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What Do They Mean to You?
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Office of Water (4606M)
EPA 815-R-20-006
June 2020
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Table of Contents
1. Introduction 1
Purpose of the Guide 1
Background 1
2. Applicability and LT2ESWTR Schedules 2
3. Summary of Regulatory Requirements 3
Disinfection profiling and benchmarking 3
Cryptosporidium 4
Turbidity and disinfection requirements 4
Combined filter effluent monitoring requirements 5
Individual filter effluent monitoring requirements 5
Recycling of filter backwash requirements 5
Uncovered finished water storage facilities 5
Sanitary surveys 6
Unfiltered Subpart H systems 6
PWS recordkeeping and reporting requirements 6
4. Additional Information 7
5. Detailed Regulatory Requirements 7
Attachment 1:1 operate a Subpart H water system that: uses conventional or direct filtration and is on
LT2ESWTR Schedule 1, 2, or 3 1
Attachment 2:1 operate a Subpart H water system that: uses conventional or direct filtration and is on
LT2ESWTR Schedule 4 1
Attachment 3:1 operate a Subpart H water system that: uses slow sand or diatomaceous earth filtration
and is on LT2ESWTR Schedule 1, 2, or 3 1
Attachment 4:1 operate a Subpart H water system that: uses slow sand or diatomaceous earth filtration
and is on LT2ESWTR Schedule 4 1
Attachment 5:1 operate a Subpart H water system that: uses alternative filtration and is on LT2ESWTR
Schedule 1, 2, or 3 1
Attachment 6:1 operate a Subpart H water system that: uses alternative filtration and is on LT2ESWTR
Schedule 4 1
Attachment 7:1 operate a Subpart H water system that: is unfiltered and is on LT2ESWTR Schedule 1,
2, or 3 1
Attachment 8:1 operate a Subpart H water system that: is unfiltered and is on LT2ESWTR Schedule 41
Attachment 9: I operate a consecutive water system that: purchases finished water from a Subpart H
water system and does not have a surface water or GWUDI source of my own 1
Attachment 10:1 operate a Subpart H water system that: must implement a Microbial Toolbox Option
under the LT2ESWTR 1
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Acronyms and Glossary
Acronyms
CDS Combined Distribution System
CFE Combined Filter Effluent
CPE Comprehensive Performance Evaluation
CWS Community Water System
DBP Disinfection Byproducts
DBPR Disinfectants and Disinfection Byproducts Rule
EPA United States Environmental Protection Agency
FBRR Filter Backwash Recycling Rule
GAC Granular Activated Carbon
GWUDI Ground Water Under the Direct Influence of Surface Water
HAA5 Haloacetic acids (Monochloroacetic, Dichloroacetic, Trichloroacetic,
Monobromoacetic and Dibromoacetic Acids)
HPC Heterotrophic Bacteria Plate
IDSE Initial Distribution System Evaluation
IESWTR Interim Enhanced Surface Water Treatment Rule
IFE Individual Filter Effluent
LT1ESWTR Long Term 1 Enhanced Surface Water Treatment Rule
LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
M-DBP Microbial/Disinfection Byproducts
MRDL Maximum Residual Disinfectant Level
MRDLG Maximum Residual Disinfectant Level Goal
NCWS Non-Community Water System
NSCEP National Service for Environmental Publications
NTIS National Technical Information Service
NTU Nephelometric Turbidity Unit
PWS Public Water System
O&M Operation and Maintenance
SDWA Safe Drinking Water Act
SUVA Specific Ultraviolet Absorption
SWTR Surface Water Treatment Rule
SWTRs Suite of Surface Water Treatment Rules
TOC Total Organic Carbon
TTHM Total Trihalomethanes
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Glossary
Combined distribution system — the interconnected distribution system consisting of the distribution
systems of wholesale systems and of the consecutive systems that receive finished water.
Comprehensive performance evaluation (CPE) — thorough review and analysis of a treatment plant's
performance-based capabilities and associated administrative, operation and maintenance practices. It is
conducted to identify factors that may be adversely impacting a plant's capability to achieve compliance
and emphasizes approaches that can be implemented without significant capital improvements. For
purpose of compliance with subparts P and T of 40 CFR 141, the comprehensive performance evaluation
must consist of at least the following components: assessment of plant performance; evaluation of major
unit processes; identification and prioritization of performance limiting factors; assessment of the
applicability of comprehensive technical assistance; and preparation of a CPE report.
Disinfection profile — a summary of Giardia lamblia inactivation through the treatment plant.
Dual sample set — a set of two samples collected at the same time and same location, with one sample
analyzed for TTHM and the other sample analyzed for HAA5. Dual sample sets are collected for the
purposes of conducting an IDSE under subpart U of 40 CFR 141 and determining compliance with the
TTHM and HAA5 MCLs under subpart V of 40 CFR 141.
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.
Filter profile — graphical representation of individual filter performance, based on continuous turbidity
measurements or total particle counts versus time for an entire filter run, from startup to backwash
inclusively, that includes an assessment of filter performance while another filter is being backwashed.
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 Inactivation — logarithm of (No/Nt), where No is the number of Cryptosporidium oocysts in a
system's untreated source water and Nt is the number of Cryptosporidium oocysts in system's finished
water after treatment.
Maximum contaminant level (MCL) — the maximum permissible level of a contaminant in water which
is delivered to any user of a public water system.
Maximum contaminant level goal (MCLG) — the maximum level of a contaminant in drinking water at
which no known or anticipated adverse effect on the health of persons would occur, and which allows an
adequate margin of safety. Maximum contaminant level goals are non-enforceable health goals.
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.
For chlorine and chloramines, a PWS is in compliance with the MRDL when the running annual average
of monthly averages of samples taken in the distribution system, computed quarterly, is less than or equal
to the MRDL. For chlorine dioxide, a PWS is in compliance with the MRDL when daily samples are
taken at the entrance to the distribution system and no two consecutive daily samples exceed the MRDL.
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MRDLs are enforceable in the same manner as maximum contaminant levels under Section 1412 of the
Safe Drinking Water Act. There is convincing evidence that addition of a disinfectant is necessary for
control of waterborne microbial contaminants. Notwithstanding the MRDLs listed in §141.65, operators
may increase residual disinfectant levels of chlorine or chloramines (but not chlorine dioxide) in the
distribution system to a level and for a time necessary to protect public health to address specific
microbiological contamination problems caused by circumstances such as distribution line breaks, storm
runoff events, source water contamination, or cross-connections.
Maximum residual disinfectant level goal (MRDLG) — the maximum level of a disinfectant added for
water treatment at which no known or anticipated adverse effect pm 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.
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), 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 (UV254) (in m -1) by its concentration of dissolved
organic carbon (DOC) (in mg/L).
Subpart H systems — public water systems using surface water or ground water under the direct influence
of surface water as a source that are subject to the requirements of subpart H of 40 CFR 141.
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.
Uncovered finished water storage facility — tank, reservoir, or other facility used to store water that will
undergo no further treatment to reduce microbial pathogens except residual disinfection and is directly
open to the atmosphere.
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1. Introduction
Purpose of the Guide
The purpose of this guide is to describe how the Suite of Surface Water Treatment Rules (SWTRs) apply
to different types of public water systems (PWSs) based on the type of filtration used and the population
of the PWS (or combine distribution system (CDS) population). The SWTRs covered by this guide
include:
• Surface Water Treatment Rule (SWTR) - June 1989
• Interim Enhanced Surface Water Treatment Rule (IESWTR) - December 1998
• Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) - January 2002
• Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) - January 2006
• Filter Backwash Recycling Rule (FBRR) - June 2001
The SWTRs are developed with the Stage 1 and Stage 2 Disinfectants and Disinfection Byproducts Rules
(DBPRs). These series of rules are known as the Microbial/Disinfection Byproduct (M-DBP) Rules
cluster and are intended to reduce microbial contaminants in the water and, at the same time, minimize
the risks posed by disinfectants and disinfection byproducts (DBPs). The DBPRs set enforceable limits
for disinfectants and DBPs, create monitoring requirements, and specify reporting procedures (including
specific monitoring requirements for consecutive systems).
This guide presents an overview of the SWTRs requirements as well as attachments that provide a
detailed description of the rule requirements for water systems according to system size and filtration
status. System operators and other readers should look at the short overview sections at the beginning of
the guide and then turn to the specific attachments that apply to their water system. A companion guide to
this document - Disinfectants and Disinfection Byproducts Rules (Stage 1 and Stage 2) What Do They
Mean to You? - addresses the DBPR required disinfectants and DBP monitoring.
The U.S. Environmental Protection Agency's (EPA's) website provides links to the original rule language
as well as the most recent guidance documents and other information for the SWTRs and Stage 1 and
Stage 2 DBPRs (https://www.epa.gov/dwreginfo/drinking-water-regulations).
Background
The 1974 Safe Drinking Water Act (SDWA) authorized EPA to regulate drinking water. Although the
SDWA was amended slightly in 1977, 1979, and 1980, significant changes occurred when the SDWA
was reauthorized in 1986 and then again in 1996. 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 was also required to establish regulations, require
disinfection of all PWSs, specify filtration requirements for nearly all water systems that draw their water
from surface sources, and develop additional programs to protect ground water sources.
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 the greatest remaining health-
risk challenge for drinking water suppliers. The 1989 SWTR required most surface water and ground
water under the direct influence of surface water (GWUDI) systems (also known as Subpart H systems) to
remove microbial contaminants physically through filtration. The 1989 SWTR set MCLGs for
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Legionella, Giardia lamblia, and viruses at zero since any exposure to these contaminants presents some
level of health risk. Specifically, the 1989 SWTR requires that a Subpart H 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 disinfectant residual must be maintained
throughout the entire distribution system. The 1989 SWTR does not specifically control for
Cryptosporidium.
The 1989 SWTR uses turbidity to measure the performance of filtration systems. In order to reduce the
public health risk associated with Cryptosporidium in finished water, the IESWTR requires improved
filtration performance by lowering the turbidity standard at Subpart H systems that serve 10,000 or more
people. The LT1ESWTR extends this requirement to systems serving fewer than 10,000 persons. The
LT2ESWTR requires additional treatment for Cryptosporidium at those surface water or GWUDI systems
with significant levels of Cryptosporidium in their source waters. Finally, the FBRR is intended to reduce
pathogen concentrations in the finished water by properly managing the backwash water and waste
streams at water treatment plants.
2. Applicability and LT2ESWTR Schedules
The SWTRs apply to PWSs that use surface water or GWUDI as a source (also known as Subpart H
systems). The 1989 SWTR applies to all Subpart H systems. The IESWTR generally only applies to
Subpart H systems serving 10,000 or more persons, although the requirement for states to conduct
sanitary surveys applies to all Subpart H systems. The LTIESWTR extends the IESWTR's requirements
to Subpart H systems that serve fewer than 10,000 persons. The LT2ESWTR applies to all Subpart H
systems, and wholesale PWSs must comply with the rule based on the population of the largest PWS in
their CDS. A CDS is an interconnected distribution system consisting of the distribution systems of
wholesale systems and of the consecutive systems that receive finished water. The CDS applies when a
consecutive system receives some or all of its finished water from a wholesale system.
If you have a Subpart H source and are this kind of system:
You are on
LT2ESWTR
Schedule:
S\ skill sci'\ mil: 1 <)<).<)<)<) or moiv |Vo|ile OR a w holcsak- s\ skill
in a CDS llial contains a s\ skin scr\ injj 1 on.(inn
1
System serving 50,000 to 99,999 people OR a wholesale system
in a CDS llial conlains a s\skm scmiiij 511.000 in W.W4
2
S\ skill scr\ iiiij 10.ooO in |vo|ile OR a w holcsak- s\ skill
in a CDS llial conlains a s\ skin sci\ inu 10.000 in
System serving fewer than 10,000 and not a wholesale system
in a CDS that contains a system serving at least 10,000
4
For more information about critical deadlines related to LT2ESWTR schedules refer to the LT2 Quick
Reference Guides by Schedule available at: https://www.epa.gov/dwreginfo/drinking-water-rule-quick-
reference-guides. The state has discretion with respect to new systems and sources that were put into use
after the initial monitoring began. New Subpart H systems and Subpart H systems that develop a new
source must conduct source water monitoring of the new sources unless the PWS provides 5.5-log of
treatment for Cryptosporidium (filtered systems) or 3.0-log treatment (unfiltered systems) using options
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from the LT2ESWTR Microbial Toolbox. New Subpart H systems and Subpart H systems with new
sources must contact the state regarding their requirements and schedule for source water monitoring.
EPA has developed compliance requirements for different filtration types (i.e., standards for PWSs that
use conventional filtration are different than standards for PWSs using slow sand filtration or for systems
that are unfiltered). IESWTR and LT1ESWTR compliance dates depended on the size of the population
served by the PWS.
3. Summary of Regulatory Requirements
Disinfection profiling and benchmarking
A disinfection benchmark is an indicator of disinfection effectiveness based on the lowest monthly
average inactivation of Giardia lamblia and viruses. The disinfection profiling and benchmarking
requirement in LT2ESWTR requires a Subpart H system that intends to make a significant change to its
disinfection practice to evaluate its disinfection practice and work with the state to assure there are no
unintended reductions in microbial protection when the system changes how it disinfects its water. The
process consists of the following three steps:
1. Determining if a PWS must develop a disinfection profile.
2. Developing the disinfection profile.
3. Calculating the disinfection benchmark and consulting with the state.
Some PWSs have already prepared a disinfection profile to comply with the requirements of the IESWTR
or LT1ESWTR. Under these rules, if a PWS had an annual average level of total trihalomethanes
(TTHM) greater than 0.064 mg/L or of haloacetic acids (HAA5) greater than 0.048 mg/L, the system was
required to develop a disinfection profile. Of these systems, those that served 10,000 or more persons had
to complete their disinfection profile by April 2001; those serving 10,000 and fewer persons had to
complete their disinfection profile by the end of 2004. Systems can use disinfection profiles developed
under IESWTR or LTIESWTR to satisfy the LT2ESWTR requirement as long as the system has not
significantly changed its treatment or its source(s) and the disinfection profile was for Giardia lamblia
and viruses.
The disinfection profile is developed by compiling Giardia lamblia and virus log inactivation values
computed over a period of at least 12 months. For PWSs that were required to comply with the
disinfection profiling requirements of the IESWTR, disinfection profile log inactivation values were
calculated using daily measurements of operational data collected during peak-hour flows. All other
PWSs developing a disinfection profile are required to calculate their disinfection profile log inactivation
values using weekly measurements of operational data collected during peak-hour flows. If a PWS is
using profiling and benchmarking information originally gathered for IESWTR or LT IESWTR
compliance and that PWS did not calculate a benchmark for viruses, the PWS must use the same
monitoring data on which the Giardia lamblia disinfection profile is based to develop the disinfection
profile for viruses.
PWSs that were required to prepare a disinfection profile under the IESWTR or LT1ESWTR must keep
their disinfection profiles on file to be reviewed during their sanitary surveys.
A PWS that decides to make a significant modification to its disinfection practice (e.g., changing the
disinfectants used in the treatment plant, moving the point of disinfection, changing the disinfection
process) may calculate a disinfection benchmark and consult with the state prior to implementing such a
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change. The state consultation process helps assure that the PWS will meet all of the standards for
Giardia lamblia, viruses, DBPs, and Cryptosporidium.
The benchmark is determined by calculating the average inactivation value for each of 12 consecutive
months. The lowest monthly average inactivation value becomes the disinfection benchmark. If a PWS is
using monitoring data from more than one year, it repeats the calculation for each year for which data are
available. The benchmark then becomes the average of the lowest monthly average values for each year.
EPA developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at:
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Cryptosporidium
EPA set a MCLG of zero for the protozoan Cryptosporidium. It also established a requirement for 2-log
(99 percent) removal of Cryptosporidium for systems that must currently filter under the 1989 SWTR.
Systems that use conventional or direct filtration meet this requirement if they are in compliance with the
strengthened turbidity performance standards for combined filter effluent (CFE) set in the IESWTR and
LT1ESWTR. Systems that use slow sand or diatomaceous earth filtration meet the 2-log removal
requirement if they are in compliance with the existing turbidity performance standards under the 1989
SWTR.
In the LT2ESWTR, EPA required all Subpart H filtered systems, including wholesale systems, to
characterize their source water and determine what, if any, additional treatment is necessary to reduce
Cryptosporidium. Subpart H unfiltered systems are required to determine what additional treatment must
be provided to reduce Cryptosporidium. Systems must conduct source water monitoring to determine an
average Cryptosporidium concentration. Based on that average, filtered systems will be classified into one
of four possible risk categories (bins). Depending on the bin in which they are placed, the systems may or
may not be required to provide additional treatment to remove or inactivate Cryptosporidium. Filtered
systems on Schedule 41 can sample fori?, coli instead of sampling for Cryptosporidium during source
water monitoring. If the E. coli sampling results exceed a trigger, depending on type of source water, the
system would then need to conduct Cryptosporidium sampling.
These new provisions, along with the new turbidity requirements, will better protect consumers from
Cryptosporidium and other pathogens.
Turbidity and disinfection requirements
The SWTRs establish requirements for the control of turbidity and require disinfection of Subpart H
systems. Subpart H systems are required to meet specific removal and/or inactivation criteria. To meet
these requirements Subpart H systems must measure the finished water turbidity as well as the
disinfection residual entering the distribution system and must maintain a detectable disinfectant residual
in the distribution system. The turbidity limits and monitoring requirements depend on whether or not the
Subpart H system is filtered and the type of filtration process that is utilized.
1 See Section 2 of this document for more information about Schedules.
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Combined filter effluent monitoring requirements
Pathogens in source water can travel through the treatment plant processes and eventually reach
customers, creating a health risk. Cryptosporidium is of particular concern because it is resistant to
commonly used disinfectants, such as chlorine. The IESWTR and LT1ESWTR established CFE turbidity
requirements to accomplish a 2-log removal of Cryptosporidium. CFE is generated when the effluent
water from individual filters in operation is combined into one stream.
Individual filter effluent monitoring requirements
Filtration is one of the most critical treatment processes for particle and pathogen removal. Subpart H
systems using conventional or direct filtration must also conduct continuous monitoring of the turbidity in
the effluent from individual filters to provide information about each filter's performance. This
requirement allows systems to identify filters whose poor performance might be masked by lower
turbidity CFE. Individual filter performance problems, indicated by an exceedance of certain turbidity
limits for specified time periods, trigger follow-up actions.
Recycling of filter backwash requirements
EPA established filter backwash requirements for Subpart H systems that meet the following criteria:
• The system treats water by conventional or direct filtration processes; and
• The system recycles one or more of the following: spent filter backwash water, thickener
supernatant or liquids from dewatering processes.
These systems were required to notify the state about their recycling practices by December 8, 2003. They
are also required to return spent filter backwash, thickener supernatant, or liquids from dewatering
processes through all the processes of a system's existing conventional or direct filtration system (if the
system recycles). Systems can receive state approval to recycle at an alternate location. Systems must
collect and retain recycling information.
Uncovered finished water storage facilities
Subpart H systems are prohibited from building any new uncovered finished water storage facilities
(reservoir, holding tank, or other storage facility). Subpart H systems that have existing uncovered
finished water storage facilities must notify the state of any uncovered finished water storage facilities
and must either:
• Cover any uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system
to achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation
and/or removal using a state-approved protocol.
These provisions will help limit re-contamination of treated water.
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Sanitary surveys
Conducting sanitary surveys on a routine basis is an important element of preventing contamination of
drinking water supplies. EPA recognizes the importance of sound sanitary surveys in helping water
systems protect public health. Sanitary surveys are an opportunity to work and communicate with water
systems in a preventative mode. These surveys are structured to determine whether a system's source,
facilities, equipment, operation and maintenance (O&M), and management are effective in producing safe
drinking water. Sanitary surveys also evaluate a system's compliance with federal drinking water
regulations, as well as state regulations and operational requirements. EPA requires that a sanitary survey
address each of the following eight elements: source; treatment; distribution system; finished water
storage; pumps, pump facilities, and controls; monitoring and reporting and data verification; system
management and operation; and operator compliance with state requirements.
States must conduct sanitary surveys for all Subpart H systems every 3 years for community water
systems (CWSs) and every 5 years for non-community water systems (NCWSs). For CWSs determined
by the state in previous sanitary surveys to have "outstanding performance," successive sanitary surveys
may be conducted at up to 5-year intervals. Conducting sanitary surveys on a regular basis is an effective
way to identify potential problems and possible reasons for trends in finished water quality and demand
that may need to be addressed.
Unfiltered Subpart H systems
In order to protect public health, unfiltered Subpart H systems are required to meet stringent source water
quality requirements. EPA requires unfiltered Subpart H systems to meet the 1989 SWTR source water
and site-specific requirements in order to remain unfiltered. In addition, unfiltered systems must include
Cryptosporidium in their watershed control programs and must meet all applicable DBPR MCLs and
maximum residual disinfectant levels (MRDLs) to remain unfiltered. Like filtered systems, they are
subject to disinfection profiling and benchmarking and sanitary survey requirements.
In the LT2ESWTR, EPA requires all unfiltered Subpart H systems, including wholesale systems, to
characterize their source water and determine what additional treatment is necessary to reduce
Cryptosporidium. Systems must conduct source water monitoring to determine a mean Cryptosporidium
concentration. Unfiltered Subpart H systems are required to provide two forms of disinfection. They must
meet the combined Cryptosporidium inactivation requirements of the LT2ESWTR and Giardia lamblia
and virus inactivation requirements of the 1989 SWTR using a minimum of two disinfectants, and each of
the two disinfectants must separately achieve the total inactivation required for Cryptosporidium, Giardia
lamblia, or viruses.
PWS recordkeeping and reporting requirements
Subpart H filtered systems must submit CFE monitoring and compliance data and report that they have
conducted individual filter turbidity monitoring, if required, to states within 10 days after the end of each
month the system serves water to the public. Additionally, Subpart H systems using conventional or direct
filtration must report to the state if certain individual filter monitoring trigger levels are exceeded. In this
case, systems must report turbidity measurements and report that filter profiles, filter self-assessments, or
Comprehensive Performance Evaluation (CPE) reports have been produced or conducted when instances
of poor filter performance occur or persist based on monitoring of individual filter performance. Systems
must maintain the results of individual filter monitoring for at least three years.
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Subpart H unfiltered systems must submit source water quality conditions (e.g. fecal and/or total conform
samples and turbidity) compliance data and monitoring to states within 10 days after the end of each
month the system serves water to the public.
In addition, Subpart H systems (filtered and unfiltered) must report disinfection residual levels to the state
within 10 days after the end of each month the system serves water to the public.
4. Additional Information
A series of guidance manuals have been developed to support the SWTRs. They are available on EPA's
website and may be available free of charge through the National Service Center for Environmental
Publications, or may be purchased through National Technical Information Service (NTIS). The manuals
can help water system operators, state agencies, and EPA implement drinking water regulations
consistently and effectively.
You may access electronic versions of available guidance documents online at EPA's website
via https://www.epa.gov/dwreginfo/drinking-water-regulations.
You also may order copies of these guidance manuals by calling:
• National Service Center for Environmental Publications (NSCEP) - 1.800.490.9198
• National Technical Information Service (NTIS) - 1.800.553.6847
5. Detailed Regulatory Requirements
EPA has developed compliance requirements for different filtration types (i.e., standards for systems that
use conventional filtration are different than standards for systems using slow sand filtration or for
systems that are unfiltered). IESWTR and LT1ESWTR compliance dates depended on the size of the
population served by the system. LT2ESWTR compliance dates depend on the size of the population
served by the Subpart H system or, if the Subpart H system sells water, the population of the largest
system in the CDS. The flowchart on page 9 will assist you in determining which attachment best applies
to your system.
This section is organized so that specific categories of systems can turn directly to their specific
requirements. The categories of systems are:
Attachment 1: I operate a Subpart H water system that:
LT2ESWTR Schedule 1, 2, or 3
Attachment 2: I operate a Subpart H water system that:
LT2ESWTR Schedule 4
Attachment 3: I operate a Subpart H water system that:
and is on LT2ESWTR Schedule 1, 2, or 3
Attachment 4: I operate a Subpart H water system that:
and is on LT2ESWTR Schedule 4
uses conventional or direct filtration and is on
1-1
uses conventional or direct filtration and is on
2-1
uses slow sand or diatomaceous earth filtration
3-1
uses slow sand or diatomaceous earth filtration
4-1
Attachment 5: I operate a Subpart H water system that: uses alternative filtration and is on LT2ESWTR
Schedule 1, 2, or 3 5-1
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Attachment 6:1 operate a Subpart H water system that: uses alternative filtration and is on LT2ESWTR
Schedule 4 6-1
Attachment 7: I operate a Subpart H water system that: is unfiltered and is on LT2ESWTR Schedule 1, 2,
or 3 7-1
Attachment 8: I operate a Subpart H water system that: is unfiltered and is on LT2ESWTR Schedule 4 8-1
Attachment 9: I operate a consecutive water system that: purchases finished water from a Subpart H water
system and does not have a surface water or GWUDI source of my own 9-1
Attachment 10: I operate a Subpart H water system that: must implement a Microbial Toolbox Option
under the LT2ESWTR 10-1
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Figure 1. Organization of Attachments
Is your
source a surface water or ground
water underthe direct influence of
surface water source?
Yes
Do you have
a conventional or direct
filtration treatment plant?
No
Yes
No
Do you sell water
to another
system?
Do you have
a slow sand or diatomaceous
earth treatment plant?
No
Yes
No
Do you sell water
to another
system?
Doyou have
an alternative filtration
treatment plant?
Yes
No
Do you sell water
to another
system?
Are you an unfiltered system?
No
Do you sell water
to another
system?
Are you a consecutive
system?
No
Do you buy
finished water
from another
system?
No
requirements
What is the
population of your
system?
What is the population of
the largest system in
yourCDS?
What is the
population of your
system?
Yes
What is the population of
the largest system in
yourCDS?
What is the
population of your
system?
Yes
What is the population of
the largest system in
yourCDS?
What is the
population of your
system?
T
Yes,
What is the population of
the largest system in
yourCDS?
See Attachments!
through 8.
Yes
Do you have a surface
water or GWUDI source
of you own?
No
Attachment 1
Attachment 2
Attachment 3
Attachment 4
Attachments
Attachment 6
Attachment?
Attachments
Attachment9 ^
Surface Water Treatment Rules
What Do They Mean to You?
9
-------
Attachment 1: I operate a Subpart H water system that: uses
conventional or direct filtration and is on LT2ESWTR Schedule 1, 2,
or 32
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses
• Giardict lamblia
• Cryptosporidium
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also, the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, use conventional or direct
filtration, and:
1) serve 10,000 or more persons and do not sell water; or
2) sell water, and the largest system in their CDS serves 10,000 or more persons.
Requirements
Removal/Inactivation Requirements for Viruses, Giardia Lamblia, and
Cryptosporidium
You must comply with the removal/inactivation requirements established for regulated pathogens. The
removal/inactivation requirements are as follows:
Microbial
MCLG
Rem oval/Inactivation
Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log)
2 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-1
-------
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
Turbidity
Turbidity is measured in two ways: combined filter effluent (CFE) and individual filter effluent (IFE). CFE
is generated when the effluent water from individual filters is combined into one stream. The CFE turbidity
results may mask the poor performance of an individual filter. The performance of each individual filter is
critical to controlling pathogen breakthrough. Due to this, IFE performance is also measured in systems
using conventional or direct filtration.
CFE turbidity must be measured every 4 hours during plant operation. The CFE turbidity for conventional
and direct filtration systems:
• Must be less than or equal to 0.3 nephelometric turbidity unit (NTU) for 95 percent of the readings
taken each month; and
• Can at no time exceed 1 NTU.
If you serve 500 or fewer persons, the frequency of monitoring may be reduced to once per day if the state
determines that less frequent monitoring is sufficient to indicate effective filtration performance. You
should check with your state on CFE requirements because the state may require additional monitoring.
IFE must be monitored continuously using an approved method and systems must calibrate turbidimeters
using the procedure specified by the manufacturer. You must record the results of IFE turbidity monitoring
every 15 minutes. If the individual filter is not providing water which contributes to the CFE, (i.e., it is not
operating, is filtering to waste, or recycled) you do not need to record or monitor the turbidity for that
specific filter.
If there is a failure in continuous IFE turbidity monitoring equipment, you must conduct grab sampling
every 4 hours in lieu of continuous monitoring but must return to 15 minute monitoring no more than 5
working days following the failure of the equipment.
Additionally, you must report IFE turbidity measurements to the state if the measurements demonstrate one
of the following:
• Any individual filter has a measured effluent turbidity greater than 0.5 NTU in two
consecutive measurements taken 15 minutes apart at the end of the first 4 hours of
continuous filter operation after the filter has been backwashed or otherwise taken offline. If
you directly serve 10,000 or more persons, you must report the filter number, the turbidity, and the
date(s) on which the exceedance occurred. In addition, you must either produce a filter profile for
the filter within 7 days of the exceedance (if you are not able to identify an obvious reason for the
abnormal filter performance) and report that the profile has been produced or report the obvious
reason for the exceedance (THIS ONLY APPLIES TO YOU IF YOU DIRECTLY SERVE
10,000 OR MORE PERSONS.)
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-2
-------
• Any individual filter has a measured turbidity level greater than 1.0 NTU in two consecutive
measurements taken 15 minutes apart. You must report the filter number, the turbidity
measurement, the date(s) on which the exceedance occurred, and the obvious reason for the
exceedance. If you directly serve 10,000 or more persons, you must produce a filter profile within 7
days of the exceedance (if you are not able to identify an obvious reason for the abnormal filter
performance) and report that the profile has been produced. (IF YOU DIRECTLY SERVE
FEWER THAN 10,000 PERSONS YOU ARE NOT REQUIRED TO COMPLETE A
FILTER PROFILE, EVEN IF YOU ARE NOT ABLE TO IDENTIFY AN OBVIOUS
REASON FOR THE ABNORMAL FILTER PERFORMANCE.)
• Any individual filter has a measured turbidity level of greater than 1.0 NTU in two
consecutive measurements taken 15 minutes apart at any time in each of 3 consecutive
months. You must report the filter number, the turbidity measurement, and the date(s) on which
the exceedance occurred. In addition, you must conduct a self-assessment of the filter within 14
days. If you directly serve fewer than 10,000 persons and have two filters that monitor CFE in lieu
of IFE, you must include both filters in the self-assessment.
• Any individual filter has a measured turbidity level of greater than 2.0 NTU in two
consecutive measurements taken 15 minutes apart at any time in each of 2 consecutive
months. You must report the filter number, the turbidity measurement, and the date(s) on which
the exceedance occurred. In addition, you must contact the state or a third party approved by the
state to conduct a comprehensive performance evaluation (CPE). Systems directly serving 10,000
or more persons must arrange for the CPE within 30 days and submit the report within 90 days. For
systems directly serving fewer than 10,000 persons they must make arrangements for the CPE
within 60 days and submit the report within 120 days.
Filter Backwash Recycling
The Filter Backwash Recycling Rule (FBRR) establishes additional requirements for Subpart H systems
that use conventional or direct filtration and recycle spent filter backwash, thickener supernatant, or liquids
from dewatering processes. The purpose of the FBRR is to improve public health protection by assessing
and changing, where needed, recycle practices for improved contaminant control, particularly microbial
contaminants. Subpart H systems that recycle are required to return specific recycle flows through all
processes of the system's existing conventional or direct filtration system or to an alternative location
approved by the state. These systems must collect recycle flow information and retain it on file. If
applicable, you must have completed all capital improvements associated with relocating recycle return
location by June 8, 2006.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size. The state
may allow you to reduce your sample to:
• 1 grab sample per day if your serve less than or equal to 500 persons.
• 2 grab samples per day taken at separate times if your serve 501 to 1,000 persons.
• 3 grab samples per day taken at separate times if your serve 1,001 to 2,500 persons.
• 4 grab samples per day taken at separate times if your serve 2,501 to 3,300 persons.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-3
-------
If you are using grab sampling instead of continuous monitoring and the residual disinfectant concentration
is below 0.2 mg/L, you must take a grab sample every 4 hours until the residual disinfectant concentration
is 0.2 mg/L or greater.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
Reporting and Recordkeeping
Monitoring
Report by:
What to Report
CFE 95 Percent Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Total number of CFE measurements and
number and percentage of CFE
measurements less than or equal to the
95th percentile limit.
CFE Maximum Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Date and time of CFE measurement that
exceeds CFE maximum limit.
IFE Monitoring -
Monitored continuously
and recorded every 15
minutes
10th day of the following
month that you served water
to the public
IFE monitoring conducted and any
follow-up actions.
Minimum Disinfection
Residual - Entry to the
distribution system
10th day of the following
month that you served water
to the public
Lowest daily value for each day, the date
and duration when the residual
disinfectant was less than 0.2 mg/L, and
when the state was notified of events
where residual disinfectant was less than
0.2 mg/L.
Minimum Disinfection
Residual -
In the distribution system
10th day of the following
month that you served water
to the public
Number of residual disinfectant or HPC
measurements taken in the month
resulting in no more than 5 percent of the
measurements as being undetectable1 in
any 2 consecutive months.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-4
-------
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs require that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-5
-------
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states' discretion.
Information about state operator certification programs can be accessed through EPA's website at
https://www.epa.gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
If you did not have 5.5-logs of treatment for Cryptosporidium, which is equivalent to meeting the treatment
requirements of Bin 4, you were required to conduct initial source water monitoring and monitor for
Cryptosporidium, E. coli, and turbidity at least monthly for 2 years. You were also required to begin a
second round of source water monitoring 6 years after the required date for your water system's initial bin
classification determination.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial bin
classification determination.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-6
-------
Bin Classification
You should have completed your source water monitoring and calculated your Cryptosporidium
concentration to determine your water system's Cryptosporidium bin classification. If you are a new
Subpart H system or a Subpart H system that developed a new source you must determine the bin
classification, based on a schedule provided by the state and no later than 6 months after the source water
monitoring is completed.
After calculating the Cryptosporidium concentration, filtered systems must use this concentration to
determine their bin classification.
Bin
Cryptosporidium Concentration (oocysts/L):
1
Less than 0.075 oocysts/L
2
0.075 oocysts/L or higher, but less than 1.0 oocysts/L
3
1.0 oocysts/L or higher, but less than 3.0 oocysts/L
4
3.0 oocysts/L or higher
For more information on determining your bin classification see Chapter 6 of EPA's Source Water
Monitoring Guidance Manual for Public Water Systems for the Final Long Term 2 Enhanced Surface
Water Treatment Rule (EPA 815-R-06-005, February 2006), available at
https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-documents.
Ultimately, the bin classification determines what, if any, additional treatment for Cryptosporidium
required at your treatment plants. Treatment plants classified in Bin 1 are not required to provide any
additional treatment (if they are in compliance with all existing standards, as applicable). Treatment plants
classified in Bins 2, 3, and 4 are required to provide additional treatment, the level of which varies
according to the type of filtration in place at the treatment plant.
Bin
Conventional Filtration
(incl. softening)
Direct
Filtration
1
None
None
2
1-log
1-5-log
3
2-log
2.5-log
4
2.5-log
3-log
Microbial Toolbox
If your bin classification put you into bins 2, 3, or 4 you will need to use one or more of the Microbial
Toolbox options to meet Cryptosporidium treatment requirements established during bin classification.
Five types of toolbox options are available to systems:
• Source protection and management options.
• Pre-filtration options.
• Treatment performance options.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-7
-------
• Additional filtration options.
• Inactivation options.
There are reporting requirements associated with each type of toolbox option, including when a system
must notify a state of their intent to use toolbox options, what a system must verify to be eligible for
treatment credit, and what reporting requirements a system must meet in order to continue to receive
Cryptosporidium treatment credit. Systems must keep results of treatment monitoring for 3 years. The state
may approve a system to certify operation within required parameters for treatment credit rather than
reporting monthly operational data for toolbox options.
See Attachment 10 for more information regarding the Microbial Toolbox.
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Removal/inactivation requirements for viruses, Giardia lamblia, and Cryptosporidium.
• Turbidity.
• Filter backwash recycling.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified personnel.
Systems that were in bins 2, 3, or 4 following completion of their initial source water monitoring must be in
compliance with the additional log inactivation and/or removal requirements. Systems that were in bins 2,
3, and 4 after completing their second round of source water monitoring must either be in compliance with
the additional log inactivation and/or removal requirements or be in the process of installing additional
treatment.
Schedule
Initial Round of
Source Water
Monitoring was
due no later than:
Calculation of Initial
Cryptosporidium
Bin Classification
was due no later
than:
Add Additional
Treatment or Control
Processes for Systems in
Bin 2, 3, and 4 by2:
Second Round of
Source Water
Monitoring was
due no later than:
1
September 2008
March 2009
April 1,2012
April 1,2017
2
March 2009
September 2009
October 1, 2012
October 1, 2017
3
March 2010
September 2010
October 1, 2013
October 1, 2018
2. States may allow up to an additional 2 years for complying with the treatment requirement for systems making
capital improvements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 1-8
-------
Attachment 2: I operate a Subpart H water system that: uses
conventional or direct filtration and is on LT2ESWTR Schedule 43
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Giardict lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, use conventional or direct
filtration, and:
1) serve fewer than 10,000 persons and do not sell water; or
2) sell water, and the largest system in their CDS serves fewer than 10,000 persons.
Requirements
Removal/Inactivation Requirements for Viruses, Giardia Lamblia, and
Cryptosporidium
You must comply with the removal/inactivation requirements established for regulated pathogens. The
removal/inactivation requirements are as follows:
Microbial
MCLG
Rem oval/Inactivation
Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log)
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
3 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-1
-------
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
Turbidity
Turbidity is measured in two ways: combined filter effluent (CFE) and individual filter effluent (IFE). CFE
is generated when the effluent water from individual filters is combined into one stream. The CFE turbidity
results may mask the poor performance of an individual filter. The performance of each individual filter is
critical to controlling pathogen breakthrough. Due to this, IFE performance is also measured in systems
using conventional or direct filtration.
CFE turbidity must be measured every 4 hours during plant operation. The CFE turbidity for conventional
and direct filtration systems:
• Must be less than or equal to 0.3 nephelometric turbidity unit (NTU) for 95 percent of the readings
taken each month; and
• Can at no time exceed 1 NTU (based on turbidity measurements recorded every 4 hours).
If you serve 500 or fewer persons, the frequency of monitoring may be reduced to once per day if the state
determines that less frequent monitoring is sufficient to indicate effective filtration performance. You
should check with your state on CFE requirements because the state may require additional monitoring.
IFE must be monitored continuously using an approved method and systems must calibrate turbidimeters
using the procedure specified by the manufacturer. You must record the results of IFE turbidity monitoring
every 15 minutes. If the individual filter is not providing water which contributes to the CFE, (i.e., it is not
operating, is filtering to waste, or recycled) you do not need to record or monitor the turbidity for that
specific filter.
If there is a failure in continuous IFE turbidity monitoring equipment, you must conduct grab sampling
every 4 hours in lieu of continuous monitoring, but must return to 15 minute monitoring no more than 5
working days following the failure of the equipment.
Additionally, you must report IFE turbidity measurements to the state if the measurements demonstrate one
of the following:
• Any individual filter has a measured turbidity level greater than 1.0 NTU in two consecutive
measurements taken 15 minutes apart. You must report the filter number, the turbidity
measurement, the date(s) on which the exceedance occurred, and the obvious reason for the
exceedance.
• Any individual filter has a measured turbidity level of greater than 1.0 NTU in two
consecutive measurements taken 15 minutes apart at any time in each of 3 consecutive
months. You must report the filter number, the turbidity measurement, and the date(s) on which
the exceedance occurred. In addition, you must conduct a self-assessment of the filter within 14
days. If you have two filters that monitor CFE in lieu of IFE, you must include both filters in the
self-assessment.
• Any individual filter has a measured turbidity level of greater than 2.0 NTU in two
consecutive measurements taken 15 minutes apart at any time in each of 2 consecutive
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-2
-------
months. You must report the filter number, the turbidity measurement, and the date(s) on which
the exceedance occurred. In addition, you must contact the state or a third party approved by the
state to conduct a comprehensive performance evaluation (CPE). You must make arrangements for
the CPE within 60 days and submit the report within 120 days.
Filter Backwash Recycling
The Filter Backwash Recycling Rule (FBRR) establishes additional requirements Subpart H systems that
use conventional or direct filtration and recycle spent filter backwash, thickener supernatant, or liquids
from dewatering processes. The purpose of the FBRR is to improve public health protection by assessing
and changing, where needed, recycle practices for improved contaminant control, particularly microbial
contaminants. Subpart H systems that recycle are required to return specific recycle flows through all
processes of the system's existing conventional or direct filtration system or to an alternative location
approved by the state. These systems must collect recycle flow information and retain it on file. If
applicable, you must have completed all capital improvements associated with relocating recycle return
location by June 8, 2006.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size. The state
may allow you to reduce your sample to:
• 1 grab sample per day if your serve less than or equal to 500 persons.
• 2 grab samples per day taken at separate times if your serve 501 to 1,000 persons.
• 3 grab samples per day taken at separate times if your serve 1,001 to 2,500 persons.
• 4 grab samples per day taken at separate times if your serve 2,501 to 3,300 persons.
If you are using grab sampling instead of continuous monitoring and the residual disinfectant concentration
is below 0.2 mg/L, you must take a grab sample every 4 hours until the residual disinfectant concentration
is 0.2 mg/L or greater.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
Reporting and Recordkeeping
Monitoring
Report by:
What to Report
CTK ')? Percent \ jilue-
Kccorded e\erv 4 hours
nionlh lluil \ou sci'\cd walcr
In iIk- public
I" da\ ol'lhc following
Toial number nl'( I \ . mcasuivmcnls and
numlvr and |viccnlaijc of( I'L
mcasuivmcnls less llian or equal in llic
l>5 |vi'ccnlilc 11mil
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-3
-------
Monitoring
Report by:
What to Report
CFE Maximum Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Date and time of CFE measurement that
exceeds CFE maximum limit.
IFE Monitoring -
Monitored continuously
and recorded every 15
minutes
10th day of the following
month that you served water
to the public
IFE monitoring conducted and any
follow-up actions.
Minimum Disinfection
Residual - Entry to the
distribution system
10th day of the following
month that you served water
to the public
Lowest daily value for each day, the date
and duration when the residual
disinfectant was less than 0.2 mg/L, and
when the state was notified of events
where residual disinfectant was less than
0.2 mg/L.
Detectable Disinfection
Residual -
In the distribution system
10th day of the following
month that you served water
to the public
Number of residual disinfectant or HPC
measurements taken in the month
resulting in no more than 5 percent of the
measurements as being undetectable1 in
any 2 consecutive months.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice.
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs requires that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-4
-------
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (.How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-5
-------
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet the requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states' discretion.
Information about state operator certification programs can be accessed through EPA's website at
https://www.epa.gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
If you did not have 5.5-logs of treatment for Cryptosporidium, which is equivalent to meeting the treatment
requirements of Bin 4, you were required to conduct initial source water monitoring and monitor for E. coli
at least once every 2 weeks for 12 months. Based on the E. coli results you may have been required to
conduct additional Cryptosporidium monitoring. You were also required to begin a second round of source
water monitoring 6 years after the required date for your water system's initial bin classification
determination.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial bin
classification determination.
Bin Classification
If you were required to conduct Cryptosporidium monitoring, you should have completed your source
water monitoring and calculated your Cryptosporidium concentration to determine your water system's
Cryptosporidium bin classification. If you are a new Subpart H system or a Subpart H system that
developed a new source you must determine the bin classification, based on a schedule provided by the
state and no later than 6 months after the source water monitoring is completed.
After calculating the Cryptosporidium concentration, filtered systems must use this concentration to
determine their bin classification.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-6
-------
Bin
Cryptosporidium Concentration (oocysts/L):
1
Less than 0.075 oocysts/L
2
0.075 oocysts/L or higher, but less than 1.0 oocysts/L
3
1.0 oocysts/L or higher, but less than 3.0 oocysts/L
4
3.0 oocysts/L or higher
For more information on determining your bin classification see Chapter 6 of EPA's Source Water
Monitoring Guidance Manual for Public Water Systems for the Final Long Term 2 Enhanced Surface
Water Treatment Ride (EPA 815-R-06-005, February 2006), available at
https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-documents.
Ultimately, the bin classification determines what, if any, additional treatment for Cryptosporidium
required at your treatment plants. Treatment plants classified in Bin 1 are not required to provide any
additional treatment (if they are in compliance with all existing standards, as applicable). Treatment plants
classified in Bins 2, 3, and 4 are required to provide additional treatment, the level of which varies
according to the type of filtration in place at the treatment plant.
Bin
Conventional Filtration
(incl. softening)
Direct
Filtration
1
None
None
2
1-log
1-5-log
3
2-log
2.5-log
4
2.5-log
3-log
Microbial Toolbox
If your bin classification put you into bins 2, 3, or 4 you will need to use one or more of the Microbial
Toolbox options to meet Cryptosporidium treatment requirements established during bin classification.
Five types of toolbox options are available to systems:
• Source protection and management options.
• Pre-filtration options.
• Treatment performance options.
• Additional filtration options.
• Inactivation options.
There are reporting requirements associated with each type of toolbox option, including when a system
must notify a state of their intent to use toolbox options, what a system must verify to be eligible for
treatment credit, and what reporting requirements a system must meet in order to continue to receive
Cryptosporidium treatment credit. Systems must keep results of treatment monitoring for 3 years. The state
may approve a system to certify operation within required parameters for treatment credit rather than
reporting monthly operational data for toolbox options.
See Attachment 10 for more information regarding the Microbial Toolbox.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-7
-------
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Removal/inactivation requirements for viruses, Giardia lamblia, and Cryptosporidium.
• Turbidity.
• Filter backwash recycling.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified operators.
As a Schedule 4 system, you should be finished with your E. coli source water monitoring. Systems that
were required to conduct Cryptosporidium monitoring and were in bins 2, 3, or 4 after completing their
initial source water monitoring must be in compliance with the additional log inactivation and/or removal
requirements.
If you were required to conduct Cryptosporidium monitoring during the second round of source water
monitoring you must have begun that monitoring by April 1, 2019. If, after you calculate your second
round of source water monitoring Cryptosporidium bin classification and you are in bin 2, 3, or 4, you have
until October 1, 2023 (with a possible 2-year extension) to complete any additional treatment or control
processes.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 2-8
-------
Attachment 3: I operate a Subpart H water system that: uses slow
sand or diatomaceous earth filtration and is on LT2ESWTR
Schedule 1, 2, or 34
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Giardict lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, use slow sand or diatomaceous
earth filtration, and:
1) serve 10,000 or more persons and do not sell water; or
2) sell water, and the largest system in their CDS serves 10,000 or more persons.
Requirements
Removal/Inactivation Requirements for Viruses, Giardia Lamblia, and
Cryptosporidium
You must comply with the removal/inactivation requirements established for regulated pathogens. The
removal/inactivation requirements are as follows:
Microbial
MCLG
Rem oval/In activation
Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log)
4 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 3-1
-------
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
Turbidity
Turbidity is measured as combined filter effluent (CFE). CFE is generated when the effluent water from
individual filters in operation is combined into one stream.
CFE turbidity must be measured every 4 hours during plant operation. The CFE turbidity for slow sand or
diatomaceous earth filtration systems:
• Must be less than or equal to 1 nephelometric turbidity unit (NTU) for 95 percent of the readings
taken each month; and
• Can at no time exceed 5 NTU (based on turbidity measurements recorded every 4 hours).
If you use slow sand or diatomaceous earth filtration and you serve 500 or fewer persons, the frequency of
monitoring may be reduced to once per day if the state determines that less frequent monitoring is sufficient
to indicate effective filtration performance. You should check with your state on CFE requirements because
the state may require additional monitoring.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size. The state
may allow you to reduce your sample to:
• 1 grab sample per day if your serve less than or equal to 500 persons.
• 2 grab samples per day taken at separate times if your serve 501 to 1,000 persons.
• 3 grab samples per day taken at separate times if your serve 1,001 to 2,500 persons.
• 4 grab samples per day taken at separate times if your serve 2,501 to 3,300 persons.
If you are using grab sampling instead of continuous monitoring and the residual disinfectant concentration
is below 0.2 mg/L, you must take a grab sample every 4 hours until the residual disinfectant concentration
is 0.2 mg/L or greater.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 3-2
-------
Reporting and Recordkeeping
Monitoring
Report by:
What to Report
CFE 95 Percent Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Total number of CFE measurements and
number and percentage of CFE
measurements less than or equal to the
95th percentile limit.
CFE Maximum Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Date and time of CFE measurement that
exceeds CFE maximum limit.
Minimum Disinfection
Residual - Entry to the
distribution system
10th day of the following
month that you served water
to the public
Lowest daily value for each day, the date
and duration when the residual
disinfectant was less than 0.2 mg/L, and
when the state was notified of events
where residual disinfectant was less than
0.2 mg/L.
Detectable Disinfection
Residual -
In the distribution system
10th day of the following
month that you served water
to the public
Number of residual disinfectant or HPC
measurements taken in the month
resulting in no more than 5 percent of the
measurements as being undetectable1 in
any 2 consecutive months.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice.
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs requires that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 3-3
-------
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (.How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 3-4
-------
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet the requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states" discretion.
Information about state operator certification programs can be accessed through EPA's website at
https://www.epa.gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
If you did not have 5.5-logs of treatment for Cryptosporidium, which is equivalent to meeting the treatment
requirements of Bin 4, you were required to conduct initial source water monitoring and monitor for
Cryptosporidium, E. coli, and turbidity at least monthly for 2 years. You were also required to begin a
second round of source water monitoring 6 years after the required date for your water system's initial bin
classification determination.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial bin
classification determination.
Bin Classification
You should have completed your source water monitoring and calculated your Cryptosporidium
concentration to determine your water system's Cryptosporidium bin classification. If you are a new
Subpart H system or a Subpart H system that developed a new source you must determine the bin
classification, based on a schedule provided by the state and no later than 6 months after the source water
monitoring is completed.
After calculating the Cryptosporidium concentration, filtered systems must use this concentration to
determine their bin classification.
Bin
Cryptosporidium Concentration (oocysts/L):
1
Less than 0.075 oocysts/L
2
0.075 oocysts/L or higher, but less than 1.0 oocysts/L
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 3-5
-------
Bin
Cryptosporidium Concentration (oocysts/L):
3
1.0 oocysts/L or higher, but less than 3.0 oocysts/L
4
3.0 oocysts/L or higher
For more information on determining your bin classification see Chapter 6 of EPA's Source Water
Monitoring Guidance Manual for Public Water Systems for the Final Long Term 2 Enhanced Surface
Water Treatment Ride (EPA 815-R-06-005, February 2006), available at
https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-documents.
Ultimately, the bin classification determines what, if any, additional treatment for Cryptosporidium
required at your treatment plants. Treatment plants classified in Bin 1 are not required to provide any
additional treatment (if they are in compliance with all existing standards, as applicable). Treatment plants
classified in Bins 2, 3, and 4 are required to provide additional treatment, the level of which varies
according to the type of filtration in place at the treatment plant.
Bin
Slow Sand
Filtration
Diatomaceous Earth
Filtration
1
None
None
2
1-log
1-log
3
2-log
2.-log
4
2.5-log
2.5-log
Microbial Toolbox
If your bin classification put you into bins 2, 3, or 4 you will need to use one or more of the Microbial
Toolbox options to meet Cryptosporidium treatment requirements established during bin classification.
Five types of toolbox options are available to systems:
• Source protection and management options.
• Pre-filtration options.
• Treatment performance options.
• Additional filtration options.
• Inactivation options.
There are reporting requirements associated with each type of toolbox option, including when a system
must notify a state of their intent to use toolbox options, what a system must verify to be eligible for
treatment credit, and what reporting requirements a system must meet in order to continue to receive
Cryptosporidium treatment credit. Systems must keep results of treatment monitoring for 3 years. The state
may approve a system to certify operation within required parameters for treatment credit rather than
reporting monthly operational data for toolbox options.
See Attachment 10 for more information regarding the Microbial Toolbox.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 3-6
-------
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Removal/inactivation requirements for viruses, Giardict lamblia, and Cryptosporidium.
• Turbidity.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified personnel.
Systems that were in bins 2, 3, or 4 following completion of their initial source water monitoring must be in
compliance with the additional log inactivation and/or removal requirements. Systems that were in bins 2,
3, and 4 after completing their second round of source water monitoring must either be in compliance with
the additional log inactivation and/or removal requirements or be in the process of installing additional
treatment.
Schedule
Initial Round of
Source Water
Monitoring was
due no later than:
Calculation of Initial
Cryptosporidium
Bin Classification
was due no later
than:
Add Additional
Treatment or Control
Processes for Systems in
Bin 2, 3, and 4 by2:
Second Round of
Source Water
Monitoring was
due no later than:
1
September 2008
March 2009
April 1,2012
April 1,2017
2
March 2009
September 2009
October 1, 2012
October 1, 2017
3
March 2010
September 2010
October 1, 2013
October 1, 2018
2. States may allow up to an additional 2 years for complying with the treatment requirement for systems making
capital improvements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 3-7
-------
Attachment 4: I operate a Subpart H water system that: uses slow
sand or diatomaceous earth filtration and is on LT2ESWTR
Schedule 45
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Giardict lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, use slow sand or diatomaceous
earth filtration, and:
1) serve fewer than 10,000 persons and do not sell water; or
2) sell water, and the largest system in their CDS serves fewer than 10,000 persons.
Requirements
Removal/Inactivation Requirements for Viruses, Giardia Lamblia, and
Cryptosporidium
You must comply with the removal/inactivation requirements established for regulated pathogens. The
removal/inactivation requirements are as follows:
Microbial
MCLG
Rem oval/In activation
Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log) (removal only)
5 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 4-1
-------
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
Turbidity
Turbidity is measured as combined filter effluent (CFE). CFE is generated when the effluent water from
individual filters in operation is combined into one stream.
CFE turbidity must be measured every 4 hours during plant operation. The CFE turbidity for slow sand or
diatomaceous earth filtration systems:
• Must be less than or equal to 1 nephelometric turbidity unit (NTU) for 95 percent of the readings
taken each month; and
• Can at no time exceed 5 NTU (based on turbidity measurements recorded every 4 hours).
If you use slow sand or diatomaceous earth filtration and you serve 500 or fewer persons, the frequency of
monitoring may be reduced to once per day if the state determines that less frequent monitoring is sufficient
to indicate effective filtration performance. You should check with your state on CFE requirements because
the state may require additional monitoring.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size. The state
may allow you to reduce your sample to:
• 1 grab sample per day if your serve less than or equal to 500 persons.
• 2 grab samples per day taken at separate times if your serve 501 to 1,000 persons.
• 3 grab samples per day taken at separate times if your serve 1,001 to 2,500 persons.
• 4 grab samples per day taken at separate times if your serve 2,501 to 3,300 persons.
If you are using grab sampling instead of continuous monitoring and the residual disinfectant concentration
is below 0.2 mg/L, you must take a grab sample every 4 hours until the residual disinfectant concentration
is 0.2 mg/L or greater.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 4-2
-------
Reporting and Recordkeeping
Monitoring
Report by:
What to Report
CFE 95 Percent Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Total number of CFE measurements and
number and percentage of CFE
measurements less than or equal to the
95th percentile limit.
CFE Maximum Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Date and time of CFE measurement that
exceeds CFE maximum limit.
Minimum Disinfection
Residual - Entry to the
distribution system
10th day of the following
month that you served water
to the public
Lowest daily value for each day, the date
and duration when the residual
disinfectant was less than 0.2 mg/L, and
when the state was notified of events
where residual disinfectant was less than
0.2 mg/L.
Detectable Disinfection
Residual -
In the distribution system
10th day of the following
month that you served water
to the public
Number of residual disinfectant or HPC
measurements taken in the month
resulting in no more than 5 percent of the
measurements as being undetectable1 in
any 2 consecutive months.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice.
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs requires that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 4-3
-------
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (.How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 4-4
-------
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states' discretion.
Information about state operator certification programs can be accessed through EPA's website at
https://www.epa.gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
If you did not have 5.5-logs of treatment for Cryptosporidium, which is equivalent to meeting the treatment
requirements of Bin 4, you were required to conduct initial source water monitoring and monitor for E. coli
at least once every 2 weeks for 12 months. Based on the E. coli results you may have been required to
conduct additional Cryptosporidium monitoring. You were also required to begin a second round of source
water monitoring 6 years after the required date for your water system's initial bin classification
determination.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial bin
classification determination.
Bin Classification
If you were required to conduct Cryptosporidium monitoring, you should have completed your source
water monitoring and calculated your Cryptosporidium concentration to determine your water system's
Cryptosporidium bin classification. If you are a new Subpart H system or a Subpart H system that
developed a new source you must determine the bin classification, based on a schedule provided by the
state and no later than 6 months after the source water monitoring is completed.
After calculating the Cryptosporidium concentration, filtered systems must use this concentration to
determine their bin classification.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 4-5
-------
Bin
Cryptosporidium Concentration (oocysts/L):
1
Less than 0.075 oocysts/L
2
0.075 oocysts/L or higher, but less than 1.0 oocysts/L
3
1.0 oocysts/L or higher, but less than 3.0 oocysts/L
4
3.0 oocysts/L or higher
For more information on determining your bin classification see Chapter 6 of EPA's Source Water
Monitoring Guidance Manual for Public Water Systems for the Final Long Term 2 Enhanced Surface
Water Treatment Ride (EPA 815-R-06-005, February 2006), available at
https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-documents.
Ultimately, the bin classification determines what, if any, additional treatment for Cryptosporidium
required at your treatment plants. Treatment plants classified in Bin 1 are not required to provide any
additional treatment (if they are in compliance with all existing standards, as applicable). Treatment plants
classified in Bins 2, 3, and 4 are required to provide additional treatment, the level of which varies
according to the type of filtration in place at the treatment plant.
Bin
Slow Sand
Filtration
Diatomaceous Earth
Filtration
1
None
None
2
1-log
1-log
3
2-log
2-log
4
2.5-log
2.5-log
Microbial Toolbox
If your bin classification put you into bins 2, 3, or 4 you will need to use one or more of the Microbial
Toolbox options to meet Cryptosporidium treatment requirements established during bin classification.
Five types of toolbox options are available to systems:
• Source protection and management options.
• Pre-filtration options.
• Treatment performance options.
• Additional filtration options.
• Inactivation options.
There are reporting requirements associated with each type of toolbox option, including when a system
must notify a state of their intent to use toolbox options, what a system must verify to be eligible for
treatment credit, and what reporting requirements a system must meet in order to continue to receive
Cryptosporidium treatment credit. Systems must keep results of treatment monitoring for 3 years. The state
may approve a system to certify operation within required parameters for treatment credit rather than
reporting monthly operational data for toolbox options.
See Attachment 10 for more information regarding the Microbial Toolbox.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 4-6
-------
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Removal/inactivation requirements for viruses, Giardia lamblia, and Cryptosporidium.
• Turbidity.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified personnel.
As a Schedule 4 system, you should be finished with your E. coli source water monitoring. Systems that
were required to conduct Cryptosporidium monitoring and were in bins 2, 3, or 4 after completing their
initial source water monitoring must be in compliance with the additional log inactivation and/or removal
requirements.
If you were required to conduct Cryptosporidium monitoring during the second round of source water
monitoring you must have begun that monitoring by April 1, 2019. If, after you calculate your second
round of source water monitoring Cryptosporidium bin classification and you are in bin 2, 3, or 4, you have
until October 1, 2023 (with a possible 2-year extension) to complete any additional treatment or control
processes.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 4-7
-------
Attachment 5: I operate a Subpart H water system that: uses
alternative filtration and is on LT2ESWTR Schedule 1, 2, or 36
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Giardict lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, use alternative filtration, and:
1) serve 10,000 or more persons and do not sell water; or
2) sell water, and the largest system in their CDS serves 10,000 or more persons.
Requirements
Removal/Inactivation Requirements for Viruses, Giardia Lamblia, and
Cryptosporidium
In order to use an alternative filtration type you must demonstrate to the state, either through a pilot plant
studies or other means determined by the state, that the alternative filtration technology along with the
disinfection treatment meet the removal and inactivation requirements for viruses, Giardict lamblia, and
Cryptosporidium.
You must comply with the removal/inactivation requirements established for regulated pathogens. The
removal/inactivation requirements are as follows:
Microbial
MCLG
Rem oval/Inactivation
Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log)
6 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 5-1
-------
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
Turbidity
Turbidity is measured as combined filter effluent (CFE). CFE is generated when the effluent water from
individual filters in operation is combined into one stream.
CFE turbidity must be measured every 4 hours during plant operation. The CFE turbidity level for
alternative filtration systems is set by the state based on the results of the systems demonstration of the
technology. However the CFE turbidity for alternative filtration systems:
• Must be less than or equal to 1 nephelometric turbidity unit (NTU) for 95 percent of the readings
taken each month; and
• Can at no time exceed 5 NTU (based on turbidity measurements recorded every 4 hours).
If you serve 500 or fewer persons, the frequency of monitoring may be reduced to once per day if the state
determines that less frequent monitoring is sufficient to indicate effective filtration performance. You
should check with your state on CFE requirements because the state may require additional monitoring.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size. The state
may allow you to reduce your sample to:
• 1 grab sample per day if your serve less than or equal to 500 persons.
• 2 grab samples per day taken at separate times if your serve 501 to 1,000 persons.
• 3 grab samples per day taken at separate times if your serve 1,001 to 2,500 persons.
• 4 grab samples per day taken at separate times if your serve 2,501 to 3,300 persons.
If you are using grab sampling instead of continuous monitoring and the residual disinfectant concentration
is below 0.2 mg/L, you must take a grab sample every 4 hours until the residual disinfectant concentration
is 0.2 mg/L or greater.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 5-2
-------
Reporting and Recordkeeping
Monitoring
Report by:
What to Report
CFE 95 Percent Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Total number of CFE measurements and
number and percentage of CFE
measurements less than or equal to the
95th percentile limit.
CFE Maximum Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Date and time of CFE measurement that
exceeds CFE maximum limit.
Minimum Disinfection
Residual - Entry to the
distribution system
10th day of the following
month that you served water
to the public
Lowest daily value for each day, the date
and duration when the residual
disinfectant was less than 0.2 mg/L, and
when the state was notified of events
where residual disinfectant was less than
0.2 mg/L.
Detectable Disinfection
Residual -
In the distribution system
10th day of the following
month that you served water
to the public
Number of residual disinfectant or HPC
measurements taken in the month
resulting in no more than 5 percent of the
measurements as being undetectable1 in
any 2 consecutive months.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice.
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs requires that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 5-3
-------
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (.How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 5-4
-------
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet the requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states' discretion.
Information about state operator certification programs can be accessed through EPA's website at
https: //www. epa. gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
If you did not have 5.5-logs of treatment for Cryptosporidium, which is equivalent to meeting the treatment
requirements of Bin 4, you were required to conduct initial source water monitoring and monitor for
Cryptosporidium, E. coli, and turbidity at least monthly for 2 years. You were also required to begin a
second round of source water monitoring 6 years after the required date for your water system's initial bin
classification determination.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial bin
classification determination.
Bin Classification
You should have completed your source water monitoring and calculated your Cryptosporidium
concentration to determine your water system's Cryptosporidium bin classification. If you are a new
Subpart H system or a Subpart H system that developed a new source you must determine the bin
classification, based on a schedule provided by the state and no later than 6 months after the source water
monitoring is completed.
After calculating the Cryptosporidium concentration, filtered systems must use this concentration to
determine their bin classification.
liin
Cryptosporidium (Oiicontrntion (oocvsts/L):
l.ess lluin 0 i>75 ooc\sis I.
2
0.075 oocysts/L or higher, but less than 1.0 oocysts/L
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 5-5
-------
Bin
Cryptosporidium Concentration (oocysts/L):
3
1.0 oocysts/L or higher, but less than 3.0 oocysts/L
4
3.0 oocysts/L or higher
For more information on determining your bin classification see Chapter 6 of EPA's Source Water
Monitoring Guidance Manual for Public Water Systems for the Final Long Term 2 Enhanced Surface
Water Treatment Ride (EPA 815-R-06-005, February 2006), available at
https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-documents.
Ultimately, the bin classification determines what, if any, additional treatment for Cryptosporidium
required at your treatment plants. Treatment plants classified in Bin 1 are not required to provide any
additional treatment (if they are in compliance with all existing standards, as applicable). Treatment plants
classified in Bins 2, 3, and 4 are required to provide additional treatment, the level of which varies
according to the type of filtration in place at the treatment plant.
Bin
Alternative Filtration Treatment Requirement
1
None
2
As determined by the state so that the total Cryptosporidium
removal and activation at the treatment plant is at least 4.0-log
3
As determined by the state so that the total Cryptosporidium
removal and activation at the treatment plant is at least 5.0-log
4
As determined by the state so that the total Cryptosporidium
removal and activation at the treatment plant is at least 5.5-log
Microbial Toolbox
If your bin classification put you into bins 2, 3, or 4 you will need to use one or more of the Microbial
Toolbox options to meet Cryptosporidium treatment requirements established during bin classification.
Five types of toolbox options are available to systems:
• Source protection and management options.
• Pre-filtration options.
• Treatment performance options.
• Additional filtration options.
• Inactivation options.
There are reporting requirements associated with each type of toolbox option, including when a system
must notify a state of their intent to use toolbox options, what a system must verify to be eligible for
treatment credit, and what reporting requirements a system must meet in order to continue to receive
Cryptosporidium treatment credit. Systems must keep results of treatment monitoring for 3 years. The state
may approve a system to certify operation within required parameters for treatment credit rather than
reporting monthly operational data for toolbox options.
See Attachment 10 for more information regarding the Microbial Toolbox.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 5-6
-------
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Removal/inactivation requirements for viruses, Giardia lamblia, and Cryptosporidium.
• Turbidity.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified personnel.
Systems that were in bins 2, 3, or 4 following completion of their initial source water monitoring must be in
compliance with the additional log inactivation and/or removal requirements. Systems that were in bins 2,
3, and 4 after completing their second round of source water monitoring must either be in compliance with
the additional log inactivation and/or removal requirements or be in the process of installing additional
treatment.
Initial Round of
Calculation of Initial
Cryptosporidium
Bin Classification
was due no later
than:
Add Additional
Second Round of
Schedule
Source Water
Treatment or Control
Source Water
Monitoring was
due no later than:
Processes for Systems in
Bin 2, 3, and 4 by2:
Monitoring was
due no later than:
1
Scpk-mlvr 2<>ox
March 2<>(W
April 1. 2«il2
April 1. 2() 17
2
March 2<>(W
Scpk-mlvr 2<)( w
Oclolvr 1. 2() 12
Oclolvr 1. 2() 17
3
March 2<) 1 <)
Scplcmlvi' 2<) 1 <)
Oclolvr 1. 2i
Oclolvr 1. 2<) 1X
2. States may allow up to an additional 2 years for complying with the treatment requirement for systems making
capital improvements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 5-7
-------
Attachment 6: I operate a Subpart H water system that: uses
alternative filtration and is on LT2ESWTR Schedule 47
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Giardict lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, use alternative filtration, and:
1) serve fewer than 10,000 persons and do not sell water; or
2) sell water, and the largest system in their CDS serves fewer than 10,000 persons.
Requirements
Removal/Inactivation Requirements for Viruses, Giardia Lamblia, and
Cryptosporidium
In order to use an alternative filtration type you must demonstrate to the state, either through a pilot plant
studies or other means determined by the state, that the alternative filtration technology along with the
disinfection treatment meet the removal and inactivation requirements for viruses, Giardict lamblia, and
Cryptosporidium.
You must comply with the removal/inactivation requirements established for regulated pathogens. The
removal/inactivation requirements are as follows:
Microbial
MCLG
Rem oval/Inactivation
Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log)
7 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 6-1
-------
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
Turbidity
Turbidity is measured as combined filter effluent (CFE). CFE is generated when the effluent water from
individual filters in operation is combined into one stream.
CFE turbidity must be measured every 4 hours during plant operation. The CFE turbidity level for
alternative filtration systems is set by the state based on the results of the systems demonstration of the
technology. However the CFE turbidity for alternative filtration systems:
• Must be less than or equal to 1 nephelometric turbidity unit (NTU) for 95 percent of the readings
taken each month; and
• Can at no time exceed 5 NTU (based on turbidity measurements recorded every 4 hours).
Your frequency of monitoring may be reduced to once per day if the state determines that less frequent
monitoring is sufficient to indicate effective filtration performance. You should check with your state on
CFE requirements because the state may require additional monitoring.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size. The state
may allow you to reduce your sample to:
• 1 grab sample per day if your serve less than or equal to 500 persons.
• 2 grab samples per day taken at separate times if your serve 501 to 1,000 persons.
• 3 grab samples per day taken at separate times if your serve 1,001 to 2,500 persons.
• 4 grab samples per day taken at separate times if your serve 2,501 to 3,300 persons.
If you are using grab sampling instead of continuous monitoring and the residual disinfectant concentration
is below 0.2 mg/L, you must take a grab sample every 4 hours until the residual disinfectant concentration
is 0.2 mg/L or greater.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 6-2
-------
Reporting and Recordkeeping
Monitoring
Report by:
What to Report
CFE 95 Percent Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Total number of CFE measurements and
number and percentage of CFE
measurements less than or equal to the
95th percentile limit.
CFE Maximum Value -
Recorded every 4 hours
10th day of the following
month that you served water
to the public
Date and time of CFE measurement that
exceeds CFE maximum limit.
Minimum Disinfection
Residual - Entry to the
distribution system
10th day of the following
month that you served water
to the public
Lowest daily value for each day, the date
and duration when the residual
disinfectant was less than 0.2 mg/L, and
when the state was notified of events
where residual disinfectant was less than
0.2 mg/L.
Detectable Disinfection
Residual -
In the distribution system
10th day of the following
month that you served water
to the public
Number of residual disinfectant or HPC
measurements taken in the month
resulting in no more than 5 percent of the
measurements as being undetectable1 in
any 2 consecutive months.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice.
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs requires that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 6-3
-------
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (.How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 6-4
-------
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet the requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states' discretion.
Information about state operator certification programs can be accessed through EPA's website at
https: //www. epa. gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
If you did not have 5.5-logs of treatment for Cryptosporidium, which is equivalent to meeting the treatment
requirements of Bin 4, you were required to conduct initial source water monitoring and monitor for E. coli
at least once every 2 weeks for 12 months. Based on the E. coli results you may have been required to
conduct additional Cryptosporidium monitoring. You were also required to begin a second round of source
water monitoring 6 years after the required date for your water system's initial bin classification
determination.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial bin
classification determination.
Bin Classification
If you were required to conduct Cryptosporidium monitoring, you should have completed your source
water monitoring and calculated your Cryptosporidium concentration to determine your water system's
Cryptosporidium bin classification. If you are a new Subpart H system or a Subpart H system that
developed a new source you must determine the bin classification, based on a schedule provided by the
state and no later than 6 months after the source water monitoring is completed.
After calculating the Cryptosporidium concentration, filtered systems must use this concentration to
determine their bin classification.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 6-5
-------
Bin
Cryptosporidium Concentration (oocysts/L):
1
Less than 0.075 oocysts/L
2
0.075 oocysts/L or higher, but less than 1.0 oocysts/L
3
1.0 oocysts/L or higher, but less than 3.0 oocysts/L
4
3.0 oocysts/L or higher
Ultimately, the bin classification determines what, if any, additional treatment for Cryptosporidium you are
required to provide at your treatment plants. Treatment plants classified in Bin 1 are not required to provide
any additional treatment (if they are in compliance with all existing standards, as applicable). Treatment
plants classified in Bins 2, 3, and 4 are required to provide additional treatment, the level of which varies
according to the type of filtration in place at the treatment plant.
Bin
Alternative Filtration Treatment Requirements
1
None
2
As determined by the state so that the total Cryptosporidium
removal and activation at the treatment plant is at least 4.0-log
3
As determined by the state so that the total Cryptosporidium
removal and activation at the treatment plant is at least 5.0-log
4
As determined by the state so that the total Cryptosporidium
removal and activation at the treatment plant is at least 5.5-log
Microbial Toolbox
If your bin classification put you into bins 2, 3, or 4 you will need to use one or more of the Microbial
Toolbox options to meet Cryptosporidium treatment requirements established during bin classification.
Five types of toolbox options are available to systems:
• Source protection and management options.
• Pre-filtration options.
• Treatment performance options.
• Additional filtration options.
• Inactivation options.
There are reporting requirements associated with each type of toolbox option, including when a system
must notify a state of their intent to use toolbox options, what a system must verify to be eligible for
treatment credit, and what reporting requirements a system must meet in order to continue to receive
Cryptosporidium treatment credit. Systems must keep results of treatment monitoring for 3 years. The state
may approve a system to certify operation within required parameters for treatment credit rather than
reporting monthly operational data for toolbox options.
See Attachment 10 for more information regarding the Microbial Toolbox.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 6-6
-------
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Removal/inactivation requirements for viruses, Giardia lamblia, and Cryptosporidium.
• Turbidity.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified personnel.
As a Schedule 4 system, you should be finished with your E. coli source water monitoring. Systems that
were required to conduct Cryptosporidium monitoring and were in bins 2, 3, or 4 after completing their
initial source water monitoring must be in compliance with the additional log inactivation and/or removal
requirements.
If you were required to conduct Cryptosporidium monitoring during the second round of source water
monitoring you must have begun that monitoring by April 1, 2019. If, after you calculate your second
round of source water monitoring Cryptosporidium bin classification and you are in bin 2, 3, or 4, you have
until October 1, 2023 (with a possible 2-year extension) to complete any additional treatment or control
processes.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 6-7
-------
Attachment 7: I operate a Subpart H water system that: is
unfiltered and is on LT2ESWTR Schedule 1, 2, or 3s
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Giardict lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, avoid filtration, and:
1) serve 10,000 or more persons and do not sell water; or
2) sell water, and the largest system in their CDS serves 10,000 or more persons.
Requirements
Inactivation Requirements for Viruses, Giardia Lamblia, and Cryptosporidium
You must comply with the inactivation requirements established for regulated pathogens. The inactivation
requirements are as follows:
Microbial
MCLG
Inactivation Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log) (through watershed control), and
99% (2-log) removal of Cryptosporidium for systems reporting
less than or equal to 0.01 oocysts/L in initial source water
monitoring or
99.9% (3-log) removal of Cryptosporidium for systems reporting
more than 0.01 oocysts/L in initial source water monitoring
8 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-1
-------
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
You must include in your watershed control programs steps to minimize the potential for contamination by
Cryptosporidium. Your watershed control program must also minimize the potential for contamination by
Giardia lamblia and viruses in source water. If you fail to meet Cryptosporidium site-specific
requirements, you must install filtration within 18 months.
Filtration Avoidance Criteria
In order to remain unfiltered you must meet certain source water quality and site specific conditions. If any
of the Filtration Avoidance Criteria are not meet you must install filtration within 18 months of the failure.
Source Water Quality Conditions
You must measure your source water turbidity. This sample must be taken prior to the first point of
disinfection. You must collect a representative grab sample of your source water at least every 4 hours, and
the turbidity cannot exceed 5 NTU. You must also monitor fecal coliform or total coliform concentrations
in representative samples of source water immediately prior to the first point of disinfection. The number of
samples you must take depends on your system size and the turbidity of your source water. If you serve:
• Less than or equal to 500 persons, you must take 1 sample per week.
• 501 to 3,300 persons, you must take 2 samples per week taken on separate days.
• 3,301 to 10,000 persons, you must take 3 samples per week taken on separate days.
• 10,001 to 25,000 persons, you must take 4 samples per week taken on separate days.
• More than 25,000 persons, you must take 5 samples per week taken on separate days.
You must also monitor on any day in which your turbidity sample exceeds 1 NTU.
Fecal coliform density must be less than or equal to 20/100 mL or your total coliform density must less
than or equal to 100/100 mL. You must meet one of these criteria in at least 90 percent of the
measurements from the previous 6 months.
Site Specific Conditions
You must calculate your system's total inactivation ratio daily and provide 3-log Giardia lamblia and 4-log
virus inactivation daily except any 1 day each month in 11 of 12 months (on an ongoing basis). You must
take daily measurements before or at the first customer at each residual disinfectant concentration sampling
point and must measure:
• Temperature.
• pH (if chlorine is used).
• Disinfection contact time (at peak hourly flow).
• Residual disinfectant concentration (at peak hourly flow).
You must comply with the MCL for total coliforms [40 CFR 141.63(a) and (b)] and the MCL fori?, coli
[40 CFR 141.63(c)] in at least 11 of the 12 previous months, and you must meet the requirements of the
Stage 1 DBPR and Stage 2 DBPR.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-2
-------
You must have:
• Adequate entry point residual disinfectant concentration.
• Detectable residual disinfectant concentration in the distribution system.
• Redundant disinfection components or automatic shut-off whenever the residual disinfectant
concentration is less than 0.2 mg/L.
• A watershed control program minimizing the potential for contamination by Cryptosporidium,
Giardia lamblia, and viruses in source water.
• An annual on-site inspection by state or an approved third party, with reported findings.
• Not been identified as a source of a waterborne disease outbreak.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
You must meet the combined Cryptosporidium, Giardia lamblia, and virus inactivation requirements
(specified in the Inactivation Requirements table at the beginning of this attachment) using a minimum of
two disinfectants. Each disinfectant must be able to achieve the total inactivation required for
Cryptosporidium, Giardia lamblia, or viruses. For example, a system may use UV to meet
Cryptosporidium and Giardia lamblia inactivation requirements and chlorine to meet virus inactivation
requirements. To meet the Cryptosporidium inactivation requirements, systems must use chlorine dioxide,
ozone, or UV.
Reporting and Recordkeeping
Disinfection requirements are more stringent for unfiltered systems than filtered systems. You will receive
a treatment technique violation if:
• You are using chlorine dioxide or ozone that fails to achieve the Cryptosporidium log inactivation
on more than 1 day in the calendar month.
• You are using UV light and fail to treat in at least 95 percent of the water that is delivered to the
public during each calendar month within validated conditions.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-3
-------
Monitoring
Report by:
What to Report
Source Water
Quality
Conditions
10th day of the
following month
that you served
water to the
public
The cumulative number of months for which results are
reported.
The number of fecal and/or total coliform samples (if a system
monitors for both, only fecal coliforms must be reported), the
dates of sample collection, and the dates when the turbidity
level exceeded 1 NTU.
The number of samples during the month that had equal to or
less than 20/100 mL fecal coliforms and/or equal to or less than
100/100 mL total coliforms, whichever are analyzed.
The cumulative number of fecal or total coliform samples,
cumulative number of samples that had equal to or less than
20/100 mL fecal coliforms or equal to or less than 100/100 mL
total coliforms, percentage of samples that had equal to or less
than 20/100 mL fecal coliforms or equal to or less than 100/100
mL total coliforms, during the previous 6 months the system
served water to the public.
The maximum turbidity level measured during the month, the
date for any measurement that exceeded 5 NTU, and the date
the occurrence was reported to the state.
The dates and number of times the turbidity exceeded 5 NTU in
the previous 12 months.
For the first 120 months of recordkeeping, the dates and total
number of events during which the turbidity exceeded 5 NTU,
and after 10 years of recordkeeping for turbidity measurements,
the dates and total number of events during which the turbidity
exceeded 5 NTU in the previous 120 months the system served
water to the public.
Site Specific
Conditions
By October 10 of
each year
Compliance with all watershed control program requirements.
Report on the on-site inspection, unless the state conducted the
inspection.
Within 24 hours
Any turbidity exceedances of 5 NTU or waterborne disease
outbreaks.
ASAP but no
later than the end
of the next
business day
Any instance where the residual disinfectant level entering the
distribution systems was less than 0.2 mg/L.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-4
-------
Monitoring
Report by:
What to Report
Minimum
Disinfection
Residual - Entry
to the
distribution
system
10th day of the
following month
that you served
water to the
public
Lowest daily value for each day, the date and duration when the
residual disinfectant was less than 0.2 mg/L, and when the state
was notified of events where residual disinfectant was less than
0.2 mg/L.
The daily residual disinfectant concentration (in mg/L) and
disinfection contact time (in minutes) used for calculating the
CT value.
If chlorine is used, the daily measurement of pH of disinfected
water following each point of chlorine disinfection.
The daily measurement of water temperature in degrees C
following each point of disinfection.
The daily CTcaic and CTcaic/CT99 9 values for each disinfectant
measurement or sequence and the sum of all CTcaic/CT99 9 values
before or at the first customer.
The daily determination of whether disinfection achieves
adequate Giardia lamblia and virus inactivation.
Detectable
Disinfection
Residual -
In the
distribution
system
10th day of the
following month
that you served
water to the
public
Number of residual disinfectant or HPC measurements taken in
the month resulting in no more than 5 percent of the
measurements being undetectable1 in any 2 consecutive months.
Source Water
Monitoring
10th day of the
following month
that you served
water to the
public
Monitoring results for Cryptosporidium.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-5
-------
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs requires that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-6
-------
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008 and cover
or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April 1,
2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet the requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states' discretion.
Information about state operator certification programs can be accessed through EPA's website at
https://www.epa.gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
You were required to conduct initial source water monitoring and monitor for Cryptosporidium at least
monthly for 2 years. You were also required to begin a second round of source water monitoring 6 years
after the date your water system was required to determine the initial monitoring's mean Cryptosporidium
level.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial determination of
the mean Cryptosporidium concentration.
Upon completing source water monitoring you must calculate your water system's mean Cryptosporidium
concentration. Note that unfiltered systems are not required to determine the highest 12-month mean; the
mean Cryptosporidium concentration is always based on all samples taken during LT2ESWTR source
water monitoring.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-7
-------
The mean Cryptosporidium level is used to determine the level of Cryptosporidium inactivation that
unfiltered systems are required to provide at each treatment plant. If the mean Cryptosporidium level is:
• Less than or equal to 0.01 oocysts/L, the system must provide at least 2-log Cryptosporidium
inactivation at that treatment plant.
• Greater than 0.01 oocysts/L, the system must provide at least 3-log Cryptosporidium inactivation at
that treatment plant.
Microbial Toolbox
As an unfiltered system you will need to meet any additional treatment requirements using the inactivation
options from the Microbial Toolbox.
See Attachment 10 for more information regarding the Microbial Toolbox.
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Inactivation requirements for viruses, Giardia lamblia, and Cryptosporidium.
• Filtration Avoidance Criteria.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified personnel.
Your compliance dates depend on the size of the population served by your system, or the number of
persons served by the largest system in your CDS, whichever is greater.
Systems that were required to provide 3-log Cryptosporidium inactivation following completion of their
initial source water monitoring must be in compliance with the additional log inactivation requirements.
Systems that were required to provide 3-log Cryptosporidium inactivation after completing their second
round of source water monitoring must either be in compliance with the additional log inactivation
requirements or be in the process of installing additional treatment.
Schedule
Initial Round of
Source Water
Monitoring was
due no later than:
Calculation of mean
Cryptosporidium
concentration was
due no later than:
Add Additional
Treatment for Systems
Required to Provide 3-
log Cryptosporidium
Inactivation2:
Second Round of
Source Water
Monitoring was
due no later than:
1
September 2008
March 2009
April 1,2012
April 1,2017
2
March 2009
September 2009
October 1, 2012
October 1, 2017
3
March 2010
September 2010
October 1, 2013
October 1, 2018
2. States may allow up to an additional 2 years for complying with the treatment requirement for systems making
capital improvements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 7-8
-------
Attachment 8: I operate a Subpart H water system that: is
unfiltered and is on LT2ESWTR Schedule 49
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Giardict lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
Requirements differ for different types of filtration (Conventional Filtration and Direct Filtration, Slow
Sand Filtration and Diatomaceous Earth Filtration, or Alternative Filtration Technologies) or unfiltered
systems. Also the timelines with which systems must comply differ based on the population served by the
system or the population served by the largest system within a combined distribution system (CDS).
This attachment applies to systems that use surface water or GWUDI, avoid filtration, and:
1) They serve fewer than 10,000 persons and do not sell water; or
2) They sell water, and the largest system in their CDS serves fewer than 10,000 persons.
Requirements
Inactivation Requirements for Viruses, Giardia Lamblia, and Cryptosporidium
You must comply with the inactivation requirements established for regulated pathogens. The inactivation
requirements are as follows:
Microbial
MCLG
Inactivation Requirements
Viruses
99.99% (4-log)
Giardia lamblia
Zero
99.9% (3-log)
Cryptosporidium
Zero
99% (2-log) (through watershed control) and,
99% (2-log) removal of Cryptosporidium for systems reporting
less than or equal to 0.01 oocysts/L in initial source water
monitoring or,
99.9% (3-log) removal of Cryptosporidium for systems reporting
more than 0.01 oocysts/L in initial source water monitoring
9 See Section 2 of this document for more information about Schedules.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-1
-------
Compliance with the log removal/inactivation requirements for viruses and Giardia lamblia can be met
through a combination of filtration and disinfection. You must also comply with the maximum residual
disinfection level (MRDL) requirements specified in Disinfectants and Disinfection Byproducts Rules
(DBPRs). EPA has developed a companion document [Disinfectants and Disinfection Byproducts Rules
(Stage 1 and Stage 2) What Do They Mean to You?, EPA 815-R-20-005, June 2020] which addresses those
rules requirements. This document is available on EPA's website at https://www.epa.gov/dwreginfo/stage-
l-and-stage-2-disinfectants-and-disinfection-bvproducts-rules.
You must include in your watershed control programs steps to minimize the potential for contamination by
Cryptosporidium. Your watershed control program must also minimize the potential for contamination by
Giardia lamblia and viruses in source water. If you fail to meet Cryptosporidium site-specific
requirements, you must install filtration within 18 months.
Filtration Avoidance Criteria
In order to remain unfiltered you must meet certain source water quality and site specific conditions. If any
of the Filtration Avoidance Criteria are not meet you must install filtration within 18 months of the failure.
Source Water Quality Conditions
You must measure your source water turbidity. This sample must be taken prior to the first point of
disinfection. You must collect a representative grab sample of your source water at least every 4 hours, and
the turbidity cannot exceed 5 NTU. You must also monitor fecal coliform or total coliform concentrations
in representative samples of source water immediately prior to the first point of disinfection. The number of
samples you must take depends on your system size and the turbidity of your source water. If you serve:
• Less than or equal to 500 persons, you must take 1 sample per week.
• 501 to 3,300 persons, you must take 2 samples per week taken on separate days.
• 3,301 to 10,000 persons, you must take 3 samples per week taken on separate days.
• 10,001 to 25,000 persons, you must take 4 samples per week taken on separate days.
• More than 25,000 persons, you must take 5 samples per week taken on separate days.
You must also monitor on any day in which your turbidity sample exceeds 1 NTU.
Fecal coliform density must be less than or equal to 20/100 mL or your total coliform density must less
than or equal to 100/100 mL. You must meet one of these criteria in at least 90 percent of the
measurements from the previous 6 months.
Site Specific Conditions
You must calculate your system's total inactivation ratio daily and provide 3-log Giardia lamblia and 4-log
virus inactivation daily except any 1 day each month in 11 of 12 months (on an ongoing basis). You must
take daily measurements before or at the first customer at each residual disinfectant concentration sampling
point and must measure:
• Temperature.
• pH (if chlorine is used).
• Disinfection contact time (at peak hourly flow).
• Residual disinfectant concentration (at peak hourly flow).
You must comply with the MCL for total coliforms [40 CFR 141.63(a) and (b)] and the MCL fori?, coli
[40 CFR 141.63(c)] in at least 11 of the 12 previous months, and you must meet the requirements of the
Stage 1 DBPR and Stage 2 DBPR.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-2
-------
You must have:
• Adequate entry point residual disinfectant concentration.
• Detectable residual disinfectant concentration in the distribution system.
• Redundant disinfection components or automatic shut-off whenever the residual disinfectant
concentration is less than 0.2 mg/L.
• A watershed control program minimizing the potential for contamination by Cryptosporidium,
Giardia lamblia, and viruses in source water.
• An annual on-site inspection by state or an approved third party, with reported findings.
• Not been identified as a source of a waterborne disease outbreak.
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals at the entry point to the distribution system and in the
distribution system. The concentration for disinfectant residuals at the entry point cannot be less than 0.2
mg/L for more than 4 hours and must be monitored continuously. Your state may allow systems serving
3,300 or fewer persons to take grab samples from 1 to 4 times per day, depending on system size.
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
You must meet the combined Cryptosporidium, Giardia lamblia, and virus inactivation requirements
(specified in the Inactivation Requirements table at the beginning of this attachment) using a minimum of
two disinfectants. Each disinfectant must be able to achieve the total inactivation required for
Cryptosporidium, Giardia lamblia, or viruses. For example, a system may use UV to meet
Cryptosporidium and Giardia lamblia inactivation requirements and chlorine to meet virus inactivation
requirements. To meet the Cryptosporidium inactivation requirements, systems must use chlorine dioxide,
ozone, or UV.
Reporting and Recordkeeping
Disinfection requirements are more stringent for unfiltered systems than filtered systems. You will receive
a treatment technique violation if:
• You are using chlorine dioxide or ozone that fails to achieve the Cryptosporidium log inactivation
on more than 1 day in the calendar month.
• You are using UV light and fail to treat at least 95 percent of the water that is delivered to the
public during each calendar month within validated conditions.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-3
-------
Monitoring
Report by:
What to Report
Source
Water
Quality
Conditions
10th day of
the
following
month that
you served
water to the
public
The cumulative number of months for which results are reported.
The number of fecal and/or total coliform samples (if a system monitors
for both, only fecal coliforms must be reported), the dates of sample
collection, and the dates when the turbidity level exceeded 1 NTU.
The number of samples during the month that had equal to or less than
20/100 mL fecal coliforms and/or equal to or less than 100/100 mL total
coliforms, whichever are analyzed.
The cumulative number of fecal or total coliform samples, cumulative
number of samples that had equal to or less than 20/100 mL fecal
coliforms or equal to or less than 100/100 mL total coliforms, percentage
of samples that had equal to or less than 20/100 mL fecal coliforms or
equal to or less
than 100/100 mL total coliforms, during the previous 6 months the
system served water to the public.
The maximum turbidity level measured during the month, the date for
any measurement that exceeded 5 NTU, and the date the occurrence was
reported to the state.
The dates and number of times the turbidity exceeded 5 NTU in the
previous 12 months.
For the first 120 months of recordkeeping, the dates and total number of
events during which the turbidity exceeded 5 NTU, and after 10 years of
recordkeeping for turbidity measurements, the dates and total number of
events during which the turbidity exceeded 5 NTU in the previous 120
months the system served water to the public.
Site Specific
Conditions
By October
10 of each
year
Compliance with all watershed control program requirements.
Report on the on-site inspection, unless the state conducted the
inspection.
Within 24
hours
Any turbidity exceedances of 5 NTU or waterborne disease outbreaks.
ASAP but
no later than
the end of
the next
business
day
Any instance where the residual disinfectant level entering the
distribution systems was less than 0.2 mg/L.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-4
-------
Monitoring
Report by:
What to Report
Lowest daily value for each day, the date and duration when the residual
disinfectant was less than 0.2 mg/L, and when the state was notified of
events where residual disinfectant was less than 0.2 mg/L.
Minimum
Disinfection
Residual -
Entry to the
distribution
system
10th day of
the
following
month that
you served
water to the
public
The daily residual disinfectant concentration (in mg/L) and disinfectant
contact time (in minutes) used for calculating the CT value.
If chlorine is used, the daily measurement of pH of disinfected water
following each point of chlorine disinfection.
The daily measurement of water temperature in degrees C following each
point of disinfection.
The daily CTcaic and CTcaic/CT99 9 values for each disinfectant
measurement or sequence and the sum of all CTcaic/CT99 9 values before or
at the first customer.
The daily determination of whether disinfection achieves adequate
Giardia lamblia and virus inactivation.
Detectable
Disinfection
Residual -
In the
distribution
system
10th day of
the
following
month that
you served
water to the
public
Number of residual disinfectant or HPC measurements taken in the month
resulting in no more than 5 percent of the measurements as being
undetectable1 in any 2 consecutive months.
Source
Water
Monitoring
10th day of
the
following
month that
you served
water to the
public
Monitoring results for Cryptosporidium.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Disinfection Profiling and Benchmarking
You must evaluate your disinfection practices and work with the state to ensure there are no unintended
reductions in microbial protection if you plan on changing how you disinfect your water. Subpart H
systems that intend to make a significant change to their disinfection practice are required to develop a
disinfection profile, calculate a disinfection benchmark, and submit the profile and benchmark when
consulting with the state before making the disinfection change.
Significant changes to disinfection practice include:
• Changes to the point of disinfection.
• Changes to the disinfectant(s) used in the treatment plant.
• Changes to the disinfection process.
• Any other modification identified by the state as a significant change to disinfection practice.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-5
-------
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
this requirement (Disinfection Profiling and Benchmarking Technical Guidance Manual, EPA 815-R-20-
003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Sanitary Surveys
The SWTRs requires that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
A sanitary survey includes eight elements. The eight elements are:
• Source (protection, physical components, and condition).
• Treatment.
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, source water vulnerability assessments, monitoring and maintenance records, construction
details of system infrastructure components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-6
-------
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir that was built before February
16, 1999, must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet the requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that this type of determinations should be left to the states' discretion.
Information about state operator certification programs can be accessed through EPA's website at
https://www.epa.gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
LT2ESWTR Source Water Monitoring
You were subject to source water monitoring requirements. For more information on source water
monitoring requirements see EPA's Source Water Monitoring Guidance Manual for Public Water Systems
for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R-06-005, February 2006),
available at https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents.
If you did not have 5.5-logs of treatment for Cryptosporidium, which is equivalent to meeting the treatment
requirements of Bin 4, you were required to conduct initial source water monitoring and monitor for
Cryptosporidium at least twice per month for 12 months, or at least once per month for 24 months. You
were also required to begin a second round of source water monitoring 6 years after the date your water
system was required to determine the initial monitoring's mean Cryptosporidium level.
If you begin to use a new surface water or GWUDI source after you were is required to begin initial source
water monitoring you must sample the new source on a schedule approved by the state. This requirements
also applies to new Subpart H systems that commence operation after the system would have otherwise
been required to begin initial source water monitoring. The state may require you to monitor before
bringing the new plant or new source on-line or may require you to monitor within a specified time-frame
after the source is brought on-line or the system begins operation. Your monitoring must be in compliance
with the other requirements of the LT2ESWTR, e.g., the number and frequency of samples and analytical
requirements. You must conduct a second round of monitoring within 6 years of the initial determination of
the mean Cryptosporidium concentration.
Upon completing source water monitoring you must calculate your water system's mean Cryptosporidium
concentration. Note that unfiltered systems are not required to determine the highest 12-month mean; the
mean Cryptosporidium concentration is always based on all samples taken during LT2ESWTR source
water monitoring.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-7
-------
The mean Cryptosporidium level is used to determine the level of Cryptosporidium inactivation that
unfiltered systems are required to provide at each treatment plant. If the mean Cryptosporidium level is:
• Less than or equal to 0.01 oocysts/L, the system must provide at least 2-log Cryptosporidium
inactivation at that treatment plant.
• Greater than 0.01 oocysts/L, the system must provide at least 3-log Cryptosporidium inactivation at
that treatment plant.
Microbial Toolbox
As an unfiltered system you will need to meet any additional treatment requirements using the inactivation
options from the Microbial Toolbox.
See Attachment 10 for more information regarding the Microbial Toolbox.
Compliance
The requirements for the SWTRs are in effect and you must be in compliance with these requirements. This
includes the requirements for:
• Inactivation requirements for viruses, Giardia lamblia, and Cryptosporidium.
• Filtration Avoidance Criteria.
• Residual disinfectant monitoring.
• Disinfection profiling and benchmarking.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified personnel.
Systems that were required to provide 3-log Cryptosporidium inactivation after completing their initial
source water monitoring must be in compliance with the additional log inactivation requirements. You must
have begun your second round of source water monitoring for Cryptosporidium by April 1, 2019. If, after
you calculate your mean Cryptosporidium concentration your system is required to provide 3-log
Cryptosporidium inactivation, you have until October 1, 2023 (with a possible 2-year extension) to
complete any additional treatment or control processes.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 8-8
-------
Attachment 9: I operate a consecutive water system that:
purchases finished water from a Subpart H water system and does
not have a surface water or GWUDI source of my own
Background
The purpose of the Suite of Surface Water Treatment Rules (SWTRs) is to improve public health protection
through the control of microbial contaminants, including requirements for removal and/or inactivation of:
• Viruses.
• Legionella bacteria.
• Giardia lamblia.
• Cryptosporidium.
The SWTRs apply to all public water systems (PWSs) using surface water or ground water under the direct
influence of surface water (GWUDI), otherwise known as "Subpart H systems." Under these rules, all
Subpart H systems are required to disinfect and to filter (unless specific filtration avoidance criteria are
met). The SWTRs also establish treatment technique requirements for control of microbial contaminants.
This attachment applies to consecutive systems that purchase finished water from a Subpart H water
system and does not have a surface water or GWUDI source of their own.
Requirements
Residual Disinfectant Monitoring
You must monitor for disinfectant residuals in the distribution system. Distribution system monitoring must
take place at the same location and frequency as Revised Total Coliform Rule (RTCR) sampling. Residual
disinfectant concentrations must be detected in at least 95 percent of the samples each month for 2
consecutive months. You may measure HPC in lieu of disinfectant residuals. If HPC is less than 500
colonies/ml, the site has the equivalent of a "detectable residual." You should check with your state to
determine if the state has any additional disinfectant residual requirements.
Sanitary Surveys
The SWTRs require that the state conduct sanitary surveys for all Subpart H systems, regardless of the
population served, no less frequently than every 3 years for community water systems (CWSs) and every 5
years for non-community water systems (NCWSs).
A sanitary survey includes eight elements, however the source water element review is not applicable to
consecutive systems. The elements that are reviewed during a sanitary survey at consecutive systems are:
• Treatment (if applicable).
• Distribution system.
• Finished water storage.
• Pumps, pump facilities, and controls.
• Monitoring, reporting, and data verification.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 9-1
-------
• Water system management and operations.
• Operator compliance with state requirements.
These elements are discussed in EPA's guidance on how to conduct a sanitary survey of a Subpart H
system (How to Conduct a Sanitary Survey of Drinking Water Systems - A Learner's Guide, EPA 816-R-
17-001, August 2019). This document is available https://www.epa.gov/dwreginfo/sanitarv-survevs.
You must provide, at the state's request, any existing information that would allow the state to perform a
sanitary survey. Examples of existing information that may be necessary to perform the survey include past
survey reports, monitoring and maintenance records, construction details of system infrastructure
components, and operations and management-related records.
Finished Reservoirs/Water Storage Facilities
The use of uncovered finished water reservoirs can lead to significant water quality degradation and
increase health risks to consumers. Finished water quality degradation has been attributed to contamination
from both internal and external sources and includes increases in the following:
• Algal growth.
• Coliform bacteria growth.
• Heterotrophic plate count (HPC) bacteria growth.
• Turbidity.
• Particulates.
• Disinfection byproducts such as total trihalomethanes (TTHM).
• Metals.
• Taste and odor.
• Insect larvae.
• Giardia lamblia and Cryptosporidium.
• Nitrification of chloraminated waters.
Some of these water quality problems are exacerbated by the loss of chlorine residual and poor hydraulic
circulation that are characteristic of large open reservoirs. In order to address these concerns, Subpart H
systems are no longer allowed to begin construction of an uncovered finished water reservoir. In addition,
Subpart H systems that operate with an uncovered finished water reservoir must either:
• Cover the uncovered finished water storage facility; or
• Treat the discharge from the uncovered finished water storage facility to the distribution system to
achieve at least 4-log virus, 3-log Giardia lamblia, and 2-log Cryptosporidium inactivation and/or
removal using a protocol approved by the state.
You were required to notify the state of each uncovered finished water reservoir by April 1, 2008, and
cover or treat the discharge from the reservoir or be in compliance with a state-approved schedule by April
1, 2009.
Qualified Personnel
The SWTRs require that Subpart H systems be operated by qualified personnel who meet the requirements
specified by the state. EPA does not specify the amount of time qualified personnel are required to spend
on site at the plant. EPA believes that these types of determinations should be left to the states' discretion.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 9-2
-------
Information about state operator certification programs can be accessed through EPA's website at
https://www.epa.gov/dwcapacitv/find-epa-drinking-water-operator-certification-contact.
Reporting and Recordkeeping
Monitoring
Report by:
What to Report
Detectable Disinfection
Residual -
In the distribution system
10th day of the following
month that you served water
to the public
Number of residual disinfectant or HPC
measurements taken in the month
resulting in no more than 5 percent of the
measurements as being undetectable1 in
any 2 consecutive months.
1. Contact your state drinking water program to determine if they have established more stringent requirements.
Compliance
All of the SWTRs requirements for consecutive systems are in effect, and you must be in compliance with
these requirements. This includes the requirements for:
• Residual disinfectant monitoring.
• Sanitary surveys.
• Finished reservoirs/water storage facilities.
• Qualified operators.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 9-3
-------
Attachment 10: I operate a Subpart H water system that: must
implement a Microbial Toolbox Option under the LT2ESWTR
Microbial Toolbox
If your bin classification put you into bins 2, 3, or 4, you will need to:
• use one or more of the Microbial Toolbox options (40 CFR 141.715 - 141.720) to meet the
Cryptosporidium treatment requirements; and
• comply with the applicable Microbial Toolbox reporting [40 CFR 141.721(f)] and recordkeeping
[40 CFR 141.722(c)] requirements.
Five types of toolbox options are available to systems:
• Source protection and management options (40 CFR 141.716).
• Pre-filtration options (40 CFR 141.717).
• Treatment performance options (40 CFR 141.718).
• Additional filtration options (40 CFR 141.719).
• Inactivation options (40 CFR 141.720).
Unfiltered systems may only use the inactivation options from the Microbial Toolbox to meet
Cryptosporidium treatment requirements.
EPA's Long Term 2 Enhanced Surface Water Treatment Rule: Toolbox Guidance Manual (EPA 815-R-09-
016, April 2010) provides technical information on applying the LT2ESWTR "Toolbox Options" of
Cryptosporidium treatment and management strategies. The document is available on EPA's website at:
https://www.epa.gOv/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-documents#lt2toolkit.
Source protection and management options
Microbial Toolbox - Watershed control program
Toolbox Option
Cryptosporidium Treatment Credit
1. Source Protection and Management Options
Watershed control program
0.5-log credit
The watershed control plan must:
• Identify an "area of influence" outside of which ('rypiosporidiiim or fecal contamination is not
likely to affect the treatment plant intake. This defined "area of influence" will be evaluated in
future watershed surveys.
• Identify potential and actual source(s) of Cryptosporidium contamination.
• Include assessment of the impact of contamination source on source water quality.
• Assess the relative impact of these sources on the system's source water quality.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-1
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• Analyze the effectiveness and feasibility of control measures that could reduce Cryptosporidium
contamination.
• State goals and specific actions the system will take to reduce source water Cryptosporidium levels,
explain how actions are expected to contribute to specific goals, identify watershed partners and
their roles, identify resource requirements and commitments, and include a schedule for plan
implementation with deadlines for specific actions identified in the plan.
If a system submits their plan and does not hear back from the state, they may assume that the plan was
approved, and a 0.5-log credit was awarded unless the state subsequently rescinds approval. In addition to
Subpart H systems establishing a new watershed control plan, systems with existing watershed control
plans may also apply for this credit.
The state may withdraw the 0.5-log credit if it determines that the system is not carrying out its watershed
control plan. The watershed control plan and the sanitary survey results must be made available to the
public.
Microbial Toolbox Reporting and Recordkeeping - Watershed control program
Systems receiving Cryptosporidium treatment credit for watershed control programs must report their
intent to the state 2 years before the applicable treatment compliance date and must submit a watershed
control plan 1 year before the applicable treatment compliance date. Systems must submit a program status
report every 12 months and must undergo a watershed sanitary survey every 3 years (CWSs) or 5 years
(NCWSs)."
Microbial Toolbox - Alternative source/intake management
Toolbox Option
Cryptosporidium Treatment Credit
1. Source Protection and Management Options
Alternative source/intake management
No prescribed credit
If a system determines its bin classification using alternative source water monitoring results, the system
must relocate the intake or permanently adopt the alternative withdrawal procedure no later than the
applicable treatment compliance date.
A system may conduct source water monitoring at an alternative intake location (in the same source or in a
different source) or using a different procedure for timing or level of withdrawal from the source. If the
state approves, the system may determine its bin classification based on the alternative source's monitoring
results. A system must concurrently conduct source water monitoring at the original source. Systems must
report alternative source water monitoring results to the state, along with information describing the
operating conditions under which the samples were collected. If a system determines its bin classification
using alternative source water monitoring results that reflect a different intake location or a different
procedure for managing the timing or level of withdrawal from the source, the system must relocate the
intake or permanently adopt the alternative withdrawal procedure no later than the applicable treatment
compliance date.
Microbial Toolbox Reporting and Recordkeeping-Alternative source/intake management
Systems must verify the relocation of their intake or the adoption of alternative withdrawal procedures by
the applicable treatment compliance date.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-2
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Pre-Filtration options
Microbial Toolbox - Presedimentation basin with coagulation
Toolbox Option
Cryptosporidium Treatment Credit
2. Pre-Filtration Options
Presedimentation basin with coagulation
0.5-log credit
Systems may receive a 0.5-log Cryptosporidium treatment credit for a presedimentation basin that meets
the following requirements:
• The presedimentation basin must be in continuous operation.
• The presedimentation basin must treat the entire plant flow taken from a Subpart H source.
• The system must continuously add coagulant to the presedimentation basin.
• The presedimentation basin must demonstrate at least a 0.5-log reduction of influent turbidity.
o Using daily turbidity measurements and calculated as follows: logio(monthly mean of daily
influent turbidity) - logio(monthly mean of daily effluent turbidity), or
o Complying with state-approved performance criteria that demonstrate at least a 0.5-log
mean removal of micron-sized particulate material.
Microbial Toolbox Reporting and Recordkeeping - Presedimentation basin with coagulation
Systems receiving Cryptosporidium treatment credit for a presedimentation basin must report monthly that
the basin was in continuous operation, the basin treated the entire plant flow taken from a Subpart H
source, coagulant was continuously added, and the basin achieved at least a 0.5-log reduction of turbidity or
complied with alternative state-approved performance criteria. Monthly results must be submitted within
the first 10 days of the following month.
Microbial Toolbox - Two-stage lime softening
Toolbox Option
Cryptosporidium Treatment Credit
2. Pre-Filtration Options
Two-stage lime softening
0.5-log credit
Systems may receive a 0.5-log credit for two-stage lime softening if:
• Chemical addition and hardness precipitation must occur in two separate and sequential softening
stages prior to filtration, and
• Both softening stages treat the entire plant flow taken from a Subpart H source.
Microbial Toolbox Reporting and Recordkeeping-Two-stage lime softening
Systems receiving a 0.5-log credit for two-stage lime softening must verify that chemical addition and
hardness precipitation occurred in two separate stages and that both stages treated the entire plant flow
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-3
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taken from a Subpart H source. Systems must report this information to the state monthly, beginning on the
applicable treatment compliance date. Monthly results must be submitted within the first 10 days of the
following month.
Microbial Toolbox - Bank filtration
Toolbox Option
Cryptosporidium Treatment Credit
2. Pre Filtration Options
Bank filtration
0.5-log credit for 25-foot setback
1.0-log credit for 50-foot setback
Systems using bank filtration when they begin the source water monitoring process are not eligible for this
credit. Systems may receive a 0.5-log credit for a bank filtration process with at least a 25-foot ground
water flow path or a 1.0-log credit for a bank filtration process with at least a 50-foot ground water flow
path, if:
• Wells are located in granular aquifers;
• Wells are horizontal or vertical;
• Vertical well flowpaths are measured from the edge of the surface water body under high flow
conditions;
• Horizontal well flowpaths are the measured distance from the bed of the river under normal flow
conditions to the closest well lateral screen;
• Systems monitor turbidity at each wellhead at least once every four hours while the process is in
operation.
The state may approve Cryptosporidium treatment credit for bank filtration based on a demonstration of
performance study that meets certain requirements.
Springs and infiltration galleries, which are not eligible for treatment credit under the bank filtration option,
are eligible for demonstration of performance credit.
Microbial Toolbox Reporting and Recordkeeping - Bank Filtration
Systems receiving Cryptosporidium treatment credit for bank filtration must verify their aquifer type and
their setback distance by the applicable treatment compliance date. Systems must report any monthly
average turbidity level, based on daily maximum values, exceeding 1 NTU and provide a report on an
assessment of the cause within 30 days following the month in which the monitoring was conducted.
Treatment performance options
Microbial Toolbox - Combined filter performance
Toolbox Option
Cryptosporidium Treatment Credit
3. Treatment Performance Options
Combined filter performance
0.5-log credit
Systems using conventional or direct filtration treatment receive this credit during any month when the
system's CFE turbidity is less than or equal to 0.15 NTU in at least 95 percent of measurements.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-4
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Microbial Toolbox Reporting and Recordkeeping - Combined filter performance
Systems must submit monthly verification of CFE turbidity levels less than or equal to 0.15 NTU in at least
95 percent of the 4 hour CFE measurements taken each month within the first 10 days of the following
month.
Microbial Toolbox - Individual filter performance
Toolbox Option
Cryptosporidium Treatment Credit
3. Treatment Performance Options
Individual filter performance
0.5-log credit
Systems using conventional or direct filtration may receive this credit, which can be in addition to the 0.5-
log combined filter performance credit.
• Filtered water turbidity for each individual filter must be less than or equal to 0.15 NTU in at least
95 percent of the measurements recorded each month.
• No individual filter may have a measured turbidity greater than 0.3 NTU in two consecutive
measurements taken 15 minutes apart.
Microbial Toolbox Reporting and Recordkeeping - Individual filter performance
Systems must submit monthly verification of IFE turbidity levels less than or equal to 0.15 NTU in at least
95 percent of samples each month in each filter and No individual filter greater than 0.3 NTU in two
consecutive readings 15 minutes apart within the first 10 days of the following month.
Microbial Toolbox - Demonstration of performance
Toolbox Option
Cryptosporidium Treatment Credit
3. Treatment Performance Options
Demonstration of performance
Determined by state
Systems may receive Cryptosporidium treatment credit for drinking water treatment processes based on a
demonstration of performance study. The study must follow a state-approved protocol and must
demonstrate the level of Cryptosporidium reduction the treatment process will achieve under the full range
of expected operating conditions. State approval must be in writing and may include monitoring and
treatment performance criteria that the system must demonstrate and report on an ongoing basis to remain
eligible for the treatment credit.
Microbial Toolbox Reporting and Recordkeeping - Demonstration of performance
Systems must submit initial testing results by the applicable treatment compliance date and must verify and
report that operating conditions are within state-approved limits monthly. Monthly results must be
submitted within the first 10 days of the following month.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-5
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Additional filtration options
Microbial Toolbox - Bag or cartridge filters (individual or in series)
Toolbox Option
Cryptosporidium Treatment Credit
4. Additional Filtration Options
Bag or cartridge filters (individual)
Up to 2.0-log
Bag or cartridge filters (in series)
Up to 2.5-log
Systems must treat the entire plant flow taken from a Subpart H source and must conduct challenge testing
to be eligible for this credit. The exact log credit is determined by removal efficiency during challenge
testing, as specified in 40 CFR 141.719(a).
Microbial Toolbox Reporting and Recordkeeping - Bag or cartridge filters (individual or in series)
Systems receiving Cryptosporidium treatment credit for bag or cartridge filters must verify that their
process meets the definition of bag or cartridge filtration and must report their removal efficiency
(determined during challenge testing) to the state by the applicable treatment compliance date. Systems
must also report monthly to the state that they treat the entire plant flow taken from a Subpart H source
within the first 10 days of the following month.
Microbial Toolbox - Membrane filtration
Toolbox Option
Cryptosporidium Treatment Credit
4. Additional Filtration Options
Membrane filtration
Equivalent to removal efficiency
The level of Cryptosporidium treatment credit a system receives is equal to the lower value of the removal
efficiency determined during challenge testing or the removal efficiency determined during direct integrity
testing, as specified in 40 CFR 141.719(b).
The membrane used by the system must undergo challenge testing to evaluate removal efficiency. Systems
must conduct direct integrity testing in a manner that demonstrates a removal efficiency equal to or greater
than the removal credit awarded to the membrane filtration process. Systems that do not implement
continuous direct integrity testing of membrane unit must conduct continuous indirect integrity monitoring
on each membrane unit. EPA's Membrane Filtration Guidance Manual (EPA 815-R-06-009, November
2005) provides additional information on membrane filtration system design and operation; membrane
filtration testing requirements; and startup and implementation considerations. The document is available
on EPA's website at: https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents#membrane.
Microbial Toolbox Reporting and Recordkeeping - Membrane filtration
Systems receiving Cryptosporidium treatment credit for membrane filtration must conduct challenge and
integrity testing and report the results by the applicable treatment compliance date. Systems must submit a
monthly report to the state on any direct integrity tests above the control limit monthly and, if applicable,
any continuous indirect integrity monitoring results triggering direct integrity testing and the corrective
action taken. Monthly results must be submitted within the first 10 days of the following month.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-6
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Microbial Toolbox - Second stage filtration
Toolbox Option
Cryptosporidium Treatment Credit
4. Additional Filtration Options
Second stage filtration
0.5-log
The second stage must consist of sand, dual media, granular activated carbon (GAC), or other fine grain
media approved by the state. The first stage of filtration must be preceded by a coagulation step, and both
filtration stages must treat the entire plant flow taken from a Subpart H source. A cap, such as GAC, on a
single stage of filtration is not eligible for this credit. The state must approve the treatment credit based on
an assessment of the design characteristics of the filtration process.
Microbial Toolbox Reporting and Recordkeeping - Second stage filtration
Systems receiving Cryptosporidium treatment credit for second stage filtration must report monthly that
second stage filtration was preceded by coagulation and that both stages of filtration treat the entire plant
flow taken from a Subpart H source. Monthly results must be submitted within the first 10 days of the
following month.
Microbial Toolbox - Slow sand filtration (as secondary filter)
Toolbox Option
Cryptosporidium Treatment Credit
4. Additional Filtration Options
Slow sand filters
2.5-log as secondary filtration
3.0-log as primary filtration
When used as a secondary process, both steps of filtration must treat the entire plant flow taken from a
Subpart H source and no disinfectant residual may be present in the influent water. The state must approve
the treatment credit based on an assessment of the design characteristics of the filtration process.
Note: Water systems that use slow sand filters as their primary filtration process received 3-log
Cryptosporidium credit under 40 CFR 141.711(a). If a system runs two slow sand filters in series it could
receive a total of 5.5 log Cryptosporidium removal credit.
Microbial Toolbox Reporting and Recordkeeping-Slow sand filters
Systems receiving Cryptosporidium treatment credit for secondary slow sand filters must report monthly
that the slow sand filter was preceded by a separate stage of filtration and that both steps treated 100
percent of plant flow taken from a Subpart H sources. Monthly results must be submitted within the first 10
days of the following month.
IN ACTIVATION OPTIONS
Unfiltered systems will need to meet any additional treatment requirements using the inactivation options
from the Microbial Toolbox.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-7
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Microbial Toolbox - Chlorine dioxide
Toolbox Option
Cryptosporidium Treatment Credit
5. Inactivation Options
Chlorine dioxide
Based on CT
Systems may receive Cryptosporidium treatment credit for chlorine dioxide inactivation. Cryptosporidium
treatment credit is determined by calculating the CT value (product of contact time in minutes and
concentration in mg/L) for the disinfection segment. Systems with several disinfection segments may
calculate CT for each segment and sum these values to determine the total CT for the treatment plant.
Systems must calculate CT at least once a day during peak hourly flow.
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
the disinfection profiling and benchmarking requirement that provides information on calculating the CT
value for systems using chlorine dioxide. (Disinfection Profiling and Benchmarking Technical Guidance
Manual, EPA 815-R-20-003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Microbial Toolbox Reporting and Recordkeeping - Chlorine dioxide
Systems receiving Cryptosporidium treatment credit for inactivation with chlorine dioxide must report a
monthly summary of daily CT values. Monthly results must be submitted within the first 10 days of the
following month.
Microbial Toolbox - Ozone
Toolbox Option
Cryptosporidium Treatment Credit
5. Inactivation Options
Ozone
Based on CT
Systems may receive Cryptosporidium treatment credit based on calculating the CT value (product of
contact time in minutes and concentration in mg/L) for the disinfection segment. Systems with several
disinfection segments may calculate CT for each segment and sum these values to determine the total CT
for the treatment plant. Systems must calculate CT at least once a day during peak hourly flow.
EPA has developed a guidance manual that provides guidance to Subpart H systems that must comply with
the disinfection profiling and benchmarking requirement that provides information on calculating the CT
value for systems using ozone. (Disinfection Profiling and Benchmarking Technical Guidance Manual,
EPA 815-R-20-003, June 2020). This document is available on EPA's website at
https://www.epa.gov/dwreginfo/guidance-manuals-surface-water-treatment-rules.
Microbial Toolbox Reporting and Recordkeeping - Ozone
Systems receiving Cryptosporidium treatment credit for inactivation with ozone must report a monthly
summary of daily CT values. Monthly results must be submitted within the first 10 days of the following
month.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-8
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Microbial Toolbox - Ultraviolet (UV) Light
Toolbox Option
Cryptosporidium Treatment Credit
5. Inactivation Options
UV
Based on UV dose
Systems may receive Cryptosporidium, Giardia lamblia, and virus treatment credit for UV light reactors by
achieving UV dose values provided in 40 CFR 141.720(d) and meeting the following requirements:
• Systems must validate and monitor UV reactors to determine the operating conditions under which
the reactor delivers the UV does required to achieve treatment credit.
• These operating conditions must include flow rate, UV intensity as measured by a UV sensor, and
UV lamp status.
• UV reactors must have undergone validation testing that includes full scale testing of the reactor
and inactivation of a test microorganism whose dose response characteristics have been quantified
with a low pressure mercury vapor lamp.
• Systems must also monitor their UV reactors to determine if the reactors are operating within
validated conditions.
• To receive treatment credit, systems must treat at least 95 percent of the water delivered to the
public during each month by UV reactors operating within validated conditions for the required
UV dose.
EPA has developed the Ultraviolet Disinfection Guidance Manual For The Final Long Term 2 Enhanced
Surface Water Treatment Ride (EPA 815-R-06-007, November 2006). This document provides background
information and guidance on UV light, microbial response to UV light, and UV reactors and is available on
EPA's website at: https://www.epa.gov/dwreginfo/long-term-2-enhanced-surface-water-treatment-rule-
documents#ultraviolet.
Microbial Toolbox Reporting and Recordkeeping - UV
Systems receiving Cryptosporidium treatment credit for UV inactivation must submit validation test results
by the applicable treatment compliance date and must submit a monthly report summarizing the percentage
of water entering the distribution system that was not treated by UV reactors operating within validated
conditions for the required dose. Monthly results must be submitted within the first 10 days of the
following month.
Surface Water Treatment Rules
What Do They Mean to You?
Attachment 10-9
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