United States Office of Water EPA 816-R-01-014

Environmental Protection (4606) June 2001

Agency

The Stage 1 Disinfectants and

Disinfection Byproducts Rule

What Does it Mean to You?
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Contents

Definitions and Abbreviations ....................................................... 1

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

Purpose of the Guide ....................................................... 3

Background .............................................................. 3

Development of the Rule ..................................................... 5

Benefits of the Rule ........................................................ 5

2. Applicability and Compliance Dates ................................................. 5

3. Summary of regulatory requirements ................................................ 7

MCLGs and MCLs for disinfection byproducts ..................................... 7

MRDLGs and MRDLs for disinfectant residuals .................................... 8

Treatment technique for disinfection byproduct precursors ............................ 8

Best available technology (BAT) ............................................... 8

Public water system recordkeeping and reporting requirements .......................... 9

Laboratory methods and certification ............................................ 9

4. Additional information .......................................................... 9

5. Detailed regulatory requirements .................................................. 10

Subpart H systems serving at least 10,000 people .................................. 13

Subpart H systems serving 500 to 9,999 people .................................... 19

Subpart H systems serving fewer than 500 people .................................. 25

Ground water systems serving at least 10,000 people ................................ 31

Ground water systems serving fewer than 10,000 people ............................. 37

Systems using chlorine dioxide ............................................... 43

Systems using ozone ...................................................... 49

Subpart H systems using conventional filtration treatment ............................. 53
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Page 1

Definitions and Abbreviations

Definitions

Enhanced coagulation ---- the addition of sufficient coagulant for improved removal of disinfection

byproduct precursors by conventional filtration treatment.

Enhanced softening ---- the improved removal of disinfection byproduct precursors by precipitative

softening.

Maximum residual disinfectant level (MRDL) ---- a level of a disinfectant added for water treatment

that may not be exceeded at the consumer’s tap without an unacceptable possibility of adverse health

effects.

Maximum residual disinfectant level goal (MRDLG) ---- the maximum level of a disinfectant added

for water treatment at which no known or anticipated adverse effect on the health of persons would

occur, and which allows an adequate margin of safety. MRDLGs are nonenforceable health goals and do

not reflect the benefit of the addition of the chemical for control of waterborne microbial contaminants.

SUVA ---- Specific Ultraviolet Absorption at 254 nanometers (nm), an indicator of the humic content of

water. It is a calculated parameter obtained by dividing a sample’s ultraviolet absorption at a wavelength

of 254 nm (UV 254) (in m -1 ) by its concentration of dissolved organic carbon (DOC) (in mg/L).

Total Organic Carbon (TOC) ---- total organic carbon in mg/L measured using heat, oxygen, ultraviolet

irradiation, chemical oxidants, or combinations of these oxidants that convert organic carbon to carbon

dioxide, rounded to two significant figures.

Abbreviations Used in This Document

BAT: Best Available Technology

CDC: Centers for Disease Control and Prevention

CWS: Community Water System

DBP: Disinfection Byproducts

DBPP: Disinfection Byproducts Precursors 

EC: Enhanced Coagulation

EPA: United States Environmental Protection Agency

ES: Enhanced Softening

ESWTR: Enhanced Surface Water Treatment Rule

FACA: Federal Advisory Committee Act

FR: Federal Register

GAC10: Granular Activated Carbon with ten minute empty bed contact time and 180 day reactivation

frequency

GWR: Ground Water Rule

GWUDI: Ground Water Under the Direct Influence of Surface Water

HAA5: Haloacetic Acids (five)(chloroacetic acid, dichloroacetic acid, trichloroacetic acid, bromoacetic

acid and dibromoacetic acid)

ICR: Information Collection Rule (issued under section 1412(b) of the SDWA)

IESWTR: Interim Enhanced Surface Water Treatment Rule

Log Inactivation: Logarithm of (N0/NT)
Page 2

Log: Logarithm (common, base 10)

LT1ESTWR: Long-Term 1 Enhanced Surface Water Treatment Rule

LT2ESWTR: Long-Term 2 Enhanced Surface Water Treatment Rule

MCL: Maximum Contaminant Level

MCLG: Maximum Contaminant Level Goal

M–DBP: Microbial and Disinfectants/Disinfection Byproducts

mg/L: Milligrams per Liter

MR: Monitoring/Reporting

MRDL: Maximum Residual Disinfectant Level

MRDLG: Maximum Residual Disinfectant Level Goal

NIPDWR: National Interim Primary Drinking Water Regulation

NSCEP: National Service for Environmental Publications

NTIS: National Technical Information Service

NTNCWS: Non-Transient Non-Community Water System

PWS: Public Water System

PWSS: Public Water Supply Supervision Program

Reg. Neg.: Regulatory Negotiation

SDWA: Safe Drinking Water Act, or the ‘‘Act,’’ as amended 1996

SDWIS: Safe Drinking Water Information System

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

TCR: Total Coliform Rule

TNCWS: Transient Non-Community Water Systems

TOC: Total Organic Carbon

TTHM: Total Trihalomethanes (chloroform, bromdichloromethane, dibromochloromethane, and

bromoform)
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1. Introduction

Purpose of the Guide

The purpose of this guide is to detail the regulatory requirements of the Stage 1

Disinfectants/Disinfection Byproducts Rule (Stage 1 DBPR). The Stage 1 DBPR, published in the

Federal Register on December 16, 1998 (63 FR 69390; www.epa.gov/OGWDW/mdbp/dbpfr.html;

66 FR 3770; www.epa.gov/safewater/mdbp/iesfr.html), is the first part of a series of rules, the

“Microbial-Disinfectants/Disinfection Byproducts Cluster” (M-DBP Cluster), to be published over the

next several years that are intended to control microbial pathogens while minimizing the public health

risks of disinfectants and disinfection byproducts (DBPs). The Stage 1 DBPR specifically addresses risks

associated with disinfectants and DBPs. This rule was published concurrently with the Interim Enhanced

Surface Water Treatment Rule (IESWTR), which addresses control of microbial pathogens.

Background

The 1974 Safe Drinking Water Act (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 (TTHMs), a group of four volatile organic chemicals

which form when disinfectants react with natural organic matter in the water. 

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

1974 law occurred when SDWA was reauthorized in 1986. Disease-causing microbial contamination

had not been sufficiently controlled under the original Act. To safeguard public health, the 1986

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

maximum contaminant levels (MCLs) for 83 named contaminants. EPA was also required to establish

regulations within certain time frames, require disinfection of all public 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 (NPDWR): 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.

The TCR covers all public water systems. Since coliforms are easily detected in water, they are used to

indicate a water system’s vulnerability to pathogens in the water. In the TCR, EPA set a MCLG of zero

for total coliforms. EPA also set a MCL for total coliforms. 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. In addition, sanitary surveys are required every five or ten years (depending on the quality of the

source water) for every system that collects fewer than five samples per month (typically systems that

serve less than 4,100 people).

EPA issued the SWTR in response to Congress’ mandate requiring disinfection, and where necessary,

filtration of systems that draw their water from surface sources before distribution. The SWTR applies to

all systems that use surface water or ground water under the direct influence of surface water (GWUDI). 

The rule sets MCLGs for Legionella, Giardia lamblia, and viruses at zero since any exposure to these

contaminants presents some level of health risk. 

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

water concentration of Giardia lamblia and viruses by at least 99.9 percent (3 log) and 99.99 percent (4

log), respectively. A detectable disinfection residual must be maintained throughout the entire

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

measuring the turbidity of the treated water since high levels of turbidity often indicate that the filtration

process is not working properly. The goal of the SWTR is to reduce risk to less than one infection per
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year per 10,000 people. However, the SWTR does not account for systems with high pathogen

concentrations that, when treated at the levels required under the rule, still may not meet this health goal,

and the rule does not specifically control for the protozoan Cryptosporidium.

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

disease-causing microbial contaminants (i.e., 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 1994, 379 waterborne

disease outbreaks were reported, with over 500,000 cases of disease. During this period, a number of

agents were implicated as the cause, including protozoa, viruses, bacteria, and several chemicals. Most of

the cases (but not the outbreaks) were associated with surface water, including a single outbreak of

cryptosporidiosis in Milwaukee (over 400,000 cases).

In response to these findings, 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 public water systems, and the estimated reduction in health risks that would result from

further regulation. The Act also increased scientific research requirements and emphasized cost-benefit

analyses in the regulatory decision process. 

Based on prevailing scientific data, the M-DBP Cluster is intended to control microbial pathogens while

minimizing the public health risk from disinfectants and DBPs. Since multiple threats require multiple

barriers, the IESWTR and Stage 1 DBPR expand on the foundation of the TCR, SWTR, and TTHM

standards to target health risk outliers unaddressed by prior regulations.

The TTHM NPDWR of 1979 set a standard for TTHMs only for public water systems (PWSs) serving

10,000 or more people. The Stage 1 DBPR builds on the TTHM Rule by lowering the MCL and

widening the range of affected systems to include all PWSs that add a disinfectant. Therefore, EPA

believes that the promulgation of the Stage 1 DBPR will significantly decrease the risks posed by DBPs

and disinfectants by covering many PWSs not currently regulated for TTHM or other DBPs. 

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

cause disease. The public health benefits of common disinfection practices are significant and wellrecognized; however, disinfection poses risks of its own. While disinfectants are effective in controlling

many harmful microorganisms, they react with organic and inorganic matter (disinfection byproduct

precursors—DBPPs) in the water and form DBPs, some of which pose health risks at 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 at high doses, the weight-of-evidence indicates that DBPs present a

potential public health problem that must be addressed. One of the most complex questions facing water

supply professionals is how to reduce risks from disinfectants and DBPs while providing increased

protection against microbial contaminants. Much of the population is exposed to these risks; therefore, a

substantial concern exists.

To address this concern, the Stage 1 DBP Rule updates and supersedes the 1979 TTHM standard by

lowering the MCL for TTHMs and establishing maximum residual disinfection level (MRDL) limits for

chlorine, chloramines, and chlorine dioxide and new MCLs for chlorite, bromate, and haloacetic acids

(HAA5) for all community water systems and nontransient noncommunity water systems that add a

chemical disinfectant for either primary or residual treatment. In addition, the Stage 1 DBP Rule requires

conventional filtration systems to remove specified percentages of organic materials measured as total

organic carbon (TOC) that may react with disinfectants to form DBPs. 
Page 5

By building on the foundation set forth by the original SDWA, the quality of drinking water has

improved and public health protection has increased. The IESWTR and Stage 1 DBP Rules are part of a

series of rules designed to expand on the foundation of prior rulemaking efforts. By encompassing

previously unaddressed health risks from microbials and disinfection byproducts, the M-DBP Cluster

continues to maximize drinking water quality and public health protection.

Development of the Rule

The new rules are a product of 6 years of collaboration among the water supply industry, environmental

and public health groups, and local, state, and federal governments. EPA first launched a rule-making

process in 1992 and convened a Regulatory Negotiation (RegNeg) Advisory Committee under the

Federal Advisory Committee Act (FACA), representing a range of stakeholders affected by possible

regulation. The 1996 SDWA Amendments required EPA to develop rules to balance the risks between

microbial pathogens and disinfection byproducts. 

In 1997, a similar FACA process was implemented with the Microbial-Disinfectants/Disinfection

Byproducts (M-DBP) Advisory Committee. The M-DBP Committee convened to collect, share, and

analyze new information available since 1994, review previous assumptions made during the RegNeg

process, as well as build consensus on the regulatory implications of this new information. Negotiations

resulted in the following three proposals: 

C A staged approach to regulation of DBPs (referred to as the Stage 1 and Stage 2 DBPRs)

incorporating Maximum Contaminant Levels (MCLs), Maximum Residual Disinfectant

Levels (MRDLs), and treatment technique requirements;

C A companion Interim Enhanced Surface Water Treatment Rule (IESWTR) designed to

improve control of microbial pathogens and prevent inadvertent reductions in microbial

safety as a result of DBP control efforts; and,

C An Information Collection Rule (ICR) to collect information necessary to reduce many

key uncertainties prior to subsequent negotiations for the Stage 2 DBPR.

Benefits of the Rule

The Stage 1 DBPR is expected to reduce the risks associated with exposure to disinfectants and DBPs.

The MCLs will reduce exposure to specific DBPs from the use of ozone (byproduct: bromate), chlorine

dioxide (byproduct: chlorite), and chlorine (byproducts: TTHM and five Haloacetic Acids—(HAA5)). In

addition, the implementation of a treatment technique (enhanced coagulation/ enhanced softening) will

reduce overall exposure to the broad range of non-specified DBPs. In the Regulatory Impact Analysis for

the Stage 1 DBPR, EPA estimated that the rule will result in a national annual average reduction in

TTHM levels of 24 percent. As many as 140 million people will have increased protection from DBPs

and their potential health risks, including bladder cancer and adverse developmental and reproductive

health effects. 

2. Applicability and Compliance Dates

The 1979 Total Trihalomethane (TTHM) Rule requirements apply only to systems serving 10,000 or

more people. The Stage 1 Disinfectants and Disinfection Byproducts Rule (DBPR) covers a larger

number of PWSs, applying to all community water systems (CWSs) and nontransient noncommunity

water systems (NTNCWSs) which add a chemical disinfectant to the water in any part of the drinking

water treatment process. In addition, certain requirements apply to transient noncommunity water

systems (TNCWSs) that use chlorine dioxide.
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Subpart H systems (PWSs that use that use surface water or ground water under the direct influence of

surface water—GWUDI—as a source) serving 10,000 or more people must comply with the

requirements of the Stage 1 DBPR no later than January 2002. Subpart H systems that serve fewer than

10,000 people, and all affected ground water systems, must comply with the requirements no later than

January 2004. 

The timetable for the Stage 1 DBPR is presented in Table 1. The Stage 1 DBPR and the IESWTR were

published simultaneously to address the inherent tradeoffs between protection from microbial

contamination and the potential health effects from disinfectants and their byproducts. These rules are

the first in a series of rules that will continue to address the public health concerns associated with

microbial pathogens and chemical disinfectants.

Table 1: Timetable for the Stage 1 DBPR Requirements

Date DBPR Requirement

December 16, 1998 Rule is published in Federal Register [63 FR 241 69390].

February 16, 1999 60-day legal challenge period ends.

February 16, 1999 Methods specified in 40 CFR 141.131 for analyzing disinfection byproducts, disinfection

residuals, and DBP precursors are approved for use [40 CFR 141.131(a)].

January 1, 2001 Large Subpart H systems should begin monitoring to determine Step 1 TOC removal

before the compliance date. 

January 1, 2002 Large Subpart H CWSs and NTNCWSs must comply with the MCLs for TTHM, HAA5,

bromate, and chlorite [40 CFR 141.64(b)(1)].

January 1, 2002 Large Subpart H CWSs and NTNCWSs must comply with the MRDLs for chlorine,

chloramines, and chlorine dioxide [40 CFR 141.65(b)(1)].

January 1, 2002 Large Subpart H TNCWSs that use chlorine dioxide must comply with the MRDL for

chlorine dioxide [40 CFR 141.65(b)(2)]. 

January 1, 2002 Requirements of Subpart L generally apply to large Subpart H CWSs and NTNCWs [40

CFR 141.130(b)(1)].

• Monitoring requirements.

• Reporting and recordkeeping requirements.

• Compliance.

• Treatment technique for control of DBP precursors.

January 1, 2003 Small Subpart H systems should begin monitoring to determine Step 1 TOC removal

before the compliance date. 

December 31, 2003 Systems which received an extension from the state to install GAC or membranes must

comply with the Stage 1 DBPR [40 CFR 141.64(b)(2)].

January 1, 2004 Small Subpart H and all ground water CWSs and NTNCWSs must comply with the

MCLs for TTHM, HAA5, bromate, and chlorite [40 CFR 141.64(b)(1)].

January 1, 2004 Small Subpart H and all ground water CWSs and NTNCWSs must comply with the

MRDLs for chlorine, chloramines, and chlorine dioxide [40 CFR 141.65(b)(1)].

January 1, 2004 Small Subpart H and all ground water TNCWSs that use chlorine dioxide must comply

with the MRDL for chlorine dioxide [40 CFR 141.65 (b)(2)].
Date DBPR Requirement

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January 1, 2004 Requirements of Subpart L generally apply to small Subpart H and all ground water

CWSs and NTNCWs [40 CFR 141.130(b)(1)].

• Monitoring requirements.

• Reporting and recordkeeping requirements.

• Compliance.

• Treatment technique for control of DBP precursors.

June 30, 2005 Systems that made a clear and irrevocable financial commitment before the applicable

compliance date to install technologies that limit TTHM and HAA5 to 0.040 mg/L and

0.030 mg/L, respectively, must have these technologies installed and operating. [40 CFR

141.135(a)(2)(iii)].

3. Summary of regulatory requirements

MCLGs and MCLs for disinfection byproducts

The Stage 1 DBPR sets maximum contaminant level goals (MCLGs) for some of the regulated DBPs, a

more stringent maximum contaminant level (MCL) for TTHM, and new MCLs for HAA5, bromate, and

chlorite. MCLGs are set at concentrations at which no known or anticipated adverse health effects are

expected to occur. They are non-enforceable public health goals. MCLs are enforceable contaminant

standards that are feasible to achieve and measure.

These MCLs, along with the MRDLs and treatment technique explained in the following paragraphs, will

help reduce exposure to DBPs and disinfectants and their associated health risks.

Disinfection Byproduct MCLG (mg/L) MCL (mg/L)

Total Trihalomethanes (TTHM) 0.080

Chloroform

Bromodichloromethane zero

Bromoform zero

Dibromochloromethane 0.06

Five Haloacetic Acids (HAA5) 0.060

Monochloroacetic Acid

Dichloroacetic Acid zero

Trichloroacetic Acid 0.3

Monobromoacetic Acid

Dibromoacetic Acid

Chlorite 0.8 1.0

Bromate zero 0.010
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Compliance for TTHM and HAA5 MCLs is based on a running annual arithmetic average, computed

quarterly, of quarterly averages of all samples. Compliance for the chlorite MCL is based on an

arithmetic average of each three sample set taken in the distribution system. Compliance for the bromate

MCL is based on a running annual arithmetic average, computed quarterly, of monthly samples. 

MRDLGs and MRDLs for disinfectant residuals

To protect against potential health risks caused by high levels of residual disinfectants, the Stage 1 DBPR

sets the following maximum residual disinfectant level goals (MRDLGs) and maximum residual

disinfectant levels (MRDLs). Like MCLGs and MCLs, respectively, MRDLGs are non-enforceable,

while MRDLs are enforceable.

Disinfectant MRDLG (mg/L) MRDL (mg/L)

Chlorine 4 (as Cl2) 4.0 (as Cl2)

Chloramines 4 (as Cl2) 4.0 (as Cl2)

Chlorine Dioxide 0.8 0.8

Systems using chlorine or chloramines may temporarily increase residual disinfectant levels to an

appropriate level protect to public health in order to address specific microbiological contamination

problems. These problems may be caused by circumstances such as, but not limited to, distribution line

breaks, storm run-off events, source water contamination events, or cross-connection events. This option

is NOT available for the use of chlorine dioxide.

Compliance for chlorine and chloramine MRDLs is based on a running annual arithmetic average,

computed quarterly, of monthly averages of all samples. Compliance for the chlorine dioxide MRDL is

based on consecutive daily samples. 

Treatment technique for disinfection byproduct precursors

The rule includes a treatment technique that applies to Subpart H systems using conventional filtration

treatment. The treatment technique was established because disinfectants can react with disinfection

byproduct precursors (DBPPs) to form both regulated and non-regulated DBPs. The treatment technique

requirements in the rule are designed to provide public health protection by minimizing the production of

all DBPs. Compliance with the treatment technique can be achieved by removing specified percentages

of Total Organic Carbon (TOC) using enhanced coagulation or enhanced softening. Alternatively,

systems may comply by showing they meet alternative compliance criteria. For example, systems which

have a low level of TOC in their source or treated water (less than 2.0 mg/L) meet alternative compliance

criteria.

Best available technology (BAT)

EPA has specified the Best Available Technology (BAT) for each MCL and MRDL established in the

rule. These technologies and methods are believed to be effective in controlling chemicals in drinking

water while remaining economically feasible for PWSs to employ. PWSs must use the specified BAT if

they wish to qualify for variances. Otherwise, systems are not required to install BAT and may use any

technology to achieve compliance.
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Chemical Best Available Technology

DBPs

TTHM and HAA5 Enhanced coagulation or granular activated carbon (GAC 10), with chlorine as

the primary and residual disinfectant

Chlorite Control of treatment processes to reduce disinfectant demand and control of

disinfection treatment processes to reduce disinfectant levels

Bromate Control of ozone treatment process to reduce production of bromate

Disinfectants Chlorine, chloramine, 

and chlorine dioxide

Control of treatment processes to reduce disinfectant demand and control of

disinfection treatment processes to reduce disinfectant levels

Public water system recordkeeping and reporting requirements

For each disinfectant, contaminant, contaminant group, and treatment technique, EPA has developed

routine compliance monitoring schemes to be protective of acute and chronic health concerns. The

compliance monitoring requirements vary by the size and type of system, the treatment employed, and

the disinfectant used. In many cases, systems may reduce monitoring frequencies after establishing a

baseline.

Systems required to sample quarterly or more frequently must report to the state within 10 days after the

end of each quarter in which the samples were collected. Those required to sample less frequently than

quarterly must report to the state within 10 days after the end of each monitoring period in which samples

were collected. Systems that are required to conduct additional monitoring because of the disinfectant

used (e.g., chlorine dioxide) are subject to additional reporting requirements if certain chemical levels are

measured. 

Laboratory methods and certification

The rule specifies analytical methods for measuring each relevant water quality parameter, disinfectant,

contaminant, and DBPP. Consistent with current regulations, only certified laboratories can analyze

samples for compliance with the MCLs. However, chlorite measured at the entrance to the distribution

systems is a trigger, not an MCL compliance sample, and may be analyzed by a party approved by the

state. For disinfectants and other specified parameters that EPA believes can be adequately measured by

other than certified laboratories, and for which there is good reason to allow on-site analysis (e.g., for

samples that may deteriorate before reaching a certified laboratory), EPA is requiring that analyses be

conducted by a party approved by the state.

4. Additional information

A series of guidance manuals have been developed to support the Interim Enhanced Surface Water

Treatment Rule and the Stage 1 Disinfectants/Disinfection Byproducts Rule. The manuals will aid EPA,

state agencies and affected public water systems in implementing the two interrelated rules, and will help

to ensure that implementation among these groups is consistent. The manuals are available on EPA’s

website at www.epa.gov/safewater/mdbp/implement.html. Additional information on ordering these

manuals is provided below.

Guidance Manual for Enhanced Coagulation and Enhanced Precipitative Softening

(EPA 815-R-99-012)

Objective: To assist utilities in implementing, monitoring, and complying with the treatment technique

requirements in the final Stage 1 Disinfectants and Disinfection Byproducts Rule and to provide

guidance to state staff responsible for implementing the treatment requirements.
Page 10

Contents: The manual provides detailed information on the total organic carbon (TOC) removal

requirement; explains how to set an alternative TOC removal percentage under the Step 2 procedure;

details monitoring, reporting, and compliance requirements; and discusses strategies that can be

employed to mitigate the potential secondary effects on plant performance due to implementation of the

treatment technique.

Alternative Disinfectants and Oxidants Guidance Manual (EPA 815-R-99-014)

Objective: To provide technical data and engineering information on disinfectants and oxidants that are

not as commonly used as chlorine, so that systems can evaluate their options for developing disinfection

schemes to control water quality problems such as zebra mussels and Asiatic clams, and oxidation to

control water quality problems associated with iron and manganese.

Contents: The manual discusses six disinfectants and oxidants: ozone, chlorine dioxide, potassium

permanganate, chloramines, ozone/hydrogen peroxide combinations, and ultraviolet light. A decision

tree is provided to assist in evaluating which disinfectant(s) is most appropriate given certain site-specific

conditions (e.g., water quality conditions, existing treatment and operator skill). The manual also

contains a summary of existing alternative disinfectants used in the United states and cost estimates for

the use of alternative disinfectants. 

M/DBP Simultaneous Compliance Manual (EPA 815-R-99-015)

Objective: To assist public water systems on complying simultaneously with various drinking water

regulations (e.g., Stage 1 Disinfectants and Disinfection Byproducts Rule, Interim Enhanced Surface

Water Treatment Rule, Lead and Copper Rule and the Total Coliform Rule). The manual discusses

operational problems systems may encounter when implementing these rules.

Contents: The manual provides detailed information on the requirements in the Stage 1 Disinfectants

and Disinfection Byproducts Rule and the Interim Enhanced Surface Water Treatment Rule.

To order copies of these guidance manuals you may contact the Safe Drinking Water Hotline at (800)

426-4791 or you may download an electronic version from the OGWDW website at:

www.epa.gov/safewater/mdbp/implement.html

Guidance manuals are also available through the National Service Center for Environmental

Publications (NSCEP) (free of charge). These documents may also be purchased through National

Technical Information Service (NTIS)

NSCEP: 1.800.490.9198

NTIS: 1.800.553.6847

5. Detailed regulatory requirements

Detailed descriptions of the monitoring and reporting requirements for public water systems (PWSs) are

presented in the following section. The Stage 1 DBPR applies to all community water systems and

nontransient noncommunity water systems that add a chemical disinfectant or oxidant, as well as

transient noncommunity water systems that treat their water with chlorine dioxide. However, systems

will monitor at various frequencies depending on type (Subpart H and ground water) and size.

Additionally, the type of chemical monitored will also vary depending on system type and the primary

disinfectant used. For this reason, tables that outline the monitoring and reporting requirements are

presented for each system size and type. 
Page 11

This section is organized so that specific categories of systems can turn right to where their specific

requirements are. Keep in mind that some systems may fall into more than one category listed below. 

The categories of systems are:

• Subpart H systems serving at least 10,000 people (Attachment 1)

• Subpart H systems serving 500-9,999 people (Attachment 2)

• Subpart H systems serving fewer than 500 people (Attachment 3)

• Ground water systems serving at least 10,000 people (Attachment 4)

• Ground water systems serving fewer than 10,000 people (Attachment 5)

• Systems using chlorine dioxide (Attachment 6)

• Systems using ozone (Attachment 7)

• Subpart H systems using conventional filtration treatment (Attachment 8)

Systems should review all the attachments which apply to them to gain a full understanding of how the

Stage 1 DBPR will affect them. For example, a surface water system serving 7,000 people using

conventional filtration and chlorine dioxide as an oxidant should review Attachments 2, 6, and 8.
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Stage 1 DPBR General Requirements

Is the System 

a CWS, NTNCWS, or a 

TNCWS which adds a chemical 

disinfectant to their water?

Does the TNCWS use 

Chlorine Dioxide?

Is system a subpart H system with

conventional treatment?

Does system use Chlorine or

Chloramine?

Does system use Ozone?

Does system use Chlorine

Dioxide?

System must conduct TTHM/HAA5 monitoring.

See attached flow charts. Requirements based

on population and source water type.

No additional requirements.

Enhanced DBP Precursor removal

requirements (Enhanced

Coagulation/Enhanced Softening)

apply. See Attachment 8.

Bromate monitoring

requirements apply. See

Attachment 7.

Chlorine Dioxide and Choritemonitoring requirements apply. See

Attachment 6.

Chlorine and Chloramine

monitoring requirements apply.

See Attachments 1-5.

The system has no 

requirements under 

Required to do Chlorine this rule.

Dioxide monitoring. See 

Attachment 6.

Yes

TNCWS

Yes 

CWS & NTNCWS

YES

YES

YES

YES

YES

NO

NO

NO

NO

NO

NO
Page 13

Attachment 1 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a surface water system or ground water system

under the direct influence of surface water that serves at

least 10,000 people . . .
(Attachment 1) I operate a surface water system or ground water system under the direct influence of

surface water that serves at least 10,000 people . . .

Page 14

You must conduct the monitoring, compliance determinations, reporting, and recordkeeping specified in

this section. In addition, you are required to conduct additional monitoring, compliance determinations,

reporting and recordkeeping if you meet any of the following criteria:

• You use chlorine dioxide in treating your water. This includes any use of chlorine dioxide, not

just chlorine dioxide used for meeting disinfection requirements. Additional requirements are

found in Attachment 6.

• You use ozone in treating your water. This includes any use of ozone, not just ozone used for

meeting disinfection requirements. Additional requirements are found in Attachment 7.

• You operate a treatment plant that uses conventional filtration treatment. Additional

requirements are found in Attachment 8.

In addition, you must develop and implement a monitoring plan that specifies 1) location and schedules

for collecting all required samples, 2) procedures for calculating compliance with MCLs, MRDLs, and

treatment techniques, and 3) if receiving water as a consecutive system, or supplying water to a

consecutive system, how the entire distribution system is represented. The monitoring plan must be

submitted to the state. 
(Attachment 1) I operate a surface water system or ground water system under the direct influence of

surface water that serves at least 10,000 people . . .

Page 15

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be conducted

TTHM and HAA5 4 samples per plant per quarter At least 25% of samples must be at locations representing maximum

residence time. Remaining samples must represent average residence

time and the entire distribution system (account for number of

people served, different sources of water, different treatment

methods).

Chlorine and

Chloramines

Same time as total coliform

samples are taken

Same locations as total coliform samples are taken.

Notes:

1. If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected

each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the

maximum residence time of the water in the distribution system. The remaining samples must be taken at locations

representative of at least average residence time in the distribution system.

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must

be conducted

Conditions for reduced monitoring

TTHM and HAA5 One sample per

plant per quarter

In the distribution system at a

location representing

maximum residence time.

• Source water annual average TOC before

any treatment # 4.0 mg/L and

• Annual average TTHM # 0.040 mg/L and

• Annual average HAA5 # 0.030 mg/L

Chlorine and 

Chloramines

No reduced

monitoring

NA NA
(Attachment 1) I operate a surface water system or ground water system under the direct influence of

surface water that serves at least 10,000 people . . .

Page 16

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the MCLs and MRDLs in the Stage 1

DBPR?

Chemical Compliance is based on . . .

TTHM and HAA5 Running annual arithmetic average, computed quarterly, of quarterly arithmetic averages of all

samples collected.

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period

exceeds the MCL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If an annual average exceeds the MCL and the system is on reduced monitoring, it must revert to

routine monitoring immediately.

Chlorine and

Chloramines

Running annual arithmetic average, computed quarterly, of quarterly averages of all samples

collected.

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period

exceeds the MRDL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If system switches between chlorine and chloramines for residual disinfection during the year,

compliance must be determined by including together all monitoring results of both chlorine and

chloramines.

NOTES:

1. Where compliance is based on a running annual average of monthly or quarterly samples or averages and the

system’s failure to monitor makes it impossible to determine compliance with the MCLs or MRDLs, this failure to

monitor will be treated as a violation for the entire period covered by the annual average. 

2. All samples taken and analyzed under the provisions of the monitoring plan must be included in determining

compliance, even if that number is greater than the minimum required. 

3. If during the first year of monitoring, any individual quarter’s average will cause the running annual average of

that system to exceed the MCL, the system is out of compliance at the end of that quarter.

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

TTHM and

HAA5

If conducting routine or reduced monitoring:

• Number of samples taken during last quarter

• Location, date, result of each sample taken during last quarter

• Arithmetic average of all samples taken in last quarter

• Annual arithmetic average of quarterly averages for last 4 quarters

• Whether MCL was exceeded (Report violation of the MCL)

Chlorine and

Chloramines

• Number of samples taken during each month of last quarter

• Monthly arithmetic average of all samples taken in each month

• Arithmetic average of all monthly averages for last 12 months

• Whether MRDL was exceeded (Report violation of MRDL)

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected. 
(Attachment 1) I operate a surface water system or ground water system under the direct influence of

surface water that serves at least 10,000 people . . .

Page 17

TTHMs & HAA5 Monitoring Requirements for Subpart H Systems Serving $10,000 Persons

Subpart H systems serving $ 10,000 persons

Routine Monitoring

4 TTHM/HAA5 samples per quarter per treatment

plant1

Is

source water avg.

TOC # 4.0 mg/L

AND

are annual averages for 

TTHM # 0.040 mg/L or

HAA5 # 0.030 mg/L?

Is running

annual average2

(computed quarterly) for

TTHM > 0.080 mg/L or

HAA5 > 0.060 mg/L?

Has system

monitored for at

least 1 year?

Reduced Monitoring

1 TTHM/HAA5 sample per treatment plant per quarter in

distribution system at location reflecting maximum

residence time

MCL Violation

Is

annual avg. of all samples

for TTHMs > 0.060 mg/L or

HAA5 > 0.045 mg/L?

NOTES

1 3 samples reflect average residence time and 1 sample reflects maximum residence time (at least 25% of samples must reflect maximum

residence time).

2 If PWS fails to complete 4 consecutive quarters of monitoring, compliance with the MCL for the last 4 quarter period must be based on 

average of available data.

YES

YES

YES

NO

NO

NO

YES NO

Is the sum of 

quarterly averages 

taken so far 

for TTHMs 

>0.320 or for HAA5s 

> 0.240?

NO

YES
(Attachment 1) I operate a surface water system or ground water system under the direct influence of

surface water that serves at least 10,000 people . . .

Page 18

Monitoring Requirements for Chlorine and Chloramine

Are you a 

CWS or NTNCWS using

chlorine or chloramine?

Which does the 

system use as the 

residual disinfectant?

Did system 

measure

chlorine with 

total coliform?

Is the running 

annual average of monthly

averages, computed 

quarterly, #4.0 mg/l?1,2,3

Is the running

 annual average of monthly

averages, computed

quarterly, #4.0mg/l?1,2,3

Did system 

measure

chloramines with

total coliform?

No monitoring for 

chlorine or

chloramine is 

required.

System must measure

chlorine in distribution 

system at same location and

time as total coliform.

MRDL Violation MR Violation

System is in compliance and 

continues routine monitoring

MR Violation

System must measure

chloramine in distribution

system at same location and 

time as total coliform.

CHLORAMINES

NO

YES

CHLORINE

YES YES

YES YES

NO

NO

NO

NO

NOTES

1. Notwithstanding the MRDLs for chlorine and chloramines, systems may increase residual disinfectant levels of

chlorine or chloramines in the distribution system to a level and for a time necessary to protect publich health to address 

specific microbiological contamination problems.

2. If system switches between use of chlorine and chloramines, compliance must be determined by including together

all monitoring results of both chlorine and chloramines in calculating compliance.

3. Running annual average is first calculated after first 12 months of monitoring.

System must

notify state and public.
Page 19

Attachment 2 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a surface water system or ground water system

under the direct influence of surface water that serves

500 to 9,999 people . . .
(Attachment 2) I operate a surface water system or ground water system under the direct influence of

surface water that serves 500 to 9,999 people . . .

Page 20

You must conduct the monitoring, compliance determinations, reporting , and recordkeeping specified in

this section. In addition, you are required to conduct additional monitoring, compliance determinations,

reporting and recordkeeping if you meet either of the following criteria:

• You use chlorine dioxide in treating your water. This includes any use of chlorine dioxide, not just

chlorine dioxide used for meeting disinfection requirements. Additional requirements are found in

Attachment 6.

• You use ozone in treating your water. This includes any use of ozone, not just ozone used for meeting

disinfection requirements. Additional requirements are found in Attachment 7.

• You operate a treatment plant that uses conventional filtration treatment. Additional requirements are

found in Attachment 8.

In addition, you must develop and implement a monitoring plan that specifies 1) location and schedules

for collecting all required samples, 2) procedures for calculating compliance with MCLs, MRDLs, and

treatment techniques, and 3) if receiving water as a consecutive system, or supplying water to a

consecutive system, how the entire distribution system is represented. For systems serving more than

3,300 people the monitoring plan must be submitted to the state. 
(Attachment 2) I operate a surface water system or ground water system under the direct influence of

surface water that serves 500 to 9,999 people . . .

Page 21

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be conducted

TTHM and

HAA5

One sample per plant per

quarter

Location representing maximum residence time.

Chlorine and

Chloramines

Same time as total

coliform samples are

taken

Same points as total coliform samples are taken.

NOTES

1. If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected

each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the

maximum residence time of the water in the distribution system. The remaining samples must be taken at locations

representative of at least average residence time in the entire distribution system (account for number of people

served, different sources of water, different treatment methods)

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must

be conducted

Conditions for reduced monitoring

TTHM and

HAA5

One sample per plant

per year during month

of warmest temperature

In the distribution system at a

location representing maximum

residence time.

• Source water annual average TOC before

any treatment # 4.0 mg/L and

• Annual average TTHM # 0.040 mg/L and

• Annual average HAA5 # 0.030 mg/L

Chlorine and

Chloramines

No reduced monitoring NA NA
(Attachment 2) I operate a surface water system or ground water system under the direct influence of

surface water that serves 500 to 9,999 people . . .

Page 22

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the MCLs and MRDLs in the Stage 1

DBPR?

Chemical Compliance is based on . . .

TTHM and

HAA5

Running annual arithmetic average, computed quarterly, of quarterly arithmetic averages of all

samples collected (routine monitoring). 

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period exceeds the

MCL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If an annual average exceeds the MCL and the system is on reduced monitoring, it must revert to routine

monitoring immediately.

Chlorine and

Chloramines

Running annual arithmetic average, computed quarterly, of quarterly averages of all samples collected.

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period exceeds the

MRDL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If system switches between chlorine and chloramines for residual disinfection during the year, compliance

must be determined by including together all monitoring results of both chlorine and chloramines. 

NOTES:

1. Where compliance is based on a running annual average of monthly or quarterly samples or averages and the

system’s failure to monitor makes it impossible to determine compliance with the MCLs or MRDLs, this failure to

monitor will be treated as a violation for the entire period covered by the annual average. 

2. All samples taken and analyzed under the provisions of the monitoring plan must be included in determining

compliance, even if that number is greater than the minimum required. 

3. If during the first year of monitoring, any individual quarter’s average will cause the running annual average of

that system to exceed the MCL, the system is out of compliance at the end of that quarter.

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

TTHM and HAA5 • Number of samples taken during last quarter (routine monitoring)

• Location, date, result of each sample taken during last quarter

• Arithmetic average of all samples taken in last quarter

• Annual arithmetic average of quarterly averages for last 4 quarters

• Whether MCL was exceeded

If conducting reduced monitoring:

• Number of samples taken during last year

• Location, date, result of each sample taken during last year

• Arithmetic average of all samples taken over last year

• Whether MCL was exceeded

Chlorine and Chloramines • Number of samples taken during each month of last quarter

• Monthly arithmetic average of all samples taken in each month

• Arithmetic average of all monthly averages for last 12 months

• Whether MRDL was exceeded 

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected. 

2. Systems required to sample less frequently than quarterly must report to the state within 10 days after the end of

each monitoring period in which samples were collected. The state may choose to perform calculations and

determine whether the MCL, MRDL, or treatment technique was met in lieu of having the system report that

information.
(Attachment 2) I operate a surface water system or ground water system under the direct influence of

surface water that serves 500 to 9,999 people . . .

Page 23

TTHM & HAA5 Monitoring for Subpart H Systems Serving Between 500-9,999 Persons

Subpart H systems serving between 500-9,999 persons

Routine Monitoring

1 TTHM/HAA5 sample per quarter per treatment

plant at location representing the maximum

residence time1.

Is source 

water TOC ann. avg. # 4.0 mg/L

AND

are annual averages for 

TTHM # 0.040 mg/L or

HAA5 # 0.030 mg/L?

Is the running

annual average2 for

TTHM > 0.080 mg/L or

HAA5 > 0.060 mg/L?

Reduced Monitoring

1 sample per treatment plant per year in the distribution system 

reflecting the maximum residence time and during month of warmest

water temperature.

MCL Violation

Is the system’s annual avg. of all samples 3 for 

TTHMs > 0.060 mg/L or HAA5 > 0.045 mg/L?

NOTES

1 If more than1 sample,at least 25% of samples must reflect max residence time.

2 If PWS fails to complete 4 consecutive quarters of monitoring, compliance with the MCL for the last 4 quarter period must be based on 

average of available data.

3

 Average of all samples taken in the year or the result of the sample for systems which must monitor no more frequently than annually.

YES

YES

YES

NO

NO

YES NO

Has system

monitored for at

least 1 year?

NO

Is the sum of 

quarterly averages 

taken so far 

for TTHMs 

>0.320 or for HAA5s 

> 0.240?

NO

YES
(Attachment 2) I operate a surface water system or ground water system under the direct influence of

surface water that serves 500 to 9,999 people . . .

Page 24

Monitoring Requirements for Chlorine and Chloramine

Are you a 

CWS or NTNCWS using

chlorine or chloramine?

Which does the 

system use as the 

residual disinfectant?

Did system 

measure

chlorine with 

total coliform?

Is the running 

annual average of monthly

averages, computed 

quarterly, #4.0 mg/l?1,2,3

Is the running

 annual average of monthly

averages, computed

quarterly, #4.0mg/l?1,2,3

Did system 

measure

chloramines with

total coliform?

No monitoring for 

chlorine or

chloramine is 

required.

System must measure

chlorine in distribution 

system at same location and

time as total coliform.

MRDL Violation MR Violation

System is in compliance and 

continues routine monitoring

MR Violation

System must measure

chloramine in distribution

system at same location and 

time as total coliform.

CHLORAMINES

NO

YES

CHLORINE

YES YES

YES YES

NO

NO

NO

NO

NOTES

1. Notwithstanding the MRDLs for chlorine and chloramines, systems may increase residual disinfectant levels of

chlorine or chloramines in the distribution system to a level and for a time necessary to protect publich health to address 

specific microbiological contamination problems.

2. If system switches between use of chlorine and chloramines, compliance must be determined by including together

all monitoring results of both chlorine and chloramines in calculating compliance.

3. Running annual average is first calculated after first 12 months of monitoring.

System must

notify state and public.
Page 25

Attachment 3 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a surface water system or ground water system

under the direct influence of surface water that serves

fewer than 500 people . . .
(Attachment 3) I operate a surface water system or ground water system under the direct influence of

surface water that serves fewer than 500 people . . .

Page 26

You must conduct the monitoring, compliance determinations, reporting , and recordkeeping specified in

this section. In addition, you are required to conduct additional monitoring, compliance determinations,

reporting and recordkeeping if you meet either of the following criteria:

• You use chlorine dioxide in treating your water. This includes any use of chlorine dioxide, not just

chlorine dioxide used for meeting disinfection requirements. Additional requirements are found in

Attachment 6.

• You use ozone in treating your water. This includes any use of ozone, not just ozone used for meeting

disinfection requirements. Additional requirements are found in Attachment 7.

• You operate a treatment plant that uses conventional filtration treatment. Additional requirements are

found in Attachment 8.

In addition, you must develop and implement a monitoring plan that specifies 1) location and schedules

for collecting all required samples, 2) procedures for calculating compliance with MCLs, MRDLs, and

treatment techniques, and 3) if receiving water as a consecutive system, or supplying water to a

consecutive system, how the entire distribution system is represented. The monitoring plan must be kept

on hand and readily available to the state and public. 
(Attachment 3) I operate a surface water system or ground water system under the direct influence of

surface water that serves fewer than 500 people . . .

Page 27

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be

conducted

TTHM and HAA5 • One sample per plant per year during month of

warmest water temperature - if MCL is exceeded

in yearly sample, system goes to increased

monitoring of 1 sample per plant per quarter

Location representing maximum

residence time.

Chlorine and Chloramines Same time as total coliform samples are taken Same points as total coliform samples

are taken.

NOTES

1. The system may revert to annual monitoring if the annual average is #40/30 based on at least four quarters of

monitoring.

2. If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected

each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the

maximum residence time of the water in the distribution system. The remaining samples must be taken at locations

representative of at least average residence time in the distribution system.

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be

conducted

Conditions for reduced

monitoring

TTHM and

HAA5

No reduced monitoring NA NA

Chlorine and

Chloramines

No reduced monitoring NA NA
(Attachment 3) I operate a surface water system or ground water system under the direct influence of

surface water that serves fewer than 500 people . . .

Page 28

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the MCLs and MRDLs in the Stage 1

DBPR?

Chemical Compliance is based on . . .

TTHM and

HAA5

Average of samples taken in the year.

• If the average of these samples exceeds the MCL, the system must increase monitoring to once per

quarter per treatment plant. Compliance will be based on 4 quarters of monitoring. 

• The system must notify the public and report to the state if in violation.

• If an annual average exceeds the MCL and the system is on reduced monitoring, it must go to increased

monitoring immediately. If a system on increased monitoring exceeds the MCL, it is in violation.

Chlorine and

Chloramines

Running annual arithmetic average, computed quarterly, of quarterly averages of all samples

collected.

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period exceeds the

MRDL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If system switches between chlorine and chloramines for residual disinfection during the year, compliance

must be determined by including together all monitoring results of both chlorine and chloramines. 

NOTES:

1. Where compliance is based on a running annual average of monthly or quarterly samples or averages and the

system’s failure to monitor makes it impossible to determine compliance with the MCLs or MRDLs, this failure to

monitor will be treated as a violation for the entire period covered by the annual average. 

2. All samples taken and analyzed under the provisions of the monitoring plan must be included in determining

compliance, even if that number is greater than the minimum required. 

3. If during the first year of monitoring, any individual quarter’s average will cause the running annual average of

that system to exceed the MCL, the system is out of compliance at the end of that quarter.

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

TTHM and

HAA5

• Number of samples taken during last year (or in last quarter if on increased monitoring)

• Location, date, result of each sample taken during last year

• Arithmetic average of all samples taken over last year

• Whether MCL was exceeded

Chlorine and

Chloramines

• Number of samples taken during each month of last quarter

• Monthly arithmetic average of all samples taken in each month

• Arithmetic average of all monthly averages for last 12 months

• Whether MRDL was exceeded 

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected. 

2. Systems required to sample less frequently than quarterly must report to the state within 10 days after the end of

each monitoring period in which samples were collected. The state may choose to perform calculations and

determine whether the MCL, MRDL, or treatment technique was met in lieu of having the system report that

information.
(Attachment 3) I operate a surface water system or ground water system under the direct influence of

surface water that serves fewer than 500 people . . .

Page 29

Subpart H systems serving <500 persons

Routine Monitoring

1 TTHM/HAA5 sample per treatment plant per

year at location reflecting maximum residence 

time and in month of warmest water temperature.

Is the system’s annual 

average, based on 4 quarters of 

monitoring, for TTHM # 0.060 mg/L 

and HAA5 # 0.045 mg/L?

Is the sample

(or the average of all samples

taken) for

TTHM > 0.080 mg/L or HAA5 

> 0.060 mg/L?1

MCL Violation

Is the average 

of all samples for

TTHM > 0.080 mg/L or

HAA5 > 0.060 mg/L?

YES

YES

NO

NO

YES

NO

Increased Monitoring

1 TTHM/HAA5 sample/treatment plant/quarter @ points

reflecting the maximum residence time in the

distribution system.

TTHM & HAA5 Monitoring for Subpart H Systems Serving <500 Persons

NOTES

1) If a system elects to sample more frequently than the minimum required, at least 25 percent of all samples collected each quarter (including those taken

in excess of the required frequency) must be taken at locations that represent the maximum residence time of the water in the distribution system. The

remaining samples must be taken at locations representative of at least average residence time in the distribution system.

MCL Violation

YES

Has system

monitored for at

least 1 year?

NO

Is the sum of 

quarterly averages 

taken so far 

for TTHMs 

>0.320 or for HAA5s 

> 0.240?

NO

YES
(Attachment 3) I operate a surface water system or ground water system under the direct influence of

surface water that serves fewer than 500 people . . .

Page 30

Monitoring Requirements for Chlorine and Chloramine

Are you a 

CWS or NTNCWS using

chlorine or chloramine?

Which does the 

system use as the 

residual disinfectant?

Did system 

measure

chlorine with 

total coliform?

Is the running 

annual average of monthly

averages, computed 

quarterly, #4.0 mg/l?1,2,3

Is the running

 annual average of monthly

averages, computed

quarterly, #4.0mg/l?1,2,3

Did system 

measure

chloramines with

total coliform?

No monitoring for 

chlorine or

chloramine is 

required.

System must measure

chlorine in distribution 

system at same location and

time as total coliform.

MRDL Violation MR Violation

System is in compliance and 

continues routine monitoring

MR Violation

System must measure

chloramine in distribution

system at same location and 

time as total coliform.

CHLORAMINES

NO

YES

CHLORINE

YES YES

YES YES

NO

NO

NO

NO

NOTES

1. Notwithstanding the MRDLs for chlorine and chloramines, systems may increase residual disinfectant levels of

chlorine or chloramines in the distribution system to a level and for a time necessary to protect publich health to address 

specific microbiological contamination problems.

2. If system switches between use of chlorine and chloramines , compliance must be determined by including together

all monitoring results of both chlorine and chloramines in calculating compliance.

3. Running annual average is first calculated after first 12 months of monitoring.

System must

notify state and public.
Page 31

Attachment 4 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a ground water system not under the direct

influence of surface water that serves at least 10,000

people . . .
(Attachment 4) I operate a ground water system not under the direct influence of surface water that

serves at least 10,000 people . . .

Page 32

You must conduct the monitoring, compliance determinations, reporting , and recordkeeping specified in

this section. In addition, you are required to conduct additional monitoring, compliance determinations,

reporting and recordkeeping if you meet either of the following criteria:

• You use chlorine dioxide in treating your water. This includes any use of chlorine dioxide, not just

chlorine dioxide used for meeting disinfection requirements. Additional requirements are found in

Attachment 6.

• You use ozone in treating your water. This includes any use of ozone, not just ozone used for meeting

disinfection requirements. Additional requirements are found in Attachment 7.

In addition, you must develop and implement a monitoring plan that specifies 1) location and schedules

for collecting all required samples, 2) procedures for calculating compliance with MCLs and MRDLs,

and 3) if receiving water as a consecutive system, or supplying water to a consecutive system, how the

entire distribution system is represented. The monitoring plan must be kept for review by the state and

public. 
(Attachment 4) I operate a ground water system not under the direct influence of surface water that

serves at least 10,000 people . . .

Page 33

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be conducted

TTHM and

HAA5

One sample per plant per

quarter

Location representing maximum residence time.

Chlorine and

Chloramines

Same time as total

coliform samples are

taken

Same points as total coliform samples are taken.

NOTES:

1. Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the

minimum number of samples required, with state approval.

2. If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected

each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the

maximum residence time of the water in the distribution system. The remaining samples must be taken at locations

representative of at least average residence time in the distribution system.

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must

be conducted

Conditions for reduced monitoring

TTHM and

HAA5

One sample per plant per

year during month of

warmest water temperature

Location representative of

maximum residence time

• Annual average TTHM # 0.040 mg/L and

• Annual average HAA5 # 0.030 mg/L

Chlorine and

Chloramines

No reduced monitoring NA NA
(Attachment 4) I operate a ground water system not under the direct influence of surface water that

serves at least 10,000 people . . .

Page 34

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the MCLs and MRDLs of the Stage 1

DBPR?

Chemical Compliance is based on . . .

TTHM and

HAA5

Running annual arithmetic average, computed quarterly, of quarterly arithmetic averages of all

samples collected.

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period exceeds the

MCL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If an annual average exceeds the MCL and the system is on reduced monitoring, it must revert to routine

monitoring immediately.

Chlorine and

Chloramines

Running annual arithmetic average, computed quarterly, of quarterly averages of all samples collected.

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period exceeds the

MRDL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If system switches between chlorine and chloramines for residual disinfection during the year, compliance

must be determined by including together all monitoring results of both chlorine and chloramines. 

NOTES:

1. Where compliance is based on a running annual average of monthly or quarterly samples or averages and the

system’s failure to monitor makes it impossible to determine compliance with the MCLs or MRDLs, this failure to

monitor will be treated as a violation for the entire period covered by the annual average. 

2. All samples taken and analyzed under the provisions of the monitoring plan must be included in determining

compliance, even if that number is greater than the minimum required. 

3. If during the first year of monitoring, any individual quarter’s average will cause the running annual average of

that system to exceed the MCL, the system is out of compliance at the end of that quarter.

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

TTHM and

HAA5

• Number of samples taken during last quarter

• Location, date, result of each sample taken during last quarter

• Arithmetic average of all samples taken during last quarter

• Annual arithmetic average of quarterly arithmetic average for last 4 quarters

• Whether MCL was exceeded

If conducting reduced monitoring:

• Number of samples taken during last year

• Location, date, result of each sample taken during last year

• Arithmetic average of all samples taken over last year

• Whether MCL was exceeded

Chlorine and

Chloramines

• Number of samples taken during each month of last quarter

• Monthly arithmetic average of all samples taken in each month

• Arithmetic average of all monthly averages for last 12 months

• Whether MRDL was exceeded 

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected.

2. Systems required to sample less frequently than quarterly must report to the state within 10 days after the end of

each monitoring period in which samples were collected. The state may choose to perform calculations and

determine whether the MCL, MRDL, or treatment technique was met in lieu of having the system report that

information.
(Attachment 4) I operate a ground water system not under the direct influence of surface water that

serves at least 10,000 people . . .

Page 35

TTHM & HAA5 Monitoring for Ground Water Systems Serving $ 10,000 Persons

Ground water systems serving $ 10,000 persons

Routine Monitoring

1 TTHM/HAA5 sample per quarter per 

treatment plant1,2

Is the system’s TTHM annual 

avg.#0.040 mg/L and

HAA5 annual avg.#0.030 mg/L?

Is the running

annual average (computed

quarterly)3 for

TTHM > 0.080 mg/L or

HAA5 > 0.060 mg/L?

Reduced Monitoring

1 TTHM/HAA5 sample per year per treatment plant in distribution

system location reflecting the maximum residence time and 

during month of warmest water temperature.

MCL Violation

Is the system’s 

annual avg. of all samples 4 for 

TTHM > 0.060 mg/L or

HAA5 > 0.045 mg/L?

NOTES

1) If more than1 sample is taken, 25% must reflect maximum residence time.

2) Multiple wells drawing water from a single aquifer may be considered one treatment plant.

3) If PWS fails to complete 4 consecutive quarters of monitoring, compliance with the MCL for the last 4 quarter period must be based on 

average of available data.

4) Average of all samples taken in the year or the result of the sample for systems which must monitor no more frequently than annually.

YES

YES

YES

NO

NO

YES NO

Has system

monitored for at

least 1 year?

NO

Is the sum of 

quarterly averages 

taken so far 

for TTHMs 

>0.320 or for HAA5s 

> 0.240?

NO

YES
(Attachment 4) I operate a ground water system not under the direct influence of surface water that

serves at least 10,000 people . . .

Page 36

Monitoring Requirements for Chlorine and Chloramine

Are you a 

CWS or NTNCWS using

chlorine or chloramine?

Which does the 

system use as the 

residual disinfectant?

Did system 

measure

chlorine with 

total coliform?

Is the running 

annual average of monthly

averages, computed 

quarterly, #4.0 mg/l?1,2,3

Is the running

 annual average of monthly

averages, computed

quarterly, #4.0mg/l?1,2,3

Did system 

measure

chloramines with

total coliform?

No monitoring for 

chlorine or

chloramine is 

required.

System must measure

chlorine in distribution 

system at same location and

time as total coliform.

MRDL Violation MR Violation

System is in compliance and 

continues routine monitoring

MR Violation

System must measure

chloramine in distribution

system at same location and 

time as total coliform.

CHLORAMINES

NO

YES

CHLORINE

YES YES

YES YES

NO

NO

NO

NO

NOTES

1. Notwithstanding the MRDLs for chlorine and chloramines, systems may increase residual disinfectant levels of

chlorine or chloramines in the distribution system to a level and for a time necessary to protect publich health to address 

specific microbiological contamination problems.

2. If system switches between use of chlorine and chloramines, compliance must be determined by including together

all monitoring results of both chlorine and chloramines in calculating compliance.

3. Running annual average is first calculated after first 12 months of monitoring.

System must

notify state and public.
Page 37

Attachment 5 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a ground water system not under the direct

influence of surface water that serves fewer than 10,000

people . . .
(Attachment 5) I operate a ground water system not under the direct influence of surface water that

serves fewer than 10,000 people . . .

Page 38

You must conduct the monitoring, compliance determinations, reporting , and recordkeeping specified in

this section. In addition, you are required to conduct additional monitoring, compliance determinations,

reporting and recordkeeping if you meet either of the following criteria:

• You use chlorine dioxide in treating your water. This includes any use of chlorine dioxide, not just

chlorine dioxide used for meeting disinfection requirements. Additional requirements are found in

Attachment 6.

• You use ozone in treating your water. This includes any use of ozone, not just ozone used for meeting

disinfection requirements. Additional requirements are found in Attachment 7.

In addition, you must develop and implement a monitoring plan that specifies 1) location and schedules

for collecting all required samples, 2) procedures for calculating compliance with MCLs, MRDLs, and

treatment techniques, and 3) if receiving water as a consecutive system, or supplying water to a

consecutive system, how the entire distribution system is represented. The monitoring plan must be

made available for review by the state and public. 
(Attachment 5) I operate a ground water system not under the direct influence of surface water that

serves fewer than 10,000 people . . .

Page 39

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be conducted

TTHM and

HAA5

One sample per plant per

year during month of

warmest water

temperature

Location representing maximum residence time.

Chlorine and

Chloramines

Same time as total

coliform samples are

taken

Same points as total coliform samples are taken.

NOTES:

1. Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the

minimum number of samples required, with state approval.

2. If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected

each quarter (including those taken in excess of the required frequency) must be taken at locations that represent the

maximum residence time of the water in the distribution system. The remaining samples must be taken at locations

representative of at least average residence time in the distribution system.

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must

be conducted

Conditions for reduced monitoring

TTHM and

HAA5

One sample per plant per

3-year cycle during

month of warmest water

temperature

Location representative

of maximum residence

time.

• Annual average TTHM # 0.040 mg/L &

annual average HAA5 # 0.030 mg/L for 2

consecutive years; OR 

• Annual average TTHM # 0.020 mg/L &

annual average HAA5 # 0.015 mg/L for 1 year

Chlorine and

Chloramines

No reduced monitoring NA NA
(Attachment 5) I operate a ground water system not under the direct influence of surface water that

serves fewer than 10,000 people . . .

Page 40

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the MCLs and MRDLs of the Stage 1

DBPR?

Chemical Compliance is based on . . .

TTHM and

HAA5

Average of samples taken in the year.

• If the average of these samples exceeds the MCL, the system must increase monitoring to once per quarter

per treatment plant.

• The system must notify the public and report to the state if in violation.

• If an annual average exceeds the MCL and the system is on reduced monitoring, it must go to increased

monitoring immediately. If a system on increased monitoring exceeds the MCL, it is in violation.

Chlorine and

Chloramines

Running annual arithmetic average, computed quarterly, of quarterly averages of all samples collected.

• If annual arithmetic average of quarterly averages covering any consecutive 4-quarter period exceeds the

MRDL, then the system is in violation.

• The system must notify the public and report to the state if in violation.

• If system switches between chlorine and chloramines for residual disinfection during the year, compliance

must be determined by including together all monitoring results of both chlorine and chloramines. 

NOTES:

1. Where compliance is based on a running annual average of monthly or quarterly samples or averages and the

system’s failure to monitor makes it impossible to determine compliance with the MCLs or MRDLs, this failure to

monitor will be treated as a violation for the entire period covered by the annual average. 

2. All samples taken and analyzed under the provisions of the monitoring plan must be included in determining

compliance, even if that number is greater than the minimum required. 

3. If during the first year of monitoring, any individual quarter’s average will cause the running annual average of

that system to exceed the MCL, the system is out of compliance at the end of that quarter.

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

TTHM and

HAA5

• Number of samples taken during last year

• Location, date, result of each sample taken during last year

• Arithmetic average of all samples taken over last year

• Whether MCL was exceeded

If conducting reduced monitoring:

• Location, date, result of last sample taken

• Whether MCL was exceeded

Chlorine and

Chloramines

• Number of samples taken during each month of last quarter

• Monthly arithmetic average of all samples taken in each month

• Arithmetic average of all monthly averages for last 12 months

• Whether MRDL was exceeded 

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected. 

2. Systems required to sample less frequently than quarterly must report to the state within 10 days after the end of

each monitoring period in which samples were collected. The state may choose to perform calculations and

determine whether the MCL, MRDL, or treatment technique was met in lieu of having the system report that

information.
(Attachment 5) I operate a ground water system not under the direct influence of surface water that

serves fewer than 10,000 people . . .

Page 41

TTHM & HAA5 Monitoring for Ground Water Systems Serving < 10,000 Persons

Ground water systems serving < 10,000 persons

Is the system’s 

annual avg. for TTHM

#0.060 mg/L and

HAA5 #0.045 mg/L?

Is the sample 

(or the average of all samples)

for TTHM > 0.080 mg/L or

HAA5 > 0.060 mg/L?

Has system

monitored for at

least 1 year?

MCL Violation

Is the 

annual avg. for 

TTHM < 0.060

mg/L and HAA5 

<0.045 mg/L?

NOTES

1) If a system elects to sample more frequently than the minimum required, at least 25 percent of all samples collected each quarter (including those taken in

excess of the required frequency) must be taken at locations that represent the maximum residence time of the water in the distribution system. The

remaining samples must be taken at locations representative of at least average residence time in the distribution system.

2) Samples must be taken during month of warmest water temperature at location representing the maximum residence time.

3) 3 year cycle begins on January 1 following the quarter in which system qualifies for reduced monitoring.

4) If PWS fails to complete 4 consecutive quarters of monitoring, compliance with the MCL for the last 4 quarter period must be based on average of 

available data.

YES

NO

Routine Monitoring

1 TTHM/HAA5 sample per treatment plant per year at 

locations reflecting the maximum residence time

during month of warmest water temperature1

Increased Monitoring

1 TTHM/HAA5 sample per treatment plant per quarter

at points reflecting the maximum residence time in

the distribution system.

Is the average

of all samples4 for

TTHM > 0.080 mg/L or

HAA5 > 0.060 mg/L?

Is the annual

average for TTHM

>0.080 mg/L or

HAA5 >0.060

mg/L?

Reduced Monitoring

1 TTHM/HAA5 sample2

per treatment plant per 3

year monitoring cycle3

Is TTHM annual

avg. #0.040 mg/L and HAA5 annual avg.

#0.030 mg/L for 2 consecutive years

O R

TTHM annual avg. #0.020 mg/L and HAA5

annual avg. #0.015 mg/L 

for 1 year?

NO

NO

NO

NO

NO

YES

YES

YES

YES YES

YES

Is the sum of 

quarterly averages 

taken so far 

for TTHMs 

>0.320 or for HAA5s 

> 0.240?

NO

YES
(Attachment 5) I operate a ground water system not under the direct influence of surface water that

serves fewer than 10,000 people . . .

Page 42

Monitoring Requirements for Chlorine and Chloramine

Are you a 

CWS or NTNCWS using

chlorine or chloramine?

Which does the 

system use as the 

residual disinfectant?

Did system 

measure

chlorine with 

total coliform?

Is the running 

annual average of monthly

averages, computed 

quarterly, #4.0 mg/l?1,2,3

Is the running

 annual average of monthly

averages, computed

quarterly, #4.0mg/l?1,2,3

Did system 

measure

chloramines with

total coliform?

No monitoring for 

chlorine or

chloramine is 

required.

System must measure

chlorine in distribution 

system at same location and

time as total coliform.

MRDL Violation MR Violation

System is in compliance and 

continues routine monitoring

MR Violation

System must measure

chloramine in distribution

system at same location and 

time as total coliform.

CHLORAMINES

NO

YES

CHLORINE

YES YES

YES YES

NO

NO

NO

NO

NOTES

1. Notwithstanding the MRDLs for chlorine and chloramines, systems may increase residual disinfectant levels of

chlorine or chloramines in the distribution system to a level and for a time necessary to protect publich health to address 

specific microbiological contamination problems.

2. If system switches between use of chlorine and chloramines, compliance must be determined by including together

all monitoring results of both chlorine and chloramines in calculating compliance.

3. Running annual average is first calculated after first 12 months of monitoring.

System must

notify state and public.
Page 43

Attachment 6 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a treatment plant that uses chlorine dioxide. . .
(Attachment 6) I operate a treatment plant that uses chlorine dioxide . . .

Page 44

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be conducted

Chlorite Daily Entrance to the distribution system.

One 3-sample set per

month

Near first customer, location representative of average residence time, location

representative of maximum residence time in distribution system.

Additional: On any day

following any daily sample

that exceeds 1.0 mg/L,

system must take 3

samples

Near first customer, location representative of average residence time, location

representative of maximum residence time in distribution system. The system

may use results to meet monthly 3-sample set monitoring requirement if the

monthly 3-sample set has not yet been taken.

Chlorine

Dioxide

Daily Entrance to the distribution system.

Additional: For any daily

sample that exceeds the

MRDL, system must take 3

samples

• For chlorine dioxide, chloramines, or chlorine used to maintain disinfectant

residual and NO booster chlorination: all samples as close as possible to

first customer at intervals of at least 6 hours

• If chlorine is used to maintain disinfectant residual AND booster

chlorination: as close as possible to first customer, location representative of

average residence time, as close as possible to end of distribution system

NOTES:

1. Not required for transient noncommunity water systems

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be

conducted

Conditions for reduced

monitoring

Chlorite

(daily)

No reduced monitoring NA NA

Chlorite

(monthly)

One 3-sample set per

quarter

Near first customer, location

representative of average residence

time, location representative of

maximum residence time in

distribution system.

• No daily sample has exceeded the

MCL

• No additional monitoring has been

required

• No quarterly sample exceeds the

MCL

Chlorine

Dioxide

No reduced monitoring NA NA

NOTES:

1. Not required for transient noncommunity water systems
(Attachment 6) I operate a treatment plant that uses chlorine dioxide . . .

Page 45

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the MCLs and MRDLs of the Stage 1

DBPR?

Chemical Compliance is based on . . .

Chlorite Average of 3-sample sets.

• If arithmetic average of any 3-sample set in the month exceeds the MCL, the system is in violation.

• The system must notify the public and report to the state if in violation.

Chlorine

Dioxide—

Acute Violation

Consecutive daily samples collected.

• If any daily sample taken at entrance to distribution system exceeds 0.8 mg/L, and on the following

day 1 or more of the 3 samples taken in the distribution system exceeds 0.8 mg/L, the system is in

acute violation.

• The system must take immediate corrective action to lower the level of chlorine dioxide below 0.8

mg/L, notify the public and report to the state.

• Failure to take samples in the distribution system following an exceedance of the MRDL at the

entrance to the distribution system is also an acute violation. System must notify public of acute

violation.

Chlorine

Dioxide—

Nonacute

Violation

Consecutive daily samples collected.

• If any two consecutive daily samples taken at entrance to distribution system exceed 0.8 mg/L, and all

distribution system samples are below 0.8 mg/L, the system is in nonacute violation.

• The system must take immediate corrective action to lower the level of chlorine dioxide below0.8

mg/L, notify the public and report to the state.

• Failure to take samples at the distribution system entrance following an exceedance of the MRDL is

also a violation. System must notify public of nonacute violation.

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

Chlorite • Number of samples taken each month for last 3 months

• Location, date, result of each sample taken during last quarter

• For each month in the reporting period, the arithmetic average of all samples taken in the month

• Whether MCL was exceed based on 3-sample set average and in which month it was exceeded. 

Chlorine

Dioxide

• Dates, results, locations of samples taken during last quarter

• Whether MRDL was exceeded

• Whether MRDL was exceeded in any two consecutive daily samples and whether resulting violation was

acute or nonacute

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected. 
(Attachment 6) I operate a treatment plant that uses chlorine dioxide . . .

Page 46

Chlorine Dioxide Monitoring for Systems Using Chlorine Dioxide

Did system

take daily sample at entrance

to distribution system the day

following the

exceedance ?

Have 2 consecutive

daily entry point samples

exceeded 0.8 mg/L?

On following day, 3 Chlorine Dioxide

distribution system samples in

addition to daily sample 1

System must notify

public of nonacute

violation.

MRDL Violation

Did system

take additional samples in

distribution system the day

following the

exceedance ?

System must notify

public of an acute

violation.

MRDL Violation

Is any

individual sample in

distribution system

>0.8 mg/L

System must take immediate

corrective action and notify

public of nonacute public

health risk. 

MRDL Violation

Acute MRDL Violation

System must take immediate

corrective action and notify the public

(141.32) and the State (141.134) 

MRDL Violation

Is daily sample

>0.8 mg/L?

Chlorine Dioxide Monitoring

1 daily sample at the entrance

to the distribution system

System must also monitor for Chlorite 

(For Chlorite monitoring

requirements see Chlorite

flow chart on next page.)

Is the system

a CWS, NTNCWS, or

TNCWS that uses Chlorine

Dioxide?

No monitoring requirements

for Chlorine Dioxide and

Chlorite

YES

YES

YES YES

YES

YES

NO

NO

NO NO

NO

NO

NOTES:

1) If chlorine dioxide or chloramines are used to maintain a disinfectant residual in the distribution system (DS), or if chlori ne is used to

maintain a disinfectant residual in the DS and there are no disinfection addition points (i.e., no booster chlorination) after the entrance to the

DS, the system must take 3 samples as close to the first customer as possible, at intervals of at least every 6 hours. If chlorine is used to

maintain a disinfectant residual in the DS and there are one or more booster chlorination stations, the system must take one sample as close

to the 1st customer as possible, one in a location representativ e of average residence time, and one as close to the end of the distribution

system as possible.

Is system a 

TNCWSs?

YES

NO
(Attachment 6) I operate a treatment plant that uses chlorine dioxide . . .

Page 47

Chlorite Monitoring Requirements for Systems Using Chlorine Dioxide

Have all chlorite

samples taken at the

entrance to or in the

distribution system for the

past year # 1.0 mg/L?

Is the arithmetic

avg. of 3 sample

set >1.0 mg/L?

System must notify the public

 (141.32) and the State (141.134). 

MCL Violation

Is sample

>1.0 mg/L?

Routine daily Monitoring

daily samples at the 

entrance to the

distribution system

Need to sample for Chlorine Dioxide and 

Chlorite. (For Chlorine Dioxide monitoring

requirements, see Chlorine

Dioxide flowchart on previous page.)

Does the system use

Chlorine Dioxide?

No monitoring requirements

for Chlorine Dioxide and

Chlorite

YES

NO

Is the 

system a CWS or

NTNCWS?

No monitoring for Chlorite

required

NO

Required Chlorite

Monitoring

Is the arithmetic MCL Violation

avg. of 3 sample

set >1.0 mg/L?

The day following the exceedance,

system must take 3 distribution

system samples (in addition to the

routine daily sample)1,2

Was system

required to conduct any

additional distribution system

monitoring (3-sample set

following exceedance at

entrance to DS)

last year?

System must notify the public

 (141.32) and the State (141.134), [if on

reduced monitoring, must revert to 

routine]. 

Routine monthly monitoring

3 sample set per month in the

distribution system 1

Reduced Monthly

Monitoring

3 sample set per quarter 1

YES

YES

YES

YES

YES

YES

NO

NO

NO

NO

NO

Note:

1) The system must take one sample at each of the following locations: near the first customer, at a location representative of average residence time, and at a location

reflecting maximum residence time in the distribution system.

2) If the system has not performed the routine monthly sampling for chlorite, they can use this 3 sample set for their monthly chlorite samples.
(Attachment 6) I operate a treatment plant that uses chlorine dioxide . . .

Page 48

This page is left intentionally blank.
Page 49

Attachment 7 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a treatment plant that uses ozone . . .
(Attachment 7) I operate a treatment plant that uses ozone . . .

Page 50

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be conducted

Bromate One sample per ozone

plant per month

Entrance to the distribution system.

Bromide One sample per ozone

plant per month

In source water (only required if the system wishes to qualify for reduced

bromate monitoring).

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be

conducted

Conditions for reduced monitoring

Bromate One sample per ozone plant

per quarter

Entrance to the distribution system. • Annual average source water

bromide concentration < 0.05 mg/L

Bromide No reduced monitoring if

wishing to conduct reduced

bromate monitoring

NA NA

NOTES:

1. System must resume monthly bromate monitoring if running annual average of source water bromide $0.05

mg/L.
(Attachment 7) I operate a treatment plant that uses ozone . . .

Page 51

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the bromate MCL in the Stage 1 DBPR?

Chemical Compliance is based on . . .

Bromate Running annual arithmetic average, computed quarterly, of monthly samples (or average of all samples

taken during the month if more than 1 sample was collected).

• If average of samples covering any consecutive 4-quarter period exceeds the MCL, the system is in

violation.

• The system must notify the public and report to the state if in violation.

NOTES:

1. Where compliance is based on a running annual average of monthly or quarterly samples or averages and the

system’s failure to monitor makes it impossible to determine compliance with the MCLs or MRDLs, this failure to

monitor will be treated as a violation for the entire period covered by the annual average. 

2. All samples taken and analyzed under the provisions of the monitoring plan must be included in determining

compliance, even if that number is greater than the minimum required. 

3. If during the first year of monitoring, any individual quarter’s average will cause the running annual average of

that system to exceed the MCL, the system is out of compliance at the end of that quarter.

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

Bromate • Number of samples taken during last quarter

• Location, date, result of each sample taken during last quarter

• Arithmetic average of monthly arithmetic averages of all samples taken in last year

• Whether MCL was exceeded

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected. 
(Attachment 7) I operate a treatment plant that uses ozone . . .

Page 52

Monitoring Requirements for Bromate for Systems using Ozonation

Routine Monitoring

1sample per month per treatment plant at the

entrance to distribution system while the ozonation

system is operating under normal conditions.

Is the system’s

annual average1 source

water bromide level

<0.05 mg/L?

Is bromate

average (running annual

arithmetic average

computed quarterly)

> 0.010 mg/L?2

Has system

monitored for at

least one year?

Reduced Monitoring

1 bromate sample per quarter per

treatment plant

MCL Violation

YES

YES

Are you a CWS or a

NTNCWS using ozone?

No monitoring for

bromate is required

YES

NO

NO

NO

YES

Notes:

1) The average is based upon representative monthly bromide measurements for one year (in months where more than one sample is taken, use the average of

all samples taken during the month).

2) If a PWS fails to complete 12 mos of monitoring, compliance must be based on average of available data.

NO

Is the sum of 

quarterly averages 

taken so far 

for bromate 

>0.040?

NO

YES
Page 53

Attachment 8 - Stage 1 Disinfectants and Disinfection Byproducts Rule Requirements

I operate a surface water system or ground water system

under the direct influence of surface water and operate

a conventional filtration treatment plant . . .
(Attachment 8) I operate a surface water system or ground water system under the direct influence of

surface water and operate a conventional filtration treatment plant . . .

Page 54

Enhanced Coagulation and Enhanced Precipitative Softening Treatment Technique

What is the goal of enhanced coagulation and enhanced precipitative softening?

The goal of enhanced coagulation and precipitaive softening is to provide additional removal of the

natural organic material (referred to as total organic carbon or “TOC”) that is a precursor to DBP

formation. TOC and disinfectants commonly used in drinking water treatment can combine to form

DBPs. Adding additional amounts of coagulant or lime to coagulation or softening treatment trains,

respectively, can increase the amount of TOC removed and thereby lower DBP levels in finished water. 

Which public water systems does the treatment technique apply to?

The treatment technique applies to Subpart H systems (systems using surface water or groundwater under

the direct influence of surface water) that use conventional treatment. Conventional treatment is defined

in §141.2 as a series of processes including coagulation, flocculation, sedimentation, and filtration

resulting in substantial particulate removal. 

How is the treatment technique implemented by public water systems?

Public water systems (PWSs) that use conventional treatment are required to remove a percentage of 

TOC from the raw water. The percent removal is based on raw water TOC and alkalinity levels. A pair

of TOC samples must be taken simultaneously in the raw water and no later than the combined filter

effluent at least once per month to calculate the percent removal and demonstrate compliance via a

running annual average. PWS unable to meet the required TOC removal may set an alternative TOC 

percent removal based on jar or pilot testing that reflects the treatability of their water. PWSs may also

use one of the alternative compliance criteria to demonstrate compliance. 

When is the treatment technique effective?

The treatment technique is effective for systems serving 10,000 or more people in January 2002. The

effective date for systems serving under 10,000 people is January 2004.
(Attachment 8) I operate a surface water system or ground water system under the direct influence of

surface water and operate a conventional filtration treatment plant . . .

Page 55

What ROUTINE MONITORING must I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be conducted

TOC and

Alkalinity

(conventional

treatment)

One paired TOC sample

per plant per month

One alkalinity sample per

plant per month at same

time as source water TOC

sample is taken

TOC (paired samples)

• In source water prior to any treatment 

• No later than the point of combined filter effluent turbidity monitoring and

representative of filtered water 

Alkalinity

• Same location as source water TOC sample is taken.

What REDUCED MONITORING may I conduct under the Stage 1 DBPR?

Chemical Frequency Where monitoring must be

conducted

Conditions for reduced

monitoring

TOC and

Alkalinity

(conventional

treatment)

One paired TOC sample

per plant per quarter

One alkalinity sample per

plant per quarter at same

time as source water TOC

sample is taken

TOC (paired samples)

• In source water prior to any

treatment 

• No later than the point of

combined filter effluent turbidity

monitoring and representative of

filtered water 

Alkalinity

• Same location as source water

TOC sample is taken.

Average treated water TOC < 2.0

mg/L for 2 consecutive years or <1.0

mg/L for 1 year
(Attachment 8) I operate a surface water system or ground water system under the direct influence of

surface water and operate a conventional filtration treatment plant . . .

Page 56

How do I DETERMINE IF MY SYSTEM IS IN COMPLIANCE with the TOC removal requirements of the

Stage 1 DBPR?

Chemical Compliance is based on . . .

TOC (conventional

treatment)

“Step 1” or “Step 2” removal targets or alternative compliance criteria (see flowcharts for determining

TOC compliance)

NOTES:

1. Where compliance is based on a running annual average of monthly or quarterly samples or averages and the

system’s failure to monitor makes it impossible to determine compliance with the treatment technique, this failure to

monitor will be treated as a monitoring violation for the entire period covered by the annual average. 

2. All samples taken and analyzed under the provisions of the monitoring plan must be included in determining

compliance, even if that number is greater than the minimum required. 

What do I have to REPORT to the State under the Stage 1 DBPR?

Chemical What must be reported

TOC and

Alkalinity

(conventional

treatment)

• Number of paired samples taken during last quarter

• Location, date, result of each paired sample and associated alkalinity taken during last quarter

• For systems using Step 1 or Step 2, enhanced coagulation or enhanced softening

• For each month in the reporting period, the arithmetic average of the percent reduction of TOC for

each paired sample and the required TOC percent removal

• Calculations for determining compliance with the TOC percent removal requirements

• For systems using an alternative compliance criterion

• Running annual arithmetic average of source water SUVA or treated water SUVA if using this

criterion for alternative compliance

• Running annual arithmetic average based on monthly average of source or treated water TOC if using

this criterion for alternative compliance

• Running annual arithmetic average of source water alkalinity or treated water alkalinity if using this

criterion for alternative compliance

• Running annual average for both TTHM and HAA5 if using this criterion for alternative compliance

• Running annual average of amount of magnesium hardness removal if using this criterion for

alternative compliance

• Whether system is in compliance with particular alternative compliance criterion

• Whether system is in compliance with the enhanced coagulation or enhanced softening percent removal

requirements for the last 4 quarters

NOTES:

1. Systems required to sample quarterly or more frequently must report to the state within 10 days after the end of

each quarter in which samples were collected. 
(Attachment 8) I operate a surface water system or ground water system under the direct influence of

surface water and operate a conventional filtration treatment plant . . .

Page 57

Disinfection Byproducts Precursor Removal

Treatment Technique

Is system

a Subpart H System

using conventional 

filtration

treatment?

Does system 

have difficulty

meeting Step 1 removals

due to water quality parameters 

or operational 

constraints?

Can system meet 

at least one of the

alternative compliance

criteria? [141.135(a)(2) and 

(3)]?

Does system 

meet Step 1 TOC 

removals [141.135(b)] as ann.

ave. (including use of

factors in 141.135(c))?

System must meet

Step 2 EC removal

requirements.

System applies to the State 

for alternative minimum TOC

removal (Step 2) requirements

within 3 mos of not meeting

Step 1.

System applies to the

State for a waiver of

 EC/ES requirements. 2

Source water

deemed not

amenable to EC/ES.

System must monitor to 

demonstrate that they 

continue to meet alternative

compliance criteria.

System in compliance

with enhanced 

coagulation/enhanced 

softening (EC/ES)

requirements.

Does system 

meet Step 2 TOC

removals?

Did State 

approve the

alternative minimum

TOC removal

(Step 2)? 2

Can system

 identify a Step 2 alternative

minimum TOC removal

requirement?

Treatment technique

requirement does

 not apply.

System must conduct

Step 2 testing to determine 

alternative minimum TOC

requirements.2

TT Violation

NO

YES

YES

NO

YES NO

NO YES

NO

YES

YES

NO

NO

YES

System must conduct

DBP Precursor

Monitoring.

Notes:

1) Subpart H = Public water systems using surface water or ground water under the direct influence of surface water.

2) Until the state approves alternate Step 2, system must meet Step 1 removals. 
(Attachment 8) I operate a surface water system or ground water system under the direct influence of

surface water and operate a conventional filtration treatment plant . . .

Page 58

Monitoring Requirements for Disinfection Byproduct Precursors (DBPP)

Is system a Subpart H system1 using

conventional filtration treatment?

Is the annual 

average (based on

quarterly monitoring)

of treated water TOC

$2.0 mg/L?

Is the system’s annual

average treated water TOC <2.0mg/L

for two consecutive years or 

<1.0mg/L for one year?

Did 

system conduct required

monitoring?

TT Violation

Return to routine

monitoring in month

following quarter where

annual average $2.0 

mg/L.

Reduced Monitoring

May reduce monitoring to one paired 

sample and one alkalinity sample per

quarter per treatment pair

1 source water alkalinity sample taken at

same time and location as source water

TOC sample.

Source water sampling2 

Minimum of 1 TOC sample per month per

treatment plant in the source water prior

to any treatment

Treated water sampling2

Minimum of 1 sample per month per 

treatment plant taken no later than

combined filter effluent

Routine Monitoring for DBP

precursors required.

No DBPP

monitoring 

requirements.

YES

NO

“paired sample”

YES

NO

NO

YES

NO

YES

Notes:

1.) Subpart H = Public water systems using surface water or ground water under the direct influence of surface water.

2.) The source water and the treated water samples are referred to as “paired samples” and are to be taken simultaneously