

27 in a timely manner and ensure that potentially contaminated water does not reach the consumer 

28 and cause compliance problems with one or more regulation. 
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1 

2 

3 

4 ISO 14001

5 

6 The ISO 14001 provides management system standards that businesses, including 

7 drinking water systems, may use to minimize adverse impacts on the environment, and to 

8 continually improve environmental performance, enabling them to simultaneously comply with 

9 multiple objectives. ISO 14001 is typically implemented by a system’s management staff, 

10 possibly with the aid of consultants. 

For additional information on HACCPs, 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, Kathy, Gregory Kirmeyer, Amie Hanson, Melita Stevens, Joanne Mullenger, and Daniel 

Deere. 2006. Application of HACCP for Distribution System Protection. AWWARF Project #2856. 

Denver, CO. 

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. Hazard Analysis and Critical Control Point. 

http://www.cfsan.fda.gov/~lrd/haccp.html 

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. 

http://www.who.int/water sanitation health/dwq/watreatment/en/
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1 

2 

3 

4 

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). 

Global Environment & Technology Foundation. 2000. The US EPA Environmental Management 

System Pilot Program for Local Government. 

Grant, Gary, 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
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1 Additional Resources

2 

3 AWWA. 1999d. Design and Construction of Small Water Systems, Second Edition. 228 pp. 

4 

5 Logsdon, G.S. et al. 2002. Filter Maintenance and Operations Guidance Manual. AWWARF 

6 Report 90908. Project #2511. 

7 

8 Renner, R.C. and B.A. Hegg. 1997. Self-Assessment Guide for Surface Water Treatment Plant 

9 Optimization. AWWARF Report 90736. Project #274. 

10 

11 Lauer, B. 2001. Self-Assessment for Treatment Plant Optimization, International Edition. 

12 AWWA Publication. 256 pp. 

13 

14 Smith, C.D., ed. 2005. Water Distribution System Assessment Workbook. AWWA. Denver, CO. 

15 85 pp. 

16 

17 Westerhoff, G.P., et al. 1998a. The Changing Water Utility: Creative Approaches to 

18 Effectiveness and Efficiency. AWWA. Denver, CO.
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