The Stage 2 

Disinfectants and 

Disinfection Byproducts 

Rule (Stage 2 DBPR) 

Implementation 

Guidance 
Office of Water (4606M) 

EPA 816-R-07-007 

www.epa.gov/safewater

August 2007 Printed on Recycled Paper
 

Disclaimer

This document provides guidance to states, tribes, and U.S. Environmental 

Protection Agency (EPA) Regions exercising primary enforcement 

responsibility under the Safe Drinking Water Act (SDWA) and contains EPA’s 

current policy recommendations for complying with the Stage 2 Disinfectants 

and Disinfection Byproducts Rule (DBPR). Throughout this document, the 

terms “state” or “states” are used to refer to all types of primacy agencies 

including U.S. territories, Indian tribes, and EPA regions. 

The statutory provisions and EPA regulations described in this document 

contain legally binding requirements. This document is not a regulation itself, 

nor does it change or substitute for those provisions and regulations. Thus, it 

does not impose legally binding requirements on EPA, states, or public water 

systems. This guidance does not confer legal rights or impose legal obligations 

upon any member of the public. 

While EPA has made every effort to ensure the accuracy of the discussion 

in this guidance, the obligations of the regulated community are determined by 

statutes, regulations, or other legally binding requirements. In the event of a 

conflict between the discussion in this document and any statute or regulation, 

this document would not be controlling. 

The general description provided here may not apply to a particular situation 

based upon the circumstances. Interested parties are free to raise questions and 

objections about the substance of this guidance and the appropriateness of the 

application of this guidance to a particular situation. EPA and other 

decisionmakers retain the discretion to adopt approaches on a case-by-case 

basis that differ from those described in this guidance where appropriate. 

Mention of trade names or commercial products does not constitute 

endorsement or recommendation for their use. 

This is a living document and may be revised periodically without public 

notice. EPA welcomes public input on this document at any time. Guidance 

provided in this document reflects provisions in 71 FR 388. 
This page intentionally left blank 
Table of Contents 

Introduction...............................................................................................................................................xv

Section 1 Rule Requirements .....................................................................................................................1

1.1 Introduction ..................................................................................................................................3

1.1.1 History ................................................................................................................................3

1.1.2 Development of the Stage 2 DBPR ....................................................................................6

1.1.3 Benefits of the Stage 2 DBPR.............................................................................................7

1.1.3.1 Quantified health benefits ............................................................................................7

1.1.3.2 Non-quantified health and non-health related benefits.................................................7

1.2 Requirements of the Rule .............................................................................................................8

1.2.1 New Definitions in the Stage 2 DBPR [40 CFR 141.2]...................................................10

1.2.1.1 What is a combined distribution system?...................................................................10

1.2.1.2 What is a consecutive system? ...................................................................................10

1.2.1.3 What is a dual sample set? .........................................................................................10

1.2.1.4 What is finished water? ..............................................................................................10

1.2.1.5 What is GAC10? ........................................................................................................10

1.2.1.6 What is GAC20? ........................................................................................................10

1.2.1.7 What is a locational running annual average?............................................................10

1.2.1.8 What is a wholesale system? ......................................................................................11

1.2.2 IDSE Requirements [40 CFR 141.600] ............................................................................11

1.2.2.1 Who is subject to IDSE requirements? [40 CFR 141.600(b)]....................................11

1.2.2.2 What are the options for the IDSE?............................................................................12

1.2.2.3 What is the time frame for compliance with the IDSE?.............................................12

1.2.2.4 What are the requirements for systems that receive a VSS Waiver or 40/30 

Certification for the IDSE?.........................................................................................13

1.2.2.5 What are the requirements for systems that must conduct a standard monitoring or an 

SSS IDSE?..................................................................................................................15

1.2.2.6 What must an SSS include? [40 CFR 141.602(a)] .....................................................15

1.2.2.7 What must a Standard Monitoring Plan include? [40 CFR 141.601(a)] ....................18

1.2.2.8 How long must the Standard Monitoring Plan or SSS Plan be retained?...................18

1.2.2.9 Who must submit an IDSE Report? ...........................................................................18

1.2.2.10 What must the IDSE Report include? ........................................................................18

1.2.2.11 How long must the IDSE Report be retained? ...........................................................19

1.2.3 Stage 2 DBPR Compliance Monitoring [40 CFR 141.620, 40 CFR 141.621] .................19

1.2.3.1 How is compliance calculated for TTHM and HAA5 under Stage 2 DBPR? [40 CFR 

141.620(d)].................................................................................................................19

1.2.3.2 What are the Stage 2 DBPR MCLs? [40 CFR 141.620] ............................................20

1.2.3.3 What are the new MCLGs? [40 CFR 141.53]............................................................20

1.2.3.4 What Are the Requirements for Developing a Stage 2 DBPR Compliance Monitoring 

Plan? [40 CFR 141.622].............................................................................................21

1.2.3.5 What are the reporting and recordkeeping requirements for Stage 2 DBPR 

Compliance Monitoring Plan? [40 CFR 141.622(c), 40 CFR 141.629(b)]................22

1.2.3.6 What Are the Compliance Deadlines for Stage 2 DBPR Compliance Monitoring? [40 

CFR 141.620(c)].........................................................................................................22

1.2.3.7 What Are the Requirements for Routine Monitoring? [40 CFR 141.621].................22

Stage 2 DBPR Implementation Guidance v August 2007 
1.2.3.8 How Do Systems Qualify for Reduced Stage 2 DBPR Monitoring? [40 CFR 141.623]

....................................................................................................................................23

1.2.3.9 What Are the Requirements for Increased Monitoring? [40 CFR 141.625, 40 CFR 

141.628]......................................................................................................................25

1.2.4 Monitoring Requirements for Consecutive Systems ........................................................25

1.2.4.1 What are the DBP monitoring requirements for consecutive systems? [40 CFR 

141.620]......................................................................................................................25

1.2.4.2 What are the Chlorine and Chloramines requirements for consecutive systems? [40 

CFR 141.624] .............................................................................................................25

1.2.5 Operational Evaluation Levels [40 CFR 141.626]............................................................26

1.2.6 Bromate Requirements [40 CFR 141.132] .......................................................................27

1.2.7 Reporting/Recordkeeping Requirements [40 CFR 141.33, 40 CFR 141.629] .................27

1.2.7.1 What monitoring information must be reported? [40 CFR 141.629(a)(2)]................27

1.2.7.2 What information for Source Water TOC for must Subpart H systems report? [40 

CFR 141.629(a)(2)]....................................................................................................28

1.2.7.3 What are the recordkeeping requirements for IDSE Plans, IDSE Reports, and 

Monitoring Results? [40 CFR 141.629(b)] ................................................................28

1.2.7.4 What are the reporting and recordkeeping requirements for consecutive systems? [40 

CFR 141.134(c), 40 CFR 141.622(c), 40 CFR 141.629(b)].......................................28

1.2.8 Public Notification of Drinking Water Violations [40 CFR 141 Subpart Q, Appendix A]

..........................................................................................................................................29

1.2.9 CCR Requirements [40 CFR 141.151, 40 CFR 141.153].................................................29

1.3 Requirements of the Rule: States or Other Primacy Agencies ...................................................30

1.3.1 Special Primacy Requirements [40 CFR 142.16] .............................................................30

1.3.2 Records Kept by States [40 CFR 142.14].........................................................................30

1.3.3 State Reporting Requirements [40 CFR 142.15] ..............................................................30

1.4 Summary of Action Dates ..........................................................................................................30

1.4.1 Applicability and Compliance Dates ................................................................................30

1.4.2 Timeline for the Stage 2 DBPR ........................................................................................33

Section 2 Resources and Guidance..........................................................................................................37

2.1 Technical Guidance Manuals .....................................................................................................39

2.2 Rule Presentation........................................................................................................................39

2.3 Factsheets and Quick Reference Guides ....................................................................................40

2.4 Frequently Asked Questions.......................................................................................................40

Section 3 State Implementation ...............................................................................................................45

3.1 Overview of Implementation......................................................................................................47

3.2 Identifying Affected Systems .....................................................................................................50

3.2.1 General Provisions............................................................................................................50

3.2.2 Initial Distribution System Evaluation (IDSE) .................................................................50

3.2.3 Wholesale and Consecutive Systems................................................................................51

3.2.4 Seasonal Systems..............................................................................................................52

3.3 Communicate Stage 2 DBPR Requirements to Affected Systems.............................................52

3.3.1 Communicating IDSE Requirements and Timeframes.....................................................52

3.3.2 Communicating Stage 2 DBPR Compliance Requirements and Timeframes ..................54

3.3.2.1 Consecutive System Compliance with the Stage 1 DBPR.........................................55

3.3.3 Methods of Communication .............................................................................................55

3.4 Update Data Management Systems............................................................................................58

Stage 2 DBPR Implementation Guidance vi August 2007 
3.5 Address Issues for Consecutive and Wholesale Systems...........................................................59

3.5.1 Reviewing Plans and Reports from Wholesale and Consecutive Systems.......................60

3.6 IDSE Option: Very Small System Waiver .................................................................................61

3.6.1 Review Considerations for the VSS Waiver.....................................................................61

3.6.2 Stage 2 DBPR Compliance Monitoring Plan for VSS Waiver Systems...........................62

3.7 IDSE Option: 40/30 Certification Alternative............................................................................63

3.7.1 Requirements for the 40/30 Certification .........................................................................64

3.7.2 Review Considerations for the 40/30 Certification...........................................................65

3.7.3 Stage 2 Compliance Monitoring Plan for 40/30 Certification Systems............................68

3.8 IDSE Option: System Specific Study.........................................................................................68

3.9 IDSE Option: Existing Monitoring System Specific Study .......................................................68

3.9.1 Review of Existing Monitoring SSS Plan.........................................................................68

3.9.1.1 Review of Required Elements for Existing Monitoring SSS Plan .............................69

3.9.1.2 Technical Review of Existing Monitoring SSS Plans................................................73

3.9.2 Review of Existing Monitoring SSS IDSE Report ...........................................................75

3.9.2.1 Review of Required Elements for Existing Monitoring IDSE Report .......................76

3.9.2.2 Technical Review of Existing Monitoring IDSE Report ...........................................77

3.10 IDSE Option: Hydraulic Modeling System Specific Study .......................................................78

3.10.1 Review of Hydraulic Modeling SSS Plan.........................................................................78

3.10.1.1 Review of Required Elements for Hydraulic Modeling SSS Plan .............................79

3.10.1.2 Technical Review of Hydraulic Modeling SSS Plans................................................81

3.10.2 Review of Hydraulic Modeling SSS IDSE Report ...........................................................87

3.10.2.1 Review of Required Elements for Hydraulic Modeling IDSE Report .......................87

3.10.2.2 Technical Review of Hydraulic Modeling IDSE Report ...........................................88

3.11 IDSE Option: Standard Monitoring.........................................................................................91

3.11.1 Review Considerations for Standard Monitoring Plan .....................................................92

3.11.1.1 Review of Required Elements for Standard Monitoring Plan....................................92

3.11.1.2 Review for Complexity of Standard Monitoring Plan ...............................................93

3.11.1.3 Review for Correct Interpretation of Standard Monitoring Requirements.................95

3.11.1.4 Technical Review of Standard Monitoring Plan ........................................................96

3.11.2 IDSE Reports for Standard Monitoring ..........................................................................108

3.11.2.1 Review of Required Elements for Standard Monitoring IDSE Report ....................108

3.11.2.2 Technical Review of Standard Monitoring IDSE Report.........................................109

3.12 Stage 2 DBPR Compliance Monitoring Plan ........................................................................111

3.12.1 Systems that Submitted an IDSE Report ........................................................................112

3.12.2 Systems that Did Not Submit an IDSE Report ...............................................................112

3.12.3 Combined Distribution Systems the State has Decided to Treat as One System............113

3.12.4 Changes to a Monitoring Plan.........................................................................................113

3.12.5 Reporting and Recordkeeping Requirements for Compliance Monitoring Plan ............113

3.13 Stage 2 DBPR Compliance Monitoring Deadlines ...............................................................113

3.13.1 System Requests for Compliance Schedule Extensions .................................................114

3.14 Stage 2 DBPR Routine Monitoring.......................................................................................114

3.14.1 TTHM and HAA5...........................................................................................................114

3.14.2 Bromate and Chlorite Monitoring...................................................................................115

3.15 Stage 2 DBPR Reduced Monitoring......................................................................................116

3.15.1 Reduced TTHM and HAA5 Monitoring.........................................................................116

3.15.1.1 Source Water TOC for Reduced Monitoring for DBPs ...........................................116

3.15.1.2 Remaining on Reduced Monitoring based on Stage 1 DBPR..................................118

Stage 2 DBPR Implementation Guidance vii August 2007 
3.15.2 Reduced Monitoring for Bromate...................................................................................118

3.16 Stage 2 DBPR Increased Monitoring ....................................................................................119

3.17 Operational Evaluations [40 CFR 141.626] ..........................................................................119

3.17.1 Operational Evaluation Level .........................................................................................119

3.17.2 Operational Evaluations..................................................................................................120

3.17.3 Evaluate System Requests for Limiting the Scope of an Operational Evaluation..........123

3.18 Special Considerations for Consecutive and Wholesale Systems ............................................123

3.18.1 DBP Monitoring .............................................................................................................123

3.18.2 Treating Combined Distribution Systems as One System for Compliance Monitoring.123

3.18.3 BATs...............................................................................................................................124

3.18.4 Chlorine and Chloramines Requirements .......................................................................124

3.18.5 Additional Resources......................................................................................................124

3.19 State Recordkeeping Requirements..........................................................................................125

Section 4 State Primacy Revision Application......................................................................................127

4.1 State Primacy Program Revision..............................................................................................129

4.1.1 The Revision Process......................................................................................................130

4.1.2 The Final Review Process...............................................................................................130

4.2 State Primacy Program Revision Extensions ...........................................................................131

4.2.1 The Extension Process ....................................................................................................131

4.2.2 Extension Request Criteria .............................................................................................132

4.2.3 Conditions of the Extension............................................................................................132

4.3 State Primacy Package .............................................................................................................136

4.3.1 The State Primacy Revision Checklist............................................................................136

4.3.2 Text of the State’s Regulation.........................................................................................136

4.3.3 Primacy Revision Crosswalk ..........................................................................................136

4.3.4 State Recordkeeping and Reporting Checklist [40 CFR 142.14, 40 CFR 142.15].........137

4.3.5 Special Primacy Requirements [40 CFR 142.16] ...........................................................138

4.3.6 Attorney General’s Statement of Enforceability [40 CFR 142.12(c)(2)] .......................138

4.3.6.1 Guidance for States on Audit Privilege and/or Immunity Laws ..............................138

4.4 Guidance for the Special Primacy Requirements of the Stage 2 DBPR...................................140

4.4.1 Special Primacy Requirements Regarding Consecutive System Monitoring .................140

Section 5 SDWIS Reporting and SNC Definitions...............................................................................143

Section 6 Public Notification and Consumer Confidence Report Examples .....................................145

Appendices 

Appendix A: Primacy Revision Crosswalk 

Appendix B: Rule Requirements 

Appendix C: Rule Factsheets and Quick Reference Guide 

Appendix D: Flowcharts 

Appendix E: IDSE Forms 

Appendix F: Template Letters 

Appendix G: Instructions & Reviewer Checklists for Stage 2 DBPR Submissions 

Appendix H: Data Collection and Tracking System (DCTS) 

Appendix I: Guidance for Reviewing Extension Requests under 1412(b)(10) of the SDWA 

Stage 2 DBPR Implementation Guidance viii August 2007 
List of Figures 

Figure 1-1. Summary of Stage 2 DBPR Requirements for Systems.............................................................9

Figure 1-2. Comparison of RAA and LRAA Compliance Calculations.....................................................20

Figure 1-3. Implementation Timeline for the Stage 2 DBPR .....................................................................34

Figure 3-1. Timeline of System and Primacy Agency Activities ...............................................................48

Figure 3-1. Timeline of System and Primacy Agency Activities (cont.)....................................................49

Figure 3-2. Example Repeating Residence Time........................................................................................84

Figure 3-3. Example Diurnal Demand Variation Pattern............................................................................85

Figure 3-4. Example Verification Graph for a Tank with Highest Water Age...........................................86

Figure 4-1. Recommended Review Process for State Request for Approval of Program Revisions........131

Stage 2 DBPR Implementation Guidance ix August 2007 
List of Tables 

Table 1-1. IDSE Plan and Report Dues Dates [40 CFR 141.600(c)]..........................................................13

Table 1-2. 40/30 Certification Eligibility Dates..........................................................................................14

Table 1-3. SSS Monitoring Locations and Frequency [40 CFR 141.602(b)] .............................................15

Table 1-4. Summary of Stage 2 DBPR MCLGs.........................................................................................21

Table 1-5. Compliance Schedule for Stage 2 DBPR TTHM and HAA5 Monitoring ................................22

Table 1-6. Stage 2 DBPR Routine Compliance Monitoring Requirements................................................23

Table 1-7. Stage 2 DBPR Reduced Monitoring Requirements for All Systems.........................................24

Table 1-8. Summary of Action Dates for the Stage 2 DBPR......................................................................31

Table 3-1. Deadlines for IDSE Plans and Reports......................................................................................53

Table 3-2. Compliance Schedule for Stage 2 DBPR ..................................................................................54

Table 3-3. Compliance Monitoring Data Requirements for the 40/30 Certification ..................................64

Table 3-4. SSS Plan Using Existing Monitoring Results, Required Elements Checklist ...........................71

Table 3-5. Minimum Requirements Checklist for Existing Monitoring Results Study Plan......................72

Table 3-6. Examples of Treatment, Distribution System, and Source Changes .........................................75

Table 3-7. IDSE Report for Existing Monitoring SSS Required Elements Checklist ................................77

Table 3-8. Modeling Study Plan Checklist Required Elements..................................................................80

Table 3-9. Modeling Study Plan Checklist—Optional Modeling Information...........................................82

Table 3-10. IDSE Report for a Modeling SSS Required Elements Checklist ............................................88

Table 3-11. Standard Monitoring Plan Required Elements Checklist ........................................................92

Table 3-12. Standard Monitoring Plan Triage Checklist ............................................................................93

Table 3-13. Standard Monitoring Requirements.........................................................................................95

Table 3-14. IDSE Report for Standard Monitoring, Required Elements Checklist..................................108

Table 3-15. Protocol for Selecting Stage 2 DBPR Compliance Monitoring Sites....................................110

Table 3-16. Compliance Schedule for Stage 2 DBPR TTHM and HAA5 Monitoring.............................114

Table 3-17. Stage 2 DBPR Routine Compliance Monitoring Requirements............................................115

Table 3-18. Stage 2 DBPR Reduced Monitoring Requirements for All Systems.....................................117

Table 4-1. State Rule Implementation and Revision Timetable for the Stage 2 DBPR ...........................129

Table 4-2. State Primacy Revision Checklist............................................................................................136

Table 6-1. System A 2014 TTHM Monitoring Results ............................................................................148

Table 6-2. System B 2014 TTHM and HAA5 Monitoring Results (mg/L)..............................................152

Table 6-3. System C Bromate and Bromide Monitoring Results (mg/L) .................................................156

Stage 2 DBPR Implementation Guidance x August 2007 
List of Examples 

Example 3-1. Sample Letter Notifying Systems of Schedule Number.......................................................56

Example 3-1. Sample Letter Notifying Systems of Schedule Number (cont.) ...........................................57

Example 3-2. Example 40/30 Certification Letter ......................................................................................64

Example 3-3. Examples of Justification ...................................................................................................107

Example 3-4. Example Rationale for Site Selection Outside of Protocol.................................................111

Example 4-1. Example Extension Request Checklist...............................................................................134

Example 4-2. Example of Attorney General’s Statement.........................................................................139

Example 6-1. Example Tier 2 Public Notification for TTHM MCL Violation ........................................150

Example 6-2. Example of a Notice in the CCR for TTHM MCL Violation.............................................151

Example 6-3. Example Tier 3 Public Notification for LRAA and Compliance Calculations for TTHM and 

HAA5 M&R Violations....................................................................................................................154

Example 6-4. Example of a Notice in the CCR for LRAA and Compliance Calculations for TTHM and 

HAA5 M&R Violations....................................................................................................................155

Example 6-5. Example Tier 3 Public Notification for Bromate M&R Violation.....................................158

Example 6-6. Example of a Notice in the CCR for Bromate M&R Violation .........................................159

Stage 2 DBPR Implementation Guidance xi August 2007 
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Stage 2 DBPR Implementation Guidance xii August 2007 
List of Acronyms and Abbreviations 

40/30 IDSE 40/30 Certification 

AWOP Area-Wide Optimization Program 

BAT Best Available Technology 

CCR Consumer Confidence Report

CDC Centers for Disease Control

CFE Combined Filter Effluent

CFR Code of Federal Regulations

CT The Residual Concentration of Disinfectant (mg/L) Multiplied by the Contact 

Time (in minutes) 

CWSs Community Water Systems

DBPs Disinfection Byproducts

DBP Precursors Disinfection Byproduct Precursors

DCTS Data Collection and Tracking System 

DOC Dissolved Organic Carbon 

DWA Drinking Water Academy 

EA Economic Analysis

EPA U.S. Environmental Protection Agency

EPS Extended Period Simulation

FBRR Filter Backwash Recycling Rule

FRDS Federal Reporting Data System

GWUDI Ground Water Under the Direct Influence of Surface Water

HAA5 Haloacetic Acids (Monochloroacetic, Dichloroacetic, Trichloroacetic, 

Monobromoacetic and Dibromoacetic Acids)

HPC Heterotrophic Plate Count 

HQ Headquarters

IDSE Initial Distribution System Evaluation

IESWTR Interim Enhanced Surface Water Treatment Rule

IFE Individual Filter Effluent

IPMC Information Processing and Management Center 

LRAA Locational Running Annual Average

LT1ESWTR Long Term 1 Enhanced Surface Water Treatment Rule

LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule

M&R Monitoring and Reporting 

MCAA Monochloroacetic Acid

MCL Maximum Contaminant Level

MCLG Maximum Contaminant Level Goal

M-DBP Cluster Microbial-Disinfectants/Disinfection Byproducts Cluster

MRDL Maximum Residual Disinfectant Level

MRL Minimum Reporting Level

Stage 2 DBPR Implementation Guidance xiii August 2007 
Stage 2 DBPR Implementation Guidance xiv August 2007 

NCWS Noncommunity Water System

NIPDWR National Interim Primary Drinking Water Regulations

NPDWR National Primary Drinking Water Regulation

NTNCWS Nontransient Noncommunity Water System

OECA Office of Enforcement and Compliance Assurance

OGC Office of General Counsel

OGWDW Office of Ground Water and Drinking Water

ORC Office of Regional Counsel

PN Public Notification 

PWS Public Water System

PWSS Public Water System Supervision

RAA Running Annual Average

SDWA Safe Drinking Water Act

SDWIS/FED Safe Drinking Water Information System/Federal

SNC Significant Non-complier

SSS System Specific Study

Stage 1 DBPR Stage 1 Disinfectants and Disinfection Byproducts Rule

Stage 2 DBPR Stage 2 Disinfectants and Disinfection Byproducts Rule

Subpart H PWS using surface water or ground water under the direct influence of surface 

water 

SUVA Specific Ultraviolet Absorbance 

SWTR Surface Water Treatment Rule

TCAA Trichloroacetic Acid

TCR Total Coliform Rule

TOC Total Organic Carbon

TTHM Total Trihalomethanes (Chloroform, Bromodichloromethane, 

Dibromochloromethane, and Bromoform)

UV Ultraviolet Light 

VSS Very Small System 

 
Introduction 

This document provides guidance to EPA regions and states exercising primary enforcement 

responsibility under the Safe Drinking Water Act (SDWA) concerning how the U.S. Environmental 

Protection Agency (EPA) interprets the Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 

DBPR) under the SDWA. It also provides guidance to the public and the regulated community on how 

EPA intends to exercise its discretion in implementing the statute and regulations. This guidance is 

designed to implement national policy on these issues. 

The SDWA provision and EPA regulations described in this document contain legally binding 

requirements. This document does not substitute for those provision or regulations, nor is it a regulation 

itself. It does not impose legally-binding requirements on EPA, states, or the regulated community and 

may not apply to a particular situation based upon the circumstances. EPA and state decision makers 

retain the discretion to adopt approaches on a case-by-case basis that differ from this guidance, where 

appropriate. Any decisions regarding a particular facility will be made based on the applicable statutes 

and regulations. Therefore, interested parties are free to raise questions and objections about the 

appropriateness of the application of this guidance to a particular situation, and EPA will consider 

whether or not the recommendations or interpretations in the guidance are appropriate in that situation 

based on the law and regulations. EPA may change this guidance in the future. 

This manual contains the following sections: 

•

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Section 1 summarizes the rule requirements of the Stage 2 DBPR and presents a timetable of 

important dates. 

 

Section 2 lists the “stand-alone” guidance materials that will help states and public water systems 

(PWSs) adopt each new requirement. 

Section 3 discusses state implementation activities. 

Section 4 covers state primacy revision requirements, including a detailed timeframe for 

application review and approval. This section also contains guidance and references to help states 

adopt each new special primacy requirement included in these rules. 

Section 5 addresses violation determination and associated reporting requirements to assist states 

in their compliance activities. 

Section 6 provides examples of violations requiring public notification and sample language to 

include in Consumer Confidence Reports (CCRs). 

The appendices of this document also provide information that will be useful to states and EPA regions 

throughout the primacy revision application process. 

•

•

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•

Appendix A contains the primacy revision application crosswalk for the rule. 

Appendix B contains the rule language of the Stage 2 DBPR. 

Appendix C contains fact sheets and quick reference guides for the rule. 

Appendix D presents flowcharts to help states and systems implement the rule. 

Stage 2 DBPR Implementation Guidance xv August 2007 
Stage 2 DBPR Implementation Guidance xvi August 2007 

•

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•

Appendix E includes a set of forms to help systems complete their Initial Distribution System 

Evaluations (IDSE) plans and reports. 

Appendix F contains various templates for letters that states can tailor to meet their needs. 

Appendix G contains guidance materials for states reviewing IDSE plans. 

Appendix H contains information about the Data Collection and Tracking System. 

Appendix I contains guidance for reviewing extension requests under Section 1412(b)(10) of the 

Safe Drinking Water Act. 

Please note that in several sections the guidance makes suggestions and offers alternatives that go beyond 

the minimum requirements of the rule. EPA does this to provide information and/or suggestions that may 

be helpful to implementation efforts. Such suggestions are prefaced by “may” or “should” and are to be 

considered advisory. They are not required elements of the Stage 2 DBPR. 

EPA expects to undertake necessary rule implementation activities during the period of early 

implementation. During this period, the state may elect to undertake some or all of the implementation 

activities in cooperation with EPA. This will facilitate continuity of implementation and ensure that 

system-specific advice and decisions are made with the best available information and are consistent with 

existing state program requirements. 

To provide clarity on who to contact for questions and interactions on Stage 2 DBPR implementation, 

EPA maintains a point of contact list with states and regional implementation contacts available at EPA’s 

Web site: www.epa.gov/safewater/disinfection/stage2/compliance.html#training. The list is updated 

periodically as EPA and state roles change. 
Section 1 

Rule Requirements 
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1.1 Introduction 

EPA finalized the Stage 2 DBPR in the Federal Register on January 4, 2006 (71 FR 388; see 

www.epa.gov/safewater/disinfection/stage2/index.html). This rule is part of a series of rules referred to as 

the “Microbial-Disinfectants/Disinfection Byproducts Cluster” (M-DBP Cluster). These rules are 

intended to improve control of microbial pathogens while minimizing public health risks of disinfectants 

and disinfection byproducts (DBPs). The Stage 2 DBPR builds upon the Stage 1 Disinfectants and 

Disinfection Byproducts Rule (Stage 1 DBPR) by addressing the health risks of DBPs in community 

water systems (CWSs) and nontransient noncommunity water systems (NTNCWSs) that add a primary or 

residual disinfectant other than ultraviolet light (UV) or deliver water that has been treated with a primary 

or residual disinfectant other than UV. Key provisions of the Stage 2 DBPR include: 

•

•

An Initial Distribution System Evaluation (IDSE) to identify compliance monitoring locations 

that represent high total trihalomethanes (TTHM) and haloacetic acids (HAA5) concentrations 

throughout the distribution system. 

Use of a locational running annual average (LRAA) calculated for each monitoring location in the 

distribution system for TTHM and HAA5 to determine compliance with the Stage 2 DBPR 

maximum contaminant levels (MCLs) for TTHM and HAA5. 

The Stage 2 DBPR was developed concurrently with the Long Term 2 Enhanced Surface Water 

Treatment Rule (LT2ESWTR), which addresses the control of microbial pathogens. The LT2ESWTR was 

finalized as a separate rule on January 5, 2006. 

1.1.1 History 

The 1974 SDWA called for EPA to regulate drinking water by creating the national interim primary 

drinking water regulations (NIPDWR). In 1979, the first interim standard addressing DBPs was set for 

total trihalomethanes (TTHM), a group of four volatile organic chemicals that form when disinfectants 

react with natural organic matter in the water. 

1986 SDWA Amendments 

Although the SDWA was amended slightly in 1977, 1979, and 1980, the most significant changes to the 

1974 law occurred when the SDWA was reauthorized in 1986. To safeguard public health, the 1986 

Amendments required EPA to set health goals, or maximum contaminant level goals (MCLGs), and 

MCLs for 83 named contaminants. Waterborne disease outbreaks of giardiasis demonstrated that diseasecausing microbial contamination had not been sufficiently controlled under the original Act. In addition, 

several hundred chemical contaminants were known to occur in the environment, but few were regulated 

in PWSs. EPA was also required to establish additional regulations within certain timeframes, require 

disinfection of source water supplies, specify filtration requirements for nearly all water systems that 

draw their water from surface sources, and develop additional programs to protect ground water supplies. 

In 1989, EPA issued two important National Primary Drinking Water Regulations (NPDWRs): the Total 

Coliform Rule (TCR) and the Surface Water Treatment Rule (SWTR). The TCR and SWTR provide the 

foundation for the M-DBP Cluster and are summarized below. 

Total Coliform Rule 

The TCR applies to all PWSs. Coliforms are easily detected in water and are used to assess a water 

system’s vulnerability to pathogens. It requires systems to sample for coliform bacteria which are used as 

Stage 2 DBPR Implementation Guidance 3 August 2007 
an indicator of whether a water system is vulnerable to pathogens. Coliforms are used because they are 

easily detected in water. In the TCR, EPA set an MCLG of zero for total coliforms. EPA also set an MCL 

for total coliforms and required testing of total coliform positive cultures for the presence of E. coli or 

fecal coliforms, which indicate more immediate health risks from sewage or fecal contamination. If more 

than 5.0 percent of the samples contain coliforms within a month, water system operators must report this 

violation to the state and the public. (For water systems that collect fewer than 40 routine samples per 

month, no more than one sample can be total coliform-positive per month.) Finally, the TCR required 

sanitary surveys every 5 years (or 10 years for noncommunity water systems (NCWSs) using disinfected 

and protected ground water) for every system that collects fewer than five routine total coliform samples 

per month. These are typically systems that serve 4,100 or fewer people. 

Surface Water Treatment Rule 

PWSs using surface water or ground water under the direct influence of surface water (GWUDI) as a 

supply are prone to microbial contamination of their source water. Pathogenic microorganisms that can 

contaminate source water can be removed or inactivated during the water treatment sedimentation, 

filtration, and disinfection processes. EPA issued the SWTR in response to a Congressional mandate 

requiring disinfection, and filtration where necessary, of systems that use surface water or GWUDI 

sources. The rule sets MCLGs for Legionella, Giardia lamblia, and viruses at zero because any exposure 

to these contaminants presents some level of health risk. The SWTR includes a treatment technique 

requirement for inactivation (or removal and inactivation) of these organisms. 

Specifically, the SWTR requires that a surface water system have sufficient treatment to reduce source 

water concentrations of Giardia lamblia and viruses by at least 99.9 percent (3.0 log) and 99.99 percent 

(4.0 log), respectively. In addition, disinfection residuals must be maintained throughout the distribution 

system. For systems that filter, the adequacy of the filtration process is determined by measuring the 

turbidity of the treated water since poor turbidity removal often indicates that the filtration process is not 

working properly. The goal of the SWTR is to reduce the public health risk for infection by Giardia 

lamblia, Legionella, or viruses to less than one infection per year per 10,000 people. 

The SWTR, however, does not account for systems with high pathogen concentrations in source water 

that, when treated at the levels required under the rule, still may not meet this health goal. The SWTR also 

does not specifically control for the protozoan Cryptosporidium, as sufficient information about its 

removal or disinfection was not available at the time the SWTR was finalized. Since the SWTR was 

promulgated, much has been learned about this organism. Most notably, Cryptosporidium is resistant to 

disinfection practices commonly employed by PWSs. Therefore, physical removal or alternative 

disinfectants are the most effective treatment methods. 

1996 SDWA Amendments 

In 1990, EPA’s Science Advisory Board, an independent panel of experts established by Congress, cited 

drinking water contamination as one of the most important environmental risks and indicated that diseasecausing microbial contaminants (e.g., bacteria, protozoa, and viruses) are probably the greatest remaining 

health-risk management challenge for drinking water suppliers. Data from the Centers for Disease Control 

(CDC) confirm this concern and indicate that between 1980 and 1998, 419 waterborne disease outbreaks 

were reported, with over 511,000 estimated cases of disease. During this period, a number of agents were 

implicated as causes of the outbreaks, including various protozoa, viruses, and bacteria, as well as several 

chemicals (Craun and Calderon 1996, Levy et al. 1998, Barwick et al. 2000). Most of the cases (but not 

the outbreaks) of illnesses were associated with surface water, including a single outbreak of 

approximately 403,000 cases of cryptosporidiosis in Milwaukee, WI (Mac Kenzie et al. 1994). 

Stage 2 DBPR Implementation Guidance 4 August 2007 
The SDWA was further amended in 1996 to improve public health protection by incorporating new data 

on the adverse health effects of contaminants, the occurrence of contaminants in PWSs, and the estimated 

reduction in health risks that would result from further regulation. The Amendments provided for use of 

best-available, peer-reviewed science in decision-making and for risk reduction and cost analyses in the 

regulatory decision process. 

TTHMs/Stage 1 DBPR/Stage 2 DBPR 

Many water systems treat their water with a chemical disinfectant to inactivate pathogens that cause 

disease. The public health benefits of common disinfection practices are significant and well-recognized; 

however, disinfection poses risks of its own. While disinfectants are effective at controlling many harmful 

microorganisms, they react with organic and inorganic matter (DBP precursors) in the water and form 

DBPs, some of which pose health risks when present above certain levels. Since the discovery of 

chlorination byproducts in drinking water in 1974, numerous toxicological studies have been conducted 

that show some DBPs to be carcinogenic and/or cause reproductive or developmental effects in laboratory 

animals. Additionally, exposure to high levels of disinfectants over long periods of time may cause health 

problems, including damage to blood and kidneys. While many of these studies have been conducted with 

disinfectants at high doses, the weight of evidence indicates that DBPs present a potential public health 

problem that must be addressed to minimize risks from long-term exposure. One of the most complex 

questions facing water supply professionals is how to reduce risks from disinfectants and DBPs while 

providing adequate protection against microbial contaminants. 

The TTHM Rule of 1979 set a TTHM MCL for CWSs serving 10,000 or more people. The Stage 1 

Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR) built on the TTHM Rule by lowering 

existing MCLs and widening the range of affected systems to include all PWSs (except most transient 

systems) that add a disinfectant. The Stage 1 DBPR established new MCLs for additional DBPs (i.e., 

chlorite, bromate, and haloacetic acids (HAA5)) as well as established maximum residual disinfection 

levels (MRDLs) for the disinfectants chlorine, chloramines, and chlorine dioxide. In addition, the Stage 1 

DBPR requires conventional filtration systems to remove specified percentages of organic materials, 

measured as total organic carbon (TOC), which may react with disinfectants to form DBPs. 

The Stage 2 DBPR builds upon the Stage 1 DBPR by providing more consistent protection from DBPs 

across the entire distribution system and by focusing on the reduction of DBP peaks. The Stage 2 DBPR 

requires systems to conduct an initial distribution system evaluation (IDSE) to identify compliance 

monitoring locations that represent high TTHM and HAA5 levels. In addition, the Stage 2 DBPR changes 

the way sampling results are averaged to determine compliance. The determination for the Stage 2 DBPR 

is based on a locational running annual average (LRAA) (i.e., compliance must be met at each monitoring 

location) instead of the system-wide running annual average (RAA) used under the Stage 1 DBPR. 

Systems are also required to conduct an operational evaluation if they have DBP levels that exceed the 

operational evaluation level. 

Filter Backwash Recycling Rule 

The Filter Backwash Recycling Rule (FBRR) complements the surface water treatment rules by reducing 

the potential for microbial pathogens, particularly Cryptosporidium oocysts, to pass through the filters 

into the finished water of conventional and direct filtration systems that recycle backwash water. The 

FBRR requires affected systems to return regulated recycle streams (e.g., spent filter backwash, thickener 

supernatant, or liquids from dewatering processes) through all processes of a system=s conventional or 

direct filtration system, unless the state approves an alternate location. In addition, the FBRR requires 

systems to notify the state in writing about recycle practices and to maintain specific records. 

Stage 2 DBPR Implementation Guidance 5 August 2007 
IESWTR/LT1ESWTR/LT2ESWTR 

The IESWTR builds on the SWTR by adding protection from Cryptosporidium by requiring filtered 

systems to meet new turbidity standards for combined filter effluent (CFE) and individual filter effluent 

(IFE). Additionally, the IESWTR requires unfiltered systems to include control of Cryptosporidium in 

their watershed control plans. The IESWTR applies to systems that serve more than 10,000 people. The 

IESWTR builds on the TCR by requiring sanitary surveys for all PWSs using surface water or GWUDI 

regardless of size. The IESWTR also requires covers for all new finished water storage facilities and 

includes disinfection profiling and benchmarking provisions to ensure systems provide continued levels 

of microbial protection while taking the necessary steps to comply with the DBP standards. 

The provisions in the LT1ESWTR address the concerns covered by the IESWTR as they apply to small 

systems (i.e., systems serving fewer than 10,000 people) using surface water or GWUDI. The 

LT2ESWTR builds upon the SWTR, IESWTR, and LT1ESWTR by supplementing existing microbial 

treatment requirements for systems where additional public health protection is needed. 

Collectively, the SWTR, IESWTR, LT1ESWTR, and LT2ESWTR place stringent treatment requirements 

on systems using surface water or GWUDI as a source. Additional information on The LT2ESWTR is 

available on EPA’s Web site: www.epa.gov/safewater/disinfection/lt2/index.html. 

The Multiple Barrier Approach 

By building on the foundation of the original SDWA, subsequent amendments to the Act have improved 

the quality of drinking water and increased public health protection. The 1996 SDWA Amendments, for 

example, require EPA to develop rules to balance the risks presented by microbial pathogens and DBPs. 

Since multiple threats require multiple barriers, the LT2ESWTR and Stage 2 DBPR expand on the 

foundation of the TCR, SWTR, TTHM Rule, Stage 1 DBPR, IESWTR, LT1ESWTR, and FBRR 

standards to target health risks not addressed by prior regulations. By encompassing these previously 

unaddressed health risks from microbials and DBPs, the M-DBP Cluster continues to maximize drinking 

water quality and public health protection. 

1.1.2 Development of the Stage 2 DBPR 

In March 1999, EPA reconvened the M-DBP Advisory Committee to develop recommendations for the 

Stage 2 DBPR and LT2ESWTR. This Committee also participated in the development of the IESWTR, 

LT1ESWTR and Stage 1 DBPR. The Committee’s members represented EPA, state, and local public 

health and regulatory agencies, local elected officials, Native American tribes, drinking water suppliers, 

chemical and equipment manufacturers, and public interest groups. Technical support for the 

Committee’s discussions was provided by a technical workgroup established by the Committee at its first 

meeting. The Committee’s activities resulted in the collection and evaluation of substantial new 

information related to key elements for both rules. This included new data on pathogenicity, occurrence, 

and treatment of microbial contaminants, specifically Cryptosporidium, as well as new data on DBP 

health risks, exposure, and control. The Committee held ten meetings (from September 1999 to July 

2000), to discuss issues pertaining to the Stage 2 DBPR and LT2ESWTR. There was also an opportunity 

for public comment at each meeting. 

In September 2000, the Committee signed the Agreement in Principle, a full statement of the consensus 

recommendations of the group. The agreement was published in a December 29, 2000 Federal Register

notice (65 FR 83015) and includes the list of committee members and their organizations. The 

Committee’s recommendations were incorporated into the proposed Stage 2 DBPR. 

Stage 2 DBPR Implementation Guidance 6 August 2007 
The M-DBP Committee reached an agreement on the following major issues regarding the Stage 2 

DBPR: 

•

•

•

•

•

Compliance calculation for TTHMs and HAA5s revised from an RAA to an LRAA. 

Compliance carried out in two phases of the rule (which was revised to a single phase in the final 

rule.) 

Performance of an IDSE. 

Continued importance of simultaneous compliance with DBP and microbial regulations. 

Unchanged MCL for bromate. 

EPA proposed the Stage 2 DBPR on August 18, 2003. After reviewing public comments on the proposed 

rule, EPA finalized the Stage 2 DBPR on January 4, 2006. 

1.1.3 Benefits of the Stage 2 DBPR 

1.1.3.1 Quantified health benefits 

Although DBPs in drinking water have also been associated with non-cancerous health effects, the 

quantified benefits that result from the Stage 2 DBPR are associated only with estimated reductions in 

DBP-related bladder cancer. A complete discussion of risk assessment methodology and assumptions can 

be found in the Final Stage 2 DBPR Economic Analysis (EA) (USEPA 2005). 

Overall, the Stage 2 DBPR may reduce an average of 103 to 541 bladder cancer cases per year. The 

present value benefits for reductions in bladder cancer that are the result of the Stage 2 DBPR are 

measured as willingness to pay (WTP) for avoiding lymphoma and bronchitis. The WTP estimates for 

lymphoma range from $233 million to $3,536 million, annualized over 25 years using a 3 percent 

discount rate. Using a 7 percent discount rate, the annualized present value benefits range from $190 

million to $2,878 million. The WTP estimates for bronchitis range from $165 million to $1,692 million 

annualized at a 3 percent discount rate, and $135 million to $1,376 million using a 7 percent discount rate. 

1.1.3.2 Non-quantified health and non-health related benefits 

Although significant benefits will result from the Stage 2 DBPR in terms of the reduction in bladder 

cancer, the major potential benefits of this rule remain unquantified. Two major unquantified healthrelated benefits are the potential reduction in adverse reproductive and developmental effects and a 

reduction in other cancers potentially associated with DBP exposure. Reproductive and developmental 

endpoints that may be associated with DBP exposure include fetal losses (miscarriage and stillbirth), 

neural tube defects, heart defects, and cleft palate. Although the science on reproductive and 

developmental health effects as a result of DBP exposure is not strong enough to include them in the 

primary Stage 2 DBPR analysis of benefits, the data appear to be sufficient to warrant concern. Both 

epidemiological and toxicological studies indicate that other cancers may be associated with DBP 

exposure, but currently there is not enough data to quantify or place a monetary value on these cancer 

risks. 

In addition to unquantified health benefits, there are many non-health benefits of the rule. The Stage 2 

DBPR may increase consumer confidence in the quality of drinking water, leading to less averting 

Stage 2 DBPR Implementation Guidance 7 August 2007 
behavior (e.g., boiling tap water or purchasing bottled water). Most people who switch to bottled water or 

use filtration devices do so because of taste and odor problems and health-related issues. Chlorine dioxide 

and chloramines have historically been used to address taste and odor problems. To the extent that the 

Stage 2 DBPR changes perceptions of the health risks associated with drinking water and improves taste 

and odor, it may reduce actions such as buying bottled water or installing filtration devices. Any resulting 

cost savings would be a regulatory benefit. 

As PWSs move from conventional treatment to more advanced technologies, other non-health benefits are 

anticipated. For example, chlorine dioxide is an alternative disinfectant that is also is effective in 

controlling the spread of zebra mussels, an invasive species that has caused significant ecological damage 

in some U.S. waterways. In addition, installation of certain advanced technologies can remove many 

contaminants in addition to those specifically targeted by the Stage 2 DBPR, including those that EPA 

may regulate in the future. For example, membrane technology (depending on pore size), can be used to 

lower DBP formation, but it will also remove many other contaminants that EPA is in the process of 

regulating. Removal of any contaminants that may face regulation could result in future cost savings to a 

water system. 

1.2 Requirements of the Rule 

The following section provides a summary of the rule requirements, preceded by information on new 

terms defined in the Stage 2 DBPR rule language. The requirements are from the final Stage 2 DBPR 

published in the Federal Register on January 4, 2006. For a copy of the actual rule language, see 

Appendix B or visit EPA’s Web site at www.epa.gov/safewater/disinfection/stage2/index.html. 

Compliance schedules 

EPA developed the Stage 2 DBPR compliance schedule for monitoring, reporting, and treatment 

requirements to provide maximum compatibility with the LT2ESWTR compliance schedule. The 

compliance schedule is divided into the following four schedules based on population served by systems: 

•

•

•

•

Schedule 1: Systems serving 100,000 or more people or belonging to a combined distribution 

system in which the largest system serves 100,000 or more. 

Schedule 2: Systems serving 50,000 to 99,999 people or belonging to a combined distribution 

system in which the largest system serves 50,000 to 99,999. 

Schedule 3: Systems serving 10,000 to 49,999 people or belonging to a combined distribution 

system in which the largest system serves 10,000 to 49,999. 

Schedule 4: Systems serving fewer than 10,000 people or belonging to a combined distribution 

system in which the largest system serves fewer than 10,000. 

Stage 2 DBPR Implementation Guidance 8 August 2007 
Figure 1-1. Summary of Stage 2 DBPR Requirements for Systems 

Systems Subject to the Stage 2 DBPR

(All CWSs and NTNCWSs that add a primary or residual disinfectant other than UV or deliver water 

that has been treated with a primary or residual disinfectant other than UV.) 

Rule Implementation

(Rule implementation activities include reading the rule, training, etc.) 

Initial Distribution System Evaluation (IDSE)

(All CWSs and NTNCWSs serving at least 10,000 people that add a primary or residual disinfectant other than UV or deliver 

water that has been treated with a primary or residual disinfectant other than UV.) 

Systems not performing an IDSE Systems performing an IDSE

NTNCWSs Systems Systems receiving 

serving receiving a a Very Small 

<10,000 people 40/30 Certification System Waiver

Systems may or may not

have to select new Stage 2 DBPR 

monitoring sites

Systems conducting Systems conducting a 

standard monitoring and system specific study and 

submitting a Standard submitting a study plan

Monitoring Plan

Systems submit an 

IDSE Report recommending 

Stage 2 DBPR monitoring sites

Stage 2 DBPR Compliance Monitoring Plans

(All systems subject to the rule must develop a Stage 2 DBPR Monitoring Plan that includes monitoring locations, monitoring

dates, and compliance calculation procedures.)

Ensure Compliance with Stage 2 DBPR MCLs

(All systems subject to the rule must meet Stage 2 DBPR MCLs. Systems may or may not have to make treatment or

operational changes.) 

Routine Monitoring Requirements

(Monitoring requirements for the Stage 2 DBPR are based on system type and population served [not number of plants per

system, as for the Stage 1 DBPR]. Systems subject to the Stage 2 DBPR may have fewer or more routine monitoring 

requirements compared to those already required by the Stage 1 DBPR.) 

Operational Evaluations 

(All systems subject to the rule that exceed the operational evaluation level must perform an operational evaluation 

and submit a report to the state within 90 days.) 

Stage 2 DBPR Implementation Guidance 9 August 2007 
1.2.1 New Definitions in the Stage 2 DBPR [40 CFR 141.2] 

1.2.1.1 What is a combined distribution system? 

 

The combined distribution system is the interconnected distribution system consisting of the distribution 

systems of wholesale systems and of the consecutive systems that receive finished water. 

1.2.1.2 What is a consecutive system? 

A consecutive system is a PWS that receives some or all of its finished water from one or more wholesale 

systems. Delivery may be through a direct connection or through the distribution system of one or more 

consecutive systems. 

1.2.1.3 What is a dual sample set? 

A dual sample set is a set of two samples collected at the same time and same location, with one sample 

analyzed for TTHM and the other sample analyzed for HAA5. Dual sample sets are collected for the 

purposes of conducting an IDSE and determining compliance with the TTHM and HAA5 MCLs. 

1.2.1.4 What is finished water? 

Finished water is water that is introduced into the distribution system of a PWS and is intended for 

distribution and consumption without further treatment, except the level of treatment necessary to 

maintain water quality (such as booster disinfection or addition of corrosion control chemicals). Within 

this definition, water entering the distribution system is finished water even if a system subsequently 

applies additional treatment like booster disinfection to maintain a disinfectant residual throughout the 

distribution system. 

1.2.1.5 What is GAC10? 

GAC10 means granular activated carbon filter beds with an empty-bed contact time of 10 minutes based 

on average daily flow and a carbon reactivation frequency of every 180 days, except that the reactivation 

frequency for GAC10 used as the best available technology for compliance with Subpart V MCLs under 

§141.64(b)(2) shall be 120 days. 

1.2.1.6 What is GAC20? 

GAC20 means granular activation carbon filter beds with an empty-bed contact time of 20 minutes based 

on average daily flow and a carbon reactivation frequency of every 240 days. 

1.2.1.7 What is a locational running annual average? 

A locational running annual average (LRAA) is the average of sample analytical results for samples at a 

particular monitoring location during the previous four calendar quarters. 

Stage 2 DBPR Implementation Guidance 10 August 2007 
1.2.1.8 What is a wholesale system? 

A wholesale system is a PWS that treats source water as necessary to produce finished water and then 

delivers some or all of that finished water to another PWS. Delivery may be through a direct connection 

or through the distribution system of one or more consecutive systems. 

1.2.2 IDSE Requirements [40 CFR 141.600] 

The Stage 2 DBPR establishes Initial Distribution System Evaluation (IDSE) requirements. The purpose 

of the IDSE is to help systems acquire adequate information about their distribution systems and DBP 

levels to select Stage 2 DBPR compliance monitoring sites that represent high TTHM and HAA5 levels 

throughout the distribution system. This section identifies which systems are required to meet IDSE 

requirements, summarizes the different IDSE options, and presents IDSE reporting requirements. 

•

•

•

EPA’s Initial Distribution System Evaluation (IDSE) Guidance Manual (EPA 815-B-06-002) 

provides more detailed information on planning and conducting IDSEs. 

The Initial Distribution System Evaluation Guide for Systems Serving < 10,000 People For The 

Final Stage 2 Disinfectants and Disinfection Byproducts Rule (EPA 815-B-06-001) provides 

guidance on conducting the IDSE, however this manual focuses on information that systems 

serving < 10,000 are most likely to use. It does not discuss the IDSE system specific study option.

EPA’s IDSE Tool is a Web-based tool that walks the user through the IDSE process. In the 

program, the Wizard determines IDSE requirements and selects the best IDSE option for your 

system. The tool creates Custom Forms your system (based on population served and system 

type) can submit electronically to EPA’s Information Processing and Management Center 

(IPMC) for EPA/state review. (Available on-line at 

www.epa.gov/safewater/disinfection/tools/index.html). 

1.2.2.1 Who is subject to IDSE requirements? [40 CFR 141.600(b)] 

Systems subject to IDSE requirements are: 

•

•

CWSs that add a primary or residual disinfectant other than UV or deliver water that has been 

treated with a primary or residual disinfectant other than UV; or 

NTNCWSs serving at least 10,000 people that add a primary or residual disinfectant other than 

UV or deliver water that has been treated with a primary or residual disinfectant other than UV. 

NTNCWSs serving fewer than 10,000 people are not subject to IDSE provisions of the Stage 2 DBPR, 

but are subject to compliance monitoring provisions. 

Stage 2 DBPR Implementation Guidance 11 August 2007 
1.2.2.2 What are the options for the IDSE? 

Systems have four ways to satisfy the IDSE requirements: 

1. Very Small System Waiver [40 CFR 141.604]

Systems serving fewer than 500 people are eligible for the Very Small System (VSS) Waiver if 

they collected TTHM and HAA5 samples under the Stage 1 DBPR or have operational TTHM 

and HAA5 data that meets the general intent of Stage 1 DBPR compliance. 

2. 40/30 Certification [40 CFR 141.603]

Systems may fulfill IDSE requirements by demonstrating low historical TTHM and HAA5 

distribution system concentrations. Systems are eligible for 40/30 Certification if eight 

consecutive calendar quarters all individual TTHM results were less than or equal to 0.040 mg/L, 

and all individual HAA5 results were less than or equal to 0.030 mg/L. 

3. System Specific Study (SSS) [40 CFR 141.602]

Systems may complete an SSS, based either on existing monitoring data or on distribution system 

modeling. Examples of acceptable studies include a hydraulic modeling study that simulates 

water movement in the distribution system or a study of recent TTHM and HAA5 monitoring 

data that encompass a wide range of sample sites, including those with representative high TTHM 

and HAA5 concentrations. 

4. Standard Monitoring [40 CFR 141.601]

Systems may complete 1 year of distribution system monitoring on a set schedule that includes 

the peak historical month for TTHM or HAA5 levels or warmest water temperature. The 

frequency of monitoring and the number and location of monitoring sites follows a standard 

monitoring scheme dependent on population served and source water. All IDSE samples must be 

taken as dual sample sets. 

1.2.2.3 What is the time frame for compliance with the IDSE? 

Table 1-1 outlines the deadlines for submittal for compliance with the IDSE based on the system’s 

schedule. 

Stage 2 DBPR Implementation Guidance 12 August 2007 
Table 1-1. IDSE Plan and Report Due Dates [40 CFR 141.600(c)] 

Compliance dates by PWS size (retail populations served)1

Requirement CWSs and 

NTNCWSs 

serving at least 

100,000 

CWSs and 

NTNCWSs 

serving 50,000-

99,999 

CWSs and 

NTNCWSs 

serving 10,000-

49,999 

CWSs 

serving 

<10,000 

NTNCWSs 

serving 

<10,000 

Submit Standard Monitoring 

Plan or submit SSS Plan OR 

submit 40/30 Certification 

OR receive VSS Waiver 

from state 

October 1, 2006 April 1, 2007 October 1, 2007 April 1, 2008 Not 

applicable 

Complete standard 

monitoring or SSS 

September 30, 

2008 March 31, 2009 September 30, 2009 

March 31, 

2010 

Not 

applicable 

Submit IDSE Report January 1, 2009 July 1, 2009 January 1, 2010 July 1, 201 Not 

applicable 

1. Wholesale and consecutive systems that are part of a combined distribution system must comply based on the 

schedule required of the largest system in the combined distribution system. 

1.2.2.4 What are the requirements for systems that receive a VSS Waiver or 40/30 Certification 

for the IDSE? 

Systems that qualify for and receive the VSS Waiver or 40/30 Certification do not have to conduct an 

IDSE, these systems will need to prepare a Stage 2 DBPR Compliance Monitoring Plan and meet 

compliance monitoring requirements, as discussed in section 3.6.2. 

Very Small System Waiver [40 CFR 141.604] 

Systems serving fewer than 500 people may be eligible for the VSS Waiver if they have collected TTHM 

and HAA5 samples under the Stage 1 DBPR or have operational TTHM and HAA5 data that meets the 

general intent of Stage 1 DBPR compliance. VSS Waivers are effective immediately for systems that 

meet the eligibility requirements and no application from the water system is necessary. Regardless of a 

system’s eligibility, a state can still require a small system to conduct standard monitoring or an SSS 

according to the schedule in Table 1-1. 

40/30 Certification [40 CFR 141.603] 

Another alternative systems have for fulfilling the IDSE requirements is to demonstrate low historical 

TTHM and HAA5 distribution system concentrations. Systems are eligible for 40/30 Certification if their 

data meet the following criteria: eight consecutive calendar quarters, with all individual TTHM results 

less than or equal to 0.040 mg/L, and all individual HAA5 results less than or equal to 0.030 mg/L. 

•

•

The eight consecutive calendar quarters must have begun no earlier than the date specified in 

Table 1-2. 

TTHM and HAA5 samples must have been analyzed by a laboratory certified under the drinking 

water certification program to perform these measurements and using approved methods. 

Stage 2 DBPR Implementation Guidance 13 August 2007 
• The system must have had no TTHM or HAA5 monitoring violations during the same eight 

consecutive calendar quarters. 

Table 1-2. 40/30 Certification Eligibility Dates 

If your 40/30 Certification 

is due 

Then your eligibility for 40/30 Certification is based on 

eight consecutive calendar quarters of Subpart L 

compliance monitoring results beginning no earlier than 1

(1) October 1, 2006 January 2004 

(2) April 1, 2007 January 2004 

(3) October 1, 2007 January 2005 

(4) April 1, 2008 January 2005 

1. Unless you are on reduced monitoring under Subpart L of this part and were not required to 

monitor during the specific period. If you did not monitor during the specified period, you 

must based your eligibility on compliance samples taken during the 12 months preceding the 

specific period. 

Some states may allow systems that were not required to comply with Stage 1 DBPR to use operational 

data to support a 40/30 Certification. The samples must meet the general intent of Stage 1 DBPR 

compliance, which would include: 

•

•

•

•

•

Samples were analyzed by approved methods at a certified lab. 

Number of sites was adequate to represent the distribution system and correlate to the number 

required under the Stage 1 DBPR. 

Sample sites were located at sites with average and maximum residence time. 

Samples were taken during the month of warmest water temperature. 

Samples were taken on a monthly, quarterly or annual basis, depending on population, 

disinfectant type, source type. 

A system selecting this option must certify its eligibility to the state according to the schedule shown in 

Table 1-1. The state may require the system to submit the following additional information: 

•

•

•

Compliance monitoring results. 

Distribution system schematics. 

Recommended Stage 2 DBPR compliance monitoring locations. 

At the state’s discretion, a system meeting all of the requirements for 40/30 Certification may still be 

required to conducted standard monitoring or an SSS. 

Stage 2 DBPR Implementation Guidance 14 August 2007 
1.2.2.5 What are the requirements for systems that must conduct a standard monitoring or an 

SSS IDSE? 

Systems that are required to conduct a standard monitoring or an SSS IDSE to comply with the provisions 

of the rule must prepare and submit an IDSE plan, conduct the IDSE, and prepare and submit a final 

IDSE Report. 

System Specific Study [40 CFR 141.602] 

To comply with the IDSE requirement, systems may choose to perform an SSS, based either on existing 

monitoring data or on extended period hydraulic modeling. Examples of acceptable studies include an 

extended period hydraulic modeling study that simulates water movement in the distribution system or 

recent TTHM and HAA5 monitoring data that encompass a wide range of sample sites, including those 

with representative high TTHM and HAA5 concentrations. 

Systems selecting this option must submit a study plan before the SSS, and an IDSE Report after the SSS, 

according to the schedule shown in Table 1-1. A system that conducts its SSS early may satisfy both 

requirements by submitting an IDSE Report in place of the study plan, as long as the IDSE Report also 

includes all information required in the study plan. 

Standard Monitoring [40 CFR 141.601] 

To comply with the IDSE requirement, systems may choose to conduct standard monitoring at a 

frequency and at the sites defined in the rule. Systems selecting this option must submit a Standard 

Monitoring Plan, then conduct monitoring in accordance with the plan as approved by EPA, and must 

submit an IDSE Report, according to the schedule shown in Table 1-1. 

1.2.2.6 What must an SSS include? [40 CFR 141.602(a)] 

An SSS must be based on either existing DBP monitoring results or an extended period simulation 

hydraulic model. The information to be included in the study plan depends on whether the system opts to 

use the existing monitoring results or the modeling approach for the IDSE. 

System Specific Study - Existing Monitoring Plan 

An SSS based on existing monitoring results must include Stage 1 DBPR TTHM and HAA5 results 

collected no more than 5 years before the submission of the plan. Monitoring results must include all 

Stage 1 DBPR compliance monitoring and additional monitoring results as necessary to meet minimum 

sampling requirements (Table 1-3). Each location must have been sampled once during the peak historical 

month for TTHM levels or HAA5 levels or the month of warmest water temperature for every 12 months 

of data submitted for that location. 

Table 1-3. SSS Monitoring Locations and Frequency [40 CFR 141.602(b)] 

System Type Population Size 

Category 

Number of Monitoring 

Locations 

Number of Samples 

TTHM HAA5

Subpart H <500 3 3 3

500-3,300 3 9 9

Stage 2 DBPR Implementation Guidance 15 August 2007 
Stage 2 DBPR Implementation Guidance 16 August 2007 

System Type Population Size Number of Samples 

Category 

Number of Monitoring 

Locations 

TTHM HAA5 

3,301-9,999 6 36 36

10,000-49,999 12 72 72

50,000-249,999 24 144 144

250,000-999,999 36 216 216

1,000,000-4,999,999 48 288 288

≥ 5,000,000 60 360 360

Ground Water <500 3 3 3

500-9,999 3 9 9

10,000-99,999 12 48 48

100,000-499,999 18 72 72

≥ 500,000 24 96 96

 

The system must certify that: 

•

•

•

The reported monitoring results include all compliance and non-compliance results generated 

during the time period beginning with the first reported result and ending with the most recent 

Stage 1 DBPR results, 

The samples were representative of the entire distribution system; and 

The distribution system and treatment regimen have not changed significantly since the samples 

were collected. 

The monitoring plan must also include: 

•

•

•

A schematic of the distribution system including: 

– Distribution system entry points and their sources. 

– Storage facilities. 

– Notes indicating the locations and dates of all completed or planned SSS monitoring. 

The system type (Subpart H [surface water or GWUDI] or ground water); and 

The population served. 

If the state rejects some of the data from a study plan, the system must either conduct additional 

monitoring to replace rejected data on a schedule the state approves, or conduct standard monitoring. 

System Specific Study – Hydraulic Modeling Plan 

An SSS based on modeling must be based on an extended period simulation hydraulic model. The model 

must simulate 24-hour variation in demand and show a consistently repeating 24-hour pattern of residence 

time. In addition, the model must be calibrated, or have calibration plans, for the current configuration of 

the distribution system during the period of high TTHM formation potential. The calibration must be 
completed no later than 12 months after a system submits its plan. The model must represent the 

following criteria: 

•

•

•

•

•

•

•

•

•

Seventy-five percent of pipe volume. 

Fifty percent of pipe length. 

All pressure zones. 

All 12-inch diameter and larger pipes. 

All 8-inch and larger pipes that connect pressure zones, influence zones from different sources, 

storage facilities, major demand areas, pumps, and control valves, or are known or expected to be 

significant conveyors of water. 

All 6-inch and larger pipes that connect remote areas of a distribution system to the main portion 

of the system. 

All storage facilities with standard operations represented in the model. 

All active pump station with controls represented in the model. 

All active control valves. 

The model should also include the following information: 

•

•

•

•

Description of all model calibration activities undertaken, and, if calibration is complete, 

– A graph of predicted tank levels versus measured tank levels for the storage facility with the 

highest residence time in each pressure zone, and 

– A time series graph of the residence time at the longest residence time storage facility in the 

distribution system showing the predictions for the entire simulation period (i.e., from time 

zero until the time it takes for the model to reach a consistently repeating pattern of residence 

time). 

Model output showing preliminary 24 hour average residence time predictions throughout the 

distribution system 

The timing and number of samples representative of the distribution system planned for at least 

one monitoring period of TTHM and HAA5 dual sample monitoring at a number of locations no 

fewer than would be required for the system under standard monitoring during the historical 

month high TTHM (at locations other than existing Stage 1 DBPR compliance monitoring 

locations). 

Description of how the system will complete all the requirements, no later than 12 months after 

the plan is submitted. 

Stage 2 DBPR Implementation Guidance 17 August 2007 
•

•

•

A schematic of the distribution system with notes indicating the locations and dates of: 

– All completed study monitoring (if calibration is complete), and 

– All Stage 1 DBPR compliance monitoring. 

A table or spreadsheet with data demonstrating that the model meets the rule requirements. 

The plan should specify the system type (Subpart H or ground water) and the population served. 

If a modeling study plan does not fully meet the requirements, the system will be required to correct the 

deficiencies and provide further information. If a system’s SSS is not approved, the system will need to 

perform standard monitoring to comply with the IDSE. 

1.2.2.7 What must a Standard Monitoring Plan include? [40 CFR 141.601(a)] 

The monitoring plan must include: 

•

•

•

•

•

Schematic of the system’s distribution system (including distribution system entry points and 

their sources, and storage facilities). 

Notes indicating locations and dates of all projected standard monitoring, and all projected Stage 

1 DBPR compliance monitoring. 

Justification for standard monitoring location selection. 

Summary of data upon with the justification is based. 

System type (Subpart H or ground water) and population served. 

1.2.2.8 How long must the Standard Monitoring Plan or SSS Plan be retained? 

Systems must retain a copy of their Standard Monitoring Plan or SSS Plan, including any state 

modification to the plan, for a period of 10 years from the date the system submitted the plan to the state. 

1.2.2.9 Who must submit an IDSE Report? 

Systems performing standard monitoring or an SSS must submit an IDSE Report to the state for approval 

according to the schedule shown in Table 1-1. 

1.2.2.10 What must the IDSE Report include? 

For systems conducting standard monitoring, the IDSE Report must include [§141.601(c)]: 

•

•

All TTHM and HAA5 analytical results from Stage 1 DBPR compliance monitoring and all 

standard monitoring completed during the period of the IDSE as individual analytical results and 

LRAAs, presented in a tabular or spreadsheet format acceptable to the state. 

If they changed since the Standard Monitoring Plan was submitted, a schematic of the distribution 

system, system type, and population served. 

Stage 2 DBPR Implementation Guidance 18 August 2007 
•

•

Explanation of any deviations from the approved Standard Monitoring Plan. 

Recommendations and justifications for Stage 2 DBPR compliance monitoring locations and 

timing. 

For systems conducting the SSS, the IDSE Report must include [§141.602(b)]: 

•

•

•

•

•

All TTHM and HAA5 analytical results from Stage 1 DBPR compliance monitoring and all 

system specific study monitoring completed during the period of the study, presented in a tabular 

or spreadsheet format acceptable to the state. 

If they changed since the system specific study monitoring plan was submitted, a schematic of the 

distribution system, system type, and population served. 

If the study was a modeling study, an update of all the information in the study plan and a 24-

hour time series graph of residence time for each Stage 2 DBPR compliance monitoring location 

selected. 

Recommendations and justifications for Stage 2 DBPR compliance monitoring locations and 

timing. 

Explanation of any deviations from the approved SSS Plan. 

1.2.2.11 How long must the IDSE Report be retained? 

Systems must retain their IDSE Report for 10 years after the date they submit it. If the state modifies the 

Stage 2 DBPR monitoring requirements in an IDSE Report or approves alternative monitoring locations, 

the system must keep a copy of the state’s notification on file for 10 years after the date of notification. 

The IDSE Report and any state notification must be available for review by the state or the public. 

1.2.3 Stage 2 DBPR Compliance Monitoring [40 CFR 141.620, 40 CFR 141.621] 

This section summarizes the requirements for Stage 2 DBPR compliance monitoring, required contents of 

the Stage 2 DBPR Compliance Monitoring Plan, reduced monitoring, increased monitoring, and special 

issues for consecutive systems. As with the IDSE monitoring, Stage 2 DBPR compliance monitoring 

requirements vary according to source type and population served. 

Stage 2 DBPR compliance monitoring applies to all CWSs and NTNCWSs that add a primary or residual 

disinfectant other than UV or deliver water that has been treated with a primary or residual disinfectant 

other than UV. 

1.2.3.1 How is compliance calculated for TTHM and HAA5 under Stage 2 DBPR? [40 CFR 

141.620(d)] 

The Stage 2 DBPR changes the way compliance is determined with MCLs by changing the way sampling 

results are averaged. Stage 2 DBPR determines compliance with the MCL on an LRAA instead of the 

system-wide RAA as is used under the Stage 1 DBPR. The primary objective of the LRAA is to reduce 

exposure to high DBP levels. For an LRAA, an annual average is calculated at each monitoring site. The 

RAA compliance calculation allows a system-wide annual average. In this situation, high DBP 

concentrations in one or more locations are averaged with lower concentrations elsewhere in the 

Stage 2 DBPR Implementation Guidance 19 August 2007 
distribution system. Figure 1-2 illustrates the difference in calculating compliance with the MCLs for 

TTHM between a Stage 1 DBPR RAA and the Stage 2 DBPR LRAA. 

Figure 1-2. Comparison of RAA and LRAA Compliance Calculations1

1st Quarter 2nd Quarter 3rd Quarter 4th Quarter

Average of All Samples Average of All Samples Average of All Samples Average of All Samples

RUNNING ANNUAL AVERAGE (RAA) OF QUARTERLY SAMPLES MUST BE BELOW MCL

Stage 1 

DBPR

Q1

Q2

Q3

Q4

LRAA 1 MUST 

BE BELOW 

MCL

Q1

Q2

Q3

Q4

LRAA 2 MUST 

BE BELOW 

MCL

Q1

Q2

Q3

Q4

LRAA 3 MUST 

BE BELOW 

MCL

Q1

Q2

Q3

Q4

LRAA 4 MUST 

BE BELOW 

MCL

Stage 2 

DBPR

1. Stage 2 DBPR sampling locations will (in most cases) be selected based on the results of an IDSE and may be 

different from Stage 1 DBPR sampling sites. 

The new Stage 2 DBPR TTHM and HAA5 LRAA requirements apply to all CWSs and NTNCWSs that 

serve chemically disinfected (i.e., add a primary or residual disinfectant other than UV or deliver water 

that has been treated with a primary or residual disinfectant other than UV) drinking water, regardless of 

whether they treat the water themselves or receive it from another system. 

Note that LRAAs are used for compliance with TTHM and HAA5 MCLs. The bromate MCL of 0.010 

mg/L, for example, is still measured as an RAA as required by the Stage 1 DBPR. 

1.2.3.2 What are the Stage 2 DBPR MCLs? [40 CFR 141.620] 

For the Stage 2 DBPR, CWSs and NTNCWSs must comply with MCLs of 0.080 mg/L and 0.060 mg/L as 

LRAAs for TTHM and HAA5, respectively, based on monitoring at locations identified in their 

monitoring plans (see sections 1.2.3.4-1.2.3.7 for a discussion of Stage 2 DBPR Compliance Monitoring 

Plans and routine monitoring requirements). 

1.2.3.3 What are the new MCLGs? [40 CFR 141.53] 

The Stage 2 DBPR establishes MCLGs for a number of DBPs. These new MCLGs do not affect the 

MCLs for TTHM or HAA5. Table 1-4 summarizes the new MCLGs. 

Stage 2 DBPR Implementation Guidance 20 August 2007 
Table 1-4. Summary of Stage 2 DBPR MCLGs 

Contaminant MCLG (mg/L) 

Bromodichloromethane zero 

Bromoform zero 

Bromate zero 

Chlorite 0.8 

Chloroform 0.07 

Dibromochloromethane 0.06 

Dichloroacetic acid zero 

Monochloroacetic acid 0.07 

Trichloroacetic acid 0.02 

1.2.3.4 What Are the Requirements for Developing a Stage 2 DBPR Compliance Monitoring 

Plan? [40 CFR 141.622] 

All systems required to conduct compliance monitoring under the Stage 2 DBPR must develop a 

Compliance Monitoring Plan. However, systems that completed an IDSE Report will have included their 

monitoring locations and dates in the report. For most systems, if they also include compliance 

calculation procedures, they may be able to meet the requirements of the Compliance Monitoring Plan 

and will not have to submit a separate document. 

For systems that are required to complete a Compliance Monitoring Plan, they must complete the plan no 

later than the date when monitoring begins (see table 1-5) and must contain the following information: 

•

•

•

•

Monitoring locations; 

 

Monitoring dates; 

Compliance calculation procedures; and 

Monitoring plans for other systems in the combined distribution system if the state has reduced 

monitoring requirements [§142.16(m)]. 

Systems that completed an IDSE but did not include the compliance calculation procedures in their IDSE 

Report must still prepare a Compliance Monitoring Plan. These systems should base their Compliance 

Monitoring Plan on the IDSE Report and any state modifications. Systems may revise their Compliance 

Monitoring Plan to reflect changes in treatment, distribution system operations and layout, or other factors 

that may affect TTHM or HAA5 formation. If there are any changes to the monitoring locations, systems 

must replace existing compliance monitoring locations with expected high TTHM or HAA5 levels. 

Systems with a VSS Waiver must comply by updating their Stage 1 DBPR monitoring plan, which was 

developed under §141.132(f). 

Systems that qualified for the 40/30 Certification and NTNCWSs that did not conduct standard 

monitoring or an SSS should use their Stage 1 DBPR monitoring sites as the basis for Stage 2 DBPR site 

Stage 2 DBPR Implementation Guidance 21 August 2007 
selection. If a system has more Stage 1 DBPR sites than required under for Stage 2 DBPR compliance 

monitoring, it must select Stage 2 DBPR compliance monitoring sites by alternating selection of locations 

representing high TTHM and high HAA5 levels until the required number of Stage 2 DBPR compliance 

monitoring locations have been identified. If a system has fewer Stage 1 DBPR sites than required by the 

Stage 2 DBPR, the system must select the sites with highest DBP levels, alternating selection of locations 

representing high TTHM levels and high HAA5 levels, starting with high TTHM. 

1.2.3.5 What are the reporting and recordkeeping requirements for Stage 2 DBPR Compliance 

Monitoring Plan? [40 CFR 141.622(c), 40 CFR 141.629(b)] 

All systems must keep their Stage 2 DBPR Compliance Monitoring Plan on file for state and public 

review. Subpart H systems serving more than 3,300 people are required to submit copies of their 

Compliance Monitoring Plans to the state before they begin compliance monitoring, unless their IDSE 

Report already contains the required information. The state may modify a system’s Compliance 

Monitoring Plan. 

1.2.3.6 What Are the Compliance Deadlines for Stage 2 DBPR Compliance Monitoring? [40 

CFR 141.620(c)] 

Table 1-5 summarizes the deadlines for Stage 2 DBPR for TTHM and HAA5 compliance monitoring. If a 

system is required to conduct quarterly monitoring, it must begin monitoring in the first full calendar 

quarter that includes the compliance date in Table 1-5. If the system is required to conduct monitoring at a 

frequency that is less than quarterly, it must begin monitoring in the calendar month recommended in the 

IDSE Report, or in the calendar month identified in the monitoring plan, no later than 12 months after the 

compliance date in Table 1-5. 

Table 1-5. Compliance Schedule for Stage 2 DBPR TTHM and HAA5 Monitoring 

Compliance dates by PWS size (retail populations served)1

Requirement CWSs and 

NTNCWSs 

serving at least 

100,000 

CWSs and 

NTNCWSs 

serving 50,000-

99,999 

CWSs and 

NTNCWSs 

serving 10,000-

49,999 

CWSs serving 

<10,000 

NTNCWSs 

serving <10,000 

Begin Stage 2 

Compliance 

(Subpart V) 

Monitoring2

April 1, 2012 October 1, 2012 October 1, 2013 October 1, 2013 

(October 1, 2014 

if Cryptosporidium 

monitoring is 

required under 

LT2ESWTR.) 

October 1, 2013 

(October 1, 2014 

if Cryptosporidium 

monitoring is 

required under 

LT2ESWTR.) 

1. Wholesale and consecutive systems that are part of a combined distribution system must comply based on the 

schedule required of the largest system in the combined distribution system. 

2. States may grant up to an additional 2 years for systems making capital improvements. See Appendix I for 

guidance on reviewing extension requests under Section 1412(b)(10) of the SDWA. 

1.2.3.7 What Are the Requirements for Routine Monitoring? [40 CFR 141.621] 

Table 1-6 shows the Stage 2 DBPR routine compliance monitoring requirements. For systems (including 

consecutive systems), monitoring requirements are based on source type and population served (instead of 

Stage 2 DBPR Implementation Guidance 22 August 2007 
the number of plants, as was the case under the Stage 1 DBPR.) The number of sampling sites may also 

increase or decrease from Stage 1 DBPR to Stage 2 DBPR. 

Depending on monitoring results, a system may be eligible for reduced monitoring under §141.623 

(Section 3.15). Some systems may be required to conduct increased monitoring if certain conditions are 

met as specified in §141.625 (Section 3.16). 

Table 1-6. Stage 2 DBPR Routine Compliance Monitoring Requirements 

Source Water 

Type 

Population Size 

Category 

Monitoring 

Frequency 1

Distribution System Monitoring Location 

Total per Monitoring Period 2

<500 per year 2 

500-3,300 per quarter 2 

3,301-9,999 per quarter 2 

10,000-49,999 per quarter 4 

50,000-249,999 per quarter 8 

250,000-999,999 per quarter 12 

1,000,000-4,999,999 per quarter 16 

Subpart H 

≥ 5,000,000 per quarter 20 

<500 per year 2 

500-9,999 per year 2 

10,000-99,999 per quarter 4 

100,000-499,999 per quarter 6 

Ground Water 

≥ 500,000 per quarter 8 

1. All systems must take at least one dual sample set during the month of highest DBP concentrations. 

2. Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for 

Subpart H systems serving 500-3,300. Systems on annual monitoring and Subpart H systems serving 500-3,300 are 

required to take individual TTHM and HAA5 samples (instead of a dual sample set) at the locations with the highest 

TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring period is 

needed if highest TTHM and HAA5 concentrations occur at the same location (and month, if monitored annually). 

1.2.3.8 How Do Systems Qualify for Reduced Stage 2 DBPR Monitoring? [40 CFR 141.623] 

Systems may qualify for reduced monitoring if their LRAAs at all monitoring locations for TTHM and 

HAA5 are no more than 0.040 mg/L and 0.030 mg/L, respectively. In addition, Subpart H systems must 

maintain annual average TOC levels of 4.0 mg/L or less in source water at each treatment plant in order to 

qualify. Systems should note that under the Stage 1 DBPR, no sampling frequency for TOC was 

specified. Beginning April 1, 2008 (or earlier if specified by the state), systems must sample for TOC 

every 30 days to qualify for reduced monitoring and sample every 90 days to remain on reduced 

monitoring. Therefore, systems on a reduced Stage 1 DBPR monitoring schedule may need to conduct 

Stage 2 DBPR compliance monitoring on a routine monitoring schedule until they have collected 

sufficient TOC data to qualify for reduced monitoring. 

Systems may remain on reduced monitoring as long as their quarterly LRAAs for TTHMs and HAA5 

remain no more than 0.040 mg/L and 0.030 mg/L, respectively (for systems with quarterly reduced 

monitoring) or their TTHM and HAA5 samples are no higher than 0.060 mg/L and 0.045 mg/L, 

respectively (for systems with annual or less frequent monitoring). In addition, Subpart H systems must 

continue to maintain annual average TOC levels of 4.0 mg/L or less in source water at each treatment 

plant. 

Stage 2 DBPR Implementation Guidance 23 August 2007 
If monitoring results indicate that a system is no longer eligible for reduced monitoring, the system must 

resume routine monitoring or begin increased monitoring the quarter immediately following the 

monitoring period in which the system exceeded the specified levels for reduced monitoring. The state 

may also use its discretion to return a system to routine monitoring. 

Table 1-7. Stage 2 DBPR Reduced Monitoring Requirements for All Systems 

Source 

Water 

Type 

Population 

Size 

Category 

Monitoring 1 Frequency 

Distribution System Monitoring Location per Monitoring 

Period 

Subpart H 

<500 - Monitoring may not be reduced. 

500-3,300 per year 1 TTHM and 1 HAA5 sample: one at the location and during the 

quarter with the highest TTHM single measurement, one at the 

location and during the quarter with the highest HAA5 single 

measurement; 1 dual sample set per year if the highest TTHM and 

HAA5 measurements occurred at the same location and quarter. 

3,301-9,999 per year 2 dual sample sets: one at the location and during the quarter with 

the highest TTHM single measurement, one at the location and 

during the quarter with the highest HAA5 single measurement. 

10,000-

49,999 

per quarter 2 dual sample sets at the locations with the highest TTHM and 

highest HAA5 LRAAs. 

50,000-

249,999 

per quarter 4 dual sample sets - at the locations with 

and two highest HAA5 LRAAs. 

the two highest TTHM 

250,000-

999,999 

per quarter 6 dual sample sets - at the locations 

and three highest HAA5 LRAAs. 

with the three highest TTHM 

1,000,000-

4,999,999 

per quarter 8 dual sample sets - at the locations with the four highest TTHM 

and four highest HAA5 LRAAs. 

≥ 5,000,000 per quarter 10 dual sample sets - at the locations with the five highest 

and five highest HAA5 LRAAs. 

TTHM 

Ground 

Water 

<500 every third year 1 TTHM and 1 HAA5 sample: one at the location and during the 

quarter with the highest TTHM single measurement, one at the 

location and during the quarter with the highest HAA5 single 

measurement; 1 dual sample set per year if the highest TTHM and 

HAA5 measurements occurred at the same location and quarter. 

500-9,999 per year 1 TTHM and 1 HAA5 sample: one at the location and during the 

quarter with the highest TTHM single measurement, one at the 

location and during the quarter with the highest HAA5 single 

measurement; 1 dual sample set per year if the highest TTHM and 

HAA5 measurements occurred at the same location and quarter. 

10,000-

99,999 

per year 2 dual sample sets: one at the location and during the quarter with 

the highest TTHM single measurement, one at the location and 

during the quarter with the highest HAA5 single measurement. 

Stage 2 DBPR Implementation Guidance 24 August 2007 
Stage 2 DBPR Implementation Guidance 25 August 2007 

Source 

Water 

Type 

Population 

Size 

Category 

Monitoring 

Frequency 1

 

Distribution System Monitoring Location per Monitoring 

Period 

100,000-

499,999 

per quarter 2 dual sample sets; at the locations with the highest TTHM and 

highest HAA5 LRAAs. 

≥ 500,000 per quarter 4 dual sample sets at the locations with the two highest TTHM and 

two highest HAA5 LRAAs. 

1. Systems on quarterly monitoring must take dual sample sets every 90 days. 

1.2.3.9 What Are the Requirements for Increased Monitoring? [40 CFR 141.625, 40 CFR 

141.628] 

If a system monitors annually or less frequently than annually on either the routine monitoring schedule 

or the reduced monitoring schedule and a TTHM sample exceeds 0.080 mg/L or a HAA5 sample exceeds 

0.060 mg/L at any location, the system must increase monitoring frequency to dual sample sets once per 

quarter (taken every 90 days) at all locations. 

A system may return to routine monitoring if the TTHM LRAA for every monitoring location is less than 

or equal to 0.060 mg/L and the HAA5 LRAA for every monitoring location is less than or equal to 0.045 

mg/L after conducting at least four consecutive quarters of increased monitoring. 

Systems on an increased Stage 1 DBPR monitoring schedule must begin Stage 2 DBPR monitoring on the 

increased schedule until they meet the requirements above for returning to the routine schedule. 

1.2.4 Monitoring Requirements for Consecutive Systems 

1.2.4.1 What are the DBP monitoring requirements for consecutive systems? [40 CFR 141.620] 

The TTHM and HAA5 sampling requirements for consecutive systems are determined in the same 

manner as for all other systems. The number of sites and monitoring frequency is based on the system’s 

population served and source type (based on wholesale system’s source water type). Thus, large 

consecutive systems will take more samples than a smaller wholesale system. 

States may modify the Stage 2 DBPR compliance monitoring requirements for consecutive systems by 

treating a combined distribution system as a single system. This is allowed to the extent that the 

interconnection of the systems justifies such modifications [§141.29]. If the state elects to use this 

authority, they must describe in their primacy application how they will implement this procedure and 

include a requirement that at least one monitoring site will be located in each water system [§142.16(m)]. 

1.2.4.2 What are the Chlorine and Chloramines requirements for consecutive systems? [40 CFR 

141.624] 

Consecutive systems that do not add a disinfectant but deliver water that was treated with a disinfectant 

other than UV must now comply with the Stage 1 DBPR analytical and monitoring requirements for 

chlorine and chloramines and associated compliance requirements and reporting requirements. These 

requirements include: 

•

•

Analytical methods [§141.131(c)], 

Monitoring of residual at the same sites as total coliform sampling [§141.132(c)(1)], 
•

•

Compliance with the MRDL [§141.133(c)(1)], and 

Reporting of results [§141.134(c)]. 

These requirements begin April 1, 2009 unless required earlier by the state. 

Additional Resources for Consecutive Systems 

EPA is preparing a guidance manual for consecutive systems to address these and other issues. 

1.2.5 Operational Evaluation Levels [40 CFR 141.626] 

TTHM and HAA5 MCL compliance is based on an LRAA, therefore a system may have individual DBP 

results significantly higher than the MCL from time to time while remaining in compliance. This situation 

is a result of the fact that high concentrations are averaged with lower concentrations at a given location. 

While this situation does not constitute an MCL violation, it might indicate a trend that could lead to an 

MCL violation in future quarters. 

The “operational evaluation level” is an LRAA threshold, meant to help systems identify if they are in 

danger of exceeding the MCL in the following monitoring quarter. The process is useful in that it alerts 

the system to the potential of an MCL violation if DBP levels remain at their current level and encourages 

them to consider what operational changes may be necessary to reduce DBP levels. 

The operational evaluation level at any location is the sum of the two previous quarters’ TTHM or HAA5 

results plus twice the current quarter’s TTHM or HAA5 result, divided by four to determine an average. 

Effectively, it is the LRAA that can be expected if the next quarter’s result is the same as the current 

quarter’s result. To determine if a system has exceeded operational evaluation levels at any sampling 

location, the following formula is used: 

If (Q1 + Q2 +2Q3)/4 > MCL at any monitoring location, 

where 

Q3 = current quarter measurement 

Q2 = previous quarter measurement 

Q1 =quarter before previous quarter measurement 

MCL=Stage 2 DBPR MCL for TTHM (0.080 mg/l) or Stage 2 DBPR MCL for HAA5 (0.060 mg/L)

then the system must conduct an operational evaluation.

If the operational evaluation level for TTHM exceeds 0.080 mg/L or the operational evaluation level for 

HAA5 exceeds 0.060 mg/L at any monitoring location, an exceedance of the operational evaluation level 

has occurred. 

If this happens, the system must conduct an operational evaluation and submit a written report of the 

evaluation to the state no later than 90 days after the system is notified of the analytical result that caused 

the exceedance. The written report must be available to the public upon request. The operational 

evaluation must include an examination of system treatment and distribution operational practices, 

including storage tank operations, excess storage capacity, distribution system flushing, changes in 

sources or source water quality, and treatment changes or problems that may contribute to TTHM and 

HAA5 formation, and what steps could be considered to minimize future exceedances. 

Stage 2 DBPR Implementation Guidance 26 August 2007 
If the system is readily able to identify the cause of the exceedance, it may request permission to limit the 

scope of the evaluation. If the state grants the request, the system must still follow the schedule for 

completing the evaluation. The state must approve the limited scope in writing, and the system must keep 

the approval with the completed report. 

For more information on operational evaluations, refer to EPA’s Operational Evaluation Guidance 

Manual (formerly titled the Significant Excursions Guidance Manual) available online at 

www.epa.gov/safewater/disinfection/stage2/compliance.html#pws. 

1.2.6 Bromate Requirements [40 CFR 141.132] 

The MCL for bromate for systems using ozone remains 0.010 mg/L (measured as an RAA) for samples 

taken at the entrance to the distribution system as established by the Stage 1 DBPR. However, the 

criterion for a system using ozone to qualify for reduced bromate monitoring has changed from 

demonstrating low levels of bromide in the source water to demonstrating low levels of bromate in the 

finished water, now that more sensitive bromate methods are available. Beginning April 1, 2009, systems 

must have a bromate RAA of 0.0025 mg/L or less based on 1 year of monthly data to qualify for reduced 

bromate monitoring. In addition, the samples must be analyzed using Method 317.0 Revision 2.0, 326.0, 

or 321.8. Systems must continue to compute the RAA quarterly after qualifying for reduced bromate 

monitoring, and if the RAA exceeds 0.0025 mg/L, the system must return to routine monitoring. 

1.2.7 Reporting/Recordkeeping Requirements [40 CFR 141.33, 40 CFR 141.629] 

Note that the state may choose to perform calculations and determine whether the system exceeded the 

MCL or the system is eligible for reduced monitoring in lieu of having the system report that information. 

1.2.7.1 What monitoring information must be reported? [40 CFR 141.629(a)(2)] 

Systems must report the following information for each monitoring location to the state within 10 days of 

the end of any quarter in which monitoring is required: 

•

•

•

•

•

Number of samples taken during the last quarter. 

Date and results of each sample taken during the last quarter. 

If monitoring is quarterly, the LRAAs of quarterly TTHM and HAA5 results for the last four 

quarters. If an LRAA calculation based on fewer than four quarters of data would cause the MCL 

to be exceeded regardless of the monitoring results of subsequent quarters, this information too 

must be submitted to the state. 

Whether an MCL was violated. 

Any operational evaluation levels that were exceeded, including location, date, and the calculated 

TTHM and HAA5 levels. 

Stage 2 DBPR Implementation Guidance 27 August 2007 
1.2.7.2 What information for Source Water TOC for must Subpart H systems report? [40 CFR 

141.629(a)(2)] 

Subpart H systems seeking to qualify for or remain on reduced TTHM/HAA5 monitoring must also report 

the following source water TOC information for each treatment plant that treats surface water or GWUDI 

to the state within 10 days of the end of any quarter in which monitoring is required: 

•

•

•

•

•

The number of source water TOC samples taken each month during the last quarter. 

The date and result of each sample taken during the last quarter. 

The quarterly average of monthly samples taken during the last quarter or the result of the 

quarterly sample. 

The RAA of quarterly averages from the past four quarters. 

Whether the RAA exceeded 4.0 mg/L. 

1.2.7.3 What are the recordkeeping requirements for IDSE Plans, IDSE Reports, and 

Monitoring Results? [40 CFR 141.629(b)] 

Systems must retain a copy of their Standard Monitoring Plan or SSS Plan, including any state 

modification to the plan, for a period of 10 years from the date it was submitted. They must also retain 

their IDSE Report for 10 years after the date they submit it. If the state modifies the Stage 2 DBPR 

monitoring requirements in an IDSE Report or approves alternative monitoring locations, the system must 

keep a copy of the state’s notification on file for 10 years after the date of notification. The IDSE Report 

and any state notification must be available for review by the state or the public. 

Systems must keep copies of Stage 2 DBPR Compliance Monitoring Plans and monitoring results for at 

least 10 years. 

1.2.7.4 What are the reporting and recordkeeping requirements for consecutive systems? [40 

CFR 141.134(c), 40 CFR 141.622(c), 40 CFR 141.629(b)] 

Consecutive systems are subject to the same reporting and recordkeeping requirements as other systems 

affected by the Stage 2 DBPR. In addition, they are required to conduct appropriate public notification 

after a violation. In their CCR, consecutive systems must include results of testing conducted by the 

wholesale system unless the consecutive system conducted equivalent testing that indicates it was in 

compliance. In this case, the consecutive system reports its own compliance monitoring results. EPA is 

preparing a guidance manual for consecutive systems to address these and other issues. 

Stage 2 DBPR Implementation Guidance 28 August 2007 
1.2.8 Public Notification of Drinking Water Violations [40 CFR 141 Subpart Q, 

Appendix A] 

In addition to the violations identified under the Stage 1 DBPR, the Stage 2 DBPR added violations 

requiring either a Tier 2 or Tier 3 notification. Tier 2 public notification is required for violations of 

TTHM or HAA5 LRAA MCLs. Tier 3 public notification of monitoring violations is required for failure 

to: 

•

•

•

Monitor for TTHM or HAA5 in accordance with the schedule in the monitoring plan. 

Return from reduced to routine monthly bromate monitoring if the RAA of bromate exceeds 

0.0025 mg/L or if samples were not analyzed using an acceptable method beginning April 1, 

2009. 

Qualify for a VSS Waiver, submit a 40/30 Certification, conduct standard monitoring or an SSS 

IDSE by the compliance deadline. The same is true for the IDSE Report for systems that 

conducted standard monitoring or an SSS IDSE. 

A description of the Stage 1 DBPR violations is in section 2 of EPA’s Implementation Guidance for the 

Stage 1 Disinfectants/Disinfection Byproducts Rule (EPA 816-R-01-012). 

1.2.9 CCR Requirements [40 CFR 141.151, 40 CFR 141.153] 

The CCR Rule requires systems to report in their annual consumer confidence reports any regulated 

contaminants that are detected. Since detection is not defined for DBP contaminants, the Stage 2 DBPR 

specifies reporting levels for the regulated DBPs. EPA has incorporated minimum reporting level (MRL) 

requirements into the laboratory certification program for DBPs and required systems to use regulatory 

MRLs as the minimum concentrations that must be reported as part of the CCRs [§141.151(d)]. 

When compliance with the MCL is determined by calculating an LRAA, systems must include the 

highest LRAA for TTHM and HAA5 and the range of individual sample results for all sampling points 

expressed in the same units as the MCL. If more than one site exceeds the MCL, the system must include 

the LRAA for all sites that exceed the MCL. 

If the system conducts an IDSE, it is required to include individual sample results collected for the IDSE 

when determining the range of TTHM and HAA5 results to be reported in the CCR for the calendar years 

that the IDSE samples were taken. 

Responsibility for the CCR rests with the individual system. Under the CCR Rule, the wholesale system 

is responsible for notifying the consecutive system of analytical results and violations related to 

monitoring conducted by the wholesale system. Consecutive systems must include analytical results of 

the wholesale system in their CCR, unless the consecutive system conducted equivalent testing 

demonstrating that it was in compliance. In the latter case, the consecutive system must report its own 

compliance monitoring results. 

Stage 2 DBPR Implementation Guidance 29 August 2007 
1.3 Requirements of the Rule: States or Other Primacy Agencies 

1.3.1 Special Primacy Requirements [40 CFR 142.16] 

To receive primacy for the Stage 2 DBPR, states must adopt regulations no less stringent than this rule. 

States must submit revisions to their programs, regulations, or authorities no later than January 4, 2008, 

although states can request an extension of up to 2 years. 

In addition, if a state elects to use its authority to modify wholesale system and consecutive system 

monitoring requirements on a case-by-case basis, the state must describe how it will implement a 

procedure for addressing the issue in its primacy application. The procedure must ensure that all systems 

have at least one compliance monitoring location. The special primacy requirements for the Stage 2 

DBPR are discussed in section 4.4 of this guidance. 

1.3.2 Records Kept by States [40 CFR 142.14] 

The current regulations in §142.14 require states with primacy to keep various records, including system 

inventories, state approvals, enforcement actions, the issuance of exemptions, and analytical results, to 

determine compliance with MCLs, MRDLs, and treatment technique requirements. 

The Stage 2 DBPR requires that the state keep records related to any decisions made pursuant to IDSE 

requirements [§141, Subpart U] and Stage 2 DBPR compliance monitoring requirements [§141, Subpart 

V]. Specifically: 

•

•

•

IDSE monitoring plans, plus any modifications made by the state, must be kept until replaced by 

approved IDSE Reports. 

System IDSE Reports and 40/30 Certifications, plus any modifications made by the state, must be 

kept until replaced or revised in their entirety. 

Operational evaluations submitted by a system must be kept for 10 years following submission. 

1.3.3 State Reporting Requirements [40 CFR 142.15] 

EPA currently requires states to report information such as violations, variance and exemption status, and 

enforcement actions to EPA under §142.15. The Stage 2 DBPR does not add any additional reporting 

requirements for states. 

1.4 Summary of Action Dates 

1.4.1 Applicability and Compliance Dates 

The Stage 2 DBPR applies to all CWSs and NTNCWSs that add a primary or residual disinfectant other 

than UV or deliver water that has been treated with a primary or residual disinfectant other than UV. The 

IDSE requirements apply to all CWSs and NTNCWSs serving at least 10,000 people that add a primary 

or residual disinfectant other than UV or deliver water that has been treated with a primary or residual 

disinfectant other than UV. Table 1-8 summarizes key compliance dates required (bold) by the Stage 2 

DBPR as well as suggested action dates. The compliance dates are designed to allow systems to comply 

simultaneously with the Stage 2 DBPR and the LT2ESWTR in order to balance risks associated with 

DBPs with risks associated with microbial pathogens. 

Stage 2 DBPR Implementation Guidance 30 August 2007 
Note the term “state” or “states” is used in the following and is used to refer to all types of primacy 

agencies including U.S. territories, Indian tribes, and EPA Regions. 

Table 1-8. Summary of Action Dates for the Stage 2 DBPR 

Date Stage 2 DBPR Action 

January 4, 2006 Final rule is published in Federal Register.

STATES

January 4, 2006 States are encouraged to begin identifying affected systems. 

January 4, 2006 States are encouraged to begin updating their data management system. 

January 4, 2006 States are encouraged to begin determining how they will address special primacy 

conditions of the rule related to wholesale and consecutive system monitoring. 

January 4, 2006 States are encouraged to begin coordinating with EPA and communicating with systems 

regarding the IDSE requirements. 

April 1, 2006 States are encouraged to communicate with affected systems regarding Stage 2 DBPR 

requirements. 

September 30, 2007 States must contact systems on Schedule 1 to approve Standard Monitoring Plan or 

SSS Plan, or contact system if review is not complete. 

October 4, 2007 States are encouraged to submit final primacy applications or extension requests to EPA. 

January 4, 2008 Final primacy applications must be submitted to EPA, unless granted an extension. 

[§142.12(b)(1)] 

March 31, 2008 States must contact systems on Schedule 2 to approve Standard Monitoring Plan or 

SSS Plan, or contact system if review is not complete. 

September 30, 2008 States must contact systems on Schedule 3 to approve Standard Monitoring Plan or 

SSS Plan, or contact system if review is not complete. 

March 31, 2009 States must contact systems on Schedule 4 to approve Standard Monitoring Plan or 

SSS Plan, or contact system if review is not complete. 

April 1, 2009 States must approve IDSE Reports for systems on Schedule 1 or contact the systems 

to inform them the states review is not complete. 

October 1, 2009 States must approve IDSE Reports for systems on Schedule 2 or contact the systems 

to inform them the states review is not complete. 

October 4, 2009 States with approved extension 

applications to EPA. 

agreements are encouraged to submit final primacy 

January 4, 2010 Final primacy applications must be submitted to EPA for systems with a full 

extension. [§142.12(b)(1)] 

2 year 

April 1, 2010 States should begin determining whether to grant up to a 2-year extension for systems 

requiring capital improvements to meet Stage 2 DBPR. 

October 1, 2010 States must approve IDSE Reports for systems on Schedule 3 and 4 or contact the 

systems to inform them the states review is not complete. 

Stage 2 DBPR Implementation Guidance 31 August 2007 
Stage 2 DBPR Implementation Guidance 32 August 2007 

Date Stage 2 DBPR Action 

SCHEDULE 1 SYSTEMS

October 1, 2006 CWSs and NTNCWSs on Schedule 1 must submit Standard Monitoring Plan or SSS 

Plan or 40/30 Certification to the state. 

October 1, 2007 CWSs and NTNCWSs on Schedule 1 whose Standard Monitoring Plan or SSS Plan 

has been approved or who have not heard back from the state should begin 

monitoring according to their plan. 

October 1, 2008 CWSs and NTNCWSs on Schedule 1 must complete their IDSE before this date. 

January 1, 2009 CWSs and NTNCWSs on Schedule 1 must submit their IDSE Report. 

April 1, 2012 Systems on Schedule 1 must begin complying with Stage 2 DBPR monitoring 

requirements and LRAA MCLs for TTHM and HAA5. [§141.620] 

SCHEDULE 2 SYSTEMS

April 1, 2007 CWSs and NTNCWSs on Schedule 2 must submit Standard Monitoring Plan or SSS 

Plan or 40/30 Certification to the state. 

April 1, 2008 CWSs and NTNCWSs on Schedule 2 whose Standard Monitoring Plan or SSS Plan 

has been approved or who have not heard back from the state should begin 

monitoring according to their plan. 

April 1, 2009 CWSs and NTNCWSs on Schedule 2 must complete their IDSE before this date. 

July 1, 2009 CWSs and NTNCWSs on Schedule 2 must submit their IDSE Report. 

October 1, 2012 Systems on Schedule 2 must begin complying with Stage 2 DBPR monitoring 

requirements and LRAA MCLs for TTHM and HAA5. [§141.620] 

SCHEDULE 3 SYSTEMS

October 1, 2007 CWSs and NTNCWSs on Schedule 3 must submit Standard Monitoring Plan or SSS 

Plan or 40/30 Certification to the state. 

October 1, 2008 CWSs and NTNCWSs on Schedule 3 whose Standard Monitoring Plan or SSS Plan 

has been approved or who have not heard back from the state should begin 

monitoring according to their plan. 

October 1, 2009 CWSs and NTNCWSs on Schedule 3 must complete their IDSE before this date. 

January 1, 2010 CWSs and NTNCWSs on Schedule 3 must submit their IDSE Report. 

October 1, 2013 Systems on Schedule 3 must begin complying with Stage 2 DBPR monitoring 

requirements and LRAA MCLs for TTHM and HAA5. [§141.620] 

SCHEDULE 4 SYSTEMS

April 1, 2008 CWSs on Schedule 4 must submit Standard Monitoring Plan or SSS Plan or 40/30 

Certification to the state. 

April 1, 2009 CWSs on Schedule 4 whose Standard Monitoring Plan or SSS Plan has been 

approved or who have not heard back from the state should begin monitoring 

according to their plan. 

April 1, 2010 CWSs on Schedule 4 must complete their IDSE before this date. 

July 1, 2010 CWSs on Schedule 4 must submit their IDSE Report. 
Stage 2 DBPR Implementation Guidance 33 August 2007 

Date Stage 2 DBPR Action 

October 1, 2013 Systems on Schedule 4 that are not required to monitor for Cryptosporidium under 

LT2ESWTR [§141.701(a)(4)] must begin complying with Stage 2 DBPR monitoring 

requirements and LRAA MCLs for TTHM and HAA5. [§141.620] 

October 1, 2014 Systems on Schedule 4 that are required to monitor for Cryptosporidium under 

LT2ESWTR [§141.701(a)(4) or (a)(6)] must begin complying with Stage 2 DBPR 

monitoring requirements and LRAA MCLs for TTHM and HAA5. [§141.620] 

CONSECUTIVE SYSTEMS

April 1, 2009 All 100 percent purchasing systems must monitor for chlorine and chloramines as 

specified under the Stage 1 DBPR. [§141.624] 

1.4.2 Timeline for the Stage 2 DBPR 

Figure 1-3 depicts the Stage 2 DBPR and LT2ESWTR requirements and implementation timeline for 

states and systems. The LT2ESWTR was promulgated concurrently with the Stage 2 DBPR to ensure that 

microbial protection is not compromised by efforts to reduce exposure to disinfection byproducts. 
Figure 1-3. Implementation Timeline for the Stage 2 DBPR 

Treatment

Installation

Treatment 

Installation

Crypto monitoring

Treatment

Installation

Crypto monitoring

E. coli

Possible 

Extension

Possible 

Extension

IDSE

IDSE

IDSE

IDSE

Includes associated consecutiv

Possible 

Extension Review submission

Review

submission

Review

submission

Review

submission

Compliance

1234

LT2 Plan or bin classification due

Stage 2 IDSE Plan or report due

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 

2006 2007 2008 2009 2012 2013 2014 2015 

Possib

Treatment Installation Extension

Compliance

(if no Crypto Monitoring)

Compliance

(if Crypto Monitoring)

Compliance

Compliance

2010 2011

Crypto monitoring

Crypto monitoring

Stage 2 DBPR Implementation Guidance 34 
References 

Barwick, R.S., D.A. Levy, G.F. Craun, M.J. Beach, and R.L. Calderon. 2000. Surveillance for 

waterborne-disease outbreaks - United States, 1997-1998. Morbidity and Mortality Weekly Report

49(SS04):1-35. 

Craun, F. and R. Calderon. 1996. Microbial risks in groundwater systems: Epidemiology of waterborne 

outbreaks. Under the Microscope: Examining microbes in groundwater. Proceedings of the Groundwater 

Foundation’s 12th Annual Fall Symposium, Boston. September. 

Levy, D.A., M.S. Bens, G.F. Craun, R.L. Calderon, and B.L. Herwaldt. 1998. Surveillance for 

Waterborne Disease Outbreaks - United States, 1995-1996. Morbidity and Mortality Weekly Report

47(55-5):1-34. 

Mac Kenzie, W.R., N.J. Hoxie, M.E. Proctor, M.S. Gradus, K.A. Blair, D.E. Peterson, J.J. Kazmierczak, 

D.A. Addiss, K.R. Fox, J.B. Rose, and J.P. Davis. 1994. A massive outbreak of Cryptosporidium

infection transmitted through the public water supply. New England Journal of Medicine 331(3):161-167.

USEPA. 2005. Final Economic Analysis for the Stage 2 DBPR. Washington, DC. Prepared by The 

Cadmus Group, Inc. 

Stage 2 DBPR Implementation Guidance 35 August 2007 
Stage 2 DBPR Implementation Guidance 36 August 2007 

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Section 2 

Resources and Guidance 
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In addition to this implementation guidance document, a variety of resource materials and technical 

guidance documents have been prepared by EPA to facilitate understanding and implementing the Stage 2 

DBPR. This section is an overview of each of these resources and includes instructions on how to obtain 

the documents. 

2.1 Technical Guidance Manuals 

The following six technical guidance manuals are being developed to support the Stage 2 DBPR. These 

manuals will aid EPA, state agencies, and affected PWSs in implementing this rule and will help ensure 

that the implementation among these groups is consistent. 

•

•

•

•

•

•

The Initial Distribution System Evaluation (IDSE) Guidance Manual (EPA 815-B-06-002) 

provides guidance on conducting the IDSE. The manual discusses the requirements and the 

implementation of IDSE sampling required by the Stage 2 DBPR. The manual discusses the 

selection of monitoring sites, alternatives to monitoring, waivers, development of monitoring 

schedules, and preparation of the IDSE Report. 

The Initial Distribution System Evaluation Guide for Systems Serving < 10,000 People For The 

Final Stage 2 Disinfectants and Disinfection Byproducts Rule (EPA 815-B-06-001) provides 

guidance on conducting the IDSE, however this manual focuses on information that systems 

serving < 10,000 are most likely to use. It does not discuss the IDSE system specific study option. 

The Operational Evaluation Guidance Manual (EPA XXX-X-XX-XXX) provides guidance on 

possible approaches to identifying exceedances of operational evaluation levels, conducting an 

operational evaluation, and operational changes that systems may make to prevent recurrence of 

operational evaluation level exceedances. 

The Small System Compliance Document (EPA 815-R-07-014) provides a streamlined version of 

the Stage 2 DBPR requirements for systems serving fewer than 10,000 people. 

The Consecutive System Guidance Manual (EPA XXX-X-XX-XXX) provides guidance on 

complying with Stage 2 DBPR monitoring requirements and MCLs to systems that purchase 

finished water. 

The Simultaneous Compliance Guidance Manual for the Long Term 2 and Stage 2 DBP Rules

(EPA 817-D-06-003) provides guidance on how to avoid and resolve various potential conflicts 

that may arise as systems comply with the Stage 2 DBPR and the LT2ESWTR. 

For more information, contact EPA’s Safe Drinking Water Hotline, (800) 426-4791, e-mail the Stage2 

Inbox, stage2mdbp@epa.gov, or see the Office of Ground Water and Drinking Water Web page. 

Reference and guidance documents are located at 

www.epa.gov/safewater/disinfection/stage2/compliance.html#pws. 

2.2 Rule Presentation 

Presentations that can be used for conducting Stage 2 DBPR training will be available on the EPA Web 

site: www.epa.gov/safewater/disinfection/disinfection/training.html. To receive information on training 

Stage 2 DBPR Implementation Guidance 39 August 2007 
presentations and to check the Drinking Water Academy (DWA) Training Calendar or join the LT2/Stage 

2 Listserv, e-mail the Stage 2 Inbox at stage2mdbp@epa.gov. 

2.3 Factsheets and Quick Reference Guides 

Factsheets and Quick Reference Guides for the Stage 2 DBPR may be useful for conveying basic 

information about the rule to water systems, new personnel, and stakeholders. These are stand-alone 

documents that are included in Appendix C of this guidance and are available online at 

www.epa.gov/safewater/disinfection/stage2/compliance.html#pws. They are: 

•

•

•

•

•

•

•

•

Fact Sheet: Stage 2 Disinfectants and Disinfection Byproduct Rule. 

Factsheet: Stage 2 DBPR IDSE 40/30 Certification and Very Small System Waiver. 

Factsheet: Stage 2 DBPR IDSE Standard Monitoring. 

Factsheet: Stage 2 DBPR IDSE System Specific Studies. 

Stage 2 Disinfectants and Disinfection Byproduct Rule: A Quick Reference Guide For Schedule 1 

Systems. 

Stage 2 Disinfectants and Disinfection Byproduct Rule: A Quick Reference Guide For Schedule 2 

Systems. 

Stage 2 Disinfectants and Disinfection Byproduct Rule: A Quick Reference Guide For Schedule 3 

Systems. 

Stage 2 Disinfectants and Disinfection Byproduct Rule: A Quick References Guide For Schedule 

4 Systems. 

2.4 Frequently Asked Questions 

Questions and Answers (Q&As) on the Stage 2 DBPR are provided in this section. These questions have 

been asked of EPA through the Safe Drinking Water Hotline, implementation training, or other means. 

For additional questions and updates to the answer provided in this document, visit EPA’s Web site at 

www.epa.gov/safewater/disinfection/stage2. 

System Schedules

Q1: How is the population determined in order to categorize systems into the schedules? Are all 

the populations of the systems in a combined distribution system added together or is the 

schedule based on the single largest system in the combined distribution system? 

A1: Your population is based on the number of consumers your system serves directly. However, if 

you are a consecutive or wholesale system (i.e., sell or buy finished water to or from another 

water system), your schedule is based on the population served by the largest system in your 

combined distribution system (not the combined population of all systems). If you are not a 

consecutive or wholesale system, your schedule is based on the population served by your 

individual system. 

Stage 2 DBPR Implementation Guidance 40 August 2007 
Q2: What are the different system schedules and their population numbers? 

A2: There are four compliance schedules. The four schedules are: 

If you are this kind of system: You are on IDSE schedule number 

Systems serving 100,000 or more people OR belonging to a 

combined distribution system in which the largest system 

serves 100,000 or more people 

1 

Systems serving 50,000 to 99,999 people OR belonging to a 

combined distribution system in which the largest system 

serves 50,000 to 99,999 

2 

Systems serving 10,000 to 49,999 OR belonging to a 

combined distribution system in which the largest system 

serves 10,000 to 49,999 

3 

Systems serving fewer than 10,000 people and/or belonging 

to a combined distribution system in which the largest system 

serves fewer than 10,000 

4 

IDSE

General

Q3: Are systems required to conduct Stage 1 DBPR compliance monitoring concurrent with 

Stage 2 DBPR IDSE monitoring? 

A3: Yes, systems regulated under the Stage 1 DBPR are required to collect their Stage 1 DBPR 

compliance sample as well as conduct Stage 2 DBPR IDSE monitoring. 

Q4: How should systems monitor during the interval between the end of IDSE monitoring and 

the beginning of Stage 2 DBPR compliance sampling? 

A4: Systems should continue Stage 1 DBPR monitoring or work with their primacy agency to begin 

Stage 2 DBPR compliance sampling earlier than required. This interval is built into the Stage 2 

DBPR to accommodate systems that may need to make significant changes to their distribution 

system to meet the requirements of the Stage 2 DBPR. 

Q5: If a system modifies its distribution system after completing its IDSE, is it required to 

complete a new IDSE? 

A5: No new IDSE Report is required, but the system should work with their primacy agency to 

change their Stage 2 DBPR Compliance Monitoring Plan to address the changes to the 

distribution system. 

Q6: Should IDSE samples be collected during the warmest months? 

A6: IDSE samples must be collected in the month of peak historical TTHM/HAA5 formation. The 

standard monitoring period or system specific study plan must include sampling during the peak 

historical month for TTHM or HAA5 levels or the month of warmest temperature (if the system 

does not have adequate historical data to determine the peak month). 

Q7: What happens to a system that does not submit an IDSE plan? 

A7: The system would be in violation if the system did not qualify for a VSS Waiver, submit a 40/30 

Certification, or conduct standard monitoring or an SSS IDSE by the compliance deadline. The 

same is true for the IDSE Report for systems that conducted standard monitoring or an SSS 

IDSE. The primacy agency will determine what enforcement action will be taken. 

Stage 2 DBPR Implementation Guidance 41 August 2007 
Q8: Is there reduced IDSE monitoring? 

A8: No, there is no reduced IDSE monitoring option available. 

 

Standard Monitoring

Q9: If a system is required to take 8 high TTHM samples, can all 8 samples be taken at the same 

location? 

A9: No, the monitoring plan must identify 8 different sites with expected high TTHM levels. These 

sites also must not be the same location as where the system currently takes their required Stage 1 

DBPR TTHM/HAA5 samples. 

Q10: What if a system’s high TTHM site and high HAA5 site are the same location? 

A10: A system cannot use the same site as both a high TTHM and high HAA5 site. If one site has been 

identified as potentially high for both TTHM and HAA5 the system should select it for whichever 

type they have fewer sites identified for. Keep in mind, each site will be sampled for both TTHM 

and HAA5. 

Q11: How should systems with multiple entry points to the distribution system complete standard 

monitoring if only one near entry point site is required? 

A11: If a system has multiple entry points to the distribution system but only one entry point sample is 

required, the system should sample near the entry point with the highest flow. 

Q12: How should a system with fewer entry points to the distribution system than the required 

number of near an entry point sites complete standard monitoring? 

A12: These systems should sample near all entry points to the distribution systems and make up the 

additional number of sites by alternating between high TTHM and high HAA5 sites, beginning 

with high TTHM, to obtain the necessary number of samples. 

Q13: If a consecutive system has multiple entry points, does a sample need to be taken at each 

meter? 

A13: No, the system only needs to monitor at the number of entry points required by the Stage 2 

DBPR. 

 

System Specific Study 

 

Q14: Can the state approve an SSS Plan using existing monitoring results with a fewer number of 

sites required in Stage 2 DBPR? 

A14: No, the number of samples required by the rule is the minimum number EPA believes is 

necessary for a system to determine their appropriate Stage 2 DBPR monitoring sites. The SSS 

using existing monitoring results and standard monitoring requirements were developed to be 

generally equivalent. The number of sites required for an existing monitoring SSS is 

approximately the number required for that system size under standard monitoring plus the 

number likely under Stage 1 DBPR compliance monitoring. 

 

40/30 Certification

 

Q15: Can a system receive 40/30 Certification if individual samples exceed 40/30 levels, but 

annual averages for TTHM and HAA5 are below these levels? 

A15: No, a system cannot receive 40/30 Certification if any samples exceed 40/30 during the 8 

consecutive quarters specified in the sampling schedule, even if the system’s averages are below 

40/30. 

Stage 2 DBPR Implementation Guidance 42 August 2007 
Q16: If a system applies for a 40/30 Certification and does not qualify, what monitoring schedule 

will the system be on? 

A16: Depending on timing, a system may be able to rejoin its original IDSE monitoring schedule. If 

this is not possible, the primacy agency will work with the system to develop a schedule that is 

appropriate. 

Q17: Will a reporting violation make a system ineligible for a 40/30 Certification (e.g., a system 

submitted its quarterly data on April 22, 12 days after the required date of April 10)? 

A17: If all other 40/30 Certification requirements are met, the system could still qualify for a 

certification. However, if a system has any TTHM or HAA5 monitoring violations during the 

period specified or fails to provide requested information to the state, including compliance 

monitoring results, the state may require standard monitoring or an SSS. 

Very Small System Waivers

Q18: What is the timeline for Very Small System Waivers? 

A18: Systems serving fewer than 500 people do not need to take action to receive a VSS Waiver, 

provided they have existing TTHM or HAA5 data. In most cases, EPA and states will work 

together to send letters to very small systems informing them that they have received a VSS 

Waiver and do not need to take any further action to comply with IDSE requirements. However, 

EPA or the state can also request that the system conduct standard monitoring, even if the system 

meets the criteria for the waiver. 

Consecutive Systems

Q19: How would a system that is served by both surface water and ground water sources comply 

with Stage 2 DBPR? 

A19: A system must follow the monitoring schedule for surface water systems if any portion of its 

water comes from a surface water source, including purchased water. 

Q20: Are consecutive systems responsible for providing public notifications of violations or 

Consumer Confidence Reports (CCRs)? 

A20: Yes. The wholesale system must provide violation information to its consecutive systems so that 

they can appropriately notify their users. 

Q21: How does Stage 2 DBPR address emergency connections? 

A21: Primacy agencies will have the discretion to determine whether systems receiving water from 

another system for emergency purposes should be considered as part of a combined distribution 

system. 

Stage 2 DBPR Compliance Monitoring

Q22: Does increased monitoring affect the entire system or only the monitoring site that exceeded 

the trigger value? 

A22: If a monitoring site triggers increased monitoring, the entire system must switch to increased 

monitoring. Increased and reduced monitoring cannot be determined on a site-by-site basis. 

Stage 2 DBPR Implementation Guidance 43 August 2007 
Stage 2 DBPR Implementation Guidance 44 August 2007 

Q23: Can systems on Stage 1 DBPR reduced monitoring that receive a VSS Waiver remain on 

reduced monitoring for Stage 2 DBPR? 

A23: These systems can remain on reduced monitoring if they have not changed monitoring locations 

and if they meet the qualifications for Stage 2 DBPR reduced monitoring. 

Notification to the Public

Q24: Is there language in the CCR Rule that explains that IDSE monitoring is not for compliance 

purposes? 

A24: There is no specific language in the CCR Rule that addresses this. Systems can include an 

explanation of IDSE sampling in their CCRs if they choose to do so. 

Information Collection and Reporting

Q25: What will the IDSE tool do? 

A25: The IDSE tool contains two features: the Wizard and the Plan/Report. The Wizard helps systems 

determine their IDSE requirements and select the best IDSE option for their system. The 

Plan/Report tool then creates Custom Forms for the system size and type that can be submitted 

electronically to the primacy agency. 

Q26: When a system is submitting an electronic IDSE plan or report using the online IDSE Tool, 

can a system log in, work on the electronic file, log out, and come back later? 

A26: Systems will be able to log on, work, save their work, and come back as many times as needed. 

However, once the plan or report is submitted, the IDSE tool considers the submission official 

and does not allow additional submissions to be made. The system can only make further changes 

by working with the primacy agency, or by sending an email to the Stage 2 Inbox at 

stage2mdbp@epa.gov. 

Q27: Not all months have 30 days and not all quarters have 90 days. How will this affect 

compliance tracking? 

A27: The term “every 90 days” was included to eliminate the possibility that a system would take 

quarterly samples at the end of one quarter and then immediately again at the beginning of next 

quarter. Samples are not temporally distributed as intended when collected in this manner. Using 

the term “every 90 days” should correct this. However, it is expected that states will use their 

discretion to account for various circumstances. The intent is to have samples taken 

approximately every 90 days. 

Other

Q28: How would a system that intermittently disinfects comply with the Stage 2 DBPR? 

A28: The system would monitor only during the quarter in which disinfection was provided. If the 

system is on yearly monitoring, it would monitor during the month of highest disinfection 

byproducts formation. The state will work with each system to further customize a monitoring 

schedule if needed. 

Q29: Are systems required to file a report every time an operational evaluation level is exceeded? 

A29: Yes. Any time an operational evaluation level is exceeded, the system is required to conduct an 

evaluation, write a report, and submit it to the state no later than 90 days after notification. This 

could happen at multiple locations or at a single location. The state can reduce the scope of the 

evaluation at its discretion on a case-by-case basis. 
Section 3 

State Implementation 
EPA expects to undertake necessary rule implementation activities 

during the period of early implementation. During the early 

implementation period, the state may elect to undertake some, or all, of 

the implementation activities, in cooperation with EPA. This will 

facilitate continuity of implementation and ensure that system-specific 

advice and decisions are made with the best available information and 

are consistent with existing state program requirements. 
3.1 Overview of Implementation 

The Stage 2 DBPR requires systems to take specific actions to comply with the rule. Monitoring, 

reporting, performance, and follow-up requirements should be clearly defined to assist systems’ 

understanding of how the rule will affect them and what they must do to comply. To meet this goal, the 

main implementation activities expected to face all primacy agencies include the following: 

•

•

•

•

•

•

•

•

•

•

•

•

•

Identify affected systems. 

Communicate Stage 2 DBPR requirements to affected systems. 

Update data management systems. 

Address special primacy conditions of the Stage 2 DBPR. 

Review and approve 40/30 Certification. 

Review and approve IDSE plans and reports. 

Review Stage 2 DBPR (Subpart V) monitoring plans. 

Ensure systems meet revised source water TOC criteria for reduced DBP monitoring. 

Ensure systems meet revised criteria for reduced bromate monitoring. 

Evaluate system requests for compliance schedule extensions. 

Evaluate system compliance with LRAA against Running Annual Average. 

Evaluate system requests for limiting the scope of an operational evaluation. 

Evaluate operational evaluations. 

States must approve Standard Monitoring Plans, study plans, and IDSE Reports or contact the system to 

notify them that the review is not complete. If states fail to do so within the timeframe in the rule, the 

system can consider them approved and begin monitoring in accordance with their plans and reports. 

Although the rule does not explicitly require states to approve monitoring plans, EPA strongly 

recommends that states undertake this activity. These various plans and reports ensure that monitoring 

locations are selected appropriately and in a manner to provide data to best protect public health under the 

Stage 2 DBPR. 

Section 3 discusses each of the items listed above. To help states’ implementation efforts, the guidance in 

this section and in section 4 may make suggestions and offer alternatives that go beyond the minimum 

primacy agency requirements specified in the subsections of §142.16. Such suggestions are prefaced by 

“may” or “should” and are to be considered advisory. They are not required elements of states’ 

applications for program revision. 

Figure 3-1 shows a timeline with system activities on the top and primacy agency activities on the 

bottom. It depicts requirements and implementation of Stage 2 DBPR . 

Stage 2 DBPR Implementation Guidance 47 August 2007 
Figure 3-1. Timeline of System and Primacy Agency Activities 

January 4, 2006 July 1, 2006 January 1, 2007 July 1, 2007 January 1, 2008 July 1, 2008 January 1, 2009

• Identify affected systems• Update data management systems• Coordinate with EPA & communicate IDSE requirements to systems

Applying for primacy - address special primacy conditions - unless granted an extension

Communicate Stage 2 DBPR 

requirements to affected systems 

Finish approving standard 

monitoring and study plans for 

systems on Schedule 1

July 1, 2009 January 1, 2010 

Finish approving standard 

monitoring and study plans for 

systems on Schedule 2

Finish approving 

standard monitoring and 

study plans for systems 

on Schedule 3

• Finish approving standard monitoring and study plans for systems on Schedule 4• Finish approving IDSE reports for systems on Schedule 1

Standard monitoring, plan, study 

plan, or 40/30 certification due 

for systems on Schedule 1

Finis

repo

Sc

Finish approving IDSE 

for systems on Sche

Standard monitoring, plan, study 

plan, or 40/30 certification due for 

systems on Schedule 2

Standard monitoring, plan, 

study plan, or 40/30 

certification due for 

systems on Schedule 3

Standard monitoring, plan, study 

plan, or 40/30 certification due 

for systems on Schedule 4

IDSE report due for 

systems on Schedule 1

IDSE report due for 

systems on Schedule 2

IDSE report due f

systems on Schedu

IDS

syste

Rule 

Promulgation

System Primacy Agency

Primacy due with 

extension

Stage 2 DBPR Implementation Guidance 48 
Stage 2 DBPR Implementation Guidance 49 

January 1, 2011 July 1, 2011 January 1, 2012 July 1, 2012 January 1, 2013 July 1, 2013 January 1, 2014 July 1, 2014 January 1, 2015 

Systems on Schedule 1 

must comply with Stage 2 

compliance monitoring

Systems on Schedule 2 

must comply with Stage 2 

compliance monitoring Systems on Schedule 3 and 

systems on Schedule 4 

monitoring for E. coli must 

comply with Stage 2 

compliance monitoring

Systems on Schedule 4 

monitoring for Crypto

must comply with Stage 2 

compliance monitoring

Note: Consecutive or wholesale systems must comply at the same time as the system with the earliest compliance dates in the combined distribution system.

System Primacy Agency Review monitoring plans for systems on Schedule 1 Review monitoring plans for systems on Schedule 2 Review monitoring plans for systems on Schedule 3 and systems on Schedule 4 monitoring for E. coli Review monitoring plans for systems on Schedule 4 monitoring for Crypto

Figure 3-1. Timeline of System and Primacy Agency Activities (cont.) 
3.2 Identifying Affected Systems 

3.2.1 General Provisions 

The Stage 2 DBPR has two distinct sections. The Initial Distribution System Evaluation (IDSE) section 

and the compliance monitoring section. 

•

•

The IDSE portion of the rule applies to all CWSs and NTNCWSs serving more than 10,000 

people that add a primary or residual disinfectant other than UV or deliver water that has been 

treated with a primary or residual disinfectant other than UV [§141.600(b)]. 

The compliance monitoring portion of the rule applies to all CWSs and all NTNCWSs that add a 

primary or residual disinfectant other than UV or deliver water that has been treated with a 

primary or residual disinfectant other than UV [§141.620(b)]. 

The latter portion of this applicability statement clarifies that the provisions of the Stage 2 DBPR 

unambiguously apply to consecutive systems that do not add a disinfectant but deliver disinfected water. 

These systems are subject to all regulatory requirements. 

States may wish to query or sort their database or other inventory information to list all affected systems. 

This data will be useful when states are performing various implementation activities (e.g., mailing letters 

to systems, determining standard monitoring requirements) and tracking compliance. 

3.2.2 Initial Distribution System Evaluation (IDSE) 

The IDSE portion of the rule is designed to help systems acquire adequate information about their 

distribution systems and DBP levels to select Stage 2 DBPR compliance monitoring sites that represent 

high TTHM and HAA5 levels throughout the distribution system. States should ensure that systems 

consider all available information in choosing the distribution system’s most representative locations for 

Stage 2 DBPR compliance monitoring. Stage 2 DBPR monitoring sites should consider information 

collected during the IDSE as well as Stage 1 DBPR monitoring sites. 

States may wish to further sort their list from 3.2.1 into sub-categories, as not all systems will need to 

receive the same information during the same timeframe. Note that Stage 2 DBPR requirements are based 

on source type and population served rather than the number of treatment plants (the approach used for 

Stage 1 DBPR requirements). In addition, compliance deadlines are based on the population of the largest 

system in the combined distribution system. The following sub-categories are suggested: 

•

•

•

•

Systems on Schedule 1–Serving ≥ 100,000 people or that are part of a combined distribution 

system in which the largest system serves ≥ 100,000 people. 

Systems on Schedule 2–Serving 50,000-99,999 people or that are part of a combined distribution 

system in which the largest system serves 50,000-99,999 people. 

Systems on Schedule 3–Serving 10,000-49,999 people or that are part of a combined distribution 

system in which the largest system serves 10,000-49,999 people. 

Systems on Schedule 4–Serving < 10,000 people or that are part of a combined distribution 

system in which the largest system serves < 10,000 people. 

Stage 2 DBPR Implementation Guidance 50 August 2007 
This last category may need to be further separated into the following sub-categories as they are subject to 

different requirements for the reasons cited below: 

•

•

NTNCWSs serving < 10,000 people are not required to perform an IDSE. 

Systems serving < 500 people, if they collected TTHM and HAA5 samples that comply with the 

Stage 1 DBPR, are granted a waiver from conducting additional monitoring under the IDSE. VSS 

Waivers are discussed in more detail in section 3.6. 

Sections 3.6 through 3.11 further discuss the IDSE and systems’ options to meet the IDSE requirements. 

3.2.3 Wholesale and Consecutive Systems 

The Stage 2 DBPR provides special clarification on the sharing of responsibilities between consecutive 

systems and the wholesale systems that supply them. This clarification extends public health protection to 

consecutive systems, which were not specifically addressed under the Stage 1 DBPR. 

States that did not require consecutive systems to monitor under Stage 1 DBPR may want to pay 

particular attention to ensuring that these systems are aware that both the IDSE and monitoring portions 

of the Stage 2 DBPR will apply to them. 

States may wish to further sort their list from 3.2.1 to denote which systems are wholesale and 

consecutive systems. These systems will have to comply with Stage 2 DBPR requirements at the same 

time as the largest system in their combined distribution system, regardless of the compliance timeframe 

associated with their own population served. In addition, systems that are 100 percent purchasing systems 

may not have had to comply with the Stage 1 DBPR and may need more communication regarding their 

responsibilities for complying with the Stage 2 DBPR. 

To account for complicated distribution system relationships and other factors, states may exercise some 

flexibility in deciding whether: 

•

•

•

Emergency and seasonal connections between a wholesale and consecutive system makes them 

part of the same combined distribution system. 

A consecutive system that produces some of its own finished water is part of the same combined 

distribution system. 

The interconnections between individual PWSs make them part of the same or different 

combined distribution system(s). 

States should consider the following factors when deciding whether systems should be considered part of 

a combined distribution system: 

•

•

•

Frequency, duration, and regularity of the connection. 

Volume and percent of finished water the consecutive system receives from the wholesale 

system. 

Quality (with respect to DBP or precursor levels) of the finished water provided by the wholesale 

system. 

Stage 2 DBPR Implementation Guidance 51 August 2007 
If the state lacks sufficient information to make a determination regarding connection type, the default 

decision is that the water system is part of a combined distribution system. 

3.2.4 Seasonal Systems 

Some systems, such as those that serve resort communities, have dramatic seasonal fluctuations in flow as 

well as population. When reviewing submittals for these systems, EPA or the state should consider issues 

such as changes in demand, peak historic month, the use of seasonal sources and the quality of those 

sources. For example, water age may be a factor for these systems during periods when there is a 

reduction in the transient population. EPA or the state will have to consider these seasonal variations in 

population as well as transient and nontransient populations in making decisions about IDSE 

requirements and determining if the system has adequately represented their system in their IDSE and 

eventually compliance monitoring. 

3.3 Communicate Stage 2 DBPR Requirements to Affected Systems 

3.3.1 Communicating IDSE Requirements and Timeframes 

As noted previously, CWSs and all NTNCWSs serving at least 10,000 people that use or deliver water 

that has been treated with a primary or residual disinfectant other than UV are subject to the IDSE 

requirements [§141.600(b)]. Systems have four options for complying with the IDSE. They can complete 

a year of standard monitoring or an SSS, or they can qualify for a 40/30 Certification or a Very Small 

System Waiver. These options are discussed in detail in sections 3.6 through 3.11. 

States should ensure that systems are aware of these requirements, can determine which option is the most 

appropriate for them, and know when each requirement must be met. Note that states will generally not 

have primacy during implementation of the IDSE for systems on the earliest schedules and will need to 

coordinate with EPA if they wish to be involved in this process. 

EPA or the state should communicate the IDSE requirements to systems as soon as possible because they 

may need consultation if they have questions regarding which alternative they will use to comply with 

this requirement. States may wish to provide additional information to systems on how to conduct 

standard monitoring or an SSS. Note that systems should receive a letter from EPA or the state notifying 

them of their correct IDSE schedule number. Systems should not proceed with conducting the IDSE 

before receiving this letter. A sample letter is provided in Example 3-1. 

The rule staggers deadlines to allow for a more even workload and greater opportunity for Primacy 

Agency involvement (e.g., through plan review and approval). The staggered schedule also provides time 

for analytical laboratories to build up capacity as needed to accommodate the sample analysis needs of 

systems. The standard monitoring and SSS Plan, monitoring, and IDSE Report submission dates are 

shown in Table 3-1. 

Systems that conduct standard monitoring or an SSS must first submit a plan to EPA or the state for 

review and approval. EPA or the state has 12 months to review and consult with the system about their 

plan. If they do not approve the plan or contact the system to notify them that the review is not complete 

by 12 months from the required submission date, the plan or certification is considered approved. The 

system must complete the standard monitoring or SSS by the date specified in Table 3-1 and then must 

prepare and submit the IDSE Report. EPA or the state has 3 months—or 9 months if the system conducts 

Cryptosporidium monitoring under Schedule 3—to approve the IDSE Report, or the report will be 

considered approved and the system will be required to implement the recommended Stage 2 DBPR 

compliance monitoring as required. 

Stage 2 DBPR Implementation Guidance 52 August 2007 
Table 3-1. Deadlines for IDSE Plans and Reports 

Submit Standard 

Monitoring Plan or SSS Plan 

or 40/30 Certification to the 

State by the Date Below or 

Receive VSS Waiver 

State Must Review 

Standard Monitoring 

Plan, SSS Plan, or 

40/30 Certification 

by 

Systems Must 

Submit IDSE 

Report to the 

State by 

State Must Review 

IDSE Report by 

Schedule 1 October 1, 2006 September 30, 2007 January 1, 2009 March 31, 2009 

Schedule 2 April 1, 2007 March 31, 2008 July 1, 2009 September 30, 2009 

Schedule 3 October 1, 2007 September 30, 2008 January 1, 2010 September 30, 2010 

Schedule 4 April 1, 2008 March 31, 2009 July 1, 2010 September 30, 2010 

States may wish to remind NTNCWSs that serve fewer than 10,000 people and systems that qualify for a 

VSS Waiver or 40/30 Certification that they do not need to complete an IDSE Report, but will need to 

develop and submit a Stage 2 DBPR Compliance Monitoring Plan. States may also want to notify systems 

that conduct standard monitoring or an SSS that they do not need to develop a Compliance Monitoring 

Plan if they include all information required by the plan, including compliance calculation procedures, in 

their IDSE Report. 

States may want to consider conducting an on-site IDSE training and involve personnel from nearby 

states. It might be helpful to set up a computer with the IDSE tool and walk the participants through the 

process of using the tool. States should encourage all systems within a combined distribution system to 

attend training sessions together. 

Some states have implemented an Area-Wide Optimization Program (AWOP). An AWOP is a strategy 

for targeting groups of higher risk systems for state assistance to maximize the public health protection 

that water treatment plants provide. Although states have a variety of tools to aid systems, ranging from 

sanitary surveys to direct technical assistance, their resources are limited. Consequently, states should 

prioritize their efforts according to the gravity of the potential public health risks posed by poorly 

performing water treatment plants. The challenge states face is to match their oversight of, and assistance 

to, water systems with the estimated risks posed to public health. 

The IDSE portion of the Stage 2 DBPR, specifically the standard monitoring requirements, can be used to 

work with the AWOP. Development of a Standard Monitoring or SSS Plan will probably be the most 

resource intensive step for systems. They will need to compile and review a variety of information, 

including distribution system layout, system operating data, and water quality data, when considering 

where to select monitoring sites. Some systems may not be comfortable with this level of analysis. 

Systems on Schedule 1 only have approximately 9 months from rule promulgation to develop their plan. 

An optimization approach for systematically identifying potential problem sites may benefit utilities. 

Remember: 

•

•

Each individual system in a combined distribution system must conduct its own IDSE, basing its 

schedule on the population of the largest system in the combined distribution system. 

The rest of the IDSE requirements (e.g., number of samples, frequency of monitoring) are based 

on the individual system’s population. 

Stage 2 DBPR Implementation Guidance 53 August 2007 
•

•

•

Systems cannot conduct one IDSE for the entire combined distribution system. 

States may exclude systems that receive water from a wholesale system only on an emergency 

basis or receive only a small percentage and small volume of water from a wholesale system from 

a combined distribution system. 

EPA’s IDSE Guidance Manual provides additional detail and examples for how to determine 

which systems are part of combined distribution systems and systems’ standard monitoring or 

study plan and report due dates. 

3.3.2 Communicating Stage 2 DBPR Compliance Requirements and Timeframes 

Under the Stage 2 DBPR, sampling must be conducted at sites identified through the IDSE or as modified 

by the IDSE Report reviewer for systems that conducted standard monitoring or an SSS. For systems that 

did not conduct standard monitoring or an SSS, sampling must be conducted at Stage 1 DBPR sites and if 

necessary, any additional sites identified in the sampling plan [§141.620(d)]. 

In addition, compliance with the MCL of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 will be based 

on a LRAA rather than a system-wide running annual average. 

All systems must develop a Stage 2 DBPR, or Subpart V, Compliance Monitoring Plan (see section 3.12) 

prior to the Stage 2 DBPR compliance date shown in Table 3-2. Systems that conducted standard 

monitoring or an SSS were required to submit an IDSE Report. This report contains many of the same 

elements as the Compliance Monitoring Plan. Generally, if a system includes their compliance calculation 

procedures in their IDSE Report, they can meet the requirements of both documents at the same time. 

(Note that this option is not available to systems if the state modifies their compliance monitoring 

requirements because they are part of a combined distribution system.) Subpart H systems serving more 

than 3,300 people must submit a copy of their monitoring plan to the state prior to the date that they 

conduct initial monitoring, and all systems must keep a copy of the plan on file for state and public 

review. 

Table 3-2 identifies the deadline for compliance with Stage 2 DBPR MCLs. States should communicate 

compliance requirements with systems in advance of these deadlines. 

Table 3-2. Compliance Schedule for Stage 2 DBPR 

Schedule Number Compliance Date for Stage 2 DBPR 1 

Schedule 1 April 1, 2012 

Schedule 2 October 1, 2012 

Schedule 3 October 1, 2013 

Schedule 4 October 1, 2013 if no Cryptosporidium monitoring is required under §141.701(a)(4) OR 

October 1, 2014 if Cryptosporidium monitoring is required under §141.701(a)(4) or (a)(6) 

1. States may grant systems up to an additional 24 months for compliance with MCLs and operational evaluation 

levels if capital improvements are necessary. See Appendix I for guidance on reviewing extension requests under 

Section 1412(b)(10) of the SDWA. 

It is important to note that systems previously on reduced monitoring may not begin Stage 2 DBPR 

compliance monitoring on reduced monitoring. Systems can qualify for reduced monitoring only after 

Stage 2 DBPR Implementation Guidance 54 August 2007 
completing 1 year of routine monitoring under the Stage 2 DBPR Compliance Monitoring Plan 

[§141.623]. Changes in the criteria for reduced monitoring are discussed in section 3.15. 

It is important that the states communicate these compliance monitoring changes from the Stage 1 DBPR 

to all systems affected by the Stage 2 DBPR. In particular, states should inform systems using ozone as a 

disinfectant of the new qualifications for reduced bromate monitoring, as discussed in section 3.15.2. 

States should also inform surface water systems that seeking to qualify for or remain on reduced 

TTHM/HAA5 monitoring for a reduced TTHM/HAA5 monitoring of the new TOC requirements as 

discussed in section 3.15.1.1. 

3.3.2.1 Consecutive System Compliance with the Stage 1 DBPR 

The Stage 1 DBPR did not specifically address consecutive systems, but under the Stage 2 DBPR, 

consecutive systems must begin complying with the Stage 1 DBPR requirements for chlorine and 

chloramines beginning April 1, 2009. States may also require systems to comply at an earlier date. As of 

this date, consecutive systems must not exceed the following maximum residual disinfectant levels 

(MRDLs) [§141.65(a)], which are the same as the maximum residual disinfectant level goals (MRDLGs) 

[§141.54]: 

•

•

4.0 mg/L for chlorine (measured as Cl2) 

4.0 mg/L for chloramines (measured as Cl2) 

3.3.3 Methods of Communication 

Written Notification 

Providing written notice of a final rule to PWSs serves two purposes: 1) the receiving system obtains a 

formal notice of upcoming regulatory requirements and a timeline for compliance (in addition to EPA’s 

publication of the rule in the Federal Register); and 2) the primacy agency has a hard-copy document that 

it may file and use in subsequent compliance tracking efforts. 

Written notification can be in the form of a letter from the state to affected systems. The letter should 

include a summary of rule requirements and timeframes and direct the reader to an appropriate contact if 

questions arise. States should consider including factsheets or other summary materials with the letter. 

Appendix C of this guidance includes additional publications that are intended to be distributed to water 

systems through mailings, training sessions, or other educational forums. These publications are available 

at www.epa.gov/safewater/disinfection/stage2. They provide overviews of the Stage 2 DBPR to help 

systems understand the provisions of the rule and determine which provisions apply to their system. They 

also describe the benefits and general implications of the rule. Although valuable, these resources do not 

substitute for official rule language. States should consider mailing official rule language with the letter or 

including in the letter the Web site address where the regulatory language can be accessed. 

A sample letter notifying systems of the Stage 2 DBPR requirements and their schedule number for 

completing the IDSE is provided in Example 3-1 (the example is for a Schedule 4 system). States may 

wish to develop similar letters and tailor the messages for the appropriate size categories covered by the 

rule, or to accommodate those systems for which the provisions are either limited or unique. 

Stage 2 DBPR Implementation Guidance 55 August 2007 
Example 3-1. Sample Letter Notifying Systems of Schedule Number 

Stage 2 DBPR Implementation Guidance 56 August 2007 
Example 3-1. Sample Letter Notifying Systems of Schedule Number (cont.) 

Stage 2 DBPR Implementation Guidance 57 August 2007 
In addition to notifying systems of their requirements, states may also want to consider providing written 

notice to a system regarding the status of their Stage 2 DBPR submitted compliance documents. 

Templates for these letters can be found in Appendix F. Written notification should include: 

•

•

•

Summary of the issue. 

Appropriate contact if questions arise. 

Fact sheet or other summary materials (optional). 

Factsheets and others materials can be found on EPA’s Stage 2 DBPR Web site at 

www.epa.gov/safewater/disinfection/stage2. 

Slide Presentation 

For some, written communication alone will not result in full comprehension of the Stage 2 DBPR 

requirements. Slide presentations can be used by state staff and other training providers to present the 

background of the rule, its benefits, and rule requirements. 

EPA developed a “Train the Trainer” program, Webcasts, and in-person training sessions to assist with 

implementation of the Stage 2 DBPR. Materials used for the training sessions are available on EPA’s 

Web site at www.epa.gov/safewater/disinfection/training.html. 

The EPA Drinking Water Academy (DWA) expects to develop a training session on the Stage 2 DBPR 

(available in Microsoft’s PowerPoint format). Copies of the presentation may be used to train other state 

personnel, technical assistance providers, water system personnel, and the public. EPA’s DWA slides will 

be available electronically by accessing EPA’s Web Site at www.epa.gov/safewater/dwa.html. 

Guidance Documents and Seminars 

Technical guidance documents developed for the Stage 2 DBPR are useful for explaining rule 

requirements and specific aspects of rule implementation to system operators. These aspects include 

conducting IDSEs and calculating LRAA for MCL compliance. The guidance documents can be used as 

stand-alone references or as supporting materials in Stage 2 DBPR-related training events. See section 2 

of this manual for more information on these references. 

3.4 Update Data Management Systems 

Although state data management systems vary to suit state-specific requirements and needs, EPA 

recommends that all states ensure that their data management systems are capable of efficiently tracking 

affected water systems compliance status and other information needed to implement this rule. States 

using Safe Drinking Water Information System (SDWIS) should review information on the Data 

Collection and Tracking System (DCTS), available on EPA’s Web site at 

www.epa.gov/safewater/disinfection/stage2. 

The Information Processing and Management Center (IPMC) is a centrally located receiving, processing, 

and mailing facility designed to facilitate coordination between EPA and states during LT2ESWTR and 

Stage 2 DBPR early implementation and to manage the workload. An integral part of the IPMC is the 

DCTS—a Web-based data management system that allows EPA and states to access and track IDSE 

submissions. 

Stage 2 DBPR Implementation Guidance 58 August 2007 
Some of the services provided by the IPMC include: 

•

•

•

•

Tracking receipt of PWS submissions, follow up conversations with PWSs, and approval 

decisions, and store all related records. 

Reviewing submissions for required components and categorize according to level of complexity 

for final review by state/EPA. 

Generating reports, including a report of PWSs who have missed their compliance deadline. 

Mailing notifications to systems. 

Systems should also be able to submit data for the IDSE to EPA or the state through the IPMC. EPA or 

the state should make systems aware of this method to submit data when corresponding with them 

regarding their IDSE option. For sample language, review the letters presented in Appendix F. 

3.5 Address Issues for Consecutive and Wholesale Systems 

This special primacy requirement is further discussed in section 4.4 of this guidance. 

Under §141.29, states can use their authority to modify a system’s compliance monitoring requirements 

by considering a combined distribution system as one system. Section 142.16(m) indicates that states can 

use this authority to modify wholesale and consecutive systems’ compliance monitoring requirements, but 

cannot modify IDSE requirements. Every system has to comply separately for the IDSE, including 

monitoring and preparing an IDSE Report (if required) based on their own system’s requirements. 

If the state modifies two or more systems’ monitoring requirements using this authority, each system’s 

monitoring plan will reflect these modifications. In addition, the Stage 2 DBPR requires that each plan be 

accompanied by the Compliance Monitoring Plans of all the other systems in their combined distribution 

system. States may consider encouraging systems in the same distribution system to send their 

Compliance Monitoring Plans in together, rather than each system sending copies of others systems’ 

plans. 

Section 142.16(m) further states that the state must describe how they intend to implement this authority 

in their application for primacy. States must have a plan for how they will implement the modifications 

and ensure that each individual system has at least one compliance monitoring site. 

Example: A group of three systems each serve a population of 20,000. Based on the Stage 2 DBPR 

requirements, each system would need 4 compliance monitoring sites for a total of 12. If the state 

considers them as one system, the system would serve 60,000 people and the total number of sites would 

be 8 instead of 12. The state can have the systems distribute the 8 samples across the three systems as 

they see fit, as long as there is at least one site in each of the three systems (i.e., no system can be void of 

a monitoring site). 

Stage 2 DBPR Implementation Guidance 59 August 2007 
Also, if a wholesale system has DBP issues, it is likely to focus on precursor removal. This option is not 

available to consecutive systems that receive treated water. Treated water may contain high DBPs as well 

as high levels of precursors and disinfectants. Therefore, the Stage 2 DBPR introduces the following best 

available technology (BAT) for consecutive systems, which are not focused on precursor removal: 

•

•

Systems serving at least 10,000 people: Chloramination and management of hydraulic flow and 

storage to minimize residence time in the distribution system. 

Systems serving fewer than 10,000 people: Management of distribution system and storage. 

3.5.1 Reviewing Plans and Reports from Wholesale and Consecutive Systems 

As EPA or the state reviews Standard Monitoring Plans, SSS Plans, and IDSE Reports, they will need to 

consider some issues that are particular to consecutive and wholesale systems in a combined distribution 

system. The Stage 2 DBPR was written to require that systems within a combined distribution system 

complete each requirement under the IDSE under the same schedule. This not only allows for systems to 

work together in preparation of their plans, monitoring, and reports, but it also allows for EPA or the state 

to review these plans and reports at the same time. 

EPA encourages consecutive and wholesale systems to share their Standard Monitoring Plan, SSS Plan, 

and IDSE Reports with each other. In particular, EPA or the state should encourage consecutive systems 

to contact their wholesale provider as soon as possible to determine what plans, if any, the wholesale 

system has already made regarding the IDSE. Consecutive systems may also want to check with their 

wholesale system to determine whether the wholesaler has conducted monitoring in the consecutive 

system’s distribution system. If this is the case, the consecutive systems may be able to use this 

information, particularly if a consecutive system wants to qualify for a VSS Waiver or a 40/30 

Certification. 

It is also recommended that consecutive and wholesale systems coordinate their IDSE and Stage 2 DBPR 

monitoring schedules to conduct monitoring at approximately the same time, though EPA recognizes that 

some groups of systems may not be able to monitor together due to the peak month monitoring 

requirement. Monitoring on concurrent schedules may allow consecutive systems to better understand the 

causes of high DBP levels in their distribution systems and for wholesalers to understand the impacts of 

treatment decisions. EPA or the state may want to recommend alternative monitoring dates to a 

consecutive system and its wholesaler if the systems have not coordinated their monitoring schedules. 

Some issues EPA and states may want to consider when reviewing plans and reports from combined 

distribution systems are: 

•

•

•

When and at what rate is water transferred to the consecutive system? This can help systems 

understand when, where, how often, and how much new water enters the distribution system. 

This information, in turn, can help systems understand where and when water has the longest 

residence times. 

What is the water age prior to the entry point? This can help systems identify when disinfectants 

will be consumed and residual levels will drop. 

Did the consecutive system and wholesale system sample during the same peak historic month? 

Consecutive and wholesale systems should sample during their peak historical month for TTHMs 

and HAA5s, which is often the month of warmest water temperature. Generally, this will be the 

same month for both the wholesaler and consecutive system, which will allow for comparison of 

Stage 2 DBPR Implementation Guidance 60 August 2007 
data. However if the systems did not sample in the same peak historic month comparison of data 

may be difficult. 

EPA and states should also examine the maps of both systems at the same time to determine if the 

systems, when considered collectively, have addressed all key DBP issues and located monitoring in as 

many key sites as possible. 

As discussed in section 3.2.3, some states may have combined distribution systems that, because of 

system contracts or agreements, are treated as one system for compliance with monitoring requirements. 

EPA or the state may continue to allow such systems to be regulated under these conditions for Stage 2 

DBPR compliance monitoring. However, the systems cannot conduct one IDSE for the entire combined 

distribution system. Each of the consecutive and wholesale systems must conduct its own IDSE (plan and 

report), with each system selecting the required number of monitoring sites for its individual system size 

and source type. Any reduction in sampling sites will be negotiated with EPA or the state during the Stage 

2 DBPR Compliance Monitoring Plan process. 

For more information on consecutive and wholesale system issues, refer to Appendix D of EPA’s IDSE 

Guidance Manual or EPA’s Consecutive System Guidance Manual. 

3.6 IDSE Option: Very Small System Waiver 

Systems serving fewer than 500 people that have taken TTHM and HAA5 samples automatically receive 

the VSS Waiver, unless notified otherwise by EPA or the state that they must conduct an IDSE 

[§141.604]. To qualify for the VSS Waiver, systems can use Stage 1 DBPR compliance data (including 

reduced monitoring data) or operational TTHM and HAA5 data, if the sampling and analysis met the 

general intent of Stage 1 DBPR compliance. Under the Stage 1 DBPR, samples must be taken and 

analyzed by EPA approved methods, represent acceptable locations, and include the month of warmest 

water temperature. Consecutive systems are also eligible for the VSS Waiver if they collected data under 

the Stage 1 DBPR, voluntarily took DBP samples that meet the intent of the Stage 1 DBPR, or if the 

wholesale system sampled within the consecutive system as one of its Stage 1 DBPR sites. 

Systems do not have to apply for the waiver, and the state does not have to approve the waiver in order 

for a system to take advantage of this IDSE option. Also, monitoring results used to receive the waiver do 

not have to be below any particular level. Systems that qualify for the VSS Waiver have no further IDSE 

requirements, but must complete a Compliance Monitoring Plan to identify their Stage 2 DBPR 

compliance monitoring sites. 

EPA or the state can require a small system to conduct standard monitoring or an SSS, regardless of its 

eligibility for the VSS Waiver, and for any reason. States may wish to conduct special technical assistance 

or training efforts to help the VSSs asked to conduct an IDSE. 

3.6.1 Review Considerations for the VSS Waiver 

Some of the criteria that EPA and states might use to evaluate the operational TTHM and HAA5 data to 

determine if a system qualifies for the VSS Waiver are presented below. 

•

•

•

•

Were samples analyzed by approved methods? 

Were samples analyzed at a certified laboratory? 

Are the sites located appropriately (average and maximum residence time)? 

Were samples taken during the month of warmest water temperature (if the data are available)? 

Stage 2 DBPR Implementation Guidance 61 August 2007 
Although EPA and states have the discretion to require VSSs to conduct either standard monitoring or an 

SSS, they should notify the system in writing. EPA and states may want to exercise this authority when 

one or a combination of more than one of the following conditions exists: 

•

•

•

•

•

Branched Distribution System. Some small rural systems, despite serving a small population, may 

have long, branched, or poorly looped distribution lines. 

Inexperienced System Operator. If EPA or the state is aware that a system operator is 

inexperienced with distribution system operations or DBP monitoring, they may decide it is 

interest of public health that the operator prepare a Standard Monitoring Plan in accordance with 

the IDSE requirements. 

High DBP Levels. States may want to review a system’s files (particularly for surface water 

systems and ground water systems with high influent TOC levels) to see if the system’s 

compliance data indicate high levels of DBPs. If individual measurements are within 10 percent 

of the MCL concentrations (10 percent of the MCL is 0.072 mg/L for TTHM and 0.054 mg/L for 

HAA5), the state may want to require the system to conduct standard monitoring. 

Difficulty Maintaining Disinfectant Residual. If a system has difficulty maintaining a disinfectant 

residual in its distribution system, the state may want to require the system to conduct standard 

monitoring or an SSS to identify their high HAA5 site. 

Stage 1 DBPR Sites Not Representative. If monitoring sites under the Stage 1 DBPR are not 

representative of the highest TTHM and HAA5 concentrations, the state may want to require the 

system to conduct standard monitoring or an SSS to identify more representative sites. 

In these examples, EPA or the state may notice something specific about the distribution system or 

historical data that convinces them that the system should conduct standard monitoring. In such instances, 

the reviewer may want to suggest specific locations where the system should consider monitoring for the 

IDSE. 

If EPA or a state determines that a system should conduct standard monitoring, this should be 

communicated to the system as early as possible. If it is early enough, the system may be able to comply 

within their original schedule. However, if the system is not notified in time to complete a Standard 

Monitoring or SSS Plan by the scheduled compliance date, the state should work with the system to set an 

alternate schedule. The alternate schedule could be based on one of the four regulatory schedules or it 

could be a schedule unique to that system. The IPMC is set up to accommodate alternative IDSE 

schedules. 

For systems that serve fewer than 500 people, standard monitoring will consist of one round of sampling 

(during peak historic month) at two locations. The first location will be at the high TTHM site. If they are 

a consecutive system, the second site will be near the entry point. If they are not a consecutive system, the 

second site will be at the high HAA5 site. Preparation of a Standard Monitoring Plan, completion of the 

monitoring, and preparation of an IDSE Report will not be a significant burden on these systems, and will 

provide them with useful information. VSSs that must complete standard monitoring will find EPA’s 

IDSE Guide for Systems Serving <10,000 helpful for understanding their requirements. 

3.6.2 Stage 2 DBPR Compliance Monitoring Plan for VSS Waiver Systems 

Systems that qualify for the VSS Waiver will not submit an IDSE Report, but will need to submit a Stage 

2 DBPR Compliance Monitoring Plan. The Stage 2 DBPR requires systems of this size to monitor for 

Stage 2 DBPR Implementation Guidance 62 August 2007 
TTHM only at their high TTHM site and for HAA5 only at their high HAA5 site. These systems do not 

have to take dual sample sets. 

Systems that serve fewer than 500 people are likely to have small, straight-forward distribution systems. 

For most systems with compact or small distribution systems, the high TTHM and HAA5 concentrations 

(based on their DBP data) will likely occur at the same site. In this case, the system can use one site for 

both high TTHM and HAA5. 

3.7 IDSE Option: 40/30 Certification Alternative 

Systems demonstrating low historic TTHM and HAA5 distribution system concentrations in accordance 

with the Stage 1 DBPR requirements may qualify for the 40/30 Certification. Systems receiving this 

certification are not required to conduct standard monitoring or an SSS, but are still required to comply 

with Stage 2 DBPR compliance monitoring requirements. Systems must meet the following criteria to 

qualify for the 40/30 Certification [§141.603]: 

•

•

•

All individual samples (i.e., NOT the running annual average (RAA)) collected for Stage 1 DBPR 

must be less than or equal to 0.040 mg/L for TTHM and less than or equal to 0.030 mg/L for 

HAA5 over an eight consecutive calendar quarter period, as specified in Table 3-3. 

No TTHM or HAA5 monitoring violations can occur during the same 8 quarter period. 

All monitoring data must have been analyzed by approved methods at a certified laboratory (per 

Stage 1 DBPR compliance monitoring requirements). 

Some states may allow systems that were not required to comply with Stage 1 DBPR to use operational 

data to support a 40/30 Certification, including data collected by a wholesale system. If the state is 

considering allowing this data to be used, they should clarify to the system that the samples should meet 

the general intent of Stage 1 DBPR compliance. 

Systems that sample less frequently than annually (ground water systems that served fewer than 10,000 

people and are on reduced TTHM and HAA5 monitoring under Stage 1 DBPR) may not have data for the 

8 consecutive quarters specified in the Stage 2 DBPR. These systems are still eligible for a 40/30 

Certification. They will base their certification on Stage 1 DBPR compliance samples taken during the 12 

months prior to the date specified in the Stage 2 DBPR (see Table 3-3). 

Consecutive systems are eligible for the 40/30 Certification if they collected data under the Stage 1 

DBPR, voluntarily took DBP samples that meet the intent of the Stage 1 DBPR, or if the wholesale 

system sampled the consecutive system as one of its Stage 1 DBPR sites. Consecutive systems are most 

likely to use operational data to qualify for the 40/30 Certification. 

Even if the system qualifies for the 40/30 Certification criteria, EPA or the state can require a system to 

perform an IDSE. Systems that do not qualify for one of the above exemptions must perform an IDSE. 

These systems have two options, described in sections 3.8 and 3.11. 

Stage 2 DBPR Implementation Guidance 63 August 2007 
Table 3-3. Compliance Monitoring Data Requirements for the 40/30 Certification 

If your 40/30 Certification is due Then your eligibility for 40/30 Certification is based on eight 

consecutive calendar quarters of Subpart L compliance monitoring 

results beginning no earlier than1

(1) October 1, 2006. January 2004. 

(2) April 1, 2006. January 2004. 

(3) October 1, 2007. January 2005. 

(4) April 1, 2007. January 2005. 

1. Unless you are on reduced monitoring under Stage 1 DBPR and were not required to monitor during the specified 

period. If you did not monitor during the specified period, you must base your eligibility on compliance samples 

taken during the 12 months preceding the specified period. 

3.7.1 Requirements for the 40/30 Certification 

The system is required to submit a statement to EPA or the state certifying that the eligibility criteria 

listed in section 3.7 were met. A sample 40/30 Certification letter is shown in Example 3-2. Once a 

system submits its certification, they have completed their IDSE requirements, unless a system is 

contacted by EPA or the state and told to conduct standard monitoring or an SSS. 

Example 3-2. Example 40/30 Certification Letter 

System Information

PWS Name_____________________ _______________________ 

__________________ _________________ 

_______________ 

 PWS ID:

Street Address: City, State, Zip:

Population Served: Source Water Type:  Ground  Surface/GWUDI 

System Type:  CWS  NTNCWS 

Combined Distribution System:  Wholesale  Consecutive  Neither 

Contact Person

Name: _______________________ ____________________ 

__________________F ____________ 

_______________________ 

Title: 

Phone Number: ax Number (if available):

Email Address (if available):

Certification

I hereby certify that each individual Stage 1 DBPR compliance sample collected from ________ to 

_______ were less than or equal to 0.040 mg/L for TTHM and 0.030 mg/L for HAA5. I 

understand that to be eligible, each individual sample must be below these values. I also certify 

that this PWS did not have any monitoring violations during this time period. 

Signature:_________________ Date:______________________

The Stage 2 DBPR IDSE requirements also include a provision that allows EPA and states to require the 

system to submit information in addition to its certification letter, namely: 

• Stage 1 DBPR compliance monitoring results, including sample location and date. 

• A distribution system schematic. 

• Recommended Stage 2 DBPR compliance monitoring locations. 

Stage 2 DBPR Implementation Guidance 64 August 2007 
EPA and states can require systems to submit the information above on an individual basis after receiving 

their certification, or they may want all systems state-wide to submit the information along with their 

certification. When deciding whether to ask for some or all of this information, EPA and states may want 

to consider whether the system is using operational data to qualify for the certification, if there are any 

known Stage 1 DBPR compliance issues for the system, and whether the system appears to be prepared 

for Stage 2 DBPR compliance monitoring. 

States should communicate their requests for additional information to EPA as soon as possible so that 

the systems can respond to any requests for additional information. 

Although systems that have an approved 40/30 Certification are not required to submit an IDSE Report, 

they must include their Stage 2 DBPR compliance monitoring recommendations in their Stage 2 DBPR 

Compliance Monitoring Plan, unless the state requests site recommendations as part of the 40/30 

Certification. 

3.7.2 Review Considerations for the 40/30 Certification 

The purpose of the EPA or state review of 40/30 Certifications is to verify that the certification meets the 

deadline and minimum criteria, decide if more information is necessary, and decide if the system should 

conduct standard monitoring or an SSS instead of receiving the 40/30 Certification. 

If EPA or the state finds that the certification is acceptable, it is recommended that a formal approval 

letter is sent so the system knows they have met all of their IDSE requirements. 

If EPA or the state finds that the certification if acceptable, no formal approval letter is required. If the 

system does not hear from EPA or the state, they can assume the certification was accepted and consider 

their IDSE compliance complete. 

EPA or the state should consider the following questions when deciding whether a system qualifies for a 

40/30 Certification based on operational data: 

•

•

•

•

•

Were samples taken and analyzed by approved methods at a certified lab? 

Were there an adequate number of sample sites for the system size? Based on the system size, did 

they take approximately as many samples as they would have under Stage 1 DBPR? Is there 

enough data to select Stage 2 DBPR sites? 

Were the samples taken at appropriate locations? Some or all of the sample sites should have 

been located at sites with maximum residence time, as required under Stage 1 DBPR. If all sites 

are near the entry point, this is not sufficient to justify 40/30 Certification. 

Were samples taken during the month of warmest water temperature for each year of operational 

data used to qualify? 

Were samples taken at the appropriate frequency? Based on population served, disinfectant type 

and source type, were samples taken on a monthly, quarterly or annual basis (as they would have 

been required to do under Stage 1 DBPR)? 

Before approving a system’s 40/30 Certification, EPA or the state may also want to consider the system’s 

type (i.e., CWS, NTNCWS), the population served by the systems, and whether the system is part of a 

combined distribution system. 

Stage 2 DBPR Implementation Guidance 65 August 2007 
Some reasons why EPA or the state may require a system that is eligible for a 40/30 Certification to 

conduct standard monitoring or an SSS include the following: 

•

•

•

Validity of Certification. EPA or the state should review the certification and consult the system’s 

records (if available) to verify that the system’s certification is valid. Each of the following 

situations would constitute an invalid 40/30 Certification and would require that the reviewer 

deny the certification. 

– DBP Samples Above 40/30. If the state’s records indicate that the system’s TTHM or HAA5 

compliance sample results for the eligibility period were greater than 0.040 mg/L and 0.030 

mg/L, respectively, the certification is invalid. 

– Individual Samples. If the system based their 40/30 Certification on the running annual 

average or the locational running annual average rather than each individual sample, the 

certification is invalid. 

– Violations. If the system has experienced any Stage 1 DBPR TTHM or HAA5 monitoring 

violations during the eligibility period, the certification is invalid. 

– Compliance Data. If the system has Stage 1 DBPR compliance data but are basing their 

40/30 Certification on operational data rather than compliance data, the certification could be 

invalid. 

Stage 1 DBPR Sites Inadequate or Not Representative. If the number of Stage 1 DBPR 

monitoring sites is significantly lower than the number of Stage 2 DBPR sites that will be 

required, EPA or the state may determine that the system does not have enough data to justify the 

40/30 Certification. Similarly, if the Stage 1 DBPR sites were poorly placed, such that the Stage 1 

DBPR data does not reflect the entire distribution system, EPA or the state may determine that 

the data are not appropriate to justify a 40/30 Certification. The reviewer may also want to 

consider in which months the system’s Stage 1 DBPR sampling took place. If a system’s data do 

not represent the months that EPA or the state considers to have the highest potential for DBP 

formation, standard monitoring or an SSS may be warranted. 

– Large Population and Few Plants. If a system has a large population, but few treatment 

plants, there may have been very few Stage 1 DBPR sites required. The system may need to 

select many Stage 2 DBPR sites. In this case, EPA or the state may decide that standard 

monitoring or an SSS should be conducted in order to obtain enough information to select 

appropriate Stage 2 DBPR sites. 

– Consecutive system. If a state allocated a wholesale system’s Stage 1 DBPR sample sites 

across the wholesale and consecutive systems, the consecutive system may have some limited 

Stage 1 DBPR data, but EPA or the state may determine that it is not adequate to represent 

the entire distribution system and justify the 40/30 Certification. 

Other DBP Data. If EPA or the state is aware of operational DBP data that indicates higher levels 

in the distribution system, or if compliance data outside the 2-year compliance period were 

significantly higher, they may want to request additional information and/or require standard 

monitoring or an SSS. 

Stage 2 DBPR Implementation Guidance 66 August 2007 
• Eligibility Period Not Representative. If EPA or the state believes that the low DBP levels 

experienced during the 2-year eligibility period that the system is relying upon for its 40/30 

Certification are not a good indication of the levels the system is currently experiencing, they may 

want to consider requiring standard monitoring or an SSS. 

– Natural Circumstances. If a system’s 2-year eligibility period spanned a period of time in 

which natural circumstances may have favored lower DBP levels in the distribution system, 

EPA or the state may want to consider requiring standard monitoring or an SSS. Such 

circumstances may include cooler temperatures or better source water quality. As an 

example, a system with multiple sources may typically be required to rely on a poorer quality 

source during high demand. If during the eligibility period the higher quality source was 

sufficient, the system’s DBP levels may have been particularly low during that period. 

– Distribution System Changes. If a system has recently made or is in the process of making 

distribution system changes that could affect DBP formation, EPA or the state may want to 

require it to conduct standard monitoring or an SSS. Such changes may include the expansion 

of the distribution system, annexation of a new area, connection of a new subdivision, 

consolidation with another small water system, or construction of a new storage tank. 

– Disinfection or Other Treatment Changes. Most treatment plant changes will not affect water 

age or relative levels of DBPs in the distribution system. However, if a system has recently 

made, or is in the process of making changes to its disinfection practices or other treatment 

changes that may impact DBP formation, the reviewer may want to consider requiring 

standard monitoring or an SSS. These changes may include the addition of booster 

chlorination in the distribution system, a change in disinfectant type, or a change in the 

location of the disinfectant application. 

– Source Changes. If a system has recently made or is in the process of making changes to its 

sources, such as a change from ground to surface source, adding or removing a source, or 

making other major changes, EPA or the state may want to determine if these changes would 

impact DBP formation and warrant standard monitoring or an SSS. 

Depending on the eligibility period upon which a system is basing their certification, they may be 

sampling immediately before the certification deadline. The system will not know whether they have met 

the eligibility criteria for 40/30 Certification until the last samples collected during the eligibility period 

are analyzed. If the DBP levels exceed the 40/30 threshold near the end of the period, they must conduct 

an IDSE through standard monitoring or an SSS. Since the deadlines for submittal of a Standard 

Monitoring Plan or an SSS Plan are the same as the 40/30 Certification deadline shown in Table 3-3, the 

system will have very little time to then prepare a Standard Monitoring or SSS Plan. 

Similarly, if EPA or the state reviews the certification and determines that the system should conduct 

standard monitoring or an SSS, the deadline for submitting a Standard Monitoring or SSS Plan will likely 

have passed. The deadline for submitting a 40/30 Certification is the same as for submitting Standard 

Monitoring and SSS Plans. If the reviewer intends to require standard monitoring or an SSS, it is best to 

notify the system as early as possible. If the system is contacted early enough, it may be able to comply 

within the original schedule. However, if the system is not notified in time to complete a Standard 

Monitoring or SSS Plan by the scheduled compliance date, EPA or the state should work with the system 

to set an alternate schedule. The alternate schedule could be based on one of the four regulatory schedules 

or it could be a schedule unique to that system. 

Stage 2 DBPR Implementation Guidance 67 August 2007 
3.7.3 Stage 2 Compliance Monitoring Plan for 40/30 Certification Systems 

Systems that qualify for the 40/30 Certification will not submit an IDSE Report, but will need to submit a 

Stage 2 Compliance Monitoring Plan. Although many systems will be able to use their Stage 1 DBPR 

sites for Stage 2 DBPR compliance monitoring, some systems (e.g., systems with relatively large 

populations and few plants) may need to identify additional sites. For these systems, the site choice 

should be similar to site selection for standard monitoring, described in section 3.11.2.2. In general, 

systems will need to consider their distribution system map, operational data, and water quality data to 

identify the best sites. 

3.8 IDSE Option: System Specific Study 

Systems can meet IDSE requirements using an SSS if their existing data or hydraulic modeling data meet 

certain requirements for an SSS [§141.602]. Some systems have detailed knowledge of their distribution 

systems by way of ongoing hydraulic modeling and/or existing widespread monitoring, which provides 

equivalent or superior monitoring site selection information compared to standard monitoring. Therefore, 

under this alternative, these systems may choose to perform an SSS in lieu of standard monitoring. 

Systems may rely on one of two data sources when preparing their study. They may use TTHM and 

HAA5 monitoring data if each location has been sampled once during the peak historical month for 

TTHM or HAA5 levels or during the month of warmest water temperature. These samples must be 

collected and analyzed in accordance with the Stage 1 DBPR requirements [§141.131], and must be 

collected no earlier than 5 years prior to the study plan submission deadline. (The number of monitoring 

locations and samples required are outlined in Table 3-5.) 

Alternatively, systems may use extended period simulation hydraulic models that simulate water age in 

the distribution system. The model must simulate variation in demand over 24 hours and show a 

consistently repeating 24-hour pattern of residence time. EPA’s IDSE Guidance Manual provides 

additional information on conducting SSSs and determining whether system specific data could be 

sufficient to meet the IDSE requirements. 

Systems conducting an SSS must submit an SSS Plan and an IDSE Report to EPA or the state. Systems 

also have the option to submit an IDSE Report at the same time as their study plan if they believe they 

have the necessary information by the time the study plan is due. 

3.9 IDSE Option: Existing Monitoring System Specific Study 

3.9.1 Review of Existing Monitoring SSS Plan 

This section contains guidance on four different categories of reviews that can be completed for study 

plans based on existing monitoring results: 

•

•

•

•

Review for required plan elements. 

Review for correct interpretation of the IDSE requirements. 

Technical review of data representativeness. 

Technical review of monitoring results. 

The first review for required plan elements will be done by the IPMC for EPA reviewers and states that 

choose to use it. The remaining reviews for correct interpretation of the IDSE requirements, technical 

Stage 2 DBPR Implementation Guidance 68 August 2007 
review of data representativeness, and technical review of standard monitoring site selection, will be 

completed by either the state or EPA. 

Chapter 5 of EPA’s IDSE Guidance Manual has in-depth information regarding how a system may 

prepare an SSS Plan using existing monitoring results. 

The state or EPA may want to request additional information from a system during the review process. 

The state or EPA can approve the plan, request that the system modify its plan, or require standard 

monitoring if the plan is not acceptable. If a system does not respond to a request to modify the plan or to 

provide more information, the state or EPA has the option of requiring standard monitoring. EPA or the 

state has 12 months after the submission deadline to complete the review of Standard Monitoring Plans. 

All correspondence between the system and the reviewer is included in the 12-month period and does not 

extend the ultimate approval deadline. If EPA or the state does not contact the system to officially 

approve or request modifications to the plan by the end of the review period, the system can consider the 

plan approved and will implement it as submitted. 

If the state or EPA intends to require standard monitoring, it is best to notify the system as early as 

possible. If it is early enough, the system may be able to comply within their original schedule. However, 

if the system is not notified in time to complete a Standard Monitoring Plan by the scheduled compliance 

date, EPA or the state should work with the system to set an alternate schedule. The alternate schedule 

could be based on one of the four regulatory schedules or it could be a schedule unique to that system. 

The IPMC is set up to accommodate alternate schedules. 

The state or EPA should notify the system in writing when its plan is approved. If changes were made 

after the original submission, the state or EPA should send a copy of the approved plan to the system for 

its records or reference the changes in a letter to clarify which version of the plan is approved. If EPA is 

reviewing plans all correspondence and recordkeeping will be through the IPMC. 

An SSS based on existing monitoring data results will be similar to the Standard Monitoring Plan, and 

many states will have the expertise to review these plans. EPA Headquarters will provide support to EPA 

Regions and states that require technical assistance in reviewing SSS Plans. 

EPA or the state should review each plan early in the review period to ensure that it contains the 

minimum elements required by the Stage 2 DBPR. 

3.9.1.1 Review of Required Elements for Existing Monitoring SSS Plan 

Tables 3-4 and 3-5 can be used to determine if the system has met the minimum requirements of the Stage 

2 DBPR for existing monitoring results study plans. Systems have the option of using the Existing 

Monitoring Results Plan Form (Form 2) in Appendix E of this document. If systems fill out all sections of 

the form according to the instructions, they have met the minimum requirements of the rule. Note that 

Form 2 asks the system to list its IDSE schedule and the number of monitoring sites and samples required 

for the system. If the system uses Form 2, verify that the following information provided is correct: 

• Schedule – Verify that the schedule is consistent with the schedule in the letter sent to the system 

by EPA or the state or with a schedule based on additional conversations with the system. This 

verification can be done by checking the schedule listed for that system in the DCTS. If the 

submitted schedule is different, EPA or the state should contact the system to discuss the required 

compliance schedule. 

Stage 2 DBPR Implementation Guidance 69 August 2007 
• Number of Locations and Samples – Verify that the number of locations and number of samples 

for both TTHM and HAA5 meet the minimum requirements of the rule, as shown in Table 3-5. 

– Note that systems must meet the requirements for both the number of sites and the number of 

samples to qualify. EPA or the state may use the checklist in Table 3-5 to make this 

determination. 

– Reviewers should evaluate the distribution system schematic to confirm that the number of 

monitoring sites is consistent with the requirements in Table 3-5. 

– Reviewers should examine the system’s data to determine if the system has collected the 

correct number of samples. If not, the reviewer should ensure that the system has planned 

enough additional monitoring to meet the criteria for the number of sites and samples. If a 

system misinterpreted its monitoring requirements, the reviewer should contact the system to 

explain what is required. 

Chapter 5 of EPA’s IDSE Guidance Manual includes many suggestions for organizing existing 

monitoring data. If the submission is difficult to understand, reviewers can request a revised SSS Plan. 

A completed example of an SSS Plan using existing monitoring results can be found in Appendix D of 

EPA’s IDSE Guidance Manual. 

Stage 2 DBPR Implementation Guidance 70 August 2007 
Table 3-4. SSS Plan Using Existing Monitoring Results, Required Elements Checklist 

Check if 

Provided 

;

Required Element Section in Form 2 

 Population served by the system I.A 

 Source water type (Subpart H or ground water) I.A 

 Identification of the peak historical month for TTHM, HAA5, or 

warmest water temperature 

III.A 

 Previously collected monitoring results IV 

 Dates of any planned SSS monitoring and Stage 1 DBPR compliance 

monitoring sampling 

VI 

A distribution system schematic with: 

 All distribution entry points

 All sources

 All storage facilities

 Locations of all completed or planned SSS monitoring

 Locations of Stage 1 DBPR compliance samples

VII 

Certification that: 

 All compliance and non-compliance data during the time period 

beginning with the first reported result and ending with the most 

recent Stage 1 DBPR result are included

 The distribution system and treatment have not significantly changed 

during period of SSS data

 Samples are representative of the entire distribution system

V 

Stage 2 DBPR Implementation Guidance 71 August 2007 
Table 3-5. Minimum Requirements Checklist for Existing Monitoring Results Study Plan 

Yes No 

  Were all samples collected and analyzed in accordance with an approved EPA method and by a 

certified laboratory?

  Were all sample results collected no earlier than 5 years prior to the system’s study plan 

submission deadline? 

  Does the system have at least the minimum number of distribution system monitoring locations 

shown in the table below from which the system collected TTHM and HAA5 samples? 

  Does the system have at least the minimum number of TTHM samples and HAA5 samples shown 

in the table below? 

  Was each monitoring location sampled once during the month of highest TTHM or highest 

temperature for every 12 months of data submitted? 

  Have the distribution system and treatment not changed significantly since samples were 

collected? 

  Are existing monitoring locations representative of the entire distribution system? 

If the system answered yes to all of the above questions, the system meets EPA’s minimum requirements for an SSS 

using existing data. Remember, though, that EPA or the state can still require systems to conduct standard 

monitoring, even if they meet the minimum requirements. 

Minimum Number of 

Samples 

Source Water 

Type 

System Size Category 

(Population Served) 

Minimum Number of 

Monitoring Locations* 

TTHM HAA5 

<500 3 3 3 

500-3,300 3 9 9 

3,301-9,999 6 36 36 

10,000-49,999 12 72 72 

50,000-249,999 24 144 144 

250,000-999,999 36 216 216 

1,000,000-4,999,999 48 288 288 

Subpart H 

≥ 5,000,000 60 360 360 

<500 3 3 3 

500-9,999 3 9 9 

10,000-99,999 12 48 48 

100,000-499,999 18 72 72 

Ground Water 

≥ 500,000 24 96 96 

*Can include Stage 1 DBPR sites 

Stage 2 DBPR Implementation Guidance 72 August 2007 
The peak historical month for existing monitoring results should be based on TTHM, HAA5, and/or 

warmest temperature. EPA or the state may generally follow the criteria for reviewing peak historical 

month provided in Section 3.11.1.4. They should ensure that the system has collected samples at least 

once during the peak month for each 12-month period of data submitted. If a system did not sample 

during the peak historical month during a year, that year of data does not count towards their minimum 

requirements. If the system has planned any additional SSS monitoring, the reviewer should also verify 

that it will collect at least one round of samples during the peak historical month. 

Submissions to the IPMC will not be considered confidential business information (CBI) and are subject 

to the Freedom of Information Act (FOIA). 

If the requirements were not correctly interpreted, EPA or the state should contact the system for more 

information. If some of the required elements on the checklists in Tables 3-4 and 3-5 are missing, EPA or 

the state should contact the system to request the missing information. Until all required elements are 

submitted, the plan should be considered incomplete and should not be reviewed further. If all boxes are 

checked, all required elements have been submitted. 

3.9.1.2 Technical Review of Existing Monitoring SSS Plans 

EPA or the state should use the system’s distribution system schematic to ensure that the sites selected 

represent the entire distribution system. EPA or the state should consider the criteria below in making this 

determination. 

Geographic representation: The distribution system schematic should allow the reviewer to ascertain if 

the sites monitored give good geographic representation of the distribution system. If a significant portion 

of the distribution system is excluded from the existing monitoring results, the reviewer should request 

the system to sample at additional sites in the areas that are not represented. 

Hydraulic representation: EPA or the state should check to see if all pressure zones are represented and 

that sites address areas that are hydraulically remote. If this information is not provided on the distribution 

system schematic, reviewers may contact systems to obtain it through a phone conversation. 

Key sites in the distribution system: If at all possible, systems should have tried to include most key 

trouble areas including long dead end lines (keeping the site prior to the last customer), areas down 

gradient of storage tanks, areas with low residual chlorine levels, and areas influenced by booster 

chlorination (depending on the water chemistry and age). 

If the reviewer determines that sites are not representative, they should contact the system and request 

more information. If EPA or the state determines, based on the new information, that the sites are 

appropriate, they can attach the information to the study plan and complete the review. However, if the 

system is unable to provide adequate justification, EPA or the state should work with the system to select 

sites for additional SSS monitoring or require standard monitoring. If the system does not respond to 

EPA’s or the state’s request for information or does not make any requested modifications, the reviewer 

can require standard monitoring. 

The Stage 2 DBPR IDSE requirements allow EPA or the state to reject some of a system’s data and 

require that system to replace the rejected data with additional SSS monitoring or to conduct standard 

monitoring. If EPA or the state question the data submitted, they should request more information from 

the system to determine if the data can be adequately justified. Some reasons why EPA or the state may 

consider rejecting a portion of a system’s data are described below. 

Stage 2 DBPR Implementation Guidance 73 August 2007 
Use of Unapproved Methods for Sample Analysis: Systems may only use samples analyzed by a certified 

laboratory using approved methods. Any data not meeting this requirement do not count toward the 

minimum number of samples and locations. 

Failure to Fully Represent Distribution System: The sampling sites for the IDSE must represent TTHM 

and HAA5 concentrations throughout the distribution system. If any significant areas of the distribution 

system are not represented with sample sites, EPA or the state should require the system to collect 

additional data in those areas or to conduct standard monitoring. 

Unusual Events: EPA or the state may want to reject any data from short periods of unusual (not routine 

seasonal) system conditions that are not representative of typical operating conditions. Some examples 

include: 

•

•

•

Main breaks during or just before sample collection that cause a shift in the flow patterns in the 

distribution system. 

Treatment equipment failures or power failures that had a significant impact on DBP levels in the 

distribution system. 

Unusual periods of drought that reduced runoff and changed TOC loading of surface water 

sources only during a single year. 

Note that this list is not all-inclusive—EPA or the state should use best professional judgment to 

determine if a temporary event should be considered unusual. 

Permanent, Significant Treatment Changes: If any significant permanent treatment process or source 

changes took place during the period for which the system submitted existing monitoring results, EPA or 

the state may want to consider rejecting any data collected before that change took place. Treatment 

changes that affected the magnitude of TTHM and HAA5 levels in the distribution system, but that are 

unlikely to have changed the DBP formation rate and relative levels of TTHMs and HAA5s in different 

parts of the system, are acceptable. For example, improved control of an existing coagulation process or 

minor changes in coagulation pH that reduce average levels of DBP precursors are acceptable. 

If treatment process or source changes have occurred and data collected prior to the change are utilized in 

an SSS, then the use of the data should have been justified. An explanation of the change and a 

demonstration that the change is unlikely to have significantly affected the relative TTHM and HAA5 

levels in the distribution system should have been provided. Specific examples of these types of changes 

are shown in Table 3-6. 

Permanent, Significant Distribution System Changes: If any significant distribution system changes took 

place during the period for which the system submitted existing monitoring results, EPA or the state 

should use their best professional judgment to determine if the modification to the distribution system 

would warrant EPA or the state rejecting any data collected before that change took place. Supply points, 

pressure zones, large transmission mains, pump stations, storage tanks, and large wholesale and retail 

Stage 2 DBPR Implementation Guidance 74 August 2007 
customers should generally be consistent throughout the data collection period for the SSS. Although this 

list is not all-inclusive, some examples are: 

•

•

Major, permanent changes in plant production rates, installation or removal of high service or 

booster pump stations, or pump operation schemes that significantly change the location of 

influence zones of treatment plants and mixing zones within the distribution system. 

Major, permanent changes in water use patterns or system hydraulics. 

Specific examples of these types of changes are shown in Table 3-6. 

Table 3-6. Examples of Treatment, Distribution System, and Source Changes 

Temporary Changes that Are Not Likely to 

Significantly Impact DBP Formation 

Permanent Changes that Warrant Exclusion of Using 

Existing Data 

•

•

Regular maintenance, rehabilitation, and upgrades of 

plant processes 

Short duration switches to free chlorine for secondary 

disinfection: 

•

•

•

To control nitrification in a chloraminated system 

For short duration emergencies 

For special disinfection operations 

•

•

•

•

•

Adding booster chlorination in the distribution 

system 

Addition of a new water source 

Addition or removal of a very high water use 

customer (industrial, institutional, or wholesale) 

Addition, deletion, or replacement of mains or 

storage tanks that significantly change water flow 

patterns 

Large main looping projects that significantly 

change water flow patterns 

Note: This list is not comprehensive—EPA or the state should use best professional judgment to determine if a 

modification to a system’s treatment or distribution system should warrant exclusion of the use of existing 

monitoring results. 

Systems are required to submit all data taken from the time of the first sample submitted through the most 

recent Stage 1 DBPR compliance samples taken. Therefore, it is possible that a subset of submitted data 

may not meet all requirements and do not count toward the minimum number of required locations and 

samples. EPA or the state should verify that systems have submitted enough qualifying data to meet the 

minimum requirements. EPA or the state should also look at data across the entire SSS period to make 

sure that older data are still representative of current water quality. 

If data are not acceptable, EPA or the state should work with the system to develop a plan to collect 

additional data during the IDSE to meet the minimum requirements. If the system has extensive data 

problems, EPA or the state may want to consider requiring standard monitoring. If all data are acceptable, 

the plan can be approved. 

3.9.2 Review of Existing Monitoring SSS IDSE Report 

All systems conducting an SSS must prepare an IDSE Report [§141.602(b)] and submit it to EPA or the 

state. The primary purpose of the IDSE Report is to provide EPA or the state with the system’s 

recommendations for where and at what frequency Stage 2 DBPR compliance monitoring should be 

conducted. In addition, the system must provide justification for these selections. Remember, systems that 

Stage 2 DBPR Implementation Guidance 75 August 2007 
include their compliance calculations procedures in their IDSE Report in addition to their monitoring 

locations and dates may not need to submit a Stage 2 Compliance Monitoring Plan. When completing the 

IDSE Report, systems have the option of using the Existing Monitoring Results SSS IDSE Report Form 

(Form 3) in Appendix E. 

There are two different categories of reviews that should be done for IDSE Reports from systems that 

conduct an SSS: 

•

•

Review of IDSE Report for required elements. 

Technical review of Stage 2 DBPR compliance monitoring site selection and schedule. 

The first review will be done by the IPMC for EPA reviewers and states that choose to use it. The 

remaining technical review of Stage 2 DBPR compliance monitoring site selection and schedule will be 

done by either state or EPA reviewers. 

If the reviewer has any concerns about a report during the review, they can either request modifications to 

the report or contact the system to ask for additional information. The reviewer may also require 

additional locations for Stage 2 DBPR compliance monitoring. The number and frequency of samples 

must comply with Table 3-17, unless EPA or the state requires additional monitoring. Systems must 

follow the site selection protocol in this subsection unless they provide EPA or the state with adequate 

justification for alternate sites. 

EPA or the state has a limited amount of time after the submission deadline to request modifications or 

approve the IDSE Report or contact the system to let them know that the review is not complete. The 

EPA or state deadlines for IDSE Reports approval, modification, or notification are listed in Table 3-1. 

These dates are within 3 months of the submission deadline for systems on Schedules 1, 2 and 4, and 

within 9 months of the submission deadline for systems on Schedule 3. Note that this is 3 or 9 months 

from the submission deadline, not the actual date of submission. If the system does not receive approval 

or modification of the report, or notification that EPA or the state has not completed their review within 

that 3- or 9-month period, the system may consider the report approved as submitted and use the Stage 2 

DBPR compliance monitoring sites recommended in the report. 

If EPA or the state needs additional time for the review, they can contact the system within the 3- or 9-

month period and let them know that the review requires additional time. 

3.9.2.1 Review of Required Elements for Existing Monitoring IDSE Report 

The basic elements required in the IDSE Report for an SSS using existing data are listed in the checklist 

in Table 3-7. States may want to encourage systems to include their compliance calculation procedures in 

their IDSE Report so that the system may meet the requirements for submitting a Stage 2 DBPR 

Compliance Monitoring Plan. Systems may use the form IDSE Report for an Existing Data SSS (Form 3) 

in Appendix E of this document. 

Stage 2 DBPR Implementation Guidance 76 August 2007 
Table 3-7. IDSE Report for Existing Monitoring SSS Required Elements Checklist 

Check if 

Provided 

;

Required Element Section in Form 

3 

 Recommendations and justification of Stage 2 DBPR compliance 

monitoring sites 

IV 

 Proposed Stage 2 DBPR Compliance Monitoring Schedule VI 

If the IDSE Report is NOT submitted at the same time as the SSS Plan 

 Additional SSS and Stage 1 DBPR compliance monitoring results in a 

tabular or spreadsheet format 

III.C & III.D 

 Population served and source water type (Subpart H or ground water) only 

if they have changed since the SSS plan. 

I.A 

 Distribution system schematic only if it has changed since the SSS Plan VII

 Explanation of any deviations from the approved SSS Plan VIII 

If some of the required elements on the checklist in Table 3-7 are missing, the reviewer should contact the 

system to request the missing information. If all boxes are checked, all required elements have been 

submitted. 

3.9.2.2 Technical Review of Existing Monitoring IDSE Report 

The purpose of the technical review of the IDSE Report is to ensure that: 

•

•

•

The system’s recommended Stage 2 DBPR compliance monitoring locations are in accordance 

with the protocol set in §141.605, or 

The system provided adequate justification for alternative locations, and 

 

The system has chosen appropriate dates on which to sample for Stage 2 DBPR compliance. 

One difference between standard monitoring and the SSS using existing monitoring results is that systems 

can have more than 1 year of TTHM and HAA5 data to analyze for site selection. Systems should rely on 

qualifying data only, and they may compare data from their peak historical month in addition to LRAAs 

as they work through the protocol for selecting Stage 2 DBPR compliance monitoring sites. However, 

they must provide a justification for relying on peak historical month data rather than LRAA data. EPA 

suggests that systems calculate annual averages for each site for which they have existing monitoring 

results and use this value to select Stage 2 DBPR compliance monitoring sites. Systems should not use 

data for a year in which the peak historical month was not sampled to calculate the LRAA. 

Remember, systems that conduct system specific studies may be submitting their IDSE Report with their 

study plans. 

EPA or the state should notify the system in writing when its report is approved. If changes were made 

after the original submission, EPA or the state should send a copy of the approved plan to the system for 

Stage 2 DBPR Implementation Guidance 77 August 2007 
its records or reference the changes in a letter to clarify which version of the report is approved. If EPA is 

reviewing reports, all correspondence and recordkeeping will be through the IPMC. 

Stage 2 DBPR Monitoring Site Selection: A system that completes an SSS must recommend Stage 2 

DBPR compliance monitoring locations using the data collected during the IDSE in addition to their 

Stage 1 DBPR sites. Justification must be provided for the final sites selected in the IDSE Report 

(including model results for water age at the relevant nodes, if a system is using modeled data). Chapter 5 

of EPA’s IDSE Guidance Manual provides a detailed discussion for Stage 2 DBPR site selection using 

existing monitoring results. 

Systems must use the protocol in Table 3-15 to select their Stage 2 DBPR compliance monitoring sites. If 

a system is required to select more than eight sampling sites it must return to the top of the protocol, each 

time selecting from those sites that have not already been identified for Stage 2 DBPR monitoring until 

the required number of sites has been selected. 

If a system arrives at Step 3 or Step 7 and has no more Stage 1 DBPR sites to select from, the system 

should skip these steps and continue with the protocol as necessary, until it has identified the required 

total number of monitoring locations. This may happen if the Stage 1 DBPR sites have the highest TTHM 

or HAA5 LRAAs and were previously selected, or if the system is a consecutive system and had little or 

no Stage 1 DBPR data, or if the system is very large but has few treatment plants. When this occurs, the 

total number of sites will be selected, but the distribution between TTHM, HAA5 and Stage 1 DBPR sites 

will be different than shown in Table 3-17. 

EPA or the state should review the IDSE Report to assure that the system followed the site selection 

protocol correctly. EPA or the state should check that the system used the correct type of Stage 1 DBPR 

site in the third and seventh steps, depending on the system’s source type. 

If the system varied from the protocol in Table 3-15 it should provide a rationale for its selections. EPA or 

the state will use their best professional judgment to review this rationale and either approve the alternate 

sites or require the system to comply with the protocol. 

Keep in mind that the goal of the IDSE is for systems to choose Stage 2 DBPR compliance monitoring 

locations that are most representative of high TTHM and HAA5 concentrations throughout the 

distribution system. 

Sampling Dates: The technical review of the IDSE Report for an SSS using existing monitoring results is 

very similar to the technical review of the IDSE Report for standard monitoring. Refer to section 3.11.1.4 

for guidance on reviewing a system’s Stage 2 DBPR monitoring site selection and schedule. 

3.10 IDSE Option: Hydraulic Modeling System Specific Study 

3.10.1 Review of Hydraulic Modeling SSS Plan 

This section contains guidance on four different categories of reviews that can be completed for study 

plans based on existing monitoring results: 

•

•

•

•

Review for required plan elements 

Review for correct interpretation of the IDSE requirements 

Technical review of data representativeness 

Technical review of monitoring results 

Stage 2 DBPR Implementation Guidance 78 August 2007 
The first review for required plan elements will be done by the IPMC for EPA reviewers and states that 

choose to use it. The remaining reviews for correct interpretation of the IDSE requirements, technical 

review of data representativeness, and technical review of standard monitoring site selection, will be 

completed by either the state or EPA. 

Chapter 6 of EPA’s IDSE Guidance Manual provides in-depth information regarding how a system may 

prepare a plan for a modeling SSS. 

The state or EPA may want to request additional information from a system during the review process. 

The state or EPA can approve the plan, request that the system modify its plan, or require standard 

monitoring if the plan is not acceptable. If a system does not respond to a request to modify the plan or to 

provide more information, the state or EPA has the option of requiring standard monitoring. EPA or the 

state has 12 months after the submission deadline to complete the review of Standard Monitoring Plans. 

All correspondence between the system and the reviewer is included in the 12-month period and does not 

extend the ultimate approval deadline. If EPA or the state does not contact the system to officially 

approve or request modifications to the plan by the end of the review period, the system can consider the 

plan approved and will implement it as submitted. 

If the state or EPA intends to require standard monitoring, it is best to notify the system as early as 

possible. If it is early enough, the system may be able to comply within their original schedule. However, 

if the system is not notified in time to complete a Standard Monitoring Plan by the scheduled compliance 

date, EPA or the state should work with the system to set an alternate schedule. The alternate schedule 

could be based on one of the four regulatory schedules or it could be a schedule unique to that system. 

The IPMC is set up to accommodate alternate schedules. 

The state or EPA should notify the system in writing when its plan is approved. If changes were made 

after the original submission, the state or EPA should send a copy of the approved plan to the system for 

its records or reference the changes in a letter to clarify which version of the plan is approved. If EPA is 

reviewing plans, all correspondence and recordkeeping will be through the IPMC. 

Some states may not have staff that are trained or experienced in reviewing the data found in hydraulic 

modeling SSS and the types of water age or water quality models that will be submitted by utilities. EPA 

Headquarters will provide support to EPA regions and states that require technical assistance in reviewing 

models or who choose to have EPA review the model entirely. 

EPA or the state should review each plan early in the review period to ensure that it contains the 

minimum elements required by the Stage 2 DBPR. For the modeling SSS, EPA or the state should also 

confirm that the system’s model meets the minimum requirements for the SSS. In addition, they should 

conduct a technical review of system’s model to ensure that it is capable of identifying distribution system 

locations with high TTHM and high HAA5 levels. 

3.10.1.1 Review of Required Elements for Hydraulic Modeling SSS Plan 

Table 3-8 can be used to determine if the system has met the minimum requirements of the Stage 2 DBPR 

for the modeling study plans. Systems have the option of using the Modeling Study Plan Form (Form 4) 

in Appendix E of this document. If systems fill out all sections of Form 4 according to the instructions, 

they have met the minimum requirements of the rule. Note that Form 4 asks the system to list its IDSE 

schedule and the required number of monitoring sites for the system. EPA or the state should verify that 

the schedule on Form 4 is consistent with the schedule in the letter sent to the system by EPA or the state. 

A completed example of a modeling study plan can be found in Appendix E of EPA’s IDSE Guidance 

Manual. 

Stage 2 DBPR Implementation Guidance 79 August 2007 
If the system used Form 4, verify that the following information is correct: 

• Schedule – Verify that the schedule is consistent with the schedule in the letter sent to the system 

by EPA or the state or with a schedule based on additional conversations with the system. This 

verification can be done by checking the schedule listed for that system in the DCTS. If the 

submitted schedule is different, EPA or the state should contact the system to discuss the required 

compliance schedule. 

• Number of sites – Verify that the number of modeling SSS monitoring sites meets the minimum 

requirements for standard monitoring, as shown in Table 3-13. If a system misinterpreted its 

monitoring requirements, the reviewer should contact the system to explain what is required. 

Table 3-8. Modeling Study Plan Checklist Required Elements 

Check if Provided 

;

Required Element Section in Form 

4 

 Population served by the system I.A 

 Source water type (Subpart H or ground water) I.A 

 Is the model an Extended Period Simulation (EPS) model? III.A 

 Does the model simulate 24-hr variation in demand and show a consistently 

repeating 24-hr pattern of residence time? (If calibration is not complete, 

this question can be answered in the IDSE Report.) 

III.A 

Tabular or spreadsheet data demonstrating that the model meets the 

following minimum requirements: 

 • 75% of pipe volume. 

 •

•

•

•

•

•

•

•

50% of pipe length. 

 All pressure zones. 

 All 12" diameter and larger pipes. 

 All 8" and larger pipes that connect pressure zones, influence zones 

from different sources, storage facilities, major demand areas, pumps, 

and control valves, or are known or expected to be significant 

conveyors of water. 

 All 6" and larger pipes that connect remote areas of a distribution 

system to the main portion of the system. 

 All storage facilities with standard operations represented. 

 All active pump stations with controls. 

 All active control valves. 

III.A & VIII 

 Model output showing 24 hour average residence time predictions 

throughout the distribution system (can be preliminary if calibration is not 

complete) 

V & VIII 

 Timing and number of samples planned for at least one round of TTHM and 

HAA5 monitoring during the historical month of high TTHM 

II & IV 

Stage 2 DBPR Implementation Guidance 80 August 2007 
Stage 2 DBPR Implementation Guidance 81 August 2007 

Check if Provided 

;

Required Element Section in Form 

4 

 Description of how all requirements will be completed no later than 12 

months after submission of the study plan 

III.D 

 A description of all calibration activities III.B, III.C, & 

III.D 

A distribution system schematic with: 

 •

•

•

•

•

All entry points 

 All sources 

 All storage facilities 

 Locations and dates of all completed SSS monitoring (if calibration is 

complete) 

 Locations and dates of Stage 1 DBPR compliance samples 

VII 

If calibration is complete: 

 •

•

•

Does the model simulate 24-hr variation in demand and show a 

consistently repeating 24-hr pattern of residence time? 

III.A 

 A graph of predicted tank levels vs. measured tank levels for the 

storage facility with the highest residence time in each pressure zone 

III.D & VIII 

 A time series graph of residence time at the longest residence time 

storage facility in the distribution system showing predictions for the 

entire EPS simulation period 

V & VIII 

Submissions to the IPMC will not be considered confidential business information (CBI) and are subject 

to the Freedom of Information Act (FOIA). 

If some of the required elements on the checklist in Table 3-8 are missing, EPA or the state should contact 

the system to request the missing information. Until all required elements are submitted, the plan should 

be considered incomplete and should not be reviewed further. If the system does not complete their 

submission, they will receive a monitoring and reporting violation. If all boxes are checked, all required 

elements have been submitted. 

3.10.1.2 Technical Review of Hydraulic Modeling SSS Plans 

EPA or the state should review modeling study plans to ensure that the model meets all minimum 

requirements as well as to ensure that the modeling basis is sound and that good technical judgment was 

used. EPA or the state should consider the modeler’s responses to questions on the Modeling Study Plan 

Form (Form 4) in Appendix E of this document to determine if the model is adequate. If a system does 

not use the forms, EPA and states can still use the information provided in this chapter to determine if a 

system submitted all the required information and to guide the review of the model and selected 

monitoring sites. 

The checklists provided in this chapter can be helpful in determining if the model meets minimum 

requirements and to help EPA or the state address all issues. EPA or the state may use the checklist in 

Table 3-8 to ensure that the system has addressed all required issues related to model development and 

calibration. If the system used Modeling Study Plan Form (Form 4) in Appendix E and adequately 
addressed all of the requirements therein, the system’s model should meet the minimum requirements and 

the system should have provided all necessary model information. If the system has not completed 

calibration or sampling, the plan must provide a description of how all requirements will be met within 12 

months of the date on which the study plan was submitted. If calibration is completed, EPA or the state 

should refer to the relevant review procedures discussed in this section below. 

In order to provide a basis for reviewing the model information referenced in Table 3-8, EPA or the state 

may wish to request additional information referenced in Table 3-9. (If calibration is not complete, EPA 

or the state may wish to ask how these questions will be addressed during calibration.) Systems are 

required to respond to any state requests for additional information. States may modify the ISDE plan (or 

report) or require standard monitoring if information contained in the submission is inadequate for review 

and approval. 

Table 3-9. Modeling Study Plan Checklist—Optional Modeling Information 

 

Check if 

Provided 

;

Information Section in 

Form 4 

Was a history of the model development and calibration provided? 

 •

•

What has the model been used for? 

 What decisions have been based on use of the model? 

III.B 

How were water demands assigned? 

 • What method was used to assign demands throughout the system? 

 •

•

•

How did the system estimate the diurnal demand variation? 

 How many demand categories were used? 

 How were large demand customers addressed? 

III.C 

What other calibration information is provided? 

 •

•

•

•

•

•

•

When was the model last calibrated? 

 What types of data were used? (e.g., tracer studies, fire flow tests) 

 When was this calibration data collected? 

 What field tests were done to collect calibration data? 

 How were friction factors/C factors determined? 

 If a water quality model is used, what parameters were used to calibrate the 

model? (chlorine residual, DBP data, SDS tests, etc.) 

 Has the distribution system changed since the model was developed and 

last calibrated? If so, systems should describe the changes. 

III.D 

Stage 2 DBPR Implementation Guidance 82 August 2007 
Stage 2 DBPR Implementation Guidance 83 August 2007 

Check if 

Provided 

;

Information Section in 

Form 4 

How was system operation represented in the model? 

 •

•

•

What time steps were used? What was the length of simulation? 

 Was modeling done using typical operating conditions during peak month 

of TTHM formation potential? 

 How were operational controls represented (e.g., time controls or logic 

controls etc.)? 

V 

In reviewing the modeling information obtained from the checklists in Tables 3-8 and 3-9, EPA or the 

state may wish to take the following information into consideration: 

•

•

•

•

Models that have been prepared for long-range master planning purposes are not likely to meet 

the minimum requirements. Models like this could be updated to meet the modeling SSS 

requirements. Calibrated models that were prepared for detailed distribution system design or 

operational studies are likely to be adequate. 

A model that has not been calibrated in the last 10 years will not likely produce results that are 

consistent with the current system configuration. 

The model must be calibrated using operating conditions that are representative of those during 

the month of peak historical TTHM formation potential. 

The model must be run for an extended time period so that system components, including the 

storage tank with the highest water age, show a pattern of repeating residence time. See Figure 3-

2 for an example. Note that a similar graph must be presented as evidence of adequate model runtime. 
Figure 3-2. Example Repeating Residence Time 

Water Age for Tank 2

0

20

40

60

80

100

120

140

0 100 200 300 400 500 600 700 800 900 1000

Time (hours)

•

•

•

•

•

“Dead-end” areas that represent significant flow demands, such as industrial customers or large 

subdivisions, should be included in the model. 

Water demands should be allocated to as many nodes in the model as possible, and the allocation 

should represent the actual spatial distribution of the demands based upon metering records. 

Water demands from all significant users should be included. 

It is imperative that the model incorporate realistic demands for the peak month of TTHM 

formation. 

System water loss should be taken into account in the allocation of demands. 

Demand variations over the time period of the model simulation must be taken into account, 

including diurnal demand fluctuations. Figure 3-3 shows an example of a diurnal demand 

variation pattern. Where applicable, diurnal fluctuation patterns that are appropriate for each type 

of user (residential, industrial, etc.) should be used in the model. 

Stage 2 DBPR Implementation Guidance 84 August 2007 
Figure 3-3. Example Diurnal Demand Variation Pattern 

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 4 8 12 16 20 24

Hour

Multiplier

Average = 1.0

•

•

•

Time steps of 1-5 minutes for model calculations typically produce acceptable results. 

The actual operation of the distribution system (whether it is done manually, through telemetry, 

through other system controls, or a combination of these methods) should be simulated for the 

entire modeling time period. In general, model controls are either logic or time-based. Logicbased controls initiate an activity based upon a system condition (e.g., a well pump is activated 

because the water level in a tank has dropped 2 feet). Time-based controls perform an activity 

simply based upon a clock setting (e.g., a booster pump turns on to pump water to a storage tank 

from 8:00 to 9:00 a.m. every morning). 

The actual data collected for model calibration will vary according to the characteristics of each 

system. In general, calibration should incorporate the following information: 

– Flow from each pump or pumping facility (including the sequential operation of each pump). 

– Water level variations in each storage facility. 

– System pressure readings. 

– System flow tests (e.g., at hydrants). 

– Friction factor tests. 

– Field tests (e.g., flow testing at hydrants, may be needed). 

Many systems collect operational data using supervisory control and data acquisition (SCADA) systems, 

chart recorders, or other types of data loggers. It is important to collect operational data over a 24-hour 

time period so that the model can be calibrated for each time step. 

Figure 3-4 shows a graph of actual water levels measured in a storage tank versus the levels predicted by 

a calibrated model. This is an example of a model that has been well-calibrated using accurate demand 

Stage 2 DBPR Implementation Guidance 85 August 2007 
and operational data. Note that similar graphs must be submitted for the tank with the longest residence 

time in each pressure zone. 

Figure 3-4. Example Verification Graph for a Tank with Highest Water Age 

Tank # 2

C alibrat ion V erif icat ion R esult s

1005

1006

1007

1008

1009

1010

1011

1012

1013

8/ 24/ 2005 0:00 8/ 24/ 2005 12:00 8/ 25/ 2005 0:00 8/ 25/ 2005 12:00 8/ 26/ 2005 0:00 8/ 26/ 2005 12:00 8/ 27/ 2005 0:00

Dat e/ Time

Measured

Modeled

Remember that the model must be calibrated using operating conditions that are representative of those 

during the peak month of TTHM formation. If the model was not calibrated using these conditions, 

additional data may be needed to properly calibrate the model. 

Modeling of systems that have multiple sources with widely varying DBP formation potential can be very 

complex. Appendix G of EPA’s IDSE Guidance Manual discusses these concerns and three approaches 

for analyzing this type of system. 

If the system has not adequately addressed all modeling questions in Table 3-8, EPA or the state should 

contact the system and request more information. If EPA or the state determines that the model and 

calibration plans are adequate, they can attach any new information to the study plan and complete the 

review. 

EPA or the state may also wish to ask how the system plans to use the data from its round of monitoring 

at TTHM and HAA5 sites. For example, will the data be used to corroborate or further calibrate the 

model? If the data are not consistent with model predictions for TTHM, what steps will the system take to 

explain the inconsistency? 

Systems conducting a modeling SSS should review all available compliance, study, or operational data to 

determine the peak month for TTHM formation for their system. This month sets the conditions for the 

model simulation and the schedule for the SSS monitoring. Systems with monthly or quarterly TTHM 

monitoring data should use this data as the basis for selecting the historical month. If a system does not 

have monthly or quarterly data, the month with warmest water temperature should be selected as the peak 

month for TTHM formation, although additional data (e.g., increases in TOC levels) may also be 

considered. 

To ensure that an appropriate peak month was selected, EPA or the state should review the data submitted 

and the justification provided by the system. The EPA or the state review should determine whether the 

Stage 2 DBPR Implementation Guidance 86 August 2007 
system carefully considered all available TTHM data. See section 3.11.1.4 for technical guidance on 

reviewing selection of the peak historical month. 

3.10.2 Review of Hydraulic Modeling SSS IDSE Report 

All systems conducting an SSS must prepare an IDSE Report [§141.602(b)] and submit it to EPA or the 

state. The primary purpose of the IDSE Report is to provide EPA or the state with the system’s 

recommendations for where and at what frequency Stage 2 DBPR compliance monitoring should be 

conducted. In addition, the system must provide justification for these selections. Remember, systems that 

include their compliance calculations procedures in their IDSE Report in addition to their monitoring 

locations and dates may not need to submit a Stage 2 Compliance Monitoring Plan. When completing the 

IDSE Report, systems have the option of using the IDSE Report for a Modeling SSS Form (Form 5) in 

Appendix E. 

There are two different categories of reviews that should be done for IDSE Reports from systems that 

conduct an SSS: 

•

•

Review of IDSE Report for required elements. 

Technical review of Stage 2 DBPR compliance monitoring site selection and schedule. 

The first review will be done by the IPMC for EPA reviewers and states that choose to use it. The 

remaining technical review of Stage 2 DBPR compliance monitoring site selection and schedule will be 

done by either state or EPA reviewers. 

If the reviewer has any concerns about a report during the review, they can either request modifications to 

the report or contact the system to ask for additional information. The reviewer may also require 

additional locations for Stage 2 DBPR compliance monitoring. The number and frequency of samples 

must comply with Table 3-17, unless EPA or the state requires additional monitoring. Systems must 

follow the site selection protocol in this subsection unless they provide EPA or the state with adequate 

justification for alternate sites. For more information about selecting sites for Stage 2 DBPR monitoring, 

refer to EPA’s IDSE Guidance Manual. 

EPA or the state has a limited amount of time after the submission deadline to request modifications or 

approve the IDSE Report or contact the system to let them know that the review is not complete. The 

EPA or state deadlines for IDSE Reports approval, modification, or notification are listed in Table 3-1. 

These dates are within 3 months of the submission deadline for systems on Schedules 1, 2 and 4, and 

within 9 months of the submission deadline for systems on Schedule 3. Note that this is 3 or 9 months 

from the submission deadline, not the actual date of submission. If the system does not receive approval 

or modification of the report, or notification that EPA or the state has not completed their review within 

that 3- or 9-month period, the system may consider the report approved as submitted and use the Stage 2 

DBPR compliance monitoring sites recommended in the report. 

If EPA or the state needs additional time for the review, they can contact the system within the 3- or 9-

month period and let them know that the review requires additional time. 

3.10.2.1 Review of Required Elements for Hydraulic Modeling IDSE Report 

The basic elements required of an IDSE Report for an SSS based on modeled data are listed in the 

checklist in Table 3-10. A completed example of an IDSE Report for a modeling SSS can be found in 

EPA’s IDSE Guidance Manual. Any required information that was not included in, or updated since, the 

Stage 2 DBPR Implementation Guidance 87 August 2007 
approved modeling study plan (e.g., because calibration was not yet complete) must be included in the 

IDSE Report (in addition to the information listed in the checklist in Table 3-10). 

Table 3-10. IDSE Report for a Modeling SSS Required Elements Checklist 

Check if 

Provided 

;

Required Element Section in Form 5

 TTHM and HAA5 analytical results in a tabular or spreadsheet format from 

all Stage 1 DBPR and SSS monitoring conducted during the period of the 

SSS 

V & XI 

 Recommendations and justification of Stage 2 DBPR compliance 

monitoring sites and dates 

VII 

 24-hr time series graph of residence time for all Stage 2 DBPR monitoring 

sites selected 

VI & XI 

If the IDSE Report is NOT submitted at the same time as the SSS Plan 

 Population served and source water type (Subpart H or ground water) only 

if they have changed since the SSS plan. 

I.A 

 Distribution system schematic only if it has changed since the SSS Plan X

 Explanation of any deviations from the approved SSS Plan XI 

Final calibration information (if not already provided with the study plan) 

 Any information that was updated since the approved IDSE plan III 

 A graph of predicted tank levels vs. measured tank levels for the storage 

facility with the highest residence time in each pressure zone 

III.B & XI 

 A time series graph of the residence time at the longest residence time 

storage facility in the distribution system showing the predictions for the 

entire simulation period 

III.C & XI 

 Model output showing 24 hour average residence time predictions 

throughout the distribution system 

III.C & XI 

3.10.2.2 Technical Review of Hydraulic Modeling IDSE Report 

The purpose of the technical review of the IDSE Report is to ensure that: 

•

•

•

The system’s recommended Stage 2 DBPR compliance monitoring locations are in accordance 

with the protocol set in §141.605, or 

The system provided adequate justification for alternative locations, and 

 

The system has chosen appropriate dates on which to sample for Stage 2 DBPR compliance. 

Systems should rely on qualifying data only, and they may compare data from their peak historical month 

in addition to LRAAs as they work through the protocol for selecting Stage 2 DBPR compliance 

Stage 2 DBPR Implementation Guidance 88 August 2007 
monitoring sites. However, they must provide a justification for relying on peak historical month data 

rather than LRAA data. 

Remember, systems that conduct system specific studies may be submitting their IDSE Report with their 

study plans. 

EPA or the state should notify the system in writing when its report is approved. If changes were made 

after the original submission, EPA or the state should send a copy of the approved plan to the system for 

its records. If EPA is reviewing reports, all correspondence and recordkeeping will be through the IPMC. 

Stage 2 DBPR Monitoring Site Selection: A system that completes an SSS must recommend Stage 2 

DBPR compliance monitoring locations using the data collected during the IDSE in addition to their 

Stage 1 DBPR sites. Justification must be provided for the final sites selected in the IDSE Report 

(including model results for water age at the relevant nodes, if a system is using modeled data). EPA’s 

IDSE Guidance Manual provides a detailed discussion for Stage 2 DBPR site selection. 

Systems must use the protocol in Table 3-15 to select their Stage 2 DBPR compliance monitoring sites. If 

a system is required to select more than eight sampling sites it must return to the top of the protocol, each 

time selecting from those sites that have not already been identified for Stage 2 DBPR monitoring until 

the required number of sites has been selected. 

If a system arrives at Step 3 or Step 7 and has no more Stage 1 DBPR sites to select from, the system 

should skip these steps and continue with the protocol as necessary, until it has identified the required 

total number of monitoring locations. This may happen if the Stage 1 DBPR sites have the highest TTHM 

or HAA5 LRAAs and were previously selected, or if the system is a consecutive system and had little or 

no Stage 1 DBPR data, or if the system is very large but has few treatment plants. When this occurs, the 

total number of sites will be selected, but the distribution between TTHM, HAA5 and Stage 1 DBPR sites 

will be different than shown in Table 3-17. 

EPA or the state should review the IDSE Report to assure that the system followed the site selection 

protocol correctly. EPA or the state should check that the system used the correct type of Stage 1 DBPR 

site in the third and seventh steps, depending on the system’s source type. 

If the system varied from the protocol in Table 3-15 it should provide a rationale for its selections. EPA or 

the state will use their best professional judgment to review this rationale and either approve the alternate 

sites or require the system to comply with the protocol. 

Keep in mind that the goal of the IDSE is for systems to choose Stage 2 DBPR monitoring locations that 

are most representative of high TTHM and HAA5 concentrations throughout the distribution system. 

Sampling Dates: The technical review of the IDSE Report for a hydraulic modeling SSS is very similar to 

the technical review of the IDSE Report for standard monitoring. Refer to section 3.11.1.4 for guidance 

on reviewing a system’s Stage 2 DBPR monitoring site selection and schedule. 

SSS IDSE Report Based on Modeled Data 

EPA or the state may wish to ask the following questions related to site selection based on modeled data: 

• How were the Stage 2 DBPR compliance monitoring sites selected to ensure that they are 

representative of the distribution system and represent nodes with high water age for TTHM? For 

Stage 2 DBPR Implementation Guidance 89 August 2007 
HAA5, do the sites represent areas with relatively high water age that are able to maintain a 

disinfectant residual? 

• Were other water quality data (e.g., non-regulatory monitoring, TCR data, other) or water quality 

modeling data used to corroborate the selected Stage 2 DBPR monitoring sites? If so, that data 

should be provided. 

In the review of modeling IDSE Reports, EPA or the state must ensure that the system’s model meets 

minimum requirements and that the system adequately completed calibration of its model. If the system 

adequately completed the IDSE Report for a Modeling SSS Form (Form 5) in Appendix E, or if the 

model calibration was completed and approved as part of the model study plan, the system’s model 

should meet the minimum requirements and the system should have provided all necessary model 

information. If the system did not use this form, or if calibration of the model was not complete or was 

changed after it was approved as part of the model study plan, EPA or the state may use the checklist in 

Table 3-10 to ensure that the system has adequately addressed all issues related to model development 

and calibration. The system must show that they fulfilled all approved plans for calibration. If the system 

has not adequately addressed all questions, EPA or the state should contact the system and request more 

information. 

In reviewing the IDSE Report, EPA or the state should also consider the following: 

•

•

Review the 24-hour residence time graph for proposed Stage 2 DBPR compliance monitoring 

sites, and verify that the sites that the model predicted to have high residence time will be high 

during the time of day when the system is likely to be sampling. For instance, if the model 

predicts an area of the distribution system to have advanced water age during the middle of the 

night, but during the day time the water age decreases substantially, then the monitoring results at 

this site (likely to take place during the day time) will be of water with low water age and will not 

reflect high DBP levels. 

Was the data from the round of monitoring at TTHM and HAA5 sites used to corroborate or 

further calibrate the model? Was the data consistent with model predictions for TTHM? If not, 

what steps did the system take to explain or correct the inconsistency? If an inconsistency is 

unexplained, EPA or the state may wish to ask the system to explain it. It may be appropriate to 

take more samples to look for diurnal DBP fluctuations at the selected locations. EPA or the state 

may wish to suggest that the system perform further model calibration if they are confident that 

the sample results are actually representative of the distribution system water quality. If SSS 

monitoring results do not coincide with model predictions, the system should attempt to reconcile 

the differences before proceeding with Stage 2 DBPR site selection. Justification must be 

provided for the final sites selected in the IDSE Report (including model results for water age at 

the relevant nodes). 

– For example, the system could monitor at the problematic sites over a 24 hour period to see if 

a water age peak was missed initially. 

– Unexpected operational changes such as main breaks, or unusually high or low water use 

could affect results. 

– The time of sample collection should be noted and compared to the water age graph to 

determine if the sample time coincided with the time of maximum water age. 

Stage 2 DBPR Implementation Guidance 90 August 2007 
– Additional field data collected during the sampling period (e.g., chlorine residual, 

Heterotrophic Plate Count (HPC)) may help to explain discrepancies between modeling and 

sampling results. 

– Systems may choose to resample at the site(s) or alternative sites. 

– Systems should verify that the model represents the current configuration of the distribution 

system. Unexpected sampling results may indicate inconsistencies in the model. 

A system that completes a modeling SSS must complete one round of TTHM and HAA5 sampling during 

the peak month for TTHM formation. The number of monitoring locations and the type of locations must 

be the same as that required for standard monitoring. Stage 1 DBPR monitoring locations cannot be used. 

Depending upon system size and type, sample locations may include near entry point sites, average 

residence time sites, high TTHM sites, and high HAA5 sites. It is important that the site selection be done 

with consideration given to the model results and that the site selection requirements of the Stage 2 DBPR 

be addressed. The site selection process should also take into account water quality data (e.g., chlorine 

residuals and HPC results). 

Systems must use the protocol in Table 3-15 to select their Stage 2 DBPR compliance monitoring sites. 

TTHM and HAA5 results and modeled water age are the most important factors in site selection. Systems 

should have considered both predicted average water age and the 24-hour variation in water age. If 

systems selected between two sites where one had large variations in water age throughout the day and 

the other was relatively consistent, they should have selected the site with consistent water age. Sites with 

discrepancies between model results and SSS monitoring results can be selected as Stage 2 DBPR 

compliance monitoring sites if justification is provided in the IDSE Report. 

If SSS monitoring results do not coincide with model predictions, the system should attempt to reconcile 

the differences before proceeding with Stage 2 DBPR site selection. For example, the system could 

monitor at the problematic sites over a 24-hour period to see if a water age peak was missed initially. 

Unexpected operational changes such as main breaks, or unusually high or low water use could affect 

results. Re-sampling at alternative sites should be considered. 

3.11 IDSE Option: Standard Monitoring 

States should be aware that any system can conduct standard monitoring [§141.601], even if they meet 

exemption criteria or have enough data to conduct an SSS. Most CWSs and NTNCWSs serving at least 

10,000 people that do not qualify for a 40/30 Certification or a VSS Waiver are likely to use this option. 

Standard monitoring data in addition to Stage 1 DBPR data will be used to select Stage 2 DBPR 

compliance monitoring locations. 

Standard monitoring entails 1 year of distribution system monitoring at more locations and greater 

frequency than Stage 2 DBPR compliance monitoring. The sampling frequency and minimum number of 

sample locations required depend on system characteristics such as population served, source water type, 

and whether the system is a consecutive system. (The monitoring periods and frequency of sampling, 

along with the minimum number of samples required, are detailed in Table 3-17.) Systems that conduct 

standard monitoring must submit a Standard Monitoring Plan and an IDSE Report to EPA or the state. 

Recommendations presented in the IDSE Report for compliance monitoring locations will be used to 

develop the Stage 2 DBPR Compliance Monitoring Plan. Note that systems are likely to report all the 

information required in the Compliance Monitoring Plan in their IDSE Report, including compliance 

calculation procedures. These systems may not need to submit a separate Compliance Monitoring Plan. 

Stage 2 DBPR Implementation Guidance 91 August 2007 
States should ensure that systems conduct standard monitoring during the peak historical month for 

TTHM or HAA5 levels or the month of warmest water temperature, if DBP data are not available. All 

IDSE samples must be taken as dual sample sets (i.e., a TTHM and a HAA5 sample must be taken at each 

site). The IDSE monitoring results will not be used to determine compliance with MCLs. Although the 

individual results are not required to be reported in the CCR, the range of values must be included. 

When notifying consecutive systems of these requirements, states may wish to send copies of the 

correspondence to the associated wholesale systems to minimize confusion about sampling 

responsibilities. 

3.11.1 Review Considerations for Standard Monitoring Plan 

Systems must submit Standard Monitoring Plans by the deadlines specified in Table 3-1. EPA or states 

should complete five different categories of reviews for Standard Monitoring Plans: 

•

•

•

•

•

Review for required plan elements. 

Review for complexity. 

Review for correct interpretation of the IDSE requirements. 

Technical review of peak historical month. 

Technical review of standard monitoring site selection. 

The first two, review for required plan elements and review for complexity, will be done by the IPMC for 

EPA reviewers and states that choose to use it. The three remaining reviews for correct interpretation of 

the IDSE requirements, technical review of peak historical month, and technical review of standard 

monitoring site selection, will be done by either the state or EPA. EPA’s IDSE Guidance Manual 

provides detailed information regarding how a system should prepare a Standard Monitoring Plan. 

3.11.1.1 Review of Required Elements for Standard Monitoring Plan 

States can use Table 3-11 to determine whether a Standard Monitoring Plan contains the required 

elements. Systems have the option of using the Standard Monitoring Plan Form (Form 6) in Appendix E. 

If systems fill out all sections of the form according to the instructions, they have met the minimum 

requirements of the rule. 

Table 3-11. Standard Monitoring Plan Required Elements Checklist 

Check if 

Provided 

;

Required Element Section in Form 6 

 Population served by the system I.A 

 Source water type (Subpart H or ground) I.A 

 Peak historical month V.A 

 Proposed dates of standard monitoring V.D 

 Dates of planned Stage 1 DBPR compliance monitoring VI 

 Justification of standard monitoring site selection IV 

 Summary of data relied on to justify standard monitoring sites III.B 

Stage 2 DBPR Implementation Guidance 92 August 2007 
Stage 2 DBPR Implementation Guidance 93 August 2007 

Check if 

Provided 

;

Required Element Section in Form 6 

A distribution system schematic with: 

 •

•

•

•

•

All entry points 

 All sources 

 All storage facilities 

 Locations of proposed standard monitoring sites 

 Locations of Stage 1 DBPR compliance sampling 

VII 

If some of the required elements on the checklist in Table 3-11 are missing, EPA or the state should 

contact the system to request the missing information. Until all required elements are submitted, the plan 

should be considered incomplete and should not be reviewed further. If all boxes are checked, all required 

elements have been submitted. 

3.11.1.2 Review for Complexity of Standard Monitoring Plan 

The checklist provided in Table 3-12 is designed to determine if a Standard Monitoring Plan is straightforward or if it is complex and requires a more in-depth review. This tool can be helpful to the reviewer to 

prioritize workload and plan for completion of all reviews by the end of the review period. 

Table 3-12. Standard Monitoring Plan Triage Checklist 

REVIEWER INFORMATION 

System Name__________________________ ___________________ 

______________________________ _______________

PWSID

Reviewer Review Date

The purpose of this checklist is to provide a brief review of a Standard Monitoring Plan based on the 

optional format provided in the guidance manual. This review will determine whether, due to complexity 

and/or adequacy issues, the plan should be considered straight forward or requiring a more detailed 

review. If 5 or more of the following issues are checked, the plan should be categorized as requiring a more 

detailed review. 

I. GENERAL INFORMATION 

□ Population is > 500,000. 

□ Population is < 10,000 and system is on Schedule 1, 2, or 3. 

□ Chloramines not checked.
III. SELECTING STANDARD MONITORING SITES 

□ Hydraulic model and/or tracer study was checked 

□ TTHM or HAA5 column has only one box checked

IV. JUSTIFICATION OF STANDARD MONITORING SITES 

□ Incomplete or inadequate justifications 

•

•

•

•

•

•

•

•

•

•

•

•

•

each is 7-10 words or less 

no data provided 

incorrect use of data 

□ All TTHM sites or all HAA5 sites have the same text for justification 

□ System has distribution storage (check schematic), but justifications do not address sites located downstream of 

storage 

V. PEAK HISTORICAL MONTH AND STANDARD MONITORING DATES 

□ Peak historic month is not well justified. 

Little or no justification given for choice of peak historic month. 

“Other” is only box checked for peak historic month. 

□ Total number of monitoring sites and number of monitoring periods do not agree with information in Section II of 

the form. 

□ Sampling schedule is incorrect (not every 60 or 90 days, incorrect frequency). 

VI. PLANNED STAGE 1 DBPR COMPLIANCE MONITORING DATES 

□ Systems has very few Stage 1 sites compared to required standard monitoring sites - Number of standard 

monitoring sites is in Section V is 4 times or more than the number of Stage 1 sites in this section. 

□ System has no Stage 1 sites (e.g., consecutive system that did not monitor under Stage 1). Check both boxes if 

true. 

VII. DISTRIBUTION SYSTEM SCHEMATIC 

□ Key distribution system components are obviously missing 

No indication of pressure zones, large transmission mains, tanks, or pumping stations, and the description of 

data and justification in Section IV of the form indicates that the system has these components. 

□ Source (check one box for each) 

two or more surface water or GWUDI sources 

two types of sources (surface/GWUDI and ground) 

□ Distribution (check both boxes if more than two apply) 

many long branches 

three or more booster chlorination sites 

four or more pressure zones 

five or more booster pump stations 

six or more finished water storage tanks in the distribution system 

□ Stage 1 and Standard Monitoring sites do not geographically represent the distribution system. 

Stage 2 DBPR Implementation Guidance 94 August 2007 
SENSITIVE INFORMATION 

□ Does the plan include sensitive information that should not be made available to the public? 

•

•

Identifying information on tanks and sources such as street names or addresses 

Security features (e.g., locations of fences, cameras, monitors) 

Note that the checklist includes a category for sensitive information. Submissions to the IPMC will not be 

considered confidential business information (CBI) and are subject to the Freedom of Information Act 

(FOIA). 

If five or more of the boxes in Table 3-12 are checked, the plan should be categorized as requiring a more 

detailed review. If fewer than 5 boxes are checked, the plan should be categorized as requiring a standard 

review. This information can then be used to assign plans to individual reviewers and/or prioritize 

workloads. 

The elements in Table 3-12 were selected to help identify systems that are either very complex or have 

difficulty understanding the IDSE requirements. 

3.11.1.3 Review for Correct Interpretation of Standard Monitoring Requirements 

Review of the Standard Monitoring Plan should include verifying that the system has identified the 

correct schedule as well as the required number and type of standard monitoring sites and monitoring 

frequency. This information is listed in the Standard Monitoring Plan Form (Form 6) in Appendix E. 

•

•

Schedule - Verify that the schedule is consistent with the schedule in the letter sent to the system 

by EPA or the state or with a schedule based on additional conversations with the system. This 

verification can be done by checking the schedule listed for that system in the DCTS. If the 

submitted schedule is different, EPA or the state should contact the system to discuss the required 

compliance schedule. 

Number and Frequency - Verify that the number and types of sites and monitoring frequency 

meet the minimum requirements of the rule, as shown in Table 3-13. If the system has fewer near 

entry points than the required number of near entry point sites, systems must make an adjustment 

to the required number of samples. If a system misinterpreted its monitoring requirements, EPA 

or the state should contact the system to explain what is required. 

Table 3-13. Standard Monitoring Requirements 

Distribution System Monitoring Locations1 Source 

Water 

Type 

Population Size 

Category 

Monitoring 

Periods and 

Frequency of 

Sampling 

Total per 

monitoring 

period 

Near 

Entry 

Points 

Average 

Residence 

Time 

High 

TTHM 

Locations 

High 

HAA5 

Locations

<500 consecutive 

systems 

2 1 - 1 - 

Subpart 

H <500 non-consecutive 

systems 

one (during 

peak historical 

month 2 - - 1 1 

Stage 2 DBPR Implementation Guidance 95 August 2007 
Stage 2 DBPR Implementation Guidance 96 August 2007 

Distribution System Monitoring Locations1 Source 

Water 

Type 

Population Size 

Category 

Monitoring 

Periods and 

Frequency of 

Sampling 

Total per 

monitoring 

period 

Near 

Entry 

Points 

Average 

Residence 

Time 

High 

TTHM 

Locations 

High 

HAA5 

Locations

500-3,300 consecutive 

systems 

2 1 - 1 - 

500-3,300 nonconsecutive systems 2 - - 1 1 

3,301-9,999 

four (every 90 

days) 

4 - 1 2 1 

10,000-49,999 8 1 2 3 2 

50,000-249,999 16 3 4 5 4 

250,000-999,999 24 4 6 8 6 

1,000,000-4,999,999 32 6 8 10 8 

> 5,000,000 

six (every 60 

days) 

40 8 10 121 10 

<500 consecutive 

systems 

2 - - 1 - 

<500 non-consecutive 

systems 

one (during 

peak historical 

month)2 2 - - 1 1 

500-9,999 2 - - 1 1 

10,000-99,999 6 1 1 2 2 

100,000-499,999 8 1 1 3 3 

Ground 

Water 

> 500,000 

four (every 90 

days) 

12 2 2 4 4 

1. A dual sample set (i.e., a TTHM and an HAA5 sample) must be taken at each monitoring location during each 

monitoring period. 

2. The peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water 

temperature. 

3.11.1.4 Technical Review of Standard Monitoring Plan 

Two primary goals of the standard monitoring schedule are to ensure that the system is sampling during 

the period of the highest DBP formation and that the sampling is spaced out evenly throughout the year 

and geographically to provide representative data. The peak historical month sets the schedule for all 

standard monitoring sampling. Standard monitoring must include sampling during the peak historical 

month, but sampling may begin prior to this month depending on the system’s compliance schedule. 

Peak Historical Month 

The “peak historical month” will either be the month with highest TTHM, highest HAA5, or warmest 

water temperature. If a system has to sample more than once during the monitoring period, the other 

sample months will be spaced at 60 days or 90 days around the peak historical month. Systems have 

discretion in selecting the peak historical month. They should review available compliance, study, or 

operational data and should use best professional judgment to determine the peak historical month. 
Systems should typically start by considering the month of highest TTHM or HAA5 levels. Ideally they 

should consider monthly data if available (rather than just quarterly data). If high TTHM and HAA5 

levels occur in different months, they should consider which contaminant is of greatest concern. For 

instance, either TTHM or HAA5 might be closer to the MCL on a regular basis. Data may also indicate 

that one of the contaminants has a dramatic peak versus a minor spike in levels. If high TTHM or HAA5 

levels occur in different months in different years, the systems should choose the year that was more 

representative of typical system operating and weather conditions. 

Systems should also consider the month of warmest water temperature. In general (but not always), the 

concentration of organic matter in water increases during the warmest months of the year and is higher in 

warmer climates. Because organic matter reacts with chlorine and other chemical disinfectants, more 

organic matter in the water can result in a higher chlorine demand to maintain a reliable residual 

throughout the distribution system. The combination of a larger chlorine dose, warmer water temperatures 

that speed up chemical reactions, and larger concentrations of organic matter often result in higher TTHM 

and HAA5 concentrations during the warmest months of the year. 

Surface water systems are likely to have adequate temperature data, while ground water systems are likely 

to have only moderate fluctuations in temperature, and may not have much data. In some situations, the 

month of warmest water temperature may not be representative of highest TOC and DBP levels. For 

instance, in New England, the month of warmest water temperature may be late summer, but these 

systems may see dramatic spikes in TOC levels in the late fall after the leaves have fallen. For systems 

that have insufficient water temperature data, other data such as ambient air or climate data may be used 

to determine the month of warmest water temperature. 

When determining whether the appropriate peak historical month was selected for a particular system, 

EPA or the state should determine what type of source(s) the system uses. If the system uses surface 

water, items EPA or the state may consider are: 

Did the system check high 

TTHM, high HAA5, and/or 

warmest temperature as a 

basis for the peak historical 

month? 

The system must use one of these factors as the basis for the peak historical 

month. They can look at additional information, but they must check at least one 

of these boxes. TTHM and HAA5 are the preferred basis for selecting peak 

historical month if the system has monthly or quarterly TTHM and HAA5 data. If 

the system has not taken regularly spaced quarterly samples, EPA or the state may 

want to consider water temperature in addition to available TTHM and HAA5 data 

when approving the peak historical month. 

Did the system select a month 

with high TTHM and high 

HAA5 and provide 

justification? 

Based on their DBP data, systems should determine the month in which TTHM 

and HAA5 levels are highest and choose this month as the peak historical month. 

If the highest TTHM and/or HAA5 levels occur at different times during different 

years, the system should choose the year of data that is most representative of 

typical system operating and weather conditions. If the highest TTHM and HAA5 

levels occur in different months, the system should consider which contaminant is 

of greater concern. If one contaminant clearly shows a higher overall trend and is 

closer to the MCL, the system should choose the month in which that contaminant 

is highest. 

Stage 2 DBPR Implementation Guidance 97 August 2007 
Did the system select a month 

with warm water temperature? 

The peak historical months is of primary concern for surface water systems that 

have wide swings in temperature. To identify the month of warmest water 

temperature, systems should calculate the average water temperature for each 

summer month. If available, they should use data from several years. If the 

warmest temperature occurs in different months in different years, the system 

should select the year(s) that are most typical of climatological and water quality 

data and water use for their region. Although the system can set their peak 

historical month based on factors other than temperature, they should not choose a 

month in which the water temperature is colder than average. 

When might a system choose a 

month based on a parameter 

other than water temperature? 

High TOC levels – If the system has data showing high TOC levels that indicate a 

high potential for DBP formation, they may determine that this month is more 

representative of high DBP levels. For example, a system in New England may 

experience spikes in organic loading to their source in the autumn when leaves fall 

from the trees. Although this may not be the warmest water month, water is still 

relatively warm and organic loading is a substantial factor. 

Low water usage – The system may choose a month based on low water usage 

corresponding to longer residences times. For example, if a system has a seasonal 

population that peaks during the summer and drops off during the fall, residence 

time during the fall will be high, and water temperatures will still be relatively 

high. 

What should have been 

submitted if a month other 

than highest TTHM, highest 

HAA5, or warmest water 

temperature month is chosen? 

If a month other than a highest TTHM, highest HAA5, or warmest water month 

temperature was selected, the submittal should include adequate justification that 

EPA or the state finds convincing. If the system does not provide adequate 

justification, EPA or the state should contact the system for more information. 

What if a system has multiple 

surface water sources? 

For systems with multiple surface water sources, the system should have used the 

source of greater concern to select the peak historical month. This should be the 

source with the warmest water temperature and/or that provides the largest volume 

of water and/or the highest potential for DBP formation (e.g., high TTHMs, high 

HAA5s, high TOC). 

What if the system has a 

mixture of surface and ground 

water sources? 

If the system has a combination of surface and ground sources, they should have 

used the surface water source(s) data to determine the peak historical month. The 

system should typically choose the month with the warmest water temperature for 

the surface water source. If a different month was selected, the system should 

provide adequate justification. An example of this might be when a low TOC 

ground water source is only active during warm months and dilutes a high TOC 

surface water source that is in operation year round. 

If the system uses ground water only, items EPA or the state may consider are: 

What are the primary 

concerns for ground water 

systems? 

Since the water temperature typically does not vary as much in ground water 

systems, selecting a warm temperature month is not as critical. If a month other 

than a warm temperature month is selected, the system should have checked high 

TTHM, high HAA5, and/or provided additional justification. 

What if the system has 

multiple ground water 

sources? 

For systems with multiple ground water sources, the source of greater concern for 

DBP formation should have been used to select the peak historical month. This 

may include considering which has greater flow, which has higher temperatures, 

or which has higher TOC and therefore a greater potential for DBP formation. 

Stage 2 DBPR Implementation Guidance 98 August 2007 
If EPA or the state has concerns about the peak historical month selected, they should contact the system 

for more information. 

Monitoring Schedule 

EPA or the state should check the projected monitoring schedule and confirm that monitoring is planned: 

•

•

At least at the frequency required by the rule, and 

That there is one round of sampling during the peak historical month. 

EPA or the state should check the projected monitoring schedule and confirm that monitoring is planned 

at least at the minimum frequency required by the rule (e.g., once a year, every 60 days, every 90 days, as 

specified in Table 3-13) and that one sampling period is during the peak historical month. Note that a 

system does not have to sample at exactly the frequency specified for the system. Sampling within the 

same week during each required month is sufficient. For example, a system on quarterly monitoring could 

sample in the third week of every third month. Holidays and sampling schedules for other water quality 

programs should be considered when developing a standard monitoring schedule. 

If EPA or the state has concerns about the monitoring schedule submitted, they should contact the system 

for more information. 

Site Selection 

The most important component of the plan review is to ensure that standard monitoring sites meet the 

intent of the Stage 2 DBPR: to find locations that are most representative of high TTHM and HAA5 

concentrations throughout the distribution system for Stage 2 DBPR compliance monitoring. EPA or the 

state should focus on whether the system considered all key information in its determinations and that 

data are not missing or misinterpreted. EPA or the state may ask the system to modify the plan in any way 

they find appropriate to ensure that standard monitoring meets this goal. 

Systems are required to include a summary of data they considered while selecting their standard 

monitoring locations. This should include a discussion of their sources, types of data that are available, 

ranges and averages of disinfectant residual concentrations, and a general discussion of distribution 

system operations. This summary will serve as a basis for the review, giving EPA and states an overview 

of what information is available to the system so they can determine whether the selected standard 

monitoring sites adequately represent areas of the distribution system likely to have high TTHM and 

HAA5 concentrations. 

EPA or the state should use whatever resources are available to review site selection for each system. The 

more familiar they are with the system, the more knowledgeable they will be in their review of the most 

appropriate sites the system should have selected. EPA or the state should use distribution system 

schematic in conjunction with the written justifications and summarized data to determine if the system's 

justifications are consistent with the geographic locations of sites. EPA’s IDSE Guidance Manual

includes extensive discussion of how systems can use available data to select their standard monitoring 

sites. 

Stage 2 DBPR Implementation Guidance 99 August 2007 
Use of Distribution System Map to Evaluate System Representation: Distribution system maps are 

essential when making site selection decisions. Maps can help systems identify the conditions described 

below: 

•

•

•

•

Pipe Dead Ends – Dead ends may occur in areas of stagnation and long water residence time. 

Pipe of large diameter may have low flows, and this may result in water with long residence 

times. Certain types of pipe or older pipe may allow biofilm build-up. Because biofilm degrades 

HAA5, pipes with biofilm build-up may have water with lower levels of HAA5. 

Water Use – Lightly developed areas may have low flows and therefore longer water residence 

times. In turn, highly developed areas may have high flows and be less likely to have high 

residence times and levels of DBPs. Areas where there is a major user also may have low 

residence time. 

Entry points and sources – Entry point locations may be sites of highest residual and lowest 

residence time. These sites are good points of reference. 

Key components – Storage tanks, pump stations, and booster chlorination stations all have 

substantial impact on residence time and DBP formation. 

EPA or the state should use the system’s map to ensure that the sites selected represent the entire 

distribution system. The system should have chosen as many priority sites as possible, depending on how 

many priority areas exist and how many sites are required. The sites should provide good geographic and 

hydraulic representation. If a system does not choose sites with good geographic coverage, they must 

provide adequate justification (e.g., the system has multiple plants with a wide variation in DBP levels). 

Most key sites in the distribution system should also be represented in the system’s Standard Monitoring 

Plan. If not, EPA or the state should consider whether there is a way to redistribute the sites to include the 

most important ones. 

If it is hard to tell on the schematic, EPA or the state should check to see if these factors are mentioned in 

the justifications. 

Water Quality Data: Water quality data will usually play a key role in determining the best standard 

monitoring sites. Note that distribution system data are only helpful if it is representative of the current 

operating conditions and system configuration. If any substantial changes have been made to the 

treatment processes (particularly the disinfection processes), distribution system operation, or physical 

layout of the distribution system, the data may no longer reflect water quality in the distribution system. 

•

•

Source Water – If the system has multiple sources, the sources may have varying levels of 

precursors, and therefore may produce finished water with higher DBPs or DBP potential. Areas 

in the distribution system that are fed primarily by sources with higher DBPs may be better sites 

for high TTHM or HAA5. 

Stage 1 DBPR Data and Other DBP Data – Existing Stage 1 DBPR monitoring data and other 

operational data will be helpful in locating areas with high TTHM or HAA5 concentrations. 

Remember that systems cannot use Stage 1 DBPR sites themselves as any of their standard 

monitoring sites. Historic data should be evaluated taking data on raw water quality at the time of 

monitoring (if available) into account. For example, samples collected during a period of 

particularly poor source water quality may have shown higher than normal DBP levels in the 

distribution system. 

Stage 2 DBPR Implementation Guidance 100 August 2007 
•

•

Disinfectant Residual Data – As water ages, disinfectants will be consumed and residual levels 

will drop. For this reason, low disinfectant residual can often (but not always) be considered an 

indication of advanced residence time. When using residuals to estimate water age, systems 

should look at the drop in residuals rather than the levels themselves. 

– Keep in mind that other factors, such as pipe age, condition, material, and lining and the 

presence of biofilm or sediment, can influence decay of disinfectant (resulting in low residual 

levels) but not lead to high DBP levels. 

– If a system uses booster chlorination, disinfectant residual levels will be elevated in areas 

affected by the booster chlorination. Booster chlorination is typically used in areas where the 

system has a difficult time maintaining a residual which is where water residence times are 

often high, so despite high residual levels, the residence time is high. 

– Sources of residual data include compliance monitoring data (SWTR residual monitoring data 

or Stage 1 DBPR chlorine, chloramines, and/or chlorine dioxide monitoring data), operational 

sample data, or data from special samples taken in response to customer complaints. 

HPC Data – A system may have collected HPC data instead of or in addition to disinfection 

residual levels or for other operational purposes. Elevated HPC levels may be indicative of 

biofilm. Because HAA biodegrades, areas in the distribution system that have no residual and/or 

elevated HPC may be areas where HAA levels have decreased. 

Distribution System Operating Data: Distribution system operating data can reflect water flow patterns 

through the distribution system, which is essential in understanding residence time and DBP formation 

potential. 

•

•

Water flows – Pump run times, information on metered flows between pressure zones, and billing 

records for major users can all provide insight into water flow patterns. Pump run times can help 

systems understand when, where, how often, and how much new water enters the distribution 

system. This information, in turn, can help systems understand where and when water has the 

longest residence times. 

– Records of flows between pressure zones can help characterize water movement and 

increased or decreased residence time. 

– Analyzing the billing records for major users can indicate where there are high flows. High 

flows will result in decreased residence time. As a consequence, areas of a distribution 

system with a major water user may not be as likely to have high DBPs as other areas of the 

distribution system. If a system’s distribution system is metered, the system can use meter 

records to track water usage. 

– If the system has access to hydraulic modeling or tracer studies, these tools will be excellent 

sources for determining average and max residence time. 

Tank level records and tank configuration – Tank operation and configuration can have a 

significant impact on residence time. In general, tanks increase residence time for water and can 

increase DBP formation. During tank fill times, the water in the vicinity of the tank will likely be 

newer. During draw times, the water downstream of the tank will likely be older. Note, however, 

that the impact of tanks on DBP formation can be complicated by individual tank configuration 

and mixing characteristics. Many tanks have a common inlet and outlet (this practice is called 

Stage 2 DBPR Implementation Guidance 101 August 2007 
“floating on the system”). This configuration sometimes results in the newest water leaving the 

tank first; older water is only drawn out during periods of highest demand. This configuration 

also prevents water mixing in the tank. During times of very high usage, areas directly 

downstream of a tank with a common inlet and outlet may be receiving very old water. 

• Booster chlorination – Booster chlorination is typically used in areas where the system has a 

difficult time maintaining a residual. This is also often where water residence times are high. In 

addition, when the disinfectant residual is increased, if precursors are still available, DBP 

formation will be increased. 

Review Individual Site Selection for the Four Types of Sites 

EPA or the state should ensure that systems have an understanding of what factors affect DBP formation 

to enable them to select sites that best represent near entry point, average residence time, high TTHM, and 

high HAA5 sites. 

•

•

•

•

•

•

Precursor concentration – The concentration of organic matter in the source water and the 

effectiveness of removal through the treatment processes will be factors in DBP formation. If a 

system has multiple sources, the sources/plants that have higher levels of precursors can be 

expected to have higher DBPs. Areas in the distribution system served primarily by these sources 

may therefore have higher DBPs. 

Disinfectant type and concentration – The disinfectant type has a dramatic impact on DBP 

formation. Free chlorine is found to form DBPs most readily. The use of chloramines results in 

very low DBP formation. When using ozone, bromate can be found as a DBP, and systems that 

use chlorine dioxide can have chlorite formation. Obviously the higher the dose, the more 

disinfectant is available for reaction with precursors. 

Water chemistry – Water temperature, pH, and alkalinity all impact DBP formation at the plant 

and in the distribution system. In general, TTHM formation increases with increasing pH. HAA5s 

are more readily formed at lower pH levels. 

Water temperature – Higher temperatures typically speed up chemical reactions and can 

accommodate faster DBP formation. In general (but not always), the concentration of organic 

matter in water increases during the warmest months of the year and is higher in warmer climates. 

In addition, because organic matter reacts with (consumes) chlorine and other chemical 

disinfectants, more organic matter in the water can result in a higher chlorine demand to achieve 

contact time (CT) and maintain a reliable residual throughout the distribution system. The 

combination of a larger chlorine dose, faster chemical reactions, and higher concentrations of 

organic matter, often result in higher TTHM and HAA5 concentrations during the warmest 

months of the year. 

Residence Time – All chemical reactions take time. In general, the more time precursors have in 

contact with the disinfectant, the more DBPs will be formed. This is particularly true of TTHM 

concentrations which are generally highest in water that has resided in the distribution system the 

longest. This is not necessarily true of HAA5 that are found to form and then degrade. 

Biodegradation – HAA5 formation and decomposition seems to follow a pattern that is different 

from that of TTHM in the distribution system. While TTHM concentrations are generally highest 

at the points in the system with the longest residence times, research suggests that HAA5 seem to 

form and then decompose due to “biodegradation.” Where biological activity is prevalent in the 

Stage 2 DBPR Implementation Guidance 102 August 2007 
distribution system (pipe with biofilm, areas with no disinfectant residual or high HPC), HAA5 

levels may not be at their highest despite advanced residence time. 

A number of factors may require professional judgment, including: 

•

•

•

•

•

•

•

•

Geographic representation – Sites should represent the entire distribution system. If a system is 

deciding between two monitoring sites, it may be appropriate to select the site that improves 

coverage of the entire distribution system (e.g., a site in a remote area of the distribution system). 

Keep in mind that systems will continue to sample under Stage 1 DBPR, so these high sites are 

already represented. 

Hydraulic representation – Systems should attempt to include sites that represent all pressure 

zones. In some situations, sites close to each other may represent different hydraulic zones. 

Multiple sources – If a system has multiple sources, they will want to consider the DBP formation 

potential of the sources and may want to select more sites in areas fed by sources with higher 

precursors and higher DBP formation potential. 

Multi-task sites – In some cases, one site may represent several potential causes for DBP 

formation. For example, a site located at the edge of the distribution system, downstream of a 

tank, and with low residual levels may cover three potential causes for DBP formation. 

Accessibility – Monitoring sites must be accessible throughout the year. Public buildings and 

TCR sampling sites are examples of sites that are accessible year-round. 

Near Entry Point Standard Monitoring Sites

When reviewing near entry point sites, EPA or the state should consider the following items: 

Location – The location of the near entry point site is important. The Stage 2 DBPR does not 

define near entry point sites explicitly, but they should be located between the entrance to the 

distribution system and the first customer, but no later than the first customer. 

More entry points than near entry point locations – If the system has more entry points than 

required near entry point locations, EPA or the state should verify if the system selected entry 

points with the highest annual water flow. 

Fewer entry points than near entry point locations – If the system has fewer entry points than 

required near entry point sites, EPA or the state should make sure that the system replaced the 

remaining samples with locations of high TTHM and HAA5 concentrations, alternating between 

locations of high TTHM concentrations and locations of high HAA5 concentrations. 

– In cases where there is an odd extra location, the system must sample at a location of high 

TTHM concentration. For example, if the system needs three additional samples, it must take 

two samples at locations of high TTHM concentration and one sample at a location of high 

HAA5 concentration. 

– Although the distribution of site types may be different than listed in Table 3-13, the total 

number of sites must be the same. 

Stage 2 DBPR Implementation Guidance 103 August 2007 
Average Residence Time Standard Monitoring Sites: Average residence time is the average age of water 

delivered to the majority of customers in a distribution system. In most distribution systems, average 

residence time is not simply one-half the maximum residence time. Ideally, it should be a flow-weighted 

or population-weighted analysis. EPA recognizes that determining this value is very complex. Systems 

should rely heavily on professional judgment and many will need to use a rough estimate of average 

residence time. 

Estimating average residence time requires a thorough understanding of the distribution system. A system 

map, used in conjunction with hydraulic modeling (if available), system operating data and disinfectant 

residual data can help systems to identify areas that are representative of average residence time. 

•

•

•

One of the best ways to calculate average residence time is by using a hydraulic model. A 

hydraulic model can take into account water flows and water use patterns. 

If modeling or tracer studies are not an option, the system may want to consider analyzing water 

flows using pump run data and metering information. 

Systems can also use disinfectant residual as a surrogate for residence time. The theory is based 

on the assumption that sites with average residual may be representative of average residence 

time. 

– When calculating average disinfectant residual, it is important to consider data from sites that 

are representative of the entire distribution system. One way to do this is to examine data 

collected at TCR monitoring sites (the TCR requires that all monitoring sites combined 

represent the distribution system). Using averages from individual monitoring sites, systems 

can calculate an overall distribution system average residual concentration. Individual sites 

with an average residual close to the distribution system average can be considered 

representative of average residence time in the distribution system. 

– As discussed earlier, if this option is used, the system has to be aware that some factors other 

than residence time can result in an increased or decreased residual. Residual data collected 

after booster chlorination should be omitted unless the system can estimate what the residual 

would be without the added disinfectant. Residual data collected in areas of the distribution 

system that are known to have biofilm growth or other factors that consume residual should 

also be omitted. 

Appropriate justification for average residence time sites differs for systems of different complexity and 

size. For small systems with straightforward distribution system layouts (e.g., simple branched layout or a 

small looped system) and few large customers, the average residence time site should be generally in the 

geographic center of the distribution system. 

Systems with multiple sources and multiple pressure zones face a greater challenge in locating sites with 

average residence time. Systems with complex distribution systems should have evaluated disinfectant 

residual data or used a hydraulic model or tracer study to select average residence time sites. EPA or the 

state should verify that the system located average residence time sites in each pressure zone and/or in the 

area influenced by each source if possible. 

High TTHM Standard Monitoring Sites: TTHM formation is strongly influenced by residence time. In 

addition, TTHM formation generally increases with increasing pH. TTHM sites should not be located at 

dead ends with no users. The sampling should be representative of water that is being consumed, not 

stagnant water. EPA or the state should verify that sites selected near dead ends are located before the last 

Stage 2 DBPR Implementation Guidance 104 August 2007 
customer or group of customers, not at the very end of the dead end line. In addition, sites should be 

upstream of booster chlorination and after the last hydrant or blowoff. 

Because TTHM formation is strongly related to water age, EPA or the state should verify that the system 

has chosen high TTHM sites that are expected to have long residence times. Excellent sites for high 

TTHM include: 

•

•

•

•

•

•

•

•

Tanks – down-gradient of storage facilities, which have increased residence time. 

Low flows – sparsely populated areas with low flows. 

Geographic dead ends – areas that are physically located at the end of a water main or group of 

water mains without looping back to the main portion of the distribution system. However, do not 

sample stagnant water after the last customer. The purpose is to sample water that customers are 

consuming. 

Hydraulic dead ends and mixing zones – areas in which there is little movement of water. 

After booster chlorination – where formation will have increased due to more available 

disinfectant. 

Low or no residual (i.e., relative to initial disinfectant levels) – likely advanced residence time. 

Low water use in general – lightly developed areas where water is allowed to age. 

Areas with high historic TTHM levels – systems cannot use Stage 1 DBPR sites for standard 

monitoring. Systems should be collecting new data, so they should locate sites where they are not 

already sampling. 

High HAA5 Sites: Different systems may find high HAA5 sites in locations with different characteristics. 

HAA5 formation and decomposition seems to follow a pattern that is different from that of TTHM in the 

distribution system. While TTHM concentrations are generally highest at the points in the system with the 

longest residence times, research suggests that HAA5 seem to form and then decompose. The 

consumption of HAA5 by microorganisms is known as biodegradation, which is more likely to occur 

when disinfectant residual levels are low or non-existent, particularly in warmer months. Therefore, a 

high HAA5 site will not necessarily be the site with the longest residence time, and may even be at a site 

with shorter residence time. Systems should have started by examining their existing Stage 1 DBPR data 

to determine which areas tend to have higher HAA5 concentrations. 

EPA or the state should verify that the system considered the more complex nature of HAA5 formation 

and degradation. They should have chosen sites where DBPs are expected to be high, but should 

differentiate between those sites expected to have high HAA5 versus those with high TTHM. 

Biofilm degrades HAA, so pipes with biofilm build-up may have water with low levels of HAA. Areas of 

known biofilm growth should be avoided when choosing high HAA5 sites, although these sites may still 

be considered for high TTHM. HPC data may indicate where areas with biofilm build-up are located. 

Areas with difficulty maintaining a disinfectant residual (< 0.2 mg/L chlorine or < 0.5 mg/L chloramines) 

should also be avoided. 

Sites should target areas with a low but detectable residual. This will indicate high residence time but a 

low likelihood of biodegradation. Good sites for HAA5 include: 

Stage 2 DBPR Implementation Guidance 105 August 2007 
•

•

•

•

After booster chlorination – where formation will have increased due to more available 

disinfectant and where any biodegradation will be halted. 

Low but detectable residual (i.e., relative to initial levels) – likely advanced residence time but 

not sites likely to have biofilm. 

Areas with high historic HAA5 levels – however, keep in mind that the system cannot use Stage 1 

DBPR sites for standard monitoring. The idea is to get more data, so systems want to locate sites 

where they are not already sampling. 

Other sites include: 

– Tanks – increased residence time. 

– Dead ends – low flows. However, do not sample stagnant water after the last customer. The 

purpose is to sample water that customers are consuming. 

– Hydraulic dead ends and hydraulic mixing zones. 

– Low water use in general – lightly developed areas where water is allowed to age. 

Remember that high HAA5 sites must be independent of the high TTHM sites. Make sure the system did 

not count any sites as both high TTHM and high HAA5 sites and that the total number of required sites 

are selected. 

Review Justifications for Adequacy 

For high TTHM, high HAA5, and average residence time sites, EPA or the state will need to read the 

justifications and determine if they are adequate. The purpose of the justification is to explain to the 

reviewer why the site was selected. The information provided should convince the reviewer that the 

system considered all available data, understood their data analysis, and selected the most appropriate site 

given the information available. Examples of adequate and poor justification are provided in Example 3-

3. 

Stage 2 DBPR Implementation Guidance 106 August 2007 
Example 3-3. Examples of Justification 

Examples of Adequate Justifications 

High TTHM site: Site #4 is at the extreme end of the distribution system, down gradient of a tank with a low turnover rate. It is in a residential area with primarily 6-inch pipes and with chlorine residual ranging from 1.0 to 1.2 in 

the summer. 

High HAA5 site: Site #6 is an area that has relatively high water age, but because it is down gradient of booster 

chlorination we do not anticipate biodegradation. Chlorine residuals are high at this site (approx 1.5 mg/L year 

round). It is on a 12-inch water main. 

Examples of Poor Justifications 

“Site #1 is a high TTHM site.” 

In this example, there is insufficient justification provided regarding why Site #1 is a high TTHM site. 

“Site #3 is a high HAA5 site. Stage 1 DBPR site A has had high HAA5’s, so we located standard monitoring site #3 

right next to it.” 

This justification works against the need for geographic representation of sampling sites because the system is 

proposing two sites next to each other. 

More examples are available in EPA’s IDSE Guidance Manual. 

Modifying and Approving a Standard Monitoring Plan 

EPA or the state has 12 months after the submission deadline to complete the review of Standard 

Monitoring Plans. 

All correspondence between the system and the reviewer should be included in the 12-month period and 

does not extend the ultimate approval deadline, unless the reviewer notifies the system that the plan is still 

under review. If EPA or the state has any concerns about a plan during the review, they can contact the 

system to ask for additional information or request modifications. When the system has not included 

enough information or when reviewing more complex systems, EPA or the state should discuss changes 

with the system. If EPA or the state determines, based on the new information, that the sites are 

appropriate, the additional information can be included in the Standard Monitoring Plan and the review 

completed. However, if the system is unable to provide adequate justification, EPA or the state should 

work with the system to select alternative sites. 

EPA or the state should notify the system in writing when its plan is approved. After the review is 

completed and the plan has been approved, EPA or the state should send a copy to the system for its 

records. If changes were made after the original submission, EPA or the state should send a copy of the 

approved plan to the system for its records. If EPA is reviewing plans all correspondence and 

recordkeeping will be through the IPMC. 

If the review is not completed within the 12-month period, EPA or the state must contact the system to let 

them know that the review requires additional time. All correspondence between the system and the 

reviewer is included in this 12-month period and does not extend the ultimate approval deadline. 

Stage 2 DBPR Implementation Guidance 107 August 2007 
If EPA or the state does not approve the system’s plan within 12 months of the required submission date 

or notify the system that their review is not complete, the system can consider the plan approved and 

conduct standard monitoring as proposed in the plan. 

States should be aware that approving the plan within 12 months is critical for enabling systems to meet 

their compliance deadlines. If EPA or a state is unable to approve the plan within this timeframe, they will 

need to provide the system with an alternate schedule for their standard monitoring (i.e., new sampling 

dates) and their IDSE Report. 

3.11.2 IDSE Reports for Standard Monitoring 

All systems that conduct standard monitoring must submit an IDSE Report [§141.601(c)] to the state. The 

primary purpose of the IDSE Report is to provide EPA or the state with the system’s recommendations 

for where and at what frequency Stage 2 DBPR compliance monitoring will be conducted. In addition, the 

system must provide justification for these selections. When completing the IDSE Report, systems have 

the option of using the IDSE Report for Standard Monitoring Form (Form 5) in Appendix E. 

EPA or the state may approve or modify the sites chosen by the system. The number and frequency of 

samples must comply with those presented in Table 3-17. Systems must follow the site selection protocol 

in this subsection unless they provide EPA or the state with adequate justification for alternate sites. 

EPA or the state has a limited amount of time after the submission deadline to request modifications or 

approve the IDSE Report or contact the system to let them know that the review is not complete. The 

EPA or state deadlines for IDSE Reports approval, modification or notification are listed in Table 3-1. 

The deadlines are within 3 months of the submission deadline for systems on Schedules 1, 2 and 4, and 

within 9 months of the submission deadline for systems on Schedule 3. Note that this is 3 or 9 months 

from the submission deadline, not the actual date of submission. If the system does not receive approval 

or modification of the report, or notification that EPA or the state has not completed their review within 

that 3- or 9-month period, the system may consider the report approved as submitted and use the Stage 2 

DBPR compliance monitoring sites recommended in the report. 

If EPA or the state needs additional time for the review, they can contact the system within the 3 or 9 

month period and let them know that the review requires additional time. 

3.11.2.1 Review of Required Elements for Standard Monitoring IDSE Report 

The basic elements required for the IDSE Report are listed in the checklist in Table 3-14. 

Table 3-14. IDSE Report for Standard Monitoring, Required Elements Checklist 

Check if 

Provided 

Required Element Section in Form 7 

;

 Explanation of any 

Plan 

deviations from approved Standard Monitoring III & VII 

 TTHM and HAA5 analytical results from 

and IDSE standard monitoring 

Stage 1 DBPR monitoring III 

 Recommendations and justification of Stage 

monitoring sites 

2 DBPR compliance IV 

Stage 2 DBPR Implementation Guidance 108 August 2007 
Stage 2 DBPR Implementation Guidance 109 August 2007 

Check if 

Provided 

;

Required Element Section in Form 7 

 Proposed Stage 2 DBPR Compliance Monitoring Schedule V.C 

If changed from the approved Standard Monitoring Plan: 

 • Distribution system schematic VI 

 • Population served by the system I.A 

 • Source water type (Subpart H or ground water) I.A 

If some of the required elements on the checklist in Table 3-14 are missing, EPA or the state should 

contact the system to request the missing information. If all boxes are checked, all required elements have 

been submitted. 

3.11.2.2 Technical Review of Standard Monitoring IDSE Report 

The purpose of the technical review of the IDSE Report is to ensure that: 

• The system’s recommended Stage 2 DBPR compliance monitoring locations are in accordance 

with the protocol set in §141.605, or 

• That the system provided adequate justification for alternative locations, and 

• That the system has chosen appropriate dates on which to sample for Stage 2 DBPR compliance. 

In addition, EPA or the state should check the IDSE Report against the Standard Monitoring Plan to 

ensure that the system conducted standard monitoring in accordance with the approved plan. If the system 

deviated from the plan, it should have explained why changes were made. If no explanation was provided 

or if the justification for changes is not adequate, EPA or the state may want to contact the system for 

more information. 

Site Selection for Compliance Monitoring 

Systems must use the protocol in Table 3-15 to select their Stage 2 DBPR compliance monitoring sites 

using a combination of their Stage 1 DBPR data and data collected for the IDSE. If a system is required to 

select more than eight sampling sites it must return to the top of the protocol, each time selecting from 

those sites that have not already been identified for Stage 2 DBPR monitoring until the required number 

of sites has been selected. Examples of Stage 2 DBPR site selection using the protocol can be found in 

EPA’s IDSE Guidance Manual. 

If a system arrives at Step 3 or Step 7 and has no more Stage 1 DBPR sites to select from, the system 

should skip these steps and continue with the protocol as necessary, until it has identified the required 

total number of monitoring locations. This may happen if the Stage 1 DBPR sites have the highest TTHM 

or HAA5 LRAAs and were previously selected, if the system is a consecutive system and had little or no 

Stage 1 DBPR data, or if the system is very large but has few treatment plants. When this occurs, the 

correct total number of sites will be selected, but the distribution between TTHM, HAA5 and Stage 1 

DBPR sites will be different than shown in Table 3-17. 
Table 3-15. Protocol for Selecting Stage 2 DBPR Compliance Monitoring Sites 

Steps1

[required by rule] 

Stage 2 Compliance Monitoring Sites 

Selected 2 

1 Select the location with the highest TTHM LRAA 1st highest TTHM site 

2 Select the remaining location with the highest HAA5 LRAA 1st highest HAA5 site 

3 For Subpart H systems: Select the remaining existing Stage 1 

DBPR average residence time compliance monitoring location 

with the highest HAA5 LRAA 

For ground water systems: Select the remaining existing Stage 1 

DBPR maximum residence time compliance monitoring 

location with the highest HAA5 LRAA 

Skip this step if you have no more Stage 1 DBPR sites

1st Stage 1 DBPR site 

4 Select the remaining location with the next highest TTHM 

LRAA. 

2nd highest TTHM site 

5 Select the remaining location with the next highest TTHM 

LRAA 

3rd highest TTHM site 

6 Select the remaining location with the next highest HAA5 

LRAA 

2nd highest HAA5 site 

7 For Subpart H systems: Select the remaining existing Stage 1 

DBPR average residence time compliance monitoring location 

with the highest TTHM LRAA 

For ground water systems: Select the remaining existing Stage 1 

DBPR maximum residence time compliance monitoring 

location with the highest TTHM LRAA

Skip this step if you have no more Stage 1 DBPR

2nd Stage 1 DBPR site 

8 Select the remaining location with the next highest HAA5 

LRAA 

3rd highest HAA5 site 

If you need more Stage 2 DBPR compliance monitoring locations, Go back to Step 1 of this protocol and repeat 

the steps until you have selected the required number of total sites. 

1. All steps are based on calculated LRAAs for standard monitoring sites and Stage 1 DBPR compliance monitoring 

sites. This means that existing Stage 1 DBPR sites can be selected in steps other than 3 or 7. Systems will stop when 

they reach the required number of Stage 2 DBPR compliance monitoring sites. 

2. Systems cannot select the same site as a highest TTHM and a highest HAA5 compliance monitoring site. 

EPA or the state should review the IDSE Report to assure that the system followed the site selection 

protocol correctly. EPA or the state should check that the system used the correct type of Stage 1 DBPR 

site in Step 3 and Step 7, depending on the system’s source type. If EPA or the state has concerns that the 

protocol was not properly followed, they should contact the system for more information. 

Although the site selection protocol is designed to select Stage 2 DBPR compliance monitoring sites 

based on the highest LRAA, EPA recognizes that a slight difference between LRAAs measured at two 

sites may not be meaningful given the normal variability that may occur at a site over time. As a result, 

the selection of a Stage 2 DBPR compliance monitoring site with a slightly lower LRAA may be 

acceptable if other factors, such as those listed below, favor the site with the lower LRAA. It will be 

Stage 2 DBPR Implementation Guidance 110 August 2007 
important for EPA or the state to consider the system’s justifications (see Example 3-4) to determine 

whether the goal of choosing representative high TTHM and HAA5 sites has been met. 

• The system may want to choose an alternate site to provide for more complete geographic 

coverage of the entire distribution system. 

• The system may want to choose a site at which it has been sampling for the Stage 1 DBPR over 

another site in order to maintain a historical record. 

• Sampling at a particular site may provide the system with the opportunity to collect other water 

quality or operational data (e.g., systems using chloramines may want to collect nitrate data at 

that site). 

Example 3-4. Example Rationale for Site Selection Outside of Protocol 

Standard monitoring site #3 has the next highest TTHM LRAA at 0.043 mg/l. This site would be 

selected next based on the protocol, however, Stage 1 DBPR site #1 is in the same vicinity of the 

distribution system and the TTHM LRAA at this site is 0.041 mg/l which is only slightly lower. We 

have chosen to use Stage 1 DBPR Site #1 as the next Stage 2 DBPR site as we feel that it would be 

useful to maintain a historical record at this site. 

Sampling schedule 

As with the standard monitoring and SSS Plans, the IDSE Report will require systems to determine a 

“peak historical month” and then to set the remainder of the sampling months at regular frequencies from 

that month. Systems should use the same peak historical month determined in their Standard Monitoring 

Plan, unless new data indicate a different month is more appropriate. EPA or the state can evaluate the 

peak historical month using the criteria in section 3.11.1.4 and any new data collected during the IDSE. 

EPA or the state should check the projected monitoring dates and confirm that monitoring is planned at 

least at the minimum frequency required by the rule (shown in Table 3-17). Note that a system does not 

have to sample at exactly the frequency specified for the system. Sampling within the same week during 

each required month is sufficient. For example, a system on quarterly monitoring could sample in the 

third week of every third month. Likewise, systems do not have to sample all locations on the same day, 

and can spread sampling out so long as they meet schedule requirements. 

3.12 Stage 2 DBPR Compliance Monitoring Plan 

All systems subject to Stage 2 DBPR must develop a Stage 2 DBPR Compliance Monitoring Plan 

[§141.622]. This plan is similar to the Stage 1 DBPR monitoring plan in that it will identify how systems 

intend to sample for compliance with the Stage 2 DBPR. Systems must prepare a plan prior to the date 

they are required to begin their Stage 2 DBPR compliance monitoring and must keep their plan on file for 

state and public review. In addition, by that same date, Subpart H system serving more than 3,300 people 

must submit their monitoring plan to EPA or the state. 

Stage 2 DBPR Implementation Guidance 111 August 2007 
The Compliance Monitoring Plan must include the following information: 

• Monitoring locations. 

• Monitoring dates. 

• Compliance calculation procedures. 

3.12.1 Systems that Submitted an IDSE Report 

Systems that conducted standard monitoring or an SSS must have included the first two items, their 

monitoring locations and monitoring dates, in their IDSE Report. If these systems also included their 

compliance calculation procedures in their IDSE Report, then their IDSE Report can serve as their 

Compliance Monitoring Plan, and they will not need to submit a separate plan. 

However, if a system that conducted standard monitoring or an SSS did not include all the information 

required for Compliance Monitoring Plan in their IDSE Report, they are required to prepare a Compliance 

Monitoring Plan. The Compliance Monitoring Plan must reflect recommendations of the IDSE Report 

and any state-mandated changes to the IDSE Report. 

3.12.2 Systems that Did Not Submit an IDSE Report 

Some systems subject to the Stage 2 DBPR are not required to submit an IDSE Report, and therefore they 

must prepare a Compliance Monitoring Plan. These systems are: 

• Systems that qualified for a VSS Waiver. 

• Systems that received a 40/30 Certification. 

• Nontransient noncommunity systems serving fewer than 10,000 people. 

In their Compliance Monitoring Plan, these systems must select their Stage 2 DBPR monitoring locations 

and dates and must discuss the compliance calculation procedures in their plan. Some of these systems 

can comply by updating their Stage 1 DBPR monitoring plan (i.e., identify additional locations for 

compliance monitoring by alternating locations with high TTHM and HAA5 levels until the required 

number of locations has been identified), which was developed under §141.132(f). 

If a system has more Stage 1 DBPR sites than the number required for Stage 2 DBPR compliance 

monitoring, they must select sites by alternating between locations representing high TTHM and high 

HAA5 levels until the required number of Stage 2 DBPR compliance monitoring locations have been 

identified. 

If a system has fewer Stage 1 DBPR sites than the number required by the Stage 2 DBPR, the system 

must begin by using the existing Stage 1 DBPR sites. They then must select additional locations by 

identifying sites in the distribution system with anticipated high DBP levels, alternating selection of 

locations representing high TTHM levels and high HAA5 levels, starting with high TTHM. The system 

must include the rationale for identifying locations as having high levels of TTHM or HAA5 in their plan. 

This process will be similar to the process used in selecting standard monitoring sites. The state may want 

to refer to section 3.11.2.2 for guidance on reviewing monitoring plans when the system had to identify 

additional sites. 

Stage 2 DBPR Implementation Guidance 112 August 2007 
3.12.3 Combined Distribution Systems the State has Decided to Treat as One System 

 

The state may modify the Stage 2 DBPR compliance monitoring requirements by treating the systems in a 

combined distribution system as a single system to the extent that the interconnection of the systems 

justifies such modifications [§141.29]. This option is discussed in more detail in section 3.18. 

3.12.4 Changes to a Monitoring Plan 

If a system makes any changes in treatment, distribution system operations and layout, or other factors 

that may affect TTHM or HAA5 formation, these changes may warrant a modification to their monitoring 

locations. In this case the system must revise their Compliance Monitoring Plan. The system must consult 

with the state regarding the need for the changes and the most appropriate modifications. The revised sites 

must replace existing compliance monitoring locations with expected high TTHM or HAA5 levels. 

Modifications to the Compliance Monitoring Plan may be initiated by the system, or the state may require 

the modifications. If the state becomes aware of major system changes (in the process of review of plans 

and specifications or during technical assistance, sanitary survey, or other system site visit), the state 

should consider if these system changes have a likelihood of affecting relative DBP levels in the 

distribution system. 

System changes that may warrant modifications to a systems’ monitoring plan may include: 

• Adding or removing a source. 

• Adding or removing a booster chlorination site 

• Adding or removing a storage tank. 

• Adding a new service area. 

• Changes to the primary or residual disinfectant site or type (but only if the change is expected to 

impact relative DBP levels in the distribution system). 

3.12.5 Reporting and Recordkeeping Requirements for Compliance Monitoring Plan 

All systems must keep their Stage 2 DBPR Compliance Monitoring Plan (or their IDSE Report if it serves 

as their monitoring plan) on file for state and public review. 

Subpart H systems serving more than 3,300 people are also required to submit copies of their monitoring 

plan or any modified monitoring plan to the state before they begin compliance monitoring. 

3.13 Stage 2 DBPR Compliance Monitoring Deadlines 

Table 3-16 summarizes the deadlines for Stage 2 DBPR for TTHM and HAA5 compliance monitoring 

[§141.620(c)]. Systems required to conduct quarterly monitoring must begin monitoring in the first full 

calendar quarter that includes the compliance deadline. If the system is required to conduct monitoring at 

a frequency that is less than quarterly, it must begin monitoring in the calendar month recommended in 

the IDSE Report, or in the monitoring plan if the IDSE Report does not specify a month. Monitoring must 

begin no later than 12 months after the compliance date in Table 3-16. 

Stage 2 DBPR Implementation Guidance 113 August 2007 
Since compliance monitoring deadlines for each schedule are more than 3 years after the system 

submitted their IDSE Report, states may want to consider sending reminders to systems in the quarter 

prior to the compliance deadline. These reminders could reiterate that the system will be switching from 

their Stage 1 DBPR monitoring locations and dates to the new Stage 2 DBPR locations and dates, and that 

compliance will then be based on the LRAA rather than the RAA. 

Table 3-16. Compliance Schedule for Stage 2 DBPR TTHM and HAA5 Monitoring 

Requirement Compliance dates by PWS size (retail populations served)1

CWSs and 

NTNCWSs 

serving at least 

100,000 

CWSs and 

NTNCWSs 

serving 50,000-

99,999 

CWSs and 

NTNCWSs 

serving 10,000-

49,999 

CWSs serving 

<10,000 

NTNCWSs 

serving <10,000 

Begin Stage 2 

DBPR 

Compliance 

Monitoring2

April 1, 2012 October 1, 2012 October 1, 2013 October 1, 2013 

(October 1, 2014 

if Cryptosporidium

monitoring is 

required under 

Subpart W.) 

October 1, 2013 

(October 1, 2014 

if Cryptosporidium

monitoring is 

required under 

Subpart W.) 

1. Wholesale and consecutive systems that are part of a combined distribution system must comply based on the 

schedule required of the largest system in the combined distribution system. 

2. States may grant up to 2 years for systems making capital improvements. See Appendix I for guidance on 

reviewing extension requests under Section 1412(b)(10) of the SDWA.

3.13.1 System Requests for Compliance Schedule Extensions 

Under Section 1412(b)(10) of the SDWA, the state may grant up to a 2-year extension on a system-bysystem basis for systems requiring capital improvements to meet Stage 2 DBPR. Beginning April 1, 2006, 

systems must comply with the Stage 2 DBPR LRAA MCLs for TTHM and HAA5 within 6 to 8.5 years 

but, with a 2-year extension, could have 8 to 10.5 years to comply. 

States should consider requiring the system to enter into an extension agreement, with construction 

milestones and interim activities that the system will undertake to protect public health during this 

extension period. States may wish to develop information and procedures on the specific content of the 

extension request and consider developing and providing forms or templates for the system’s use. See 

Appendix I for guidance on reviewing extension requests under Section 1412(b)(10) of the SDWA. 

3.14 Stage 2 DBPR Routine Monitoring 

3.14.1 TTHM and HAA5 

Table 3-17 shows the Stage 2 DBPR routine compliance monitoring requirements for TTHM and HAA5 

[§141.621]. 

Subpart H systems serving more than 3,300 people and ground water systems serving 10,000 or more 

people are required to collect dual samples (monitoring for both TTHM and HAA5) at each monitoring 

location. Subpart H systems, serving 3,300 and fewer people and ground water systems serving fewer 

than 10,000 people systems can collect one sample at each site. These systems will collect a TTHM 

Stage 2 DBPR Implementation Guidance 114 August 2007 
sample at the site identified as a high TTHM site and an HAA5 sample at the site identified as a high 

HAA5 site. If one site is identified as high for both TTHM and HAA5, one dual sample may be taken at 

this site. 

All systems must sample during the month of highest DBP formation. 

Table 3-17. Stage 2 DBPR Routine Compliance Monitoring Requirements 

Source Water 

Type 

Population Size 

Category 

Monitoring 

Frequency 1

Distribution System Monitoring Location Total 

per Monitoring Period 2

<500 per year 2 

500-3,300 per quarter 2 

3,301-9,999 per quarter 2 

10,000-49,999 per quarter 4 

50,000-249,999 per quarter 8 

250,000-999,999 per quarter 12 

1,000,000-4,999,999 per quarter 16 

Subpart H 

≥ 5,000,000 per quarter 20 

<500 per year 2 

500-9,999 per year 2 

10,000-99,999 per quarter 4 

100,000-499,999 per quarter 6 

Ground Water 

≥ 500,000 per quarter 8 

1. All systems must take at least one dual sample set during the month of highest DBP concentrations. 

2. Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for 

Subpart H systems serving 500-3,300. Systems on annual monitoring and Subpart H systems serving 500-3,300 are 

required to take individual TTHM and HAA5 samples (instead of a dual sample set) at the locations with the highest 

TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring period is 

needed if highest TTHM and HAA5 concentrations occur at the same location (and month, if monitored annually). 

3.14.2 Bromate and Chlorite Monitoring 

CWSs and NTNCWSs using ozone are required to conduct bromate monitoring. The MCL for bromate 

for systems using ozone remains 0.010 mg/L (measured as an RAA) for samples taken at the entrance to 

the distribution system as established by the Stage 1 DBPR. 

The criterion, however, for a system using ozone to qualify for reduced bromate monitoring has changed 

from demonstrating low levels of bromide in the source water, a precursor to bromate when ozonation is 

used, to demonstrating low levels of bromate in the finished water. Under the Stage 2 DBPR, reduced 

monitoring criteria are based on the bromate RAA of 0.0025 mg/L or less [§141.132(b)(3)(ii)]. New 

analytical methods that are more sensitive than older methods have become available, allowing bromate 

to measured to levels of 0.001 mg/L or lower. The Stage 1 DBPR requirements are effective until March 

Stage 2 DBPR Implementation Guidance 115 August 2007 
31, 2009, after which time systems must meet the requirements included in the Stage 2 DBPR (see section 

3.15.2 for information on reduced bromate monitoring). 

Additionally, EPA has reduced the MRL for chlorite to 0.020, based on approved analytical methods for 

determining compliance with the chlorite MCL [§141.131]. EPA recognizes that numerous PWSs have 

been obtaining data on low concentrations and have been using the data in their CCRs. Setting the MRL 

at 0.020 mg/L is reflective of current laboratory practices and current data expectations by water systems. 

This change does not affect the system monitoring or compliance with the chlorite MCL established 

under the Stage 1 DBPR. 

3.15 Stage 2 DBPR Reduced Monitoring 

3.15.1 Reduced TTHM and HAA5 Monitoring 

The criteria to qualify for reduced TTHM and HAA5 monitoring remain consistent with those included in 

the Stage 1 DBPR. Systems may qualify for reduced monitoring if: 

• TTHM LRAA at each monitoring location is no more than 0.040 mg/L. 

• HAA5 LRAA at each monitoring location is no more than 0.030 mg/L. 

• The annual average TOC level at each treatment plant is 4.0 mg/L or less for Subpart H systems 

(discussed in more detail below). 

[§141.623] 

Note that reduced monitoring is not allowed on a location-by-location basis. All sites must meet the 

criteria in order for the system to reduce monitoring. 

Systems required to monitoring quarterly under routine monitoring must continue to meet these criteria in 

order to remain on reduced monitoring. For systems on annual or less frequent routine monitoring the 

LRAAs for TTHM and HAA5 must remain no higher than 0.060 mg/L and 0.045 mg/L, respectively and 

Subpart H systems must continue to meet the TOC criteria. 

If reduced monitoring results indicate that a system is no longer eligible for reduced monitoring, the 

system must resume routine monitoring the quarter immediately following the monitoring period in which 

the system exceeded the specified levels for reduced monitoring. 

If a system that is required to monitor annually or less frequently on routine monitoring exceeds the 

TTHM and HAA5 MCL, this system must go to increased monitoring in the quarter immediately 

following the monitoring period in which the system exceeded the MCL. 

The state may also use its discretion to return a system to routine monitoring. 

3.15.1.1 Source Water TOC for Reduced Monitoring for DBPs 

The Stage 2 DBPR specifies a sampling frequency for all systems taking TOC source water samples. 

Beginning April 1, 2008 (unless the state specifies an earlier date), systems must take TOC samples every 

30 days at a location prior to treatment to qualify for reduced monitoring [§141.132(b)(1)(iii)]. These 

samples must be averaged quarterly for the most recent 4 quarters, which are used to calculate an RAA. If 

Stage 2 DBPR Implementation Guidance 116 August 2007 
the system’s RAA for TOC is 4.0 mg/L or lower and it meets the criteria listed in section 3.16.1.1 for 

TTHM and HAA5, then the system qualifies for reduced DBP monitoring. 

Systems on a reduced Stage 1 DBPR monitoring schedule will need to conduct Stage 2 DBPR 

compliance monitoring on a routine monitoring schedule until they have collected sufficient TOC data to 

qualify for reduced monitoring. 

Once the system is on reduced monitoring, it can reduce its TOC monitoring to every 90 days to remain 

on reduced monitoring. 

Table 3-18. Stage 2 DBPR Reduced Monitoring Requirements for All Systems 

Source 

Water 

Type 

Population 

Size 

Category 

Monitoring 1 Frequency 

Distribution System Monitoring Location per Monitoring Period 

Subpart H <500 - monitoring may not be reduced 

500-3,300 per year 1 TTHM and 1 HAA5 sample: one at the location and during the quarter 

with the highest TTHM single measurement, one at the location and 

during the quarter with the highest HAA5 single measurement; 1 dual 

sample set per year if the highest TTHM and HAA5 measurements 

occurred at the same location and quarter. 

3,301-9,999 per year 2 dual sample sets: one at the location and during the quarter with the 

highest TTHM single measurement, one at the location and during the 

quarter with the highest HAA5 single measurement 

10,000-

49,999 

per quarter 2 dual sample sets at the locations with the highest TTHM 

HAA5 LRAAs 

and highest 

50,000-

249,999 

per quarter 4 dual sample sets - at the locations with the two highest TTHM and two 

highest HAA5 LRAAs 

250,000-

999,999 

per quarter 6 dual sample sets - at the locations 

three highest HAA5 LRAAs 

with the three highest TTHM and 

1,000,000-

4,999,999 

per quarter 8 dual sample sets - at the locations with the four highest TTHM and four 

highest HAA5 LRAAs 

≥ 5,000,000 per quarter 10 dual sample sets - at the locations with the five highest 

highest HAA5 LRAAs 

TTHM and five 

Ground 

Water 

<500 every third 

year 

1 TTHM and 1 HAA5 sample: one at the location and during the quarter 

with the highest TTHM single measurement, one at the location and 

during the quarter with the highest HAA5 single measurement; 1 dual 

sample set per year if the highest TTHM and HAA5 measurements 

occurred at the same location and quarter. 

500-9,999 per year 1 TTHM and 1 HAA5 sample: one at the location and during the quarter 

with the highest TTHM single measurement, one at the location and 

during the quarter with the highest HAA5 single measurement; 1 dual 

sample set per year if the highest TTHM and HAA5 measurements 

occurred at the same location and quarter. 

Stage 2 DBPR Implementation Guidance 117 August 2007 
Stage 2 DBPR Implementation Guidance 118 August 2007 

Source 

Water 

Type 

Population 

Size 

Category 

Monitoring 

Frequency 1

 

Distribution System Monitoring Location per Monitoring Period 

10,000-

99,999 

per year 2 dual sample sets: one at the location and during the quarter with the 

highest TTHM single measurement, one at the location and during the 

quarter with the highest HAA5 single measurement. 

100,000-

499,999 

per quarter 2 dual sample sets; at the locations with the highest TTHM and highest 

HAA5 LRAAs. 

≥ 500,000 per quarter 4 dual sample sets at the locations with the two highest TTHM and two 

highest HAA5 LRAAs 

1. Systems on quarterly monitoring must take dual sample sets every 90 days. 

3.15.1.2 Remaining on Reduced Monitoring based on Stage 1 DBPR 

Systems that were on reduced monitoring for TTHM and HAA5 under Stage 1 DBPR may remain on 

reduced monitoring under Stage 2 DBPR if they meet all of the following criteria: 

• They received a VSS Waiver or 40/30 Certification for IDSE. 

• They meet the reduced monitoring criteria under Stage 2 DBPR. 

• They will be monitoring at the same locations for Stage 2 DBPR as they did for Stage 1 DBPR. 

If the system was required to identify additional Stage 2 DBPR sites or select a fewer number of Stage 2 

DBPR sites compared to their Stage 1 DBPR sampling, they may not remain on reduced monitoring and 

must begin routine monitoring as outlined in 3.14. Systems can regain their reduced monitoring status 

once reduced monitoring criteria under Stage 2 DBPR are met. 

3.15.2 Reduced Monitoring for Bromate 

CWSs and NTNCWSs using ozone are required to conduct bromate monitoring. The MCL for bromate 

for systems using ozone remains 0.010 mg/L (measured as an RAA) for samples taken at the entrance to 

the distribution system as established by the Stage 1 DBPR. However, the criterion for a system using 

ozone to qualify for reduced bromate monitoring has changed from demonstrating low levels of bromide 

in the source water to demonstrating low levels of bromate in the finished water. Bromide is the precursor 

for bromate when ozonation is used. Under the Stage 2 DBPR, reduced monitoring criteria are based on 

the bromate RAA of 0.0025 mg/L or less [§141.132(b)(3)(ii)]. New analytical methods, that are more 

sensitive than older methods, have become available allowing bromate to be measured to levels of 0.001 

mg/L or lower. The Stage 1 DBPR requirements are effective until March 31, 2009, after which time 

systems must meet the requirements included in the Stage 2 DBPR. 

Under the Stage 2 DBPR, systems must have 1 year of data with bromate samples analyzed under a new 

analytical method to qualify for reduced bromate monitoring, now that more sensitive bromate methods 

are available. Beginning April 1, 2009, systems must have a bromate RAA of 0.0025 mg/L or less based 

on 1 year of monthly data to qualify for reduced bromate monitoring. Therefore, systems sampling for 

bromate under the Stage 1 DBPR will need to collect new data to qualify for reduced monitoring under 

the Stage 2 DBPR. These systems may choose to stop monitoring for bromide in March 2008 and begin 

monthly monitoring for bromate using an approved analytical method. This will enable systems to qualify 

for reduced bromate monitoring on April 1, 2009, if their RAA based on their bromate data is 0.0025 

mg/L or less. 
After qualifying for reduced monitoring, systems may remain on reduced monitoring if they continue to 

have a bromate RAA of 0.0025 mg/L or lower. If their RAA exceeds 0.0025 mg/L, the system must 

return to routine bromate monitoring the following month under §141.132(b)(3)(i). 

3.16 Stage 2 DBPR Increased Monitoring 

If a system monitors annually or less frequently than annually (on routine or reduced monitoring), they 

will be required to increase monitoring to dual sample sets taken quarterly (taken every 90 days) if: 

• Any TTHM sample at any location exceeds 0.080 mg/L, or 

• Any HAA5 sample at any location exceeds 0.060 mg/L. 

[§141.625] 

Note that this requirement is based on each individual sample. Also, increased monitoring is required on a 

system-wide basis. If any site meets the criteria, the system must increase monitoring at all sites. 

Systems on quarterly monitoring are not subject to increased monitoring. 

A system may return to routine monitoring if the TTHM LRAA for every monitoring location is less than 

or equal to 0.060 mg/L and the HAA5 LRAA for every monitoring location is less than or equal to 0.045 

mg/L after conducting at least four consecutive quarters of increased monitoring. 

Systems on Increased Monitoring Under Stage 1 DBPR [40 CFR 141.628] 

Systems that were on an increased Stage 1 DBPR monitoring schedule must begin Stage 2 DBPR 

monitoring on the increased schedule until they meet the requirements for returning to the routine 

schedule. 

When states are reviewing IDSE Reports and/or Compliance Monitoring Plans for systems on increased 

monitoring, they should make the system aware of this requirement. The standard monitoring or SSS Plan 

or IDSE Report should either show the additional monitoring dates, or the state should consider 

modifying the standard monitoring or SSS Plan or IDSE Report to indicate that unless the system 

achieves routine monitoring prior to the Stage 2 DBPR compliance monitoring date, the increased 

monitoring requirements must be met. In addition, systems that are put on an increased schedule in the 

interim period between the IDSE and compliance monitoring periods should be made aware of this 

requirement. 

3.17 Operational Evaluations [40 CFR 141.626] 

TTHM and HAA5 MCL compliance for the Stage 2 DBPR is based on an LRAA, therefore a system may 

have individual DBP results significantly higher than the MCL from time to time while remaining in 

compliance. This situation is a result of the fact that high concentrations are averaged with lower 

concentrations at a given location. While this situation does not constitute an MCL violation, it might 

indicate a trend that could lead to an MCL violation in future quarters. 

3.17.1 Operational Evaluation Level 

The “operational evaluation level” is an LRAA threshold, meant to help systems identify if they are in 

danger of exceeding the MCL in the following monitoring quarter. The process is useful in that it alerts 

Stage 2 DBPR Implementation Guidance 119 August 2007 
the system to the potential of an MCL violation if DBP levels remain at their current level and encourages 

them to consider what operational changes may be necessary to reduce DBP levels. 

The operational evaluation level at any location is the sum of the two previous quarters’ TTHM or HAA5 

results plus twice the current quarter’s TTHM or HAA5 result, divided by four to determine an average. 

Effectively, it is the LRAA that can be expected if the next quarter’s result is the same as the current 

quarter’s result. To determine if a system has exceeded operational evaluation levels at any sampling 

location, the following formula is used: 

If (Q1 + Q2 +2Q3)/4 > MCL at any monitoring location,

where 

Q3 = current quarter measurement 

Q2 = previous quarter measurement 

Q1 =quarter before previous quarter measurement 

MCL=Stage 2 DBPR MCL for TTHM (0.080 mg/l) or Stage 2 DBPR MCL for HAA5 (0.060 mg/L)

then the system must conduct an operational evaluation.

If the operational evaluation level for TTHM exceeds 0.080 mg/L or the operational evaluation level for 

HAA5 exceeds 0.060 mg/L at any monitoring location, an exceedance of the operational evaluation level 

has occurred. 

3.17.2 Operational Evaluations 

If a system, including a consecutive system, exceeds the operational evaluation level, they must conduct 

an operational evaluation and submit a written report of the evaluation to the state no later than 90 days 

after receipt of the analytical result that caused the exceedance. The written report must be made available 

to the public upon request. 

The operational evaluation must include an examination of system treatment and distribution operational 

practices. It must include storage tank operations, excess storage capacity, distribution system flushing, 

changes in sources or source water quality, and treatment changes or problems that may contribute to 

TTHM and HAA5 formation. It must then identify opportunities to reduce DBP concentrations in the 

distribution system and steps that could be considered to minimize future exceedances. 

State review of the operational evaluations submitted by systems should address whether the system has 

identified the probable reason for the exceedance and considered what actions could be taken to avoid an 

MCL exceedance as well as to avoid the problem from arising in the future. If the exceedance is related to 

a seasonal or on-going issue, the state should consider whether the system is adequately addressing the 

problem to eliminate the cause rather than accepting it as a periodic event. 

The exceedance may be rooted in source water issues, treatment processes, distribution system 

configuration or operation, or a combination of any or all of these components. The evaluation should 

consider the system holistically as well as examining specific areas of concern. 

Below is a brief discussion of some issues and possible actions that the state may consider in conducting 

their reviews. However, for a more complete discussion of operational evaluations, refer to EPA’s 

Stage 2 DBPR Implementation Guidance 120 August 2007 
Operational Evaluation Guidance Manual (formerly titled the Significant Excursions Guidance Manual) 

available online at www.epa.gov/safewater/disinfection/stage2/compliance.html#pws. 

Source water management 

Systems that experience an exceedance of the operational evaluation level may want to begin the 

evaluation by examining source water data and source management practices. Systems that have multiple 

water sources will need to determine which sources were in use at and just prior to the operational 

evaluation level exceedance and which source(s) likely influenced the location at which the exceedance 

occurred. 

The evaluation should address any available source water precursor concentrations (including TOC, 

dissolved organic carbon (DOC), specific ultraviolet absorbance (SUVA)) and review these data during 

the time period that would have most impacted distribution system TTHM and HAA5 levels. A 

comparison of historical concentrations to the concentrations prior to the exceedance may show if the 

system experienced a sudden increase in these concentrations which may have resulted in the exceedance. 

Many of the factors that contribute to DBP precursors in source waters also affect turbidity and particle 

counts. Therefore, increased turbidity levels can serve as an indicator of an event that may have resulted 

in increased DBP precursors in the source water. 

If such an increase is identified, the system should further examine other watershed or operational data to 

determine the cause of the increase in DBP precursors. Seasonal issues such as heavy rainfall or snow 

melt, algae bloom, spring or fall turnover, exceptionally high flows, exceptionally low flows, or another 

major event in the watershed might have impacted precursor concentrations and caused the exceedance. 

If the issue is identified as a source problem, the system may consider a variety of actions to help prevent 

future exceedances. If the source has dramatic seasonal variations in water quality due to issues such as 

temperature, algae blooms, runoff, or spring and fall turn over, the system may consider relying more 

heavily on a groundwater source or a higher quality surface water source to supplement a poorer quality 

surface water supply during high DBP periods. This can be a valuable strategy to reduce DBP levels that 

may spike during certain seasons. Another option to address some of these seasonal issues is construction 

of a multiple level intake. Drawing from a lower level during an algae bloom, or a higher level during 

seasonal turn over can help a system avoid DBP spikes. 

Treatment plant operation 

The evaluation should also examine treatment data and processes during the time period that would have 

most impacted distribution system TTHM and HAA5 levels. 

The report may include a review of finished water data collected prior to the operational evaluation level 

exceedance to help focus the evaluation. Key parameters to review include provide useful information on 

what factors may have contributed to increased DBP levels include: 

• DBP Precursors Levels (TOC, SUVA, DOC, Bromide) 

• pH 

• Temperature 

• Turbidity 

• Disinfectant Concentration 

• TTHM and HAA5 Concentrations 

Stage 2 DBPR Implementation Guidance 121 August 2007 
The evaluation should address treatment issues that impact both precursor removal and disinfectant 

practices. Some possible factors that may have contributed to the exceedance include: 

• Substantial increase or decrease in flows to treatment components. 

• Substantial changes in plant flow rate that may have resulted in a decrease in settling time or 

carry-over of process solids. 

• Changes in chemical feed rate or coagulation practices. 

• Maintenance activities in the plant that may have caused solids (and correspondingly precursors) 

carry over to the point of disinfectant addition. 

• The addition or removal of any treatment processes. 

• Poor regulation or failure of chemical feed system. 

• Changes in primary disinfectant type or dose. 

• Changes in flows to the clearwell or temperature in clearwell. 

• Poorly controlled or excessive disinfectant dose. 

If the system determines that the primary issue that caused the exceedance is related to treatment, they 

will want to examine how the plant can optimize precursor removal and/or disinfection practices to avoid 

an MCL exceedance and future operational evaluation level exceedances. Prior to any change in 

disinfection practices systems should (and systems subject to the LT2WSWTR are required to) conduct 

disinfection profiling and benchmarking and consult with the state about proposed changes. 

Distribution system infrastructure or operations 

Finally, the evaluation should address the distribution system and examine distribution data and 

operational practices to determine the cause of the operational evaluation level exceedance. The system 

should gather distribution system monitoring and operations data that reflect conditions just prior to and 

during the time of the operational evaluation level exceedance. Types of information that could be useful 

include: 

• Temperature data 

• Disinfectant residual data 

• Pump station and storage facility operating data (e.g., tank level data) 

• Meter data (to determine if demand was lower than normal) 

• Residual data 

• Maintenance records (planned and emergency) 

• Customer complaint records 

Stage 2 DBPR Implementation Guidance 122 August 2007 
Some factors to consider in evaluating if the exceedance was caused by actions or practices in the 

distribution system include: 

• Unusually low system demand (including drop in use of a high-volume user) causing an increase 

in water age. 

• Unusually high demand or event that could cause a tank or reservoir to be drawn down more than 

usual, drawing stagnant water from the tank. 

• Maintenance events such as cleaning of a tank, repair of a water main, or water main flushing. 

• Change of the pattern of flow through the distribution system that may allow older water from 

stagnant zones to be drawn into other areas of the distribution system where water use is higher. 

If the evaluation indicates that the primary factor that caused the exceedance of the operational evaluation 

level is related to distribution system issues, the system will examine steps that may be taken to address 

these issues. Changes to tank configuration or operation to minimize hydraulic residence time and/or 

maximize mixing should be considered including modification to inlet configuration, cut in and cut out 

levels, longer fill time, higher inlet velocity, or mixing to avoid thermal stratification. Some other 

distribution system remedies may include looping dead end mains, periodic flushing of high water age 

portions of the distribution system, downsizing oversized pipe, and cleaning and lining cast or ductile iron 

pipe to reduce chlorine demand. 

3.17.3 Evaluate System Requests for Limiting the Scope of an Operational Evaluation 

If the system is readily able to identify the cause of the operational evaluation level exceedance, it may 

request permission to limit the scope of the evaluation. If the request is granted by the state, the system 

still must follow the schedule for completing the evaluation and submitting the report. The state must 

approve the limited scope in writing, and the system must keep the approval with the completed report. 

States may want to encourage systems to contact them after an exceedance to discuss next steps and to 

determine whether they qualify to limit the scope of their evaluation. 

3.18 Special Considerations for Consecutive and Wholesale Systems 

3.18.1 DBP Monitoring 

The TTHM and HAA5 sampling requirements for consecutive systems are determined in the same 

manner as for all other systems. The number of sites and monitoring frequency is based on the system’s 

population served and source type (based on wholesale system’s source water type). Thus, large 

consecutive systems will take more samples than a smaller wholesale system. 

3.18.2 Treating Combined Distribution Systems as One System for Compliance 

Monitoring 

As discussed in 3.12.3, §141.29 gives the state the authority to treat systems in a combined distribution 

system as a single system with respect to their monitoring requirements as long as the interconnection of 

Stage 2 DBPR Implementation Guidance 123 August 2007 
the systems justifies such modifications. If the state elects to use this authority to modify one or more 

systems’ Stage 2 DBPR compliance monitoring requirements, the rule requires the following: 

• The state must describe in their primacy application a procedure for implementing this process 

(see section 4). 

• The state must require that each system have at least one monitoring site. 

• Each system must submit the monitoring plans for all other systems in the combined distribution 

system along with their monitoring plan. 

The state may want to consider encouraging all systems in the combined distribution system to submit 

their plans at the same time. 

3.18.3 BATs 

Compliance with the Stage 2 DBPR can be especially challenging for consecutive systems. If a wholesale 

system has DBP issues, it is likely to focus on precursor removal. However, this option is not available to 

consecutive systems that receive treated water. If a consecutive system receives treated water that 

contains high DBPs and/or high levels of precursors and disinfectants, they have limited options for 

controlling DBPs. 

Therefore, the Stage 2 DBPR provides best available technologies (BATs) for consecutive systems, which 

are not focused on precursor removal. For all systems, the management of hydraulic flow and storage to 

minimize residence time in the distribution system is a BAT. For larger systems (those serving at least 

10,000 people) chloramination is also a BAT. 

3.18.4 Chlorine and Chloramines Requirements 

Consecutive systems that do not add a disinfectant but deliver water that has been treated with a 

disinfectant other than UV must now comply with the Stage 1 DBPR analytical and monitoring 

requirements for chlorine and chloramines and associated compliance requirements and reporting 

requirements including: 

• Analytical methods [§141.131(c)]. 

• Monitoring of residual at the same sites as total coliform sampling [§141.132(c)(1)]. 

• Compliance with the MRDL [§141.133(c)(1)]. 

• Reporting of results [§141.134(c)]. 

These requirements begin April 1, 2009 unless required earlier by the state [§141.624] 

3.18.5 Additional Resources 

EPA is preparing a guidance manual for consecutive systems to address these and other issues. 

Stage 2 DBPR Implementation Guidance 124 August 2007 
3.19 State Recordkeeping Requirements 

Section 142.14 requires states with primacy to keep various records, including: 

• Analytical results to determine compliance with MCLs, MRDLs, and treatment technique 

requirements. 

• System inventories. 

• State approvals. 

• Enforcement actions. 

• Issuance of variances and exemptions. 

The Stage 2 DBPR requires that the state keep records related to any decisions made pursuant to IDSE 

requirements and Stage 2 DBPR requirements. States also must retain copies of IDSE monitoring plans 

and 40/30 Certifications, including any modifications required by the state, until they are replaced or 

revised in their entirety. States must keep operational evaluations for 10 years. 

Stage 2 DBPR Implementation Guidance 125 August 2007 
Stage 2 DBPR Implementation Guidance 126 August 2007 

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Section 4 

State Primacy Revision 

Application 
This page intentionally left blank 
40 CFR Part 142 sets out requirements for states to obtain and/or retain primary enforcement 

responsibility (primacy) for the Public Water System Supervision (PWSS) program as authorized by 

Section 1413 of the SDWA. The 1996 SDWA Amendments updated the process for states to obtain 

and/or retain primacy. On April 28, 1998, EPA promulgated the Primacy Rule to reflect these statutory 

changes (63 FR 23361). 

4.1 State Primacy Program Revision 

Pursuant to §142.12, Revision of State Programs, complete and final requests for approval of program 

revisions to adopt new or revised EPA regulations must be submitted to the EPA Administrator no later 

than 2 years after promulgation of the new or revised federal regulations (see Table 4-1). Until those 

applications are approved, EPA regions have responsibility for directly implementing the Stage 2 DBPR. 

The state and EPA can agree to implement the rule together during this period. However, if a state is 

eligible for interim primacy, it will have full implementation and enforcement authority. States that have 

primacy for all existing NPDWRs are considered to have interim primacy for any new or revised 

regulation. Interim primacy for the Stage 2 DBPR would begin on the date the final and complete primacy 

revision application is submitted or the effective date of the new state regulation (whichever is later), and 

ends when EPA makes a final determination. 

A state may be granted an extension of time, up to 2 years, to submit its application package. During any 

extension period, an extension agreement outlining the state’s and EPA’s responsibilities is required. 

Table 4-1. State Rule Implementation and Revision Timetable for the Stage 2 DBPR 

EPA/State Action Time Frame 

Rule published by EPA January 4, 2006 

State and region establish a process and agree upon a schedule for application 

review and approval (optional) 

March 4, 2006 

State, at its option, submits draft program revision package to region including: 

Preliminary Approval Request, Draft State Regulations and/or Statutes, 

Regulation Crosswalk 

July 4, 2006 

(Recommended) 

Regional (and Headquarters if necessary) review of draft Completed within 90 days of 

state submittal of draft 

(Recommended) 

State submits complete and final program revision package to 

Adopted State Regulations 

Regulation Crosswalk 

§142.10 Primacy Update Checklist 

§142.14 and §142.15 Reporting and Recordkeeping 

§142.16 Special Primacy Requirements 

Attorney General’s Enforceability Certification 

region including: January 4, 2008* 

States with approved extensions submit complete and final 

package 

program revision January 4, 2010** 

Stage 2 DBPR Implementation Guidance 129 August 2007 
Stage 2 DBPR Implementation Guidance 130 August 2007 

EPA/State Action Time Frame 

EPA final review and determination: 

Regional Review (program and ORC) 

Headquarters Concurrence and Waivers (Office of Ground Water and 

Drinking Water (OGWDW)) 

Public Notice 

Opportunity for Hearing 

EPA’s Determination 

Completed within 90 days of 

state submittal of final package 

(45 days region) 

(45 days Headquarters)*** 

* EPA suggests submitting an application by October 4, 2007 to ensure timely approval. EPA regulations allow 

states until January 4, 2008 for this submittal. 

** EPA suggests submitting an application by October 4, 2010 for states with approved extensions to ensure timely 

approval. 

*** At least one state application per region. 

4.1.1 The Revision Process 

EPA recommends a two-step process for approval of state program revisions. The steps consist of 

submission of a draft request (optional) and submission of a complete and final request for program 

approval. Figure 4-1 diagrams these processes and their timing. 

Draft Request—The state may submit a draft request for EPA review and tentative determination. The 

request should contain drafts of all required primacy application materials (with the exception of a draft 

Attorney General’s Statement). A draft request should be submitted as soon as practicable; EPA 

recommends submitting it within 6 months of rule promulgation. EPA will make a tentative determination 

as to whether the state program meets the applicable requirements. EPA intends to make a tentative 

determination within 90 days. 

Complete and Final Request—This submission must be in accordance with §142.12(c)(1) and (2) and 

include the Attorney General’s statement. The state should also include its response to any comments or 

program deficiencies identified in the tentative determination (if applicable). Submission of only a final 

request may make it more difficult for states to address any necessary changes within the allowable time 

for state rule adoption. 

EPA recommends that states submit their complete and final revision package within 21 months of rule 

promulgation (by October 4, 2008). This will ensure that states will have interim primacy as soon as 

possible and will prevent backlogs of revision applications to adopt future federal requirements. 

The state and region should agree to a plan and timetable for submitting the state primacy revision 

application as soon as possible after rule promulgation—ideally within 5 months of promulgation. 

4.1.2 The Final Review Process 

Once a state application is complete and final, EPA has a regulatory (and statutory) deadline of 90 days to 

review and approve or disapprove the revised program. OGWDW will conduct a detailed concurrent 

review of the first state package from each region. The regional office should submit its comments with 

the state’s package within 45 days for review by Headquarters (HQ). When the region has identified all 

significant issues, OGWDW waives concurrence on all other state programs in that region, although EPA 

HQ retains the option to review additional state programs as appropriate. The Office of General Counsel 

(OGC) has delegated its review and approval to the Office of Regional Counsel (ORC). 
In order to meet the 90-day deadline for packages undergoing review by HQ, the review period is equally 

split by giving the regions and HQ 45 days each to conduct their respective reviews. For the first package 

in each region, regions should forward copies of the primacy revision applications and their evaluations to 

the Drinking Water Protection Division Director in OGWDW no later than 45 days after state submittal. 

The Drinking Water Protection Division Director takes the lead on the HQ review process. 

Figure 4-1. Recommended Review Process for State Request for Approval of Program 

Revisions 

4.2 State Primacy Program Revision Extensions 

4.2.1 The Extension Process 

Under §142.12(b), states may request that the 2 year deadline for submitting the complete and final 

packages for EPA approval of program revisions be extended for up to 2 additional years in certain 

circumstances. The extension request must be submitted to EPA within 2 years of the date that EPA 

published the regulation. The Regional Administrator has been delegated authority to approve extension 

applications. Concurrence by HQ on extensions is not required. 

Therefore, the state must either adopt regulations pertaining to the Stage 2 DBPR and submit a complete 

and final primacy revision application or request an extension of up to 2 years by January 4, 2008. 

Stage 2 DBPR Implementation Guidance 131 August 2007 
4.2.2 Extension Request Criteria 

For an extension to be granted under §142.12(b), the state must demonstrate that it is requesting the 

extension because it cannot meet the original deadline for reasons beyond its control and despite a good 

faith effort to do so. A critical part of the extension application is the state’s proposed schedule for 

submission of its complete and final request for approval of a revised primacy program. The application 

must also demonstrate at least one of the following: 

(i) That the state currently lacks the legislative or regulatory authority to enforce the new or revised 

requirements; 

(ii) That the state currently lacks the program capability adequate to implement the new or revised 

requirements; or, 

(iii) That the state is requesting the extension to group two or more program revisions in a single 

legislative or regulatory action. 

In addition, the state must be implementing the EPA requirements to be adopted in its program revision 

within the scope of its current authority and capabilities. 

4.2.3 Conditions of the Extension 

Until the State Primacy Revision Application has been submitted, the state and EPA regional office will 

share responsibility for implementing the primary program elements as indicated in the extension 

agreement. The state and the EPA regional office should discuss these elements and address terms of 

responsibility in the agreement. 

These conditions will be determined during the extension approval process and are decided on a case-bycase basis. The conditions must be included in an extension agreement between the state and the EPA 

regional office. 

Conditions of an extension agreement may include: 

• Informing PWSs of the new EPA (and upcoming state) requirements and the fact that the region 

will be overseeing implementation of the requirements until they approve the state program 

revisions or until the state submits a complete and final revision package if the state qualifies for 

interim primacy. 

• Collecting, storing, and managing laboratory results, public notices, and other compliance and 

operation data required by the EPA regulations. 

• Assisting the region in the development of the technical aspects of enforcement actions and 

conducting informal follow-up on violations (e.g., telephone calls, letters). 

• Providing technical assistance to PWSs. 

Stage 2 DBPR Implementation Guidance 132 August 2007 
• For states whose request for an extension is based on a current lack of program capability 

adequate to implement the new requirements, taking steps agreed to by the region and the state to 

remedy the deficiency during the extension period. 

• Providing the region with all the information required under §142.15 for state reporting. 

Example 4-1 provides a checklist the region can use to review state extensions or to create an extension 

agreement. 

Until states have primacy, EPA is the primacy enforcement authority. However, historically states have 

played a role in implementation for various reasons—most importantly, since states have the local 

knowledge and expertise and have established relationships with their systems. 

The state and EPA should be viewed as partners in this effort, working toward two very specific public 

health-related goals. The first goal is to achieve a high level of compliance with the regulation. The 

second goal is to facilitate efficient co-regulation during the transition period before the state has primacy, 

including interim primacy, for the rule. In order to accomplish these goals, education, training, and 

technical assistance will need to be provided to water suppliers on their responsibilities under the Stage 2 

DBPR. 

Stage 2 DBPR Implementation Guidance 133 August 2007 
Example 4-1. Example Extension Request Checklist 

{Date}

{Regional Administrator}

Regional Administrator 

U.S. EPA Region {Region}

{Street Address}

{City, State, Zip}

RE: Request/approval for an Extension Agreement 

Dear {Regional Administrator}: 

 The State of {State} is requesting an extension to the date that the final primacy revisions are due to EPA 

for the Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) {insert date - no later than 

January 4, 2010}, as allowed by 40 CFR 142.12, and would appreciate your approval. Staff of the {State 

Department/Agency} have conferred with your staff and have agreed to the requirements listed below for this 

extension. This extension is being requested because the State of {State}: 

 Is planning to group two or more program revisions into a single legislative or regulatory action. 

 Currently lacks the legislative or regulatory authority to enforce the new or revised requirements. 

 Currently lacks adequate program capability to implement the new or revised requirements. 

{State Department/Agency} will be working with EPA to implement the Stage 2 DBPR within the scope 

of its current authority and capability, as outlined in the six areas identified in §142.12(b)(3)(i-vi): 

i) Informing PWSs of the new EPA (and upcoming state) requirements and the fact that EPA will be overseeing 

implementation of the requirements until EPA approves the state revision. 

State EPA 

____ ____ 

____ ____ 

____ ____ 

____ ____

____ ____ 

____ ____ 

____ ____

____ ____ 

Provide copies of regulation and guidance to other state agencies, public water systems (PWSs), 

technical assistance providers, associations, or other interested parties. 

Educate and coordinate with state staff, PWSs, the public, and other water associations about the 

requirements of this regulation. 

Notify affected systems of their requirements under the Stage 2 DBPR. 

 Other: 

ii) Collecting, storing, and managing laboratory results, public notices, and other compliance and operation data 

required by the EPA regulations. 

State EPA 

____ ____ Devise a tracking system for PWS reporting pursuant to the Stage 2 DBPR. 

Keep PWSs informed of reporting requirements during development and implementation. 

Report Stage 2 DBPR violation and enforcement information to SDWIS as required. 

 Other: 

iii) Assisting EPA in the development of the technical aspects of the enforcement actions and conducting informal 

follow-up and violations (telephones calls, letters, etc.). 

State EPA 

Issue notices of violation (NOVs) for treatment technique, MCL, and monitoring/ reporting 

violations of the Stage 2 DBPR. 

Stage 2 DBPR Implementation Guidance 134 August 2007 
____ ____ 

____ ____ 

____ ____

____ ____ 

____ ____ 

____ ____ 

____ ____ 

____ ____

____ ____

____ ____ 

____ ____

____ ____

____ ____ 

____ ____ 

____ ____

Provide immediate technical assistance to PWSs with treatment technique, MCL and/or 

monitoring/reporting violations to try to bring them into compliance. 

Refer all violations to EPA for enforcement if they have not been resolved within 60 days of the 

incident that triggered the violation. Provide information as requested to conduct and complete any 

enforcement action referred to EPA. 

 Other: 

iv) Providing technical assistance to PWSs. 

State EPA 

Conduct training within the state for PWSs on Stage 2 DBPR rule requirements. 

Provide technical assistance through written and/or verbal correspondence with PWSs. 

Provide on-site technical assistance to PWSs as requested and needed to ensure compliance with 

this regulation. 

Coordinate with other technical assistance providers and organizations to provide accurate 

information and aid in a timely manner. 

 Other: 

v) Providing EPA with all information prescribed by the State Reporting Requirements in §142.15. 

State EPA 

 Report any violations incurred by PWSs for this regulation each quarter. 

Report any enforcement actions taken against PWSs for this regulation each quarter. 

 Report any variances or exemptions granted for PWSs for this regulation each quarter. 

 Other: 

vi) For states whose request for an extension is based on a current lack of program capability to implement the new 

or revised requirements, taking the following steps to remedy the capability deficiency. 

State EPA 

Acquire additional resources to implement these regulations (list of specific steps being taken 

attached as {List A}). 

Provide quarterly updates describing the status of acquiring additional resources. 

 Other: 

I affirm that the {State Department/Agency} will implement provisions of the Stage 2 DBPR as outlined above. 

 

______________________________________________________________________________ 

{Agency Director or Secretary} Date 

______________________________________________________________________________ 

{Name of State Agency}

I have consulted with my staff and approve your extension for the aforementioned regulation. I affirm that EPA 

Region {Region} will implement provisions of the Stage 2 DBPR as outlined above. 

______________________________________________________________________________ 

Regional Administrator Date 

EPA Region {Region}

This Extension Agreement will take effect upon the date of the last signature. 

Stage 2 DBPR Implementation Guidance 135 August 2007 
Stage 2 DBPR Implementation Guidance 136 August 2007 

4.3 State Primacy Package 

The Primacy Revision Application package should consist of the following sections: 

 State Primacy Revision Checklist 

 Text of the State’s Regulation 

 Primacy Revision Crosswalk 

 State Reporting and Recordkeeping Checklist 

 Special Primacy Requirements 

 Attorney General’s Statement of Enforceability 

4.3.1 The State Primacy Revision Checklist 

This section is a checklist of general primacy requirements, as shown in Table 4-2. In completing this 

checklist, the state must identify the program elements that it has revised in response to new federal 

requirements. If an element has been revised, the state should indicate a “Yes” answer in the 

“Revision to State Program” column and should submit appropriate documentation. For elements 

that did not require revision, the state need only list the citation and date of adoption in the “Revision to 

State Program” column. During the application review process, EPA will insert findings and comments in 

the final column. 

The 1996 SDWA Amendments include new provisions for PWS definition and administrative penalty 

authority. States must adopt provisions at least as stringent as these new provisions, now codified at 

§142.2 and §142.10. Failure to revise these elements can affect primacy for the Stage 2 DBPR. 

States may bundle the primacy revision packages for multiple rules. If states choose to bundle 

requirements, the Attorney General’s Statement should reference all of the rules included. 

4.3.2 Text of the State’s Regulation 

Each primacy application package should include the text of the state regulation. 

4.3.3 Primacy Revision Crosswalk 

The Primacy Revision Crosswalk, in Appendix A, should be completed by states in order to identify state 

statutory or regulatory provisions that correspond to each federal requirement. If the state’s provisions 

differ from federal requirements, the state should explain how its requirements are no less stringent. 

Table 4-2. State Primacy Revision Checklist 

Required Program Elements Revision to State 

Program 

EPA 

Findings/Comments 

'142.10 Primary Enforcement 

B Definition of Public Water System*

'142.10(a) Regulations No Less Stringent 

'142.10(b)(1) Maintain Inventory 

'142.10(b)(2) Sanitary Survey Program 
Stage 2 DBPR Implementation Guidance 137 August 2007 

Required Program Elements Revision to State 

Program 

EPA 

Findings/Comments 

'142.10(b)(3) Laboratory Certification Program 

'142.10(b)(4) Laboratory Capability 

'142.10(b)(5) Plan Review Program 

'142.10(b)(6)(i) Authority to apply regulations 

'142.10(b)(6)(ii) Authority to sue in courts of competent 

jurisdiction 

'142.10(b)(6)(iii) Right of Entry 

'142.10(b)(6)(iv) Authority to require records 

'142.10(b)(6)(v) Authority to require public notification 

'142.10(b)(6)(vi) Authority to assess civil and criminal penalties

'142.10(b)(6)(vii) Authority to require CWSs to provide CCRs 

'142.10(c) Maintenance of Records 

'142.10(d) Variance/Exemption Conditions (if 

applicable)** 

'142.10(e) Emergency Plans 

'142.10(f) Administrative Penalty Authority* 

'142.10(g) Electronic Reporting Regulations*** 

* New requirement from the 1996 Amendments. Regulations published in the April 28, 1998 Federal Register. 

** New regulations published in the August 14, 1998 Federal Register.

*** New regulations published in the October 13, 2005 Federal Register.

4.3.4 State Recordkeeping and Reporting Checklist [40 CFR 142.14, 40 CFR 142.15] 

The Stage 2 DBPR does not add any state reporting requirements, but does include state recordkeeping 

requirements. 

The state should use the Primacy Revision Crosswalk in Appendix A to demonstrate that state 

recordkeeping requirements are consistent with federal requirements. If state requirements are not the 

same as federal requirements, the state must explain how its requirements are “no less stringent” as per 40 

CFR §142.10. States may want to include in their State Primacy Revision Application how long the state 

will keep the records and in what format the data will be kept. 

The Primacy Revision Crosswalk includes state recordkeeping requirements indicating that the state must: 

• Keep records of the IDSE monitoring plans, plus any modifications made by the state. The state 

keeps these records until replaced or revised by approved IDSE Reports. [§142.14(a)(8)(i)] 

• Keep records of system IDSE Reports and 40/30 Certifications, plus any modifications required 

by the state until reversed or revised in their entirety. [§142.14(a)(8)(ii)] 
Stage 2 DBPR Implementation Guidance 138 August 2007 

• Keep records of operational evaluations submitted by systems for 10 years following submission. 

[§142.14(a)(8)(iii)] 

4.3.5 Special Primacy Requirements [40 CFR 142.16] 

The Special Primacy Requirements section of the crosswalk is where the state has the opportunity to 

describe how it will satisfy these provisions. Special primacy conditions pertain to specific regulations 

where implementation of the rule involves activities beyond general primacy provisions. States must 

include these rule-distinct provisions in a application for approval or revision of their program. Section 

4.4 provides guidance on how states may choose to meet the special primacy requirements of the Stage 2 

DBPR. 

4.3.6 Attorney General’s Statement of Enforceability [40 CFR 142.12(c)(2)] 

The complete and final primacy revision application must include an Attorney General’s Statement 

certifying that the state regulations were duly adopted and are enforceable (unless EPA has waived this 

requirement by letter to the state). The Attorney General’s Statement should also certify that the state 

does not have any audit privilege or immunity laws or, if it has such laws, that these laws do not prevent 

the state from meeting the requirements of the SDWA. If a state has submitted this certification with a 

previous revision package, then the state should indicate the date of submittal and the Attorney General 

need only certify that the status of the audit laws has not changed since the prior submittal. An example of 

an Attorney General’s Statement is presented in Example 4-2. 

4.3.6.1 Guidance for States on Audit Privilege and/or Immunity Laws 

In order for EPA to properly evaluate the state’s request for approval, the State Attorney General or 

independent legal counsel should certify that the state’s environmental audit immunity and/or privilege 

and immunity law does not affect its ability to meet enforcement and information gathering requirements 

under SDWA. This certification should be reasonably consistent with the wording of the state audit laws 

and should demonstrate how state program approval criteria are satisfied. 

EPA will apply the criteria outlined in its “Statement of Principles” memo issued on February 14, 1997, 

(www.epa.gov/epaoswer/hazwaste/state/policy/policies.htm) to determine whether states with audit laws 

have retained adequate enforcement authority for any authorized federal programs. The principles 

articulated in the guidance are based on the requirements of federal law, specifically the enforcement and 

compliance and state program approval provisions of environmental statutes and their corresponding 

regulations. The Principles provide that if provisions of state law are ambiguous, it will be important to 

obtain opinions from the State Attorney General or independent legal counsel interpreting the law as 

meeting specific federal requirements. If the law cannot be so interpreted, changes to state laws may be 

necessary to obtain federal program approval. Before submitting a package for approval, states with audit 

privilege and/or immunity laws should initiate communications with appropriate EPA regional offices to 

identify and discuss the issues raised by the state’s audit privilege and/or immunity law. 

The guidance for states on Audit Law Privilege and/or Immunity Laws is currently under review. If 

amended, EPA will issue an addendum to this document with the revised guidance. 
Example 4-2. Example of Attorney General’s Statement 

Model Language 

I hereby certify, pursuant to my authority as (1) and in accordance with the Safe Drinking Water Act as amended, 

and (2), that in my opinion the laws of the [State/Commonwealth of (3)] [or tribal ordinances of (4)] to carry out 

the program set forth in the “Program Description” submitted by the (5) have been duly adopted and are 

enforceable. The specific authorities provided are contained in statutes or regulations that are lawfully adopted at 

the time this Statement is approved and signed and will be fully effective by the time the program is approved. 

I. For States with No Audit Privilege and/or Immunity Laws 

Furthermore, I certify that [State/Commonwealth of (3)] has not enacted any environmental audit privilege and/or 

immunity laws. 

Model Language 

II. For States with Audit Laws that do Not Apply to the State Agency Administering the Safe Drinking 

Water Act 

Furthermore, I certify that the environmental [audit privilege and/or immunity law] of the [State/Commonwealth 

of (3)] does not affect the ability of (3) to meet enforcement and information gathering requirements under the 

Safe Drinking Water Act because the [audit privilege and/or immunity law] does not apply to the program set 

forth in the “Program Description.” The Safe Drinking Water Act program set forth in the “Program Description” 

is administered by (5); the [audit privilege and/or immunity law] does not affect programs implemented by (5), 

thus the program set forth in the “Program Description” is unaffected by the provisions of [State/Commonwealth 

of (3)] [audit privilege and/or immunity law]. 

III. For States with Audit Privilege and/or Immunity Laws that Worked with EPA to Satisfy Requirements 

for Federally Authorized, Delegated, or Approved Environmental Programs 

Furthermore, I certify that the environmental [audit privilege and/or immunity law] of the [State/Commonwealth 

of (3)] does not affect the ability of (3) to meet enforcement and information gathering requirements under the 

Safe Drinking Water Act because [State/Commonwealth of (3)] has enacted statutory revisions and/or issued a 

clarifying Attorney General’s Statement to satisfy requirements for federally authorized, delegated, or approved 

environmental programs. 

Seal of Office 

 _______________________________________

_______________________________________

_______________________________________

 Signature 

 

 Name and Title 

 

 Date 

(1) State Attorney General or attorney for the primacy agency if it has independent legal counsel. 

(2) 40 CFR 142.11(a)(6)(i) for initial primacy applications or 40 CFR 142.12(c)(1)(iii) for primacy program 

revision applications. 

(3) Name of state or commonwealth. 

(4) Name of tribe. 

(5) Name of primacy agency. 

Stage 2 DBPR Implementation Guidance 139 August 2007 
4.4 Guidance for the Special Primacy Requirements of the Stage 2 DBPR 

In addition to adopting basic primacy requirements specified in 40 CFR 142, states are required to adopt 

primacy provisions pertaining to specific regulations where implementation of the rule involves activities 

beyond general primacy provisions. The purpose of these provisions is to allow state flexibility in 

implementing a regulation that (1) applies to specific system configurations within the particular state and 

(2) can be integrated with a state’s existing PWSS Program. States must include these rule-distinct 

provisions in an application for approval or revision of their program. This section contains information 

and guidance that states can use when addressing the special primacy requirements of the Stage 2 DBPR. 

The guidance addresses special primacy conditions in the same order that they occur in the rule. In the 

state primacy revision application packages, the state must explain how they intend to accomplish the 

requirements from §142.16. 

4.4.1 Special Primacy Requirements Regarding Consecutive System Monitoring 

§142.16 Special primacy requirements. (m) Requirements for states to adopt §141, Subparts U and V. In 

addition to the general primacy requirements elsewhere in this part, including the requirements that state 

regulations be at least as stringent as federal requirements, an application for approval of a state 

program revision that adopts §141, Subparts U and V, must contain a description of how the state will 

implement a procedure for addressing modification of wholesale system and consecutive system 

monitoring on a case-by-case basis for part 141 Subpart V outside the provisions of §141.29 of this 

chapter, if the state elects to use such an authority. The procedure must ensure that all systems have at 

least one compliance monitoring location. 

Guidance 

§141.29 allows states to modify monitoring requirements of consecutive systems to the extent that the 

interconnection of the systems justifies treating them as a single system for monitoring purposes. 

The Stage 2 DBPR gives states the opportunity to specify alternative monitoring requirements for 

multiple consecutive systems in a combined distribution system. These modifications must not undermine 

public health protection and all systems, including consecutive systems, must comply with the TTHM and 

HAA5 MCLs based on the LRAA. However, such a program would allow the state to establish 

monitoring requirements that account for complicated distribution system relationships, such as where 

neighboring systems buy from and sell to each other regularly throughout the year, water passes through 

multiple consecutive systems before it reaches a user, or a large group of interconnected systems have a 

complicated combined distribution system. 

If states choose to address this issue and develop procedures for addressing consecutive systems outside 

the provisions of the Stage 2 DBPR, they should consider the following: 

• As a minimum, each consecutive system must collect at least one sample among the total number 

of samples required for the combined distribution system. Each consecutive system must base 

compliance on samples collected within its distribution system. 

• The consecutive system is responsible for ensuring that required monitoring is completed and the 

system is in compliance. 

• The consecutive system may conduct the monitoring itself or arrange for the monitoring to be 

done by the wholesale system or another outside party. Whatever approach it chooses, the 

consecutive system must document its monitoring strategy as part of its DBP monitoring plan. 

Stage 2 DBPR Implementation Guidance 140 August 2007 
States can satisfy the special primacy condition regarding consecutive system monitoring by including a 

copy of the procedure they will use for addressing consecutive systems outside the provisions of §141.29. 

Alternatively, states can simply attest that they will not use an authority to address consecutive system 

monitoring outside of §141.29. 

References for more detailed guidance

1. USEPA. Consecutive System Guidance Manual. EPA XXX-X-XX-XXX. Unpublished, check the 

following Web site for availability: www.epa.gov/safewater/disinfection/stage2. 

2. AWWARF. 2002. Guidance Manual for Monitoring Distribution System Water Quality. Denver, 

CO. 325 pp. 

3. Routt, J.C., N.G. Pizzi. 2000. Kentucky-American Water's Cooperative, Step-wise Process of 

Assisting Two Small Contiguous Systems in Complying with Pending D/DBP Requirements. 

Proceedings AWWA WQTC, November 2000. 

4. Taylor, J.S. et al. 2005. Effects of Blending on Distribution System Water Quality. AWWARF. 

Denver, CO. 

5. AWWA. 2004. G200-04: Distribution System Operations and Management. Denver, CO. 

6. AWWA. 2003. Principles and Practices of Water Supply Operations: Water Transmission and 

Distribution, Third Edition. Denver, CO. 553 pp. 

7. Lauer, William C., ed. 2005. Water Quality in the Distribution System. AWWA. Denver, CO. 

1,083 pp. 

Stage 2 DBPR Implementation Guidance 141 August 2007 
Stage 2 DBPR Implementation Guidance 142 August 2007 

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Section 5 

SDWIS Reporting and SNC 

Definitions 

Note: This section is under development. 
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Section 6 

Public Notification and 

Consumer Confidence Report 

Examples 
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This section provides examples of violations that systems may incur under the Stage 2 DBPR. These 

examples address the public notification and CCR requirements for systems that incur these kinds of 

violations. Public notification and notification in the CCR are required follow-up activities for violations 

of the National Primary Drinking Water Regulations. Also included in the examples are sample public 

notices and sample excerpts from CCR reports that would meet these public notification and CCR 

requirements. In the public notification samples, the language in italics is required in Appendix B to 

Subpart Q of 40 CFR 141. 

EPA has developed CCRWriter and CCRiWriter to help CWSs quickly create their CCRs. The 

CCRWriter is a desktop application. A CD-ROM of the software can be ordered by contacting the Safe 

Drinking Water Hotline at 1-800-426-4791. The CCRiWriter is a web-based version of the CCRWriter 

and requires internet access to use. The CCRiWriter can be obtained from EPA’s Web site at 

www.epa.gov/safewater/ccr/tools.html. 

Stage 2 DBPR Implementation Guidance 147 August 2007 
Issue 1: TTHM MCL Violation 

System Description - System A 

System A is a small Subpart H system that uses two large ground water wells determined to be under the 

direct influence of surface water. The system treats the water from each well by filtration through bag and 

cartridge filters and by disinfection with chlorine on a full-time basis. The system utilizes two 

filtration/disinfection treatment plants known as WTP 1 and WTP 2. 

Population Served: 8,200

Source #1: Well 1

Treatment: Filtration, chlorine

Source #2: Well 2

Treatment: Filtration, chlorine

This system was required to comply with the TTHM and HAA5 RAA requirement under the Stage 1 

DBPR but is now required to comply with the LRAA requirement on Schedule 4 under Stage 2 DBPR. 

System A conducted E. coli monitoring under the LT2ESWTR and was able to avoid Cryptosporidium

monitoring, so it must begin complying with Stage 2 DBPR by October 1, 2013. Note that for compliance 

with Stage 2 DBPR, System A is required to collect two dual sample sets per quarter at representative 

high TTHM and HAA5 sites. 

The operator takes the dual samples during times when the disinfection systems are operating under 

normal conditions and collects the samples at the locations and according to the schedule specified in the 

provisions of the system’s Compliance Monitoring Plan. 

Situation

Table 6-1 summarizes the Stage 2 DBPR TTHM monitoring results for four quarters at two sites 

beginning October 1, 2013. In July 2014, System A’s operator collects the fourth scheduled set of two 

TTHM samples (at locations defined in the Compliance Monitoring Plan). The operator enters the values 

on the TTHM monitoring forms and calculates a quarterly arithmetic average concentration for each 

sampling location. 

Table 6-1. System A 2014 TTHM Monitoring Results 

Distribution System Results (mg/L) 

Quarterly Sampling Dates Location 1 Location 2 

October 2013 0.030 0.020 

January 2014 0.063 0.059 

April 2014 0.200 0.072 

July 2014 0.300 0.078 

Sum 0.593 0.229 

÷ 4 0.148 0.057 

Compliance Calculation 4th Quarter LRAA 0.148 > 0.08 0.057 < 0.08 

Stage 2 DBPR Implementation Guidance 148 August 2007 
Public Notification and Consumer Confidence Report Requirements

System A has completed a full year of monitoring under Stage 2 DBPR and must use this data to compute 

LRAAs at each location. (After this time, the system will compute LRAAs each quarter.) The operator 

sums quarterly TTHM results and divides by 4 to determine LRAA compliance with the Stage 2 DBPR 

MCL of 0.08 mg/L. The TTHM result for location 1 is 0.148 mg/L; therefore, the operator must report an 

MCL violation. The LRAA for location 2 is below the MCL. 

This is an MCL violation and requires Tier 2 public notification. The system must provide public 

notification as soon as practical but no later than 30 days after of learning of the violation. Notification 

must be provided by mail or other direct delivery method (such as hand delivery), and any other method 

reasonably expected to reach affected individuals that would not have received the information by mail or 

the direct delivery method used. The system was aware of the violation on July 15, 2014. 

An example of a public notice that fulfills the public notification requirements for these violations is 

shown in Example 6-1. 

All MCL violations must also be included in the CCR. An explanation of how the system returned to 

compliance could also be included. An example of a report of these violations that could be used in the 

system’s CCR is shown in Example 6-2. 

Stage 2 DBPR Implementation Guidance 149 August 2007 
Example 6-1. Example Tier 2 Public Notification for TTHM MCL Violation 

IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER 

TTHM MCL Violation at System A 

Our water system recently violated a drinking water standard. Although this incident was not an emergency, as 

our customers, you have a right to know what happened and what we did to correct this situation. 

We routinely monitor for the presence of drinking water contaminants. Testing results from October 2013 to July 

2014 show that our system exceeds the standard, or maximum contaminant level (MCL), for total trihalomethanes 

(TTHMs). We became aware of this situation on July 15, 2014. The standard for TTHMs is 0.080 mg/L averaged 

at each sampling location for a year. The level of TTHMs averaged at one location for a year was 0.148 mg/L. 

What should I do?

There is nothing you need to do unless you have a severely compromised immune system, have an infant, or are 

elderly. These people may be at increased risk and should seek advice about drinking water from their health care 

providers. If you have specific health concerns, consult your doctor. 

You do not need to boil your water or take other corrective actions. If a situation arises where the water is no 

longer safe to drink, you will be notified within 24 hours. We will announce any emergencies on Channel 22 or 

Radio Station KMMM (97.3 FM). 

What does this mean? 

This is not an emergency. If it had been, you would have been notified within 24 hours. 

Some people who drink water containing trihalomethanes in excess of the MCL over many years may experience 

problems with their liver, kidneys, or central nervous system, and may have an increased risk of getting cancer. 

What is being done?

TTHMs are four volatile organic chemicals which form when disinfectants react with natural organic matter in the 

water. We are working to minimize the formation of TTHMs while ensuring an adequate level of disinfection to 

protect customers from exposure to bacteria. We have since taken samples at this location and throughout the 

system and had them tested. They show that we now meet the standards. 

For more information, please contact John Johnson, manager of System A, at 555-1234 or write to 2600 Winding 

Rd., Townsville, SA 12345. 

Please share this information with all the other people who drink this water, especially those who may not have 

received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can 

do this by posting this notice in a public place or distributing copies by hand or mail.

This notice is being sent to you by System A. 

State Water System ID# SA1234582. Sent: July 20, 2014 

Stage 2 DBPR Implementation Guidance 150 August 2007 
Example 6-2. Example of a Notice in the CCR for TTHM MCL Violation 

Water Quality Data

Contaminant MCL MCLG Detected Date Violation Source 

TTHMs [Total Avg=148 By-product of 

trihalomethanes] 

(ppb) (LRAA) 120 0 

Range: 30 - 

300 

July 

2014 Yes* 

drinking water 

chlorination 

*System A exceeded the MCL for TTHMs at the end of July. The system’s locational running annual 

average (LRAA) for location 1 was 148 ppb. More information about this violation is provided in the 

violation section. 

Violation

Testing results from October 2013 to July 2014 show that our system exceeds the standard, or 

maximum contaminant level (MCL), for total trihalomethanes (TTHMs). The standards for 

TTHMs are 0.080 mg/L averaged at any individual monitoring location averaged over the year. 

The level of TTHMs averaged over an individual monitoring location was 0.148 mg/L. TTHM 

are four volatile organic chemicals which form when disinfectants react with natural organic 

matter in the water. We are working to minimize the formation of TTHMs while ensuring an 

adequate level of disinfection to protect customers from exposure to bacteria. 

We have since taken samples at this location and throughout the system and had them tested. 

They show that we meet the standards. 

• 

• 

Stage 2 DBPR Implementation Guidance 151 August 2007 
Issue 2: LRAA and Compliance Calculations for TTHM and HAA5 M&R Violations 

System Description - System B 

System B is a small Subpart H system serving 8,900 people. They are on Schedule 4 and the requirements 

of Stage 2 DBPR are applicable on or before October 1, 2014 because System B is required to monitoring 

for Cryptosporidium under the LT2ESWTR. 

The system uses surface water treated at a conventional filtration plant. The system uses chlorine as a 

chemical disinfectant applied at one location and must monitor TTHM and HAA5 according to the 

requirements of §141.621(a). Under the Stage 2 DBPR, samples must be taken in the distribution system 

at a frequency of two dual sample sets every 90 days. One quarterly set must be taken during the peak 

historical month for DBP concentrations. All monitoring must take place at the locations recommended to 

the primacy agency in the IDSE Report submitted under §141.600–605. 

Population Served: 8,900 

Source: Surface water 

Treatment: Conventional filtration, chlorine 

Situation

Table 6-2 presents a summary of System B’s TTHM and HAA5 monitoring results. 

Table 6-2. System B 2014 TTHM and HAA5 Monitoring Results (mg/L) 

2014 2015

Parameter JUL AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUN

TTHM Site 1 0.068 0.070 0.070 

MCL = 

0.080 

mg/L Site 2 0.072 0.070 0.068 

HAA5 Site 1 0.042 0.055 0.038 

MCL = 

0.060 

mg/L Site 2 0.040 0.060 0.046 

2016 2017

Parameter JUL AUG SEPT OCT NOV DEC JAN FEB MAR APR MAY JUN LRAA

TTHM Site 1 NS 0.069 

MCL = 

0.080 

mg/L Site 2 NS 0.070 

HAA5 Site 1 NS 0.045 

MCL = 

0.060 

mg/L Site 2 NS 0.049 

NS=No sample taken 

LRAA=Locational running annual average 

Stage 2 DBPR Implementation Guidance 152 August 2007 
In August 2015, System B reviews the data for the first year of compliance monitoring for the Stage 2 

DBPR. However, System B did not complete the necessary monitoring of TTHM and HAA5 in the fourth 

quarter, July 2015. 

Public Notification and Consumer Confidence Report Requirements

System B’s sampling record shows a major monitoring and reporting (M&R) violation in 2015 resulting 

from a failure to take the required samples. In this case, when only two samples per quarter are required, 

the failure to sample for one quarter is a major M&R violation and must be reported to SDWIS for both 

TTHM and HAA5. 

The system must provide Tier 3 public notice of the violation within 1 year of learning of the violation. 

Notification must be provided by mail or other direct delivery method (such as hand delivery), and any 

other reasonably expected method to reach affected individuals that would not have received the 

information by mail or the direct delivery method used. 

Since System B is a CWSs, it could use the CCR to inform the public of the Tier 3 violations if the CCR 

is released within 1 year of the system’s learning of the violations. For this particular example, the system 

became aware of the violations on August 15, 2015. The public could therefore be informed of the 

violation in the CCR produced for calendar year 2015 if the CCR is released prior to July 1, 2016 (the 

CCR for calendar year 2015 is required to be released by July 1, 2016, for compliance with the CCR 

Rule). In this situation, additional public notification would not be required. However, whether public 

notification is provided by the CCR for calendar year 2015 or by other means, this violation would still 

have to be reported by the system in the CCR produced for calendar year 2015, since all violations of 

National Primary Drinking Water Rules must be reported in the CCR for the calendar year in which the 

system became aware of the violation. The violation report in the CCR should include similar information 

contained in the public notice. 

An example of a public notice that fulfills the public notification requirements for this violation is shown 

in Example 6-3. An example of a report of this violation in the CCR is shown in Example 6-4. 

Stage 2 DBPR Implementation Guidance 153 August 2007 
Example 6-3. Example Tier 3 Public Notification for LRAA and Compliance Calculations 

for TTHM and HAA5 M&R Violations 

IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER 

Monitoring and Reporting Requirements Not Met for System B 

Our water system recently failed to collect the correct number of drinking water samples. Although this incident 

was not an emergency, as our customers, you have a right to know what happened and what we did to correct this 

situation. 

We routinely monitor for the presence of drinking water contaminants. In July 2015 our system failed to collect 

the required number of samples to test for total trihalomethanes (TTHMs) and haloacetic acids (HAA5s) in our 

drinking water. We became aware of this situation on August 15, 2015. Based on the data we collected over the 

past year, we are not in violation of the standards for either TTHM or HAA5s. The standard for TTHMs is 0.080 

mg/L at any individual monitoring location averaged over the year and for HAA5 is 0.060 mg/L at any individual 

monitoring location averaged over the year. 

What should I do?

There is nothing you need to do. You do not need to boil your water or take other corrective actions. You may 

continue to drink the water. If a situation arises where the water is no longer safe to drink, you will be notified 

within 24 hours. We will announce any emergencies on Channel 22 or Radio Station KMMM (97.3 FM). 

What was done?

TTHMs and HAA5s are a group of chemicals that are formed when chlorine or other disinfectants used to control 

microbial contaminants in drinking water react with naturally occurring organic and inorganic matter in water. 

We are working to minimize the formation of TTHMs and HAA5s while ensuring an adequate level of 

disinfection to protect customers from exposure to bacteria. 

We have set-up new procedures at the systems to ensure all samples are collected and analyzed according to our 

monitoring plan. 

For more information, please contact John Johnson, manager of System B, at 555-1234 or write to 2600 Winding 

Rd., Townsville, SA 12345. 

Please share this information with all the other people who drink this water, especially those who may not have 

received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can 

do this by posting this notice in a public place or distributing copies by hand or mail.

This notice is being sent to you by System B. 

State Water System ID# SA1234589. Sent: August 22, 2015

Stage 2 DBPR Implementation Guidance 154 August 2007 
Example 6-4. Example of a Notice in the CCR for LRAA and Compliance Calculations for 

TTHM and HAA5 M&R Violations 

Violation

Our water system recently failed to collect the correct number of drinking water samples. We 

routinely monitor for the presence of drinking water contaminants. In July 2015, our system failed to 

collect the required number of samples to test for total trihalomethanes (TTHMs) and haloacetic acids 

(HAA5s) in our drinking water. Using the data we have collected over the past year, we are not in 

violation of the standards for either TTHM or HAA5s. The standards for TTHMs are 0.080 mg/L at 

any individual monitoring location averaged over the year and for HAA5s are 0.060 mg/L at any 

individual monitoring location averaged over the year. 

TTHMs and HAA5s are a group of chemicals that are formed when chlorine or other disinfectants 

used to control microbial contaminants in drinking water react with naturally occurring organic and 

inorganic matter in water. We are working to minimize the formation of TTHMs and HAA5s while 

ensuring an adequate level of disinfection to protect customers from exposure to bacteria. Since we 

failed to collect the correct number of samples in July 2015, any potential health effects related to the 

use of that water are unknown. 

We have set-up new procedures at the systems to ensure all samples are collected and analyzed 

according to our monitoring plan. 

• 

• 

• 

Stage 2 DBPR Implementation Guidance 155 August 2007 
Issue 3: Bromate M&R Violation 

System Description - System D 

System D is a small Subpart H CWS that serves 4,700 people. They have one surface water source, and 

treat with a direct filtration plant that uses both ozone and chlorine as disinfectants. Because they use 

ozone, under the Stage 1 DBPR, System D was required to monitor for bromate at the entrance to the 

distribution system from their plant. The routine monitoring frequency was monthly, but the system was 

able to qualify for reduced monitoring of quarterly sampling because their monthly source water bromide 

RAA levels were less than 0.05 mg/l. 

Population Served: 4,700

Source: Surface water

Treatment: Softening plant, ozone, chlorine

After March 31, 2009, if System D wants to continue reduced monitoring for bromate, they will need 

qualify using the new criteria under the Stage 2 DBPR. To meet the new criteria for reduced monitoring, 

System D needs to conduct monthly monitor for bromate for 1 year using Method 317.0 Revision 2.0, 

326.0, or 321.8. Note that systems cannot use Method 300.1 to qualify for reduced monitoring. 

Situation

In April 2009, System D discontinues its bromide sampling and begins sampling monthly for bromate 

using one of the new sampling methods. By March 2010, System D has a full year of monthly samples, 

and their RAA is 0.0015. This is below 0.0025 mg/L so the system now qualifies for reduced bromate 

sampling. In the second quarter of 2010, the system begins quarterly monitoring. However, in December 

2010, their Bromate RAA is 0.0060 mg/L which exceeds 0.0025 mg/l. The system should have resumed 

monthly monitoring at that point. 

On April 12, 2011, the state sent System D a letter indicating that their records showed that the system 

had failed to resume routine monitoring. System D began routine monitoring that month. 

Table 6-3 summarizes System D’s bromate monitoring results. 

Table 6-3. System C Bromate and Bromide Monitoring Results (mg/L) 

JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC 

2008 Bromide 0.004 0.003 0.002 0.002

Bromate 

2009 Bromide 0.01 

Bromate 0.0010 0.0020 0.0015 0.0016 0.0010 0.0020 0.0010 0.0005 0.0010 0.0025

2010 Bromide 

Bromate 0.0020 0.0020 0.0010 0.0020 0.0025 0.0060

Stage 2 DBPR Implementation Guidance 156 August 2007 
Stage 2 DBPR Implementation Guidance 157 August 2007 

JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV DEC 

2011 Bromate NS NS 0.0010 0.0020 0.0025 0.0018 0.0010 0.0023 0.0026 0.0024 0.0020

2012 Bromate 0.0010 0.0010 0.0020 0.0022 0.0010 0.0020 

Note: RAAs are calculated on a quarterly basis for Bromide and Monthly for Bromate. RAA = Running Annual 

Arithmetic Average 

NS = No samples taken 

Public Notification and Consumer Confidence Report Requirements

System D is not eligible for a reduction in monitoring frequency after the month of December 2010 

because the bromate RAA (0.0030 mg/L) is greater than 0.0025 mg/L for the four most recent quarters. 

Beginning in January 2011, System D is required to begin monitoring monthly for bromate. Since System 

D did not collect another bromate sample until March 2011, System D is in violation of the monitoring 

and reporting requirement. 

 

The system must provide Tier 3 public notice of the violation within 1 year of learning of the violation. 

Notification must be provided by mail or other direct delivery method (such as hand delivery), and any 

other method reasonably expected to reach affected individuals that would not have received the 

information by mail or the direct delivery method used. 

Since System D is a CWS, it could use the CCR to inform the public of the Tier 3 violations provided that 

the CCR is released within 1 year of the system’s learning of the violation. This system was alerted to the 

violation on April 12, 2011, therefore the system would need to use the CCR produced for calendar year 

2011to inform the public of the violation. The system could use this CCR if the CCR is released prior to 

April 12, 2012 (the CCR for calendar year 2011 is required to be released by July 1, 2012, for compliance 

with the CCR Rule). In this situation, additional public notification would not be required. 

However, whether public notification is provided by the CCR for calendar year 2011 or by other means, 

this violation would still have to be reported by the system in the CCR produced for calendar year 2011. 

All violations of National Primary Drinking Water Rules must be reported in the CCR for the calendar 

year in which the system became aware of the violation. The violation report in the CCR should include 

similar information contained in the public notice. 

An example of a public notice that fulfills the public notification requirements for this violation is shown 

in Example 6-5. An example of a report of this violation in the CCR is shown in Example 6-6. 
Example 6-5. Example Tier 3 Public Notification for Bromate M&R Violation 

IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER 

Monitoring and Reporting Requirements Not Met for System D 

On April 12, 2011 we became aware that our system recently failed to collect the correct number of drinking 

water samples. Although this incident was not an emergency, as our customers, you have a right to know what 

happened and what we did to correct this situation. 

Our system qualified to reduce the number of samples we are required to analyze for bromate in March 2010. 

Bromate is a chemical that is formed when a system uses ozone to disinfect drinking water and it reacts with 

naturally occurring bromide in source water. We were allowed to take 1 sample per quarter rather than 1 sample 

per month. In December 2010, the running annual average exceeded 0.0025 mg/L and we no longer qualify for 

reduced quarterly bromate monitoring. Beginning in January 2011, we failed to begin monitoring monthly for 

bromate. 

What should I do?

There is nothing you need to do. You do not need to boil your water or take other corrective actions. You may 

continue to drink the water. If a situation arises where the water is no longer safe to drink, you will be notified 

within 24 hours. We will announce any emergencies on Channel 22 or Radio Station KMMM (97.3 FM). 

What was done?

We began monitoring monthly for bromate in April 2011 and will continue to monitoring on this schedule until or 

unless we qualify for reduced monitoring. 

For more information, please contact John Johnson, manager of System D, at 555-1234 or write to 2600 Winding 

Rd., Townsville, SA 12345. 

Please share this information with all the other people who drink this water, especially those who may not have 

received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can 

do this by posting this notice in a public place or distributing copies by hand or mail.

This notice is being sent to you by System D. 

State Water System ID# SA1234589. Sent: May 15, 2011

Stage 2 DBPR Implementation Guidance 158 August 2007 
Example 6-6. Example of a Notice in the CCR for Bromate M&R Violation 

Violation

• Our system failed to collect the correct number of drinking water samples. Our system qualified to 

reduce the number of samples required to monitor for bromate in March 2010. Bromate is a chemical 

that is formed when a system uses ozone to disinfect drinking water and it reacts with naturally 

occurring bromide in source water. We were allowed to take 1 sample per quarter rather than 1 sample 

per month. In December 2010, the running annual average exceeded 0.0025 mg/L and we no longer 

qualify for reduced quarterly bromate monitoring. Beginning in January 2011, we failed to begin 

monitoring monthly for bromate. Since we failed to collect the correct number of samples in 2011, 

any potential health effects related to the use of that water are unknown. 

• We began monitoring monthly for bromate in April 2011 and will continue to monitoring on this 

schedule until reduced monitoring is again appropriate. 

Stage 2 DBPR Implementation Guidance 159 August 2007 
Stage 2 DBPR Implementation Guidance 160 August 2007 

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