SEPA Disinfectants and
s™1"-*» Disinfection Byproducts
Rules
(Stage 1 and Stage 2)
What Do They Mean to You?
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Office of Water (4606M)
EPA 815-R-20-005
June 2020
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Contents
Contents i
Definitions and Acronyms ii
Definitions ii
Acronyms iii
1. Introduction 1
Purpose of the Guide 1
Background 1
2. Applicability and Compliance Dates 2
3. Summary of Regulatory Requirements 3
MRDLGs and MRDLs for disinfectants only; MCLGs and MCLs for disinfection byproducts 3
Monitoring plan 4
Laboratory methods and certification 4
Monitoring 4
Compliance 4
Public water system recordkeeping and reporting requirements 5
Operational evaluation levels 5
Best available technology 6
Treatment technique for disinfection byproduct precursors 6
4. Additional Information 7
5. Detailed Regulatory Requirements 7
Attachment 1: CWSs and NTNCWSs use a primary or residual disinfectant other than ultraviolet
(UV) light or deliver water that has been treated with a primary or residual disinfectant other
than UV light 9
Attachment 2: TTHM and HAA5 monitoring for systems that deliver water that has been treated
with a disinfectant other than UV light 13
Attachment 3: CWSs and NTNCWSs that deliver water that has been treated with chlorine or
chloramines 27
Attachment 4: Systems that deliver water that has been treated with chlorine dioxide 29
Attachment 5: Systems that deliver water that has been treated with ozone 33
Attachment 6: Subpart H systems that operate a conventional filtration treatment plant 35
Disinfectants and Disinfection Byproducts Rules i
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Definitions and Acronyms
Definitions
Combined distribution system (CDS) - the interconnected distribution system consisting of the
distribution systems of wholesale systems and of the consecutive systems that receive some or all of their
finished water from those wholesale systems.
Consecutive system - a public water system (PWS) that receives some or all of its finished water from
one or more wholesale systems. Delivery may be through a direct connection or through the distribution
system of one or more consecutive systems.
Dual sample set - a set of two samples collected at the same time and same location, with one sample
analyzed for total trihalomethanes (TTHM) and the other analyzed for five haloacetic acids (HAA5).
Enhanced coagulation - the addition of sufficient coagulant for improved removal of disinfection
byproduct precursors by conventional filtration treatment.
Enhanced softening - the removal of disinfection byproduct precursors by precipitative softening.
Locational running annual average (LRAA) - the average of analytical results for samples taken at a
particular monitoring location during the previous four calendar quarters.
Log - Logarithm (common, base 10).
Log inactivation - Logarithm of (NO/NT).
Maximum contaminant level (MCL) - the highest level of a contaminant that is allowed in drinking
water. MCLs are set as close to maximum contaminant level goals (MCLGs) as feasible using the best
available treatment technology and taking cost into consideration. MCLs are enforceable standards.
Maximum contaminant level goal (MCLG) - the level of a contaminant in drinking water below which
there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-
enforceable public health goals.
Maximum residual disinfectant level (MRDL) - the maximum level of a disinfectant added for water
treatment that may not be exceeded without an unacceptable possibility of adverse health effects. MRDLs
are enforceable standards analogous to MCLs.
Maximum residual disinfectant level goal (MRDLG) - the maximum level of a disinfectant added for
water treatment at which no known or anticipated health effects 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 disinfectant for control of waterborne microbial contaminants.
Running annual average (RAA) - the average of all sample analytical results taken during the previous
four calendar quarters.
Specific Ultraviolet Absorption (SUVA) - Specific Ultraviolet Absorption at 254 nanometers (nm) is 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 m1) by its concentration of dissolved
organic carbon (in milligrams per liter).
Subpart H - a public water system (PWS) using surface water or ground water under the direct influence
of surface water.
Total Organic Carbon (TOC) - total organic carbon in milligrams per liter is 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.
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Acronyms
BAT: Best Available Technology
CDS: Combined Distribution System
CWS: Community Water System
DBP: Disinfection Byproducts
DBPP: Disinfection Byproducts Precursors
DBPR: Disinfectants and Disinfection Byproducts Rule
EC: Enhanced Coagulation
EPA: United States Environmental Protection Agency
ES: Enhanced Softening
FR: Federal Register
GAC10: Granular Activated Carbon with 10-minute empty bed contact time and 180-day reactivation
frequency
GAC20: Granular Activated Carbon with 20-minute empty bed contact time and 240-day reactivation
frequency
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)
IDSE: Initial Distribution System Evaluation
LRAA: Locational Running Annual Average
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
nm: Nanometer
NOM: Naturally Occurring Material - A DBPP
NTNCWS: Nontransient Noncommunity Water System
OEL: Operational Evaluation Level
PWS: Public Water System
RAA: Running Annual Average
RTCR: Revised Total Coliform Rule
SDWA: Safe Drinking Water Act
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
TNCWS: Transient Noncommunity Water System
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TOC: Total Organic Carbon
TTHM: Total Trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and
bromoform)
UV: Ultraviolet
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1. Introduction
Purpose of tie Guide
The purpose of this guide is to provide an overview of the regulatory requirements of the Stage 1 and
Stage 2 Disinfectants and Disinfection Byproducts Rules (DBPRs). The Stage 1 DBPR was published in
the Federal Register on December 16, 1998 and the Stage 2 DBPR was published in the Federal Register
on January 4, 2006. The U.S. Environmental Protection Agency (EPA) website provides links to the
original rule language as well as the most recent guidance documents and other information
(https://www.epa.gov/dwreginfo/stage-l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules').
With these rules EPA set enforceable limits for disinfectants and disinfection byproducts (DBPs), created
monitoring requirements and specify planning and reporting procedures. This guide presents an overview
of the rule requirements as well as attachments that provide detailed descriptions of the rule requirements
for water systems according to system size, source water type and disinfectant used. Water system
operators and other readers should look at the short overview sections (Sections 1-4) at the beginning of
this guide and then turn to the specific attachment in Section 5 that apply to their water system.
Background
The 1974 Safe Drinking Water Act (SDWA) required EPA to regulate drinking water. Although the
SDWA was amended slightly in 1977, 1979 and 1980, the most significant changes occurred when
SDWA was reauthorized in 1986. To safeguard public
health, the 1986 Amendments required EPA to set
health goals, or maximum contaminant level goals
(MCLGs) and maximum contaminant levels (MCLs)
for 83 contaminants. EPA also was required to
establish regulations, require disinfection of water
systems (all those using surface water and as
necessary, those using ground water), 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 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 (such as, bacteria, protozoa and viruses) are the greatest remaining
health-risk challenge for drinking water suppliers. Water systems add disinfectants to reduce the risk of
these contaminants, but the disinfectants react with naturally occurring materials (NOMs) in the water to
form DBPs.
The Stage 1 and Stage 2 DBPRs
ARE INTENDED TO HELP CONTROL
PATHOGENS WHILE MINIMIZING
THE PUBLIC HEALTH RISK FROM
DISINFECTANTS AND DBPS.
DBP formation is influenced by several factors, including precursor concentrations and water
temperature. For instance, DBPs formed from NOMs are produced at a higher rate as the temperature of
the water increases. This usually leads to
higher disinfectant demand and higher
total trihalomethanes (TTHM) and five
haloacetic acid (HAA5) concentrations
during summer months and in warmer
climates. The Stage 1 and Stage 2 DBPRs
are intended to minimize the public
health risk from DBPs and disinfectants
that are used to control pathogens. By
Pi etui ;-;oi in
W.itei
Added
Disinfectant
DBP
+
=
NnhiinlOi same
Ma teii.il
Ei omu'le
Chlorine
Chi oi amines
Ozone
Chloi me
Dioxide
TTHM
HAAS
Bromnte
Chlorite
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building on the foundation set forth by the original SDWA, the quality of drinking water has improved
and public health protection has increased.
To address the complex balance between water disinfection risks and benefits, EPA established maximum
residual disinfectant levels (MRDLs) for chlorine, chloramines and chlorine dioxide, and MCLs for DBPs
(chlorite, bromate, TTHM and HAA5). The Stage 1 and Stage 2 DBPRs require all community water
systems (CWSs) and nontransient noncommunity water systems (NTNCWSs) that use a primary or
residual disinfectant other than ultraviolet (UV) light or deliver water that has been treated with a primary
or residual disinfectant other than UV light to comply with all monitoring requirements associated with
the:
• MCL for TTHM and HAA5.
• MRDL for chlorine or chloramines.
• MCL for bromate (for systems that use ozone).
• MRDL for chlorine dioxide (for systems that use chlorine dioxide).
• MCL for chlorite (for systems that use chlorine dioxide).
Transient noncommunity water systems (TNCWSs) that use chlorine dioxide, must comply with the
MRDL for chlorine dioxide. In addition, water systems with a surface or ground water under the direct
influence of surface water source (Subpart H systems) that use conventional filtration must comply with
the treatment technique requirement and remove NOMs measured as total organic carbon (TOC) that may
react with disinfectants to form DBPs.
Following promulgation of the Stage 1 DPBR, EPA determined that the required monitoring sites may
not be representative of higher DBP concentrations that occur in distribution systems. Therefore, the
Stage 2 DPBR was promulgated to require more consistent and equitable protection from DBPs across the
entire distribution system, reduce DBP peaks and ultimately, provide more equitable public health
protection. To achieve this CWSs and NTNCWSs that serve 10,000 or more persons were required to
conduct an evaluation of their water system's distribution systems. This evaluation, called an Initial
Distribution System Evaluation (IDSE), was used to identify the areas in the distribution system with high
DBPs concentrations. The sample sites identified in the IDSE are used by CWSs and NTNCWSs as the
basis for selecting their TTHM and HAA5 compliance monitoring sites. The IDSE requirement was a
one-time requirement and all CWSs and NTNCWSs serving 10,000 or more persons should have
completed their IDSE.
This guide addresses the ongoing monitoring required by the Stage 1 and Stage 2 DBPRs.
2. Applicability and Compliance Dates
The Stage 1 DBPR analytical and monitoring requirements for chlorine, chloramines, bromate, chlorine
dioxide and chlorite apply to all CWSs and NTNCWSs that add a chemical disinfectant to the water in
any part of the drinking water treatment process. In addition, certain requirements apply to TNCWSs that
use chlorine dioxide. The Stage 2 DBPR analytical and
monitoring requirements for TTHM and HAA5 apply to
all CWSs and NTNCWSs that either add a primary or
residual disinfectant other than UV light, or deliver water
that has been treated with a primary or residual disinfectant
other than UV light. Consecutive systems that do not add a
disinfectant but deliver water that was treated with a
disinfectant other than UV light must also comply with the
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Compliance dates depend on
THE POPULATION SERVED BY
THE SYSTEM OR THE LARGEST
SYSTEM WITHIN A COMBINED
DISTRIBUTION SYSTEM.
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Stage 1 DBPR analytical and monitoring requirements for chlorine and chloramines and associated
compliance and reporting requirements.
Under the Stage 2 DPBR, compliance dates are dependent on the population served by a system or the
population served by the largest system within a combined distribution system (CDS). A CDS is an
interconnected distribution system consisting of the distribution systems of wholesale systems and of the
consecutive systems that receive some or all of their finished water from those wholesale systems.
Table 1 - Stage 2 DBPR TTHM and HAA5 Compliance Monitoring Compliance Dates
IF YOU ARE THIS TYPE OF SYSTEM
YOU MUST HAVE BEGUN COMPLYING WITH
SUBPART V TTHM/HAA5 MONITORING BY: 1
Systems that are not part of a combined distribution system and systems that serve the largest
population in the combined distribution system
(1) System serving >100,000
April 1, 2012
(2) System serving 50,000-99,999
October 1, 2012
(3) System serving 10,000-49,999
October 1, 2013
(4) System serving <10,000
October 1, 2013 if no Cryptosporidium monitoring is required
under Long-Term 2 Enhanced Surface Water Treatment Rule
(LT2ESWTR)
OR
October 1, 2014 if Cryptosporidium monitoring is required
under LT2ESWTR
Other systems that are part of a combined distribution system
(5) Consecutive system or wholesale system
at the same time as the system with the earliest compliance
date in the combined distribution system
3. Summary of Regulatory Requirements
MKDLGs and MRDLs for disinfectants only; MCLGs and MCLs for
disinfection byproducts
EPA established maximum residual disinfectant level goals (MRDLGs) and MRDLs for three chemical
disinfectants - chlorine, chloramine and chlorine dioxide - and established MCLGs and MCLs for
TTHM, HAA5, chlorite and bromate, as described in the tables below. All MCLs and MRDLs are in
milligrams per liter (mg/L).
Table 2 - Regulated Disinfectants
Regulated Disinfectants
MRDL (mg/L)
MRDLG (mg/L)
Chlorine
4.0 as Cl2
4 as CI2
Chloramines
4.0 as Cl2
4 as CI2
Chlorine dioxide
0.8 as C102
0.8 as CIO2
1 The state may grant up to an additional 24 months for compliance with MCLs and operational evaluation levels if
the water system is required to make capital improvements to comply with an MCL.
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Table 3 - Regulated Contaminants
Regulated Contaminants
MCL (mg/L)
MCLG (mg/L)
TTHM
0.080
Three individual MCLGs were
established:
Bromodichloromethane at Zero
Dibromochloromethane at 0.06
Bromoform at Zero
HAA5
0.060
Two individual MCLGs were
established:
Dichloroacetic acid at Zero
Trichloroacetic acid at 0.3
Bromate (plants that use ozone)
0.010
Zero
Chlorite (plants that use chlorine dioxide)
1.0
0.8
Monitoring plan
Each water system must develop and implement a monitoring plan that details how it will meet all
applicable requirements. The monitoring plan must include specific locations and schedules for collecting
samples, and how the water system will calculate compliance with MCLs, MRDLs and removal
requirements. The monitoring plan must be kept on file for state and public review, and must contain
monitoring plans for any other systems in the CDS if the state has allowed combined monitoring.
Laboratory methods and certification
Analysis for DBPs must be conducted by laboratories that have been certified by EPA or the state.
Chlorite measured at the entrance to the distribution system 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 on-site (for example, for samples that may deteriorate
before reaching a certified laboratory), EPA requires that analyses be conducted by a party approved by
the state. Additional information on approved methods can be found on EPA's website at:
https ://www. epa. gov/dwanalvticalmethods.
Monitoring
EPA has developed compliance monitoring schemes for each MRDL, MCL and treatment technique to be
protective of acute and chronic health concerns. The compliance monitoring requirements vary by the size
and type of the water system, the treatment employed and the disinfectant used. In many cases, water
systems may reduce monitoring frequencies after establishing a baseline. In some cases, water systems
that exceed an MCL or MRDL may need to increase the number of samples or monitoring frequency.
Compliance
Compliance is based on a running annual average (RAA) calculated quarterly, locational running annual
average (LRAA) calculated quarterly, a single sample result or an average of a selected number of
samples, depending on which disinfectant or DBP is being monitored.
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Water systems must notify the public and report to the state if they are in violation of an MCL, MRDL or
treatment technique. If a water system fails to monitor, the system is in violation of the monitoring
requirements for each quarter that the monitoring result would have been used in calculating compliance.
All violations require public notification.2 All samples taken and analyzed under the provisions of the
monitoring plan must be included in determining compliance, even if there are more than the minimum
required.
A water system is considered in violation if the RAA or LRAA of all samples for a consecutive 4-quarter
period exceeds the MCL or MRDL. The system would also be in violation of the MCL or MRDL if they
will exceed the MCL or MRDL based on fewer than 4 quarters of data and regardless of the monitoring
results of subsequent quarters.
If the sum of 3 quarters of sampling causes a water system to exceed the MCL even
with a 4th quarter sample of 0 mg/L, the water system, has an MCL violation after 3
quarters. For example, Quarter 1 = 0.009, Quarter 2 = 0.010, Quarter 3 = 0.015;
Average = 0.011 for first three quarters. Average exceeds the MCL after 3 quarters,
water system, is in violation of the MCL.
Public water system recordkeeping and reporting requirements
Water 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. 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 (for example, chlorine dioxide) are subject to additional reporting requirements if certain
chemical levels are measured.
Operational evaluation levels
EPA included operational evaluation levels (OELs) for TTHM and HAA5 in order to better track
contaminant levels in drinking water. TTHM and HAA5 OELs must be calculated by all water systems
required to comply with the TTHM and HAA5 MCLs. An OEL is calculated as the sum of the 2 previous
quarters' sample results plus twice the current quarter's result, divided by four to determine an average.
An OEL for TTHM is exceeded at any monitoring location where the OEL is greater than 0.080 mg/L.
For HAA5, the OEL is exceeded at any monitoring location where the OEL is greater than 0.060 mg/L.
If you exceed an OEL, you must
conduct an operational evaluation
and submit a written report to the
state no later than 90 days after
receiving the exceedance result.
The evaluation must include an
examination of system treatment
and distribution practices,
including storage tank operations,
excess storage capacity,
distribution system flushing,
2 Failure to take distribution system samples the day an entry point sample exceeded the chlorine dioxide MRDL is a
monitoring violation and requires Tier 1 public notice be provided, not Tier 3 public notice.
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Operational Evaluation Level
(Qi + Qi + 2 Q'i) MCL
4_ '
Where Q\ is the TTHM or HAA5 quarterly sample result from
two quarters ago, Qi is the result from last quarter, and Q> is
the most recent result (current quarter) which is then multiplied
by 2 to predict possible level for the next quarter.
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changes in sources or source water quality and treatment changes. The report must be made available to
the public upon request. The scope of the evaluation may be limited, if the water system is able to identify
the cause of the OEL exceedance. EPA developed a guidance manual that describes the requirements for
operational evaluations and provides guidance for documenting and reporting OEL exceedances. This
guidance manual is available on EPA's website (https://www.epa.gov/dwreginfo/stage-l-and-stage-2-
disinfcctants-and-disinfcction-bvproducts-rulcs).
Best available technology
EPA specified best available technologies (BATs) for each MCL and MRDL. These technologies and
methods are believed to be effective in controlling chemicals in drinking water while remaining
economically feasible. Public water systems (PWSs) must use the specified BAT if they wish to qualify
for variances; otherwise, systems are not required to install a BAT and may use any approved technology
to achieve compliance.
Table 4 - DBPRs Best Available Technology Options
Disinfectant or
DBP
Contaminant/
Disinfectant
Best Available Technology
DBPs
TTHM and HAA5
Enhanced coagulation or enhanced softening with granular activated
carbon with an empty bed contact time of ten minutes (GAC10) or
granular activated carbon with an empty bed contact time of 20 minutes
(GAC20), with chlorine as the primary and residual disinfectant, or
nanofiltration with a maximum filter weight of 1,000 Daltons.
DBPs
Chlorite
Control of treatment processes to reduce disinfectant demand and control
of disinfection treatment processes to reduce disinfectant levels.
DBPs
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.
Treatment technique for disinfection byproduct precursors
EPA specified a treatment technique that applies to Subpart H systems using conventional filtration
treatment. The treatment technique requirements are designed to provide public health protection by
minimizing DBP precursors (DBPPs) and thus the production of all DBPs. Compliance with the treatment
technique can be achieved by removing specified percentages of TOC using enhanced coagulation or
enhanced softening. The required TOC removal is listed in the table below.
Table 5 - Step 1 TOC - Required Percent Removal of TOC
Source Water TOC
(mg/L)
Source Water Alkalinity, mg/L as CaC03
0-60
> 60-120
>120
> 2.0 to 4.0
35.0%
25.0%
15.0%
> 4.0 to 8.0
45.0%
35.0%
25.0%
>8.0
50.0%
40.0%
30.0%
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When providing TOC removal, Subpart H systems may show that they meet alternative compliance
criteria. For example, a system that has less than 2.0 mg/L TOC in its source or treated water meets an
alternative compliance criterion. Another criterion allows the system to be in compliance if the RAA of a
system's source water TOC is less than 4.0 mg/L, the RAA of source water alkalinity is greater than 60
mg/L, and either the TTHM RAA is less than or equal to 0.040 mg/L and the HAA5 RAA is less than or
equal to 0.030 mg/L, or the state has determined that the system has made a clear and irrevocable
commitment to installing technology to limit TTHM and HAA5 to those levels. For those systems using
Specific Ultraviolet Absorption (SUVA) as an alternative compliance criterion they must be less than or
equal to 2.0 L/mg-m, calculated quarterly as a RAA. See Attachment 6 for specific information on
alternative compliance criteria.
4. Additional Information
A series of guidance manuals have been developed to support the Stage 1 and Stage 2 DBPR. They are
available on EPA's website (https://www.epa.gov/dwreginfo/stage-l-and-stage-2-disinfectants-and-
disinfcction-bvproducts-rulcs) and are also available free of charge through the National Service Center
for Environmental Publications (https://www.epa.gov/nscep'). The manuals can help water system
operators, state agencies and EPA implement drinking water regulations consistently and effectively.
5. Detailed Regulatory Requirements
Detailed descriptions of the monitoring requirements for PWSs are presented in the following sections.
The Stage 1 and Stage 2 DBPR apply to all CWSs and NTNCWSs that add a disinfectant other than UV
light, or deliver water that has been treated with any disinfectant other than UV light, as well as TNCWSs
that treat their water with chlorine dioxide. However, systems must monitor at particular frequencies and
locations depending on source water type (Subpart H and ground water) and population served by the
system. Additionally, monitoring requirements for specific chemicals will vary depending on system type
and the primary disinfectant used. For this reason, the monitoring requirements are presented in separate
attachments for each system size and type.
This section is organized into separate attachments so that specific categories of systems can turn to their
specific requirements. Keep in mind that some systems may fall into more than one category. Use the
flowchart on the next page to determine which of the attachments apply to your water system.
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Disinfectant and Disinfection Byproduct Rules General Requirements
Is the system a CWS, NTNCWS, or a
TNCWS that delivers water that has
been treated with a disinfectant
other than UV light?
No requirements.
NO
NO
Is the system a
TNCWs?
YES
Does the TNCWS
use chlorine dioxide?
System must conduct TTHM/HAA5
monitoring according; to population
served and source water type. See
Attachments 1 and 2.
monitoring. See Attachment 4
Does system deliver water
that has been treated with
chlorine or chloramines?
Chlorine and chloramines
monitoring requirements apply.
See Attachment 3.
NO
Does system deliver water
that has been treated with
chlorine dioxide?
YES
f \
Chlorine dioxide and chlorite
monitoring requirements apply.
See Attachment 4.
NO
T
Does system deliver water
that has been treated with
ozone?
YES
Bra-mate monitoring
requirements apply.
See Attachment 5,
NO
Is system a subpart H
system with conventional
filtration treatment?
YES
f
IOC removal requirements (enhanced
coagulation/enhanced softening)
apply. See Attachment 6.
NO
No additional requirements.
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Attachment 1: CWSs and NTNCWSs use a primary or residual disinfectant
other than ultraviolet (I V) light or deliver water that has been treated with a
primary or residual disinfectant other than I V light
Monitoring Location Site Selection Protocol
If you treat water with a chemical disinfectant, or deliver water that has been treated with a chemical
disinfectant, you must identify in your monitoring plan the locations with representative high TTHM and
HAA5 concentrations in your distribution system.
The number of required sampling sites for TTHM and HAA5 compliance monitoring will depend on your
source type and population served by the system. Please refer to the appropriate flowchart in this
attachment for the number of sample sites that you must identify.
The site selection protocol below explains how you must select your TTHM and HAA5 monitoring
locations:
Step
#
Criteria
Site
1
Select the location with the highest TTHM LRAA
1st highest TTHM site
2
Select the remaining location with the highest HAA5 LRAA
1st highest HAA5 site
3
For subpart H systems: Select the remaining existing Stage 1 DBPR average
residence time compliance monitoring location with the highest HAA5 LRAA
For ground water systems: Select the remaining existing Stage 1 DBPR
maximum residence time compliance monitoring location with the highest
HAA5LRAA
Skip this step if you have no more Stage 1 DBPR sites
1st Stage 1 DBPR site
4
Select the remaining location with the next highest TTHM LRAA
2nd highest TTHM site
5
Select the remaining location with the next highest TTHM LRAA
3rd highest TTHM site
6
Select the remaining location with the next highest HAA5 LRAA
2nd highest HAA5 site
7
For subpart H systems: Select the remaining existing Stage 1 DBPR average
residence time compliance monitoring location with the highest TTHM LRAA
For ground water systems: Select the remaining existing Stage 1 DBPR
maximum residence time compliance monitoring location with the highest
TTHM LRAA
Skip this step if you have no more Stage 1 DBPR
2nd Stage 1 DBPR site
8
Select the remaining location with the next highest HAA5 LRAA
3rd highest HAA5 site
Notes:
• If you need more compliance monitoring locations, go back to Step 1 of this protocol and repeat the steps
until you have selected the required number of total sites.
• You may recommend locations other than those listed in the protocol if you provide a rationale for selecting
other locations and your state approves of the alternate locations.
Routine Monitoring
If you treat water with a chemical disinfectant, or deliver water that has been treated with a chemical
disinfectant, the number and frequency of TTHM/HAA5 samples you must take depends on your
system's source type and the size of the population served. If you are required to monitor quarterly, you
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must take dual sample sets every 90 days at each monitoring location included in your monitoring plan.
If you are required to monitor TTHM/HAA5 annually, you are only required to take individual samples
annually at the locations with the highest TTHM and HAA5 concentrations, respectively.
Increased Monitoring
If you monitor annually or less frequently than annually and a TTHM sample exceeds 0.080 mg/L or a
HAA5 sample exceeds 0.060 mg/L at any location, you must increase monitoring frequency to dual
sample sets once per quarter (taken every 90 days) at all monitoring locations. You may return to routine
monitoring if the TTHM LRAA for every monitoring location is less than or equal to 0.060 mg/L and the
HAA5 LRAA for every monitoring location is less than or equal to 0.045 mg/L after conducting at least
four consecutive quarters of increased monitoring.
Re DUC ED IV! ON ITORING
If you qualify and your state allows, you may be able to reduce your monitoring for TTHM and HAA5
LRAAs. Remember, TTHM and HAA5 monitoring requirements are tied together. In order to reduce the
water system's monitoring frequency, your system must meet the qualifications for both TTHM and
HAA5 reduced monitoring and the state must approve. In addition, if you exceed the MCL for either
TTHM or HAA5 while on reduced monitoring, you must increase or return to routine monitoring for both
TTHM and HAA5.
• For qualified systems on reduced quarterly monitoring, you may remain on reduced monitoring
as long as the TTHM LRAA is less than or equal to 0.040 mg/L and the HAA5 LRAA is less than
equal to 0.030 mg/L at each monitoring location.
• For qualified systems on reduced annual or less frequent monitoring, you may remain on a
reduced monitoring schedule as long as each TTHM sample is less than or equal to 0.060 mg/L
and each HAA5 sample is less than or equal to 0.045 mg/L.
• In addition, qualified Subpart H systems on reduced monitoring schedule must maintain a
source water annual average TOC level, before any treatment, of less than or equal to 4.0 mg/L at
each Subpart H treatment plant.
If your system fails to meet the criteria list above at any of the sampling locations, you must return to
routine monitoring.
Compliance
You are in violation if the LRAA for any monitoring location covering any consecutive 4-quarter period
exceeds the TTHM MCL of 0.080 mg/L or HAA5 MCL of 0.060 mg/L. If your LRAA, based on fewer
than 4 quarters of data exceeds one of the MCLs regardless of the monitoring results of subsequent
quarters you would be in violation. If you fail to monitor, you are in violation of the monitoring
requirements for each quarter that the missed monitoring result would have been used in the compliance
calculation.
You must calculate your LRAA based on the quarterly results at each site for the previous consecutive 4-
quarter period.3 The table below provides an example TTHM LRAA calculation (results reported in
mg/L). For example, the LRAA for the 4th quarter of 2013 is the average of the quarterly results from
3 Stage 2 DBPR compliance can also be based on a single sample result (if the result is 4 times the MCL). If your
system monitors once a year or less often, you should use your single sample result to determine compliance.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
Page 10
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quarters 1-4 in 2013. Note that the reported LRAAs for quarters 1-3 in 2013 are based on results from
previous quarters not reported on this table.
Table 1.1 - TTHM Monitoring Results
Sample Sites
1st quarter
2013
2nd quarter
2013
3rd quarter
2013
4th quarter
2013
1st quarter
2014
2nd quarter
2014
Site 1 Quarterly Results
0.045
0.060
0.125
0.070
0.041
0.064
Silo 1 - l.k \ \
o.o5 1
o o"4
o o"5
o.o~4
o o~5
Sue 2 Qimiiei'K kesiilis
0 o4u
o 055
o||5
O O(il)
0 044
o (Ki5
Sue: I.RW
11.042
0.04'J
o.o" I
0.0()S
O.d(i')
o.o" I
You must calculate a LRAA for each of the TTHM and HAA5 sample sites.
If an OEL is exceeded at any monitoring location, you must conduct an operational evaluation and submit
a written report of the evaluation to the state within 90 days. An OEL exceedance occurs when the sum of
the two previous quarters' results plus twice the current quarter's result, divided by four to determine an
average, exceeds an MCL.
Reporting
You must report to the state within 10 days after the end of each quarter. You must report the number of
TTHM and HAA5 samples taken during the last 3 months, and the location, date and result of each
sample taken during the last quarter. You must report the LRAAs of all quarterly samples, however the
state may choose to perform this calculation and determine if the MCL was exceeded. If an LRAA
calculation based on fewer than 4 quarters of data would cause the MCL to be exceeded regardless of the
monitoring results of subsequent quarters, you must submit this information to the state.
If you are a Subpart H system looking to qualify or remain on reduced monitoring, you must also report
your RAA of every 30 days or every 90 days TOC samples and whether or not you exceed 4.0 mg/L.
You must report any OELs that were exceeded, including location, date and the calculated TTHM and
HAA5 levels. You must submit a written report to the state no later than 90 days after being notified of
the result that causes your system to exceed the OEL.
Disinfectants and Disinfection Byproducts Rules
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Disinfectants and Disinfection Byproducts Rules Page 12
What Do They Mean to You?
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Attachment 2: TTIIM and HAAS monitoring for systems that deliver water
that has been treated with a disinfectant other than I V light
TTHM and HAA5 monitoring requirements for Subpart H systems that deliver water that has been
treated with a disinfectant other than UV light and the largest system in the CDS serves at least
5,000,000 people
Is LRAA2
(computed quarterly)
for TTHM > 0,080 t*g/L or
HAAS > 0.060 mg/L?
YES
A fc
NO
Are TTHM LRAA < 0.040 ng/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual average TOC
(taken every 30 days)5 < 4.0 mg/L?
NO
YES
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual
average TOC < 4.0 mg/L4?
NO
YES
NOTES
Subpart H systems serving
at least 5,000,000 people
20 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPK monitoring plan
Routine Vfomtoi mj
Reduced Monitoring
10 dual sample sets every 90 days in distribution system at the
5 locations with the highest TTHM LRAA and the
5 locations with the highest HAAS LRAA.
1. Monitoring locations must be based on Stage 2 DPBR monitoring plan. See Attachment 1 for an explanation of the
site selection protocol.
2, Systems must calcuiatethe arithmetic average of results for each monitoring location, and an exceedance at any
location is an MCI violation, fa PW5 fails to complete 4 consecutive quarers of monitoring, compliance with the
MCL for the last 4-quarter period must be based on the average or available data.
3. Subpart H systems which lue conventional filtration must monitor for TOC monthly instead of every 3C days.
4, Subpart H systems that do not use conventional filtration qualify for reduced TTHM and HAA5 monitoring, a system
may reduce source waterTQC monitoring to TOC samples taken every 9C days. Subpatt Hsystems using
conventional filtration must remain ori monthly TOC monitoring until the system's annual average treated water TOC
' 2,C mg/L for 2 consecutive years or < 1,0 mg'Lftr one year. After systems meet this requirement, they can reduce
TOC monitoring from monthly to quarterly.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
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TTHM and HAA5 monitoring requirements for Subpart H systems that deliver water
that has been treated with a disinfectant other than UV light and the largest system in
the CDS serves 1,000,000 to 4,999,999 people
Subpart H systems serving
1,000,000 to 4,999,999 people
Routine Monitoring
16 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan1
%
/ is LRAA2 \
M
Vioic
tsOP
{computed quarterly)
for TTHM > O.OSO mg/L or
HAAS > 0,060 mg/L?
YES
NO
NO
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual average TOC
{taken every 30 days)3 < 4.0 mg/L?
YES
Reduced Monitoring
8 dual sarrpie sets every 90 days in distribution system at the
4 locations with the highest TTHM LRAA and the
4 locations with the highest HAAS LRAA.
NO
NOTES
1.
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual
average TOC £ 4.0 mg/L4?
YES
Monitoring locations must be based on Stage 2 3P3R monitoring plan. See Attachment »for an explanation of the
sue selection protocol.
2. Systems must calculate the arithmetic avei age of results for each monitoring location, and an exceedance at any
location is an MCL violation, -fa PWS fails to complete 4 consecutive quarters of monitoring, compliance with the
MCLfor the last 4-quarter period must be based on the average of available data
3. Subpart H systems which use conventional filtration must monitor for TOC monthly instead of every 30 days.
4. Subpart H systems that do not use conventional filtration qualify for reduced TTHM and HAAS monitoring, a
system may reduce source water TOC monitoring to TOC samples taken every 90 days. Subpart H systems using
conventional filtration must remain on monthly TOC monitoring until the system's annual average treated water
TOC •' 2X mg/L for 2 consecutive years or < i.C mg/L for one year. After systems meet this requirement, they ran
reduce TOC monitoring from monthly to quarterly.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
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TTHM and HAA5 monitoring requirements for Subpart H systems that deliver water
that has been treated with a disinfectant other than UV light and the largest system in
the CDS serves 250,000 to 999,999 people
Is LRAA2
(computed quarterly)
for TTHM > 0,080 mg/L or
HAAS > 0.060 mg/L?
NO
Are TTHM LRAA < 0,040 mg/L
and HAAS LRAA < 0,030 mg/L
AND
is source water annual average IOC
{taken every 30 days)3 < 4,0 mg/L?
NO
YES
Are TTHM LRAA < 0,040 mg/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual
average TOC < 4.0 mg/L4?
NO
YES
NOTES
Subpart H systems serving
250,000 to 999,999 people
Routine Monitoring
12 dual sample sets every 90 days at monitoring
locations based on Stage 2DBPR monitoring plan1
Reduced Monitoring
6 dual sample sets every 90 days in distribution system at the
3 locations with the highest TTHM LRAA and the
3 locations with the highest HAAS LRAA
i.
2,
Monitoring locations must be based on Stage 2 3P3R monitoring plan. See Attachment i for an explanation of the
site selection protocol.
Systems must calculate the arithmetic average of results for each monitoring location, and an exceedante at any
location is an MCL violation, f a PWS fails to complete 4 consecutive quarters of monitoring, compliance with the
MCL for the last 4-quarter period must he based on the average of available data-
3. Subpart H systems which use conventional filtration must monitor for TOC monthly instead of every 32 davs
4, Subpart H systems that do not use conventional filtration qualify for reduced TTHM and HAAS monitoring, a
system may reduce soiree water TOC monitoring to TOC samples taken every 90 days. Subpart H systems using
conventional filtration must remain on mont hly TOC monitoring until the system's annual average treated water
TOC - 2.C mg/L for 2 consecutive years or < :,C mg/L for one year. After systems meet this requirement, they can
reduce TOC monitoring from monthly to quarterly.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
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THM and HAA5 monitoring requirements for Subpart H systems that deliver water that has been
treated with a disinfectant other than UV light and the largest system in the CDS serves 50,000 to
249,999 people
NOTES
.
Is LRAA2
(computed quarterly)
for TTHM > 0,080 mg/L or
HAA5 > 0,060 mg/L?
YES
NO
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual average TOC
{taken every 30 days)3 < 4.0 mg/L?
NO
YES
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA £ 0.030 mg/L
AND
Is source water annual
average TOC < 4.0 mg/L4?
NO
YES
Subpart H systems serving
50,000'to 249,999 people
Routine Monitoring
8 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan
Reduced Monitoring
4 dual sample sets every 90 days in distribution system at the
2 locations with the highest TTHM LRAA and tfie
2 locations with the highest HAAS LRAA.
Monitoring locations must be based on Stage 2 DPBR monitoring plan. See Attarhment 1 for an explanation of the
site selection protocol.
2, Systems must calculatethe arithmetic average of results for each monitoring location, and an exceedance at any
location is an MCI violation, :f a PV.'S fails to complete 4 consecutive quarters of monitoring, compliance with the
MCL for the last 4-quarter period must be based on the average of available data
3, Subpart H systems which use conventional filtration must monitor for TOC monthly instead of every 30 days,
4-, Subpart H systems that do not use conventional filtration qualify for reduced TTHM and HAAS monitoring, a
system may reduce source water TCC monitoring to TOC samples taken every 90 days. Subpart H systems using
conventional filtration must remain on monthly TOC monitoring until the system's annual average treated water
TOC < 2.C mg/L for 2 consecutive years cr < 1,o mg/L for one year, After systems meet this requirement, they can
reduce TOC monitoring from monthly to quarterly
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
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TTHM and HAA5 monitoring requirements for Subpart H systems that deliver water that has been
treated with a disinfectant other than UV light and the largest system in the CDS serves 10,000 to
49,999 people
Subpart H systems serving
10,000 to 49,999 people
Routine Monitoring
4 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan1
Is LRAA2
(computed quarterly)
for TTHM > 0.030 mg/l or
HAAS > 0.060 mg/L?
y
YES
NO
NO
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual average TOC
{taken every 30 days)1 •_ 4 0 mg/L?
YES
Reduced Monitoring
2 dual sample sets every 90 days in distribution system.
1 at tKe location with the highest TTHM LRAA and
1 at the location with the highest HAAS LRAA
NO
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0,030 mg/L
AND
is source water annual
average TOC < 4.0 mg/L4?
YES
NOTES
1. Monitoring locations must be based on Stage 2 DPBR monitoring plan. See Attachment 1 for an explanation of the
site selection protocol,
2. Systems must calculate the arithmetic average of results for each monitoring location, and an exceedance a! any
locdtion is an MCL violation. :f a PWS fails to complete 4 consecutive quarters cf monitoring, compliance with the
MCL for the last 4-quarter period must be based on the average of available data.
3. Subpart H systems which use conventional filtration must monitor for TOC monthly instead of every 30 days,
4. Subpart H systems that do not use conventional filtration qualify for reduced TTHM and HAAS monitoring, a
system may reduce source water TOC monitoring to TOC samples taken every 9G days. Subpart H systems using
conventional filtration must remain on monthly TOC monitoring until the system's annual average treated water
TOC «-* 2,0 mg/L for 2 consecutive years or < 1.0 mg/L 'or one year. After systems meet this requirement, they can
reduce TOC monitoring from monthly to quarterly,
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
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TTHM and HAA5 monitoring requirements for Subpart H systems that deliver water
that has been treated with a disinfectant other than UV light and the largest system in
the CDS serves 3,301 to 9,999 people
is IRA ft2
{computed quarterly)
for TTHM > 0.080 mg/L or
HAA5 > 0.060 mg/L?
YES
NO
Are TTHM LRAA I' 0.040 mg/L
and HAAS LRAA < 0.030 mg/L
AND
is source water annual average TOC
{taken every 30 days)3 < 4.0 mg/L?
NO
YES
A k
Are TTHM RAA < 0.060 mg/L
and HAAS RAA < 0.045 mg/L
AND
is source water annual
average TOC < 4.0 mg/L4?
NO
YES
Subpart H systems serving
3,301 to 9,999 people
Routine Monitoring
2 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan
Reduced Monitoring
2 dual sample sets every year.
1 at the location and during the quarter with the highest TTHM single
measurement and 1 at the location and during the quarter with the
highest HAAS single measurement
NOTES
1. Monitoring locations must be based on Stage 2 DPS1? monitoring plan. See Attachment 1 for an explanation of the
site selection protocol,
2. Systems must calculate the arithmetic average of remits for each monitoring location, and an exceedance at any
location is an MCL violation, 'f a PWS fails to complete 4 consecutive quarters of monitoring, compliance with the
MCLfor the last 4-quarter period must be based on the average of available data.
3. Subpart H systems which use conventional filtration must monitor for TOC monthly instead cf every 30 days.
4. Subpart H systems that do not use conventional filtration qualify for reduced TTHM and HAAS monitoring, a
system may reduce source water TOC monitoring to TOC samples taken ever/ 3C days, Subpart H systems using
conventional filtration must remain on monthly TOC monitoring until the system's annual average treated water
TOC i 2,0 mg/L for 2 consecutive years or *¦ 1,0 mg/L for one year. After systems meet this requirement, they can
reduce TOC monitoring from monthly to quarterly.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
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TTHM and HAA5 monitoring requirements for Subpart H systems that deliver water that has been
treated with a disinfectant other than UV light and the largest system in the CDS serves 500 to
3,300 people
Subpart H systems serving
500 to 3,300 people
Routine Monitoring
2 Individual samples every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan1
3l
Is LRAA2 (computed quarterly)
for TTHM > 0.080 mg/L or HAAS > 0,060 mg/L?
YES
NO
Are TTHM LRAA < 0.040
mg/L and HAAS LRAA <
0.030 mg/L AND
is source water annual
average TOC (taken every
30 days)3 < 4.0 mg/L?
4 YES
Reduced Monitoring
1 TTHM/HAA5 sample every year. 1 at
the location and during the quarter
with the highest TTHM single
measurement and 1 at the 'ocation
and durmg the quarter with the
highest HAAS single measurement
Are TTHM LRAA < 0.060 mg/L
and HAAS LRAA. < 0.045 mg/L
AND is source water annual
average TOC < 4.0 mg/L4?
Ino
YES
Are TTHM > 0.080 mg/L
and HAAS > 0,060 mg/L?
YES
Increased Monitoring
2 dual sample sets every 90 days at
monitoring locations based on Stage 2
DBPR monitoring plan1
.NO j
Has the system
monitored for at least 4
consecutive quarters1?
YES
Are TTHM LRAA < 0.060 mg/L
and HAAS LRAA < 0.045 mg/L?
NO
is TTHM LRAA2 > 0.080 mg/L
or HAAS LRAA > 0,060 mg/L?
.YES
MCL
Violation
MOTES 4
i. Monitoring locations must be based cn Stage I DP3S monitoring plan. See Attachment 1 for an explanation of the site
selection protocol.
2- Systems must calculate the arithmeticaverage of results for each monitoring location, and an exceedance at any
location is an MCL violation, 'fa PWS fails to complete 4 consecutive quarters of monitoring, compliance with the MCL
for the last 4-quarter period must be based on the averageof available data.
3, Subpart H systems which use conventional filtration must monitor for TOC monthly instead of every 3C days,
4. Subpart H systems that do not use conventional filtration qualify for reduced TTHM and HAA5 monitoring, a system
may reduce source waterTOC monitoring to TOC samples taken every 90 days, Subpart H systems using conventional
filtration must remain on monthly TOC monitoring until the system's annual average treated waterTOC - 2 0 mg/L for 2
consecutive years or ^ 1,0 mg/L for one year. After systems meet this requirement, they can reduce TOC monitoring
from monthly to quarterly.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
Page 19
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TTHM and HAA5 monitoring requirements for Subpart H systems that deliver water that
has been treated with a disinfectant other than UV light and the largest system in the CDS
serves fewer than 500 people
is TTHM > 0.080 mg/L
or HAAS > 0.060 mg/L?
YES
Has the system monitored
for at ieast 4
consecutive quarters3 ?
j k
NO
YES
NO
is TTHM IRAA3
> 0.080 mg/L of
HAAS LRAA
> 0.060 mg/L?
Are TTHM LRAA < 0.060 mg/L
and HAAS LRAA < 0.045 mg/L?
YES
NO
MCL
Violation
Increased Monitoring
Dual sample sets every 90 days at
all monitoring locations
Subpart H systems servin]
fewer than 500 people
Routine Monitoring
2 Individual samples per year at monitoring
locations based on Stage 2 DBPR monitoring plan1-2
NOTES
1. Only one dual sample set atone monitoring location per year is needed if the highest TTHM and HAAS
concentrations occur at the same location and month.
2. Monitoring locations must be based on Stage 2 DP3S monitoring plan. See Attachment 1 for an explanation of the
site selection protocol.
3. Systems must calculate the arithmetic average of results for each monitoring location f a PWS fails tc complete 4
consecutive quarters of monitoring, compliance with the MCL for the last 4-quarter period must be based on the
arerageof available data.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
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TTHM and HAA5 monitoring requirements for ground water systems that deliver water that
has been treated with a disinfectant other than UV light and the largest system in the CDS
serves at least 500,000 people
Ground water systems serving
at least 500,000 people
Routine Monitoring
8 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan1
Is LRAA2
(computed quarterly)
for TTHM > 0,080 mg/L or
HAA5 > 0.060 mg/L?
J"
YES
NO
NO
is the TTHM LRAA < 0,040 mg/L
and HAAS LRAA < 0.030 mg/L?
YES
1
r
Reduced Monitoring
4 dual sample sets every 90 days in distribution system at the
2 locations with the highest TTHM LRAA and the
2 locations with the highest HAAS LRAA
r
NO
Are TTHM LRAA < 0,040 mg/L
and HAAS LRAA < 0.030 mg/L?
YES
NOTES
Monitoring locations must be based on Stage 2 DPBR monitoring plan. See Attachment 1 for an explanation of the
site selection protocol
syst ems must calculate the arithmeticaverage of results for each monitoring location, and an exceedance at any
location is an MCL violation, 'fa PA'S fails to complete 4 consecutive quarters of monitoring, compliance with the
MCI for the last 4-quarte<- period must be based on the average of available data.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
Page 21
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TTHM and HAA5 monitoring requirements for ground water systems that deliver water that
has been treated with a disinfectant other than UV light and the largest system in the CDS
serves 100,000 to 499,999 people
Ground water systems serving
100,000 to 499,999 people
Routine Monitoring
6 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan1
(computed quarterly)
for TTHM >0.080 mg/L or
HAAS > 0.060 mg/L?
YES
NO
NO
Is the TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0.030 mg/L?
YES
r
Reduced Monitoring
2 dual sample sets every 90 days in distribution system.
1 at the location with the highest TTHM LRAA and
1 at the location with the highest HAAS LRAA
MO
Are TTHM LRAA < 0.040 mg/L
and HAAS LRAA < 0.030 mg/L?
YES
NOTES
Monitoring locations must be based on Stage 2 DBPR monitoring plan. See Attachment i for an explanation of the
site selection protocol.
Systems must calculate the arithmetic average of results for each monitoring location, and an exceedance at any
location is an MCL violation, 'fa PV.'S fails to complete 4 consecutive quarters of monitoring, compliance with . the
MCL for the last ^-quarter period must be based on the average of available data.
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
Page 22
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TTHM and HAA5 monitoring requirements for ground water systems that deliver water that
has been treated with a disinfectant other than UV light and the largest system in the CDS
serves 10,000 to 99,999 people
Is LRAA2
{computed quarterly)
for TTHM > 0,080 mg/L or
HAAS > 0.060 mg/L?
YES
NO
f
Is the TTHM LRAA _ 0.040 mg/L
and HAAS LRAA i. 0.030 mg/L?
NO
YES
Are TTHM sample < 0.060 mg/L
and HAAS sample < 0.045 mg/L?
NO
YES
Ground water systems serving
10,000 to 99,999 people
Routine Monitoring
4 dual sample sets every 90 days at monitoring
locations based on Stage 2 DBPR monitoring plan1
Reduced MonitoiiiK
2 dual sample sets per year.
1 at the location and during the quarter with the highest TTHM single
measurement and
1 at the location and during the quarter with the highest HAAS single
measurement
NOTES
1. Monitoring locations must be based on Stage 2 38R monitoring plan. See Attachment 1 for an explanation of the
site selection protocol,
2. Systems must calculate the arithmetic average of results for each monitoring location, and an exceedance at any
location is w MCL '•notation, if a PWS fails to complete 4 consecutive quarters of monitoring, compliance with the
MCLfor the last 4-quarter period must be based on the average of available data,
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
Page 23
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TTHM and HAA5 monitoring requirements for ground water systems that deliver water that
has been treated with a disinfectant other than UV light and the largest system in the CDS
serves 500 to 9,999 people
Ground water systems serving
500 to 9,999 people
Routine Monitoring
2 individual samples per year at locations
based on Stage 2 DBPR monitoring plan1
Is TTHIV > 0 080 mg/L
or HAA5 > 0,060 mg/L?
YES
NO
Is the
TTHM LRAA £ 0 040 mg/L
and HAAS LRAA < 0.030
mg/L?
YES
Reduced Monitoring
1 TTHM sample and 1 HAA5 sample
per year. The TTHM sample at the
location and during the quarter
with the highest TTHM LRAA and
the HAAS sample at the iocat'on
and during the quarter with the
highest HAAS LRAA2
I
Are
TTHM < 0,060 mg/L
and HAAS < 0,045 mg/L?
NO
Are
TTHM > 0.080 mg/L
and HAA5 > 0.060 mg/L?
YES
Increased Monitoring
2 dual sample sets every 90 days at
locations based on Stage 2 DBPR
monitor! ig plan1
NO
Has the system
monitored for at least 4
consecutive quarters'?
YES
Are
TTHM LRAA < 0.060 mg/L
and HAAS LRAA < 0.045 mg/L?
NO
TTHM LRAA3 > 0,080 mg/L
or HAAS LRAA > 0.060 mg/L?
YES
MCL
Violation
NOTES
1, Monitoring locations must be based on the Stage 2 DBPR monitoring plan. See Attachment 1 for an explanation of the
site selection protocol.
2, One dual sample set per year if the highest TTHM and HAAS measurements occurred in the same location and quarter,
3, fa P'iVS fails to complete 4 consecutive quarters of monitoring, compliance with the MCL for the last 4-quarter period
must be based on the average of available data
Disinfectants and Disinfection Byproducts Rules
What Do They Mean to You?
Page 24
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TTHM and HAA5 monitoring requirements for ground water systems that deliver water that
has been treated with a disinfectant other than UV light and the largest system in the CDS
serves fewer than 500 people
Are yearly samples for
TTHM > 0.080 mg/L
of HAAS > 0.060 mg/L?
YES
NO
Is the
TTHM LRAA < 0.040 mg/L
and HAA5 LRAA s 0.030
mg/L?
NO
YES
Has the system
monitored for at least 4
consecutive quarters3?
NO
A L
YES
Are
TTHM LRAA. < 0.060 mg/L
and HAAS LRAA < 0,045 mg/L?
YES
NO
Are
TTHM < 0.060 mg/L
and HAAS £ 0.045 mg/L?
NO
TTHM LRAA3 > 0.080 mg/L
or HAAS LRAA > 0.060 mg/L?
YES
YES
NO
Are
TTHM > 0.080 mg/L
and HAAS > 0.060 mg/L?
YES
NO
MCL
Violation
Ground water systems serving
fewer than 500 people
Increased Monitoring
2 dual sample sets every 90 days at
locations based on Stage 2 DBPR
monitoring plan1
Routine Monitor',ir
2 individual samples per year at locations
based on Stage 2 DBPR monitoring plan1
Reduced Monitoring
1 TTHM sample and 1 HAAS sample
every 3-year cycle. The TTHM
sample at the location with the
highest TTHM result and the HAAS
sample at the location with the
highest HAAS result2
NOTES
1. Monitoring locations musi be based on the Stage 2 DBPR monitoring plan. See Attachment it'or an explanation
the site selection protocol,
2. One dual sample set per '/ear if the highest TTHM and HAAS measurements occurred in the same location and
quarter.
3. if a PW5 fails to complete 4 consecutive quarters of monitoring, compliance with the MCL for the last 4-quarter
period must be based on the average of available data.
if
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Attachment 3: CWSs and NTNCWSs that deliver water that has been treated
with chlorine or chloramines
Routine \lonitoring
If you deliver water that has been treated with chlorine or chloramines, you must sample for chlorine and
chloramines at the same time and location as your Revised Total Coliform Rule (RTCR) samples.
REDUCED MONITORING
There is no reduced monitoring specifically allowed for chlorine and chloramines samples. Your chlorine
and chloramines samples are tied to your RTCR routine and repeat samples.
Compliance
You must notify the public and report to the state if you are in violation. You must determine compliance
with a RAA, computed quarterly, of monthly averages of all samples collected. If an annual arithmetic
average of monthly averages covering any consecutive 4-quarter period exceeds the MRDL, then you are
in violation of the MRDL. If you switch between chlorine and chloramines for residual disinfection
during the year, you must determine compliance by including together all monitoring results for both
chlorine and chloramines.
The MRDL for chlorine and chloramines is 4.0 mg/L. Notwithstanding the MRDL, systems may increase
residual disinfectant levels of chlorine or chloramines in the distribution system to a level and for a time
necessary to protect public health to address specific microbiological contamination problems.
Reporting
You must report to the state within 10 days after the end of each quarter during which samples were
collected. You must report the number of samples taken during each month of last quarter, the monthly
arithmetic average of all samples taken in each month and the RAA of all monthly averages for the last 12
months. You also must report whether a MRDL was exceeded.
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Monitoring Requirements for Chlorine and Chloramines
lHluRINE
NO
YES
Violation
r
%
r
Is the RAA of
monthly averages,
computed quarterly,
< 4.0 mg/L?12 3
YES
Are you a CWS or
NTNCWS using chlorine
or chloramine?
YES
Which
chemical was used to
disinfect the water?
System must measure
chlorine in distribution
system at same location and
time as RTCR samples,
1
Did system
measure chlorine
with total colfform?
System must
notify
state and
public.
MRDL
No monitoring for
chlorine or
'NO *
chloramines is
required.
CHLORAMINES
/
System most measure
chloramines in distribution
system at same location arid
time as RTCR samples.
Did system
measure chloramines
with total coHform?
YES
MR
%
Violation
1
System is in compliance
and continues routine
monitoring.
Ss the RAA of
monthly averages,
computed quarterly,
< 4.0 img/l?1'2'3
YES
NOTES
L Notwithstanding the WOLsfor 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 p meet public health to
address specific microbiological contamination problems,
2. ,-f 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, The RAA is first calculated after first 12 months of monitoring,
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Attachment 4: Systems that deliver water that has been treated with chlorine
dioxide
Systems Adding Chlorine Dioxide
If you treat water with chlorine dioxide you must sample for chlorine dioxide as a residual disinfectant.
All CWSs, NTNCWSs and TNCWSs that add chlorine dioxide, regardless of the purpose (for example,
disinfection, oxidation, or maintenance of a residual), must monitor for chlorine dioxide. You must
comply with the MRDL for chlorine dioxide, which is 0.8 mg/L.
Chlorine Dioxide Routine Monitoring
You must sample every day you use chlorine dioxide at the entry point to the distribution system. If any
daily sample exceeds the MRDL, you must conduct increased monitoring.
Chlorine Dioxide Increased Monitoring
If any daily chlorine dioxide sample exceeds the MRDL, you must take three samples the following day.
If you operate booster chlorination you must sample as close as possible to the first customer, at a
location in the distribution system representing average residence time and as close as possible to the end
of the distribution system. If you do not operate booster chlorination then all samples must be as close as
possible to the first customer at intervals of at least 6 hours.
Chlorine Dioxide Reduced Monitoring
There is no reduced monitoring for the daily sampling of chlorine dioxide.
Chlorine Dioxide Compliance
You must notify the public and report to the state if you are in violation. There are acute and non-acute
violations for chlorine dioxide monitoring. You have incurred an acute violation if any daily sample taken
at entrance to the distribution system exceeds 0.8 mg/L, and on the following day one or more of the three
samples taken in the distribution system exceeds 0.8 mg/L. You 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.
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, you have incurred a non-acute violation. The system
must take immediate corrective action to lower the level of chlorine dioxide below 0.8 mg/L. Failure to
take samples at the entrance to the distribution system following an exceedance of the MRDL is also a
non-acute violation.
Chlorine Dioxide Reporting
You must report to the state within 10 days after the end of each quarter during which samples were
collected.
You must report the dates, results and locations of chlorine dioxide samples taken during last quarter,
whether a MRDL was exceeded and whether a MRDL was exceeded in any two consecutive daily
samples. You must report any acute or non-acute violations.
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CWSs and NTNCWSs Delivering Water Treated with Chlorine Dioxide
If you deliver water treated with chlorine dioxide, you must sample for chlorite as a contaminant. All
CWSs and NTNCWSs that deliver water treated with chlorine dioxide must monitor for both chlorine
dioxide and for the DBP, chlorite. You must comply with the MRDL for chlorine dioxide, which is 0.8
mg/L. In addition, you must comply with the MCL for chlorite, which is 1.0 mg/L. The requirements to
sample for both chlorine dioxide and chlorite help to improve public health by reducing exposure to
DBPs.
Chlorite Routine Monitoring
You must sample for chlorite every day you deliver water treated with chlorine dioxide at the entry point
to the distribution system. If any daily sample exceeds 1.0 mg/L you must conduct increased monitoring.
Additionally, you must collect one 3-sample set per month. One sample must be taken from the location
representative of average residence time in the distribution system, one sample from the location
representing maximum residence time and one sample at the entry point to the distribution system.
Chlorite Increased Monitoring
If any daily sample exceeds 1.0 mg/L, you must take three samples the following day. You must sample
as close as possible to the first customer, at a location representative of maximum residence time and at a
location representative of average residence time in the distribution system.
Chlorite Reduced Monitoring
There is no reduced monitoring for the daily samples for chlorite.
If you qualify and your state allows, you may reduce monthly chlorite monitoring to one 3-sample set per
quarter if no daily or monthly sample has exceeded the MCL and no additional monitoring has been
required. The quarterly 3-sample set must be taken from a location near the first customer, a location
representative of average residence time and a location representative of maximum residence time in
distribution system.
Chlorite Compliance
You must notify the public and report to the state if you are in violation.
Compliance for the chlorite MCL is determined by an average of 3-sample sets. If the arithmetic average
of any 3-sample set in the month exceeds the MCL, the system is in violation.
Chlorite Reporting
You must report to the state within 10 days after the end of each quarter during which samples were
collected.
You must report the number of chlorite samples taken during the last 3 months, and the location, date and
result of each sample taken during the last quarter. You must report the monthly arithmetic average of all
samples taken in each 3-sample set taken, and you also must report whether the MCL was exceeded and
how many times it was exceeded in the 3 months.
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Chlorine Dioxide Monitoring Requirements for Systems Adding Chlorine Dioxide
YES
Does the system
deliver water treated
with chlorine dioxide?
NO
No monitoring
requirements
for chlorine dioxide.
Is system a
TNCWS?
YES
System must also monitor for chlorite
(For chlorite monitoring requirements
see chlorite flow chart on page 4-4),
Chlorine Dioxide
Monitoring
1 sample per day at the
entrance to the
distribution system,1
is daily sample
> 0.8 mg/L?
YES
YES
NO
Did system take
additional
samples in
distribution system
the day following
the exceedance?
On following day, 3 chlorine dioxide distribution
system samples in addition to daily sample.2
Did system take daily sample at
entrance to distribution system the
day following the exceedance?
NO
System must notify public of
nonacute violation.
YES
System must
notify public
of nonacute
violation.
ViRDL
Have 2
consecutive daily
entry point
samples exceeded
0,8 mg/L?
YES
Acute MRDi
Violation
System must take
immediate
«—
corrective action
YES
and notify the
public and the state.
System must take
Immediate
corrective action
and notify public
of nonacute
health risk.
Is any individual
sample in
distribution system
> 0.8 mg/L?
J
NO
NOTE
1.
2.
Samp'e taken every da1, thatch lor nedicx'de s used
*ch cr ned-o\«de, ch'oranvnes, orch'ortneare used to na nta«n a d-s n">ctant'esdua nthe d stnbut'on system, and
there are no d s rpect-on addt onpc.nts( .e , no booster clTornat on) a^terthe entranceto the d.stnbut on sy stem, the
system must take 5 samp es as c osetc the ~ rst customer as pess.b-e, at nte-va s o*' at ieast every g hours, fchlcr neis
used to ma nta.n a d s rr'ectan? -es dua'.n the d str but on system and there are one or more booster ch'cr nat'on
stations, the system must take one samp'e as close to the first customer as pcss be. one -n a 'ocat-on representat'veot
average residence t me, and one as dcsetothe end o'the d-strbut'on system as possib'e.
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Chlorite Monitoring Requirements for CWSs and NTCWSs Delivering Water Treated with
Chlorine Dioxide
Doss ths system d€?l Iver
water treated with
chlorine dioxide?
NO
YES
is system a
CWS or NTNCWS?
NO
VcS
Mo monitoring
requirements
for chlorite.
No monitoring for
chlorite required.
Need to sample for chlorine dioxide andcnlorlte
?or chlorine dioxide monitoring requirements, seethlorsne dioxide flowchart on page31J,
Routine Dally Monitoring
tally sample at the entrance
to the distribution system.
NO
•s sample
• 1.0 mg/'L?
I
YES
Required
chlorite
monitoring
Routine Monthly -Vionitoring
3 sample set permorsth in the
distribution system.-
System must notify the
public arid the state.
increased Daily Monitoring
Tie day foi tew ngthe exceedance,
system must take 3 distribution
system samples tin addition to the
routine dally sample).1-'
r
is the arithmetic
average of the 3 sample
set> 1.
0 mg/L?
YES
r
1 System m j.
t notify the
1 publscard the state.
YES
is the arithmetic
average of the 3
sample set
> l.C mg/L?
r—-
Have at! chlorite samples
ta«en at the entrance to
or mthe distribution
system for the past year
i?
HO'ES
Was system required to
conduct any additional
distribution system
monitoring! J-sampleset
foi !ov; ing exceedance at
entrance to distribution
system} iastyear3
Reduced Mo
n storing
0tC
uaner
The system wust take cne sample Bleach of the following eeat:onr nearthe -:rs? customer. at a iscat on
rtpresentaf ¦/£ c* average res'dentetinie, and at a location naxtnrum res dense t-ms -nth# cHstr fcvt'en
system
The svstem «ust take cut sample at each of the following locations: as c'ose as possible ts the nrst customer, at a
eca: :on r ei: rese«3t: ve c? a «r age res ideneetime, and at a 1 ocation rer ie cf ng maximum res "«ien ce time in the
d'str;but:on sysaw.
f the svstem has not performed the routine monthly samplingfor eh or 't«. they cart yse this 3 sample set for their
nrenthh- ch or tesarop es
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Attachment 5: Systems that deliver water that lias been treated with ozone
If you are CWS or NTNCWS that operates a treatment plant that uses ozone, you must monitor for the
DBP bromate.
Routine Monitoring
You must collect one bromate sample per month per treatment plant at the entry point to the distribution
system while the ozonation system is operating under normal conditions.
Re DUC ED VI ON ITORING
You may collect one bromate sample per quarter per treatment plant at the entry point to the distribution
system.
If you qualify and your state allows, you may conduct reduced monitoring only if the RAA of your
routine monitoring bromate results is less than or equal to 0.0025 mg/L.
Compliance
The MCL for bromate is 0.010 mg/L. You must notify the public and report to the state if you are in
violation of the MCL. Bromate compliance is determined by a running annual arithmetic average,
computed quarterly, of monthly samples (or average of all samples taken during the month if more than
one sample was collected). If the average of monthly samples covering any consecutive 4-quarter period
exceeds the MCL, the system is in violation.
If you fail to monitor, you are in violation of the monitoring requirements for each quarter that the
monitoring result would have been used in the compliance calculation. All samples taken and analyzed
under the provisions of your monitoring plan must be included in determining compliance, even if there
are more than the minimum required. If during the first year of monitoring, any individual quarter's
average will cause the RAA of that system to exceed the MCL, the system is out of compliance at the end
of that quarter.
Reporting
You must report to the state within 10 days after the end of each quarter during which samples were
collected. You must report the number of samples taken during last quarter, the location, date and result
of each sample and the arithmetic average of monthly arithmetic averages of all samples taken in the last
year. You also must report whether the MCL was exceeded.
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Monitoring Requirements for Bromate for Systems Using Ozone
NTNO.VS ii-.nit o:ons?
NO
NO
I-; the ium of quarterl,
a erate-; taken so far
tor bromate
(I 040
Has the system
monitored for at least 4
YES
YES
s Inornate a';eia?e
computed quartet I
YES
NO
Is bromate P.AA
•. '• III. t ••
NO
YES
Ho monitonnr
for hi ornate is
required
1 In ornate sample per i|uaitei
per treatment plant at entry
point to the distrihutioi
Reduced I !uniform?
Routine Monitoring
1 sample per month per treatment
plant at the entry point to distribution
system ¦. hile the ozonation system is
operating undei normal condition-.
MOTES
1, tf a PVV5 fails to complete 4 consecutive quartets of monitor mg compliance with the MClfot the last 4-quaiter
period must be based on the average of a .ailable data,
i, The average is based upon representatr.emonthiy bromide measurement? for 1 yeat (in months ihete (hoi*
than one sample is taken, use the a^erageof all samples taten during the month),
Disinfectants and Disinfection Byproducts Rules
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Attachment 6: Subpart H systems that operate a conventional filtration
treatment plant
If you operate a Subpart H system and operate a conventional treatment plant, then you must comply with
TOC removal requirements.
Routine \lonitoring
You must take one monthly paired TOC sample and one monthly alkalinity sample at the same time. The
TOC paired sample includes one measurement from the source water prior to any treatment, and one
measurement no later than the point of combined filter effluent turbidity monitoring and representative of
filtered water. The alkalinity sample must be taken at the same location as the source water TOC sample.
Re DUC ED IV! ON ITORING
If you qualify and your state allows, you may reduce monitoring to one paired TOC sample and one
alkalinity sample at the same time per quarter, if you have an average treated water TOC less than 2.0
mg/L for 2 consecutive years, or less than 1.0 mg/L for 1 year. Reduced monitoring locations are the
same as routine monitoring locations.
Compliance
There are different ways of determining compliance with the TOC removal requirement. Using the
monitoring results you can determine TOC removal using enhanced coagulation or enhanced softening.
The required TOC removal is listed in the table below.
Table 6.1 - Step 1 TOC - TOC Removal (3 by 3 Matrix)
Source Water TOC
Source Water Alkalinity, mg/L as CaC03
(mg/L)
0-60
> 60-120
>120
> 2.0 to 4.0
35.0%
25.0%
15.0%
> 4.0 to 8.0
45.0%
35.0%
25.0%
>8.0
50.0%
40.0%
30.0%
You may also show you are in compliance with the TOC removal requirement by using one of the
following alternative compliance criteria:
1. RAA of monthly source water TOC samples less than 2.0 mg/L.
2. RAA of monthly treated water TOC samples less than 2.0 mg/L.
3. RAA of source water TOC less than 4.0 mg/L, RAA of source water alkalinity greater than 60
mg/L, and either:
a. TTHM RAA less than or equal to 0.040 mg/L and HAA5 RAA less than or equal to
0.030 mg/L; or
b. The CWS or NTNCWS has made a "clear and irrevocable commitment" to installing
technology to limit TTHM and HAA5 to those levels.
4. TTHM RAA less than or equal to 0.040 mg/L and HAA5 RAA less than or equal to 0.030 mg/L,
and the CWS or NTNCWS uses only chlorine for primary disinfection and maintenance of a
residual.
5. RAA of SUVA prior to any treatment less than or equal to 2.0 L/mg-m.
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6. RAA of treated water SUVA less than or equal to 2.0 L/mg-m.
7. Softening systems only: Softening that results in a RAA of treated water alkalinity less than 60
mg/L (as calcium carbonate).
8. Softening systems only: Softening that results in a RAA for the removal of magnesium hardness
(as calcium carbonate) of at least 10 mg/L.
Finally, if you cannot achieve compliance with TOC removal requirement using one of these two methods
you should contact your state and discuss Step 2 TOC removal or a waiver.
Where 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. All samples taken under the provisions of the monitoring plan must be included in
determining compliance, even if that number is greater than the minimum required.
Reporting
You must report to the state within 10 days after the end of each quarter during which samples were
collected. You must report the number of paired samples taken during last quarter, the location, date and
result of each paired sample and associated alkalinity taken during last quarter. You also must report
whether system is in compliance with the enhanced coagulation or enhanced softening percent removal
requirements for the last 4 quarters.
Systems using Step 1 or Step 2 enhanced coagulation or enhanced softening must report:
• 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 TOC percent removal requirements.
Systems using an alternative compliance criterion must report:
• RAA of source water SUVA or treated water SUVA if using this criterion for alternative
compliance.
• RAA based on monthly average of source or treated water TOC if using this criterion for
alternative compliance.
• RAA of source water alkalinity or treated water alkalinity if using this criterion for alternative
compliance.
• RAA for both TTHM and HAA5 if using this criterion for alternative compliance.
• RAA of amount of magnesium hardness removal if using this criterion for alternative compliance.
• Whether system is in compliance with particular alternative compliance criterion.
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Disinfection Byproducts Precursor Removal Treatment Technique
Is" system a Subpart H system using
conventional ;iltr ation treatment?
NO
Treatment technique
requirements do not apply.
YES
System must conduct
DBP precursor monitoring,
Can -System meet
at I east one o£ the
alternative
compli ance criteri a
[141,U5( a)|2)
and • 35] ?
NO
Does system have
difficulty meeting-
Step i removals due to
"vater quality
parameters or
operational constraints?
no
Does system meet
Step 1 TOC removals
[141.135(b)} as annual
average {including use of
factors in 141.135(c)]?
MO
11
. h 'I'll!' 'I I
NO
System in
compliance i I th
enhanced
coagulation/
enhanced
roHeninf (EC'E'.i
r equir em-rnts
System must
monitor to
demonstr ate that
they continue to
meet alter native
compliance
criter ia,
' YES *
'r
'yes
System must
conduct Step 2
testing to
determine
alternative
minimum TOC
requirements,1
NO
Did State
appr ove the
alternative
minimum
TOC removal
(Step 2j?
Step 2 TOC remoi als?
YES
System must meet
Step 2 EC removal
requir einerits,
1 V
Can system
identify a Step
2 alternative
minimum TOC
r em oval
i equirement?
i ES
Source water deemed
not amenable to EC/ES.
NO
S y ste m a p p I i e s to th e
Statefor alternative
minimum TOC removal
(Step 2; requirements
within i months of not
meeting Step 1
YES
"tern applies te the,
tate for ct ai et c"
Ec. E ^ r t luii-rncritj.1
NOTE
I Until the system receives a wafrerfrom the state, they must meet Step i. removals.
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Monitoring Requirements for Disinfection Byproduct Precursors
Is system a Subpart H system using
conventional filtration treatment?
NO
YES
No DBP precursors
monitoring
requirements.
Routine Monitoring for
DBP precursors required.
Source Water Sampling1
Minimum of 1 TOC sample
per month per treatment
plant in the source water
pi ior to any treatment.
Paired Sample
4 h
Treated Water Sampling1
Minimum of 1 TOC sample
per month per treatment
D'ant taken no later than
combined filter effluent.
* i1
1 source water alkalinity
sample taken at same time
and location as source water
TOC paired sample.
Did system
conduct required
monitoring?
NO
YES
NO
Is the system's annual average treated
water TOC < 2,0' mg/L for two consecutive
years or < i.O mg/L for one year?
Return to routine
monitoring in month
following quarter
where annual average
> 2.0 mg/L
YES
Reduced Monitoring
May reduce monitoring to one paired
sample and one a'kalinity sanple
every 90 days per treatment plant.
YES
Is the annua' average
{baseo on quarterly
mon'toiing) of treated
water TOC > 2,0 mg/L?
NOTE
1. The source water and the treated water samples are referred to as paired samples and are to be taken
simultaneously.
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