United States
Environmental Protection
Agency
Office of Water
(4606)
EPA816-R-01-015
June 2001
The Interim Enhanced Surface
Water Treatment Rule
What Does it Mean to You?

-------

-------
TABLE OF CONTENTS
Definitions and Abbreviations  	•	3
1. Introduction	5
       Purpose of the Guide	5
       Background	5
       Development of the Rule	6
       Benefits of the Rule 	7
2. Applicability and Compliance Dates	7
3. Summary of Requirements  	9
       Disinfection profiling and benchmarking	9
       Cryptosporidium  	10
       Strengthened turbidity requirements	10
       Individual filter monitoring requirements	10
       Uncovered finished water storage facilities	10
       Public water system recordkeeping and reporting requirements	10
       Sanitary surveys  	11
       Unfiltered Systems	11
4. Additional Information	11
5. Detailed regulatory requirements	13
       Combined filter effluent turbidity monitoring	14
       Individual filter turbidity monitoring	20
       Disinfection profiling and benchmarking	 24
                                             Pagel

-------
This page is left intentionally blank.
             Page 2

-------
Definitions and Abbreviations
Definitions

Comprehensive performance evaluation (CPE) — is a 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.

Disinfection profile — is a summary of daily Giardia lamblia inactivation through the treatment plant.

Filter profile — is a 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.

Uncovered finished water storage facility — is a tank, reservoir, or other facility used to store water
that will undergo no further treatment except residual disinfection and is open to the atmosphere.
Abbreviations Used in  This Document
CCP:
CDC:
CPE:
CTA:
CWS:
DBF:
DBPP:
DBPR:
EC:
EPA:
ES:
ESWTR:
FACA:
FR:
GAC10:

GWR:
GWUDI:
HAAS:

hrs:
ICR:
Composite Correction Program
Centers for Disease Control
Comprehensive Performance Evaluation
Comprehensive Technical Assistance
Community Water System
Disinfection Byproducts
Disinfection Byproducts Precursors
Disinfectants/Disinfection Byproducts Rule
Enhanced Coagulation
United States Environmental Protection Agency
Enhanced Softening
Enhanced Surface Water Treatment Rule
Federal Advisory Committee Act
Federal Register
Granular activated carbon with ten minute empty bed contact time and 180 day
reactivation frequency
Ground Water Rule
Ground Water Under the Direct Influence of Surface Water
Haloacetic acids (Monochloroacetic, Dichloroacetic, Trichloroacetic,
Monobromoacetic and Dibromoacetic Acids)
Hours
Information Collection Rule
                                           PageS

-------
ffiSWTR:
Log Inactivation:
Log:
LT1ESWTR:
LT2ESWTR:
LTESWTR:
MCL:
MCLG:
M-DBP:
MR:
MRDL:
MRDLG:
NCWS:
NSCEP:
NTIS:
NTNCWS:
NTU:
PWS:
RegNeg.:
SDWAor'TheAct":
SDWIS:
Subpart H:

SUVA:
SWTR:
TNCWS:
TOG:
TTHM:
x log removal:
Interim Enhanced Surface Water Treatment Rule
Logarithm of (N,/NT)
Logarithm (common, base 10)
Long Term 1 Enhanced Surface Water Treatment Rule
Long Term 2 Enhanced Surface Water Treatment Rule
Long Term Enhanced Surface Water Treatment Rule
Maximum Contaminant Level
Maximum Contaminant Level Goal
Microbial and Disinfectants/Disinfection Byproducts
Monitoring/Reporting
Maximum Residual Disinfectant Level
Maximum Residual Disinfectant Level Goal
Non-Community Water System
National Service for Environmental Publications
National Technical Information Service
Non-Transient Non-Community Water System
Nephelometric Turbidity Unit
Public Water System
Regulatory Negotiation
Safe Drinking Water Act
Safe Drinking Water Information System
PWS using surface water or ground water under the direct influence of surface
water
Specific Ultraviolet Absorption
Surface Water Treatment Rule
Transient Non-Community Water System
Total Organic Carbon
Total Trihalomethanes
Reduction to 1 /10* of original concentration

                                            Page 4

-------
 1. Introduction
Purpose of the Guide

The purpose of this guide is to detail the regulatory requirements of the Interim Enhanced Surface Water
Treatment Rule (IESWTR). The IESWTR, published in the Federal Register on December 16, 1998 (63
FR 69478; www.epa.gov/OGWDW/mdbp/ieswtrfr.htmk 66 FR 3770;
www.epa.gov/safewater/mdbp/iesfr.html: Appendix H—rule language only), is the first part of a series of
rules, the "Microbial-Disinfectants/Disinfection Byproducts Cluster" (M-DBP Cluster), to be published
over the next several years that are intended to control microbial pathogens while minimizing the public
health risks of disinfectants and disinfection byproducts (DBFs). The IESWTR is designed to address the
health risks from microbial contaminants without significantly increasing the potential risks from
chemical contaminants. This rule was published concurrently with the Stage 1 Disinfectants/Disinfection
Byproducts Rule (Stage 1 DBPR), which addresses control of disinfectants and their byproducts.
Background

The 1974 Safe Drinking Water Act (SDWA) called for EPA to regulate drinking water by creating the
national interim primary drinking water regulations (NIPDWR).  In 1979, the first interim standard
addressing DBFs was set for total trihalomethanes (TTHMs), a group of four volatile organic chemicals
which form when disinfectants react with natural organic matter in the water.

Although SDWA was amended slightly in 1977, 1979, and 1980, the most significant changes to the
1974 law occurred when SDWA was reauthorized in 1986.  Disease-causing microbial contamination
had not been sufficiently controlled under the original Act. To safeguard public health, the  1986
Amendments required EPA to set health goals, or maximum contaminant level goals (MCLGs) and
maximum contaminant levels (MCLs) for 83 named contaminants.  EPA was also required  to establish
regulations within certain time frames, require disinfection of all public water supplies, specify filtration
requirements for nearly all water systems that draw their water from surface sources, and develop
additional programs to protect ground water supplies.

In 1989, EPA issued two important National Primary Drinking Water Regulations (NPDWR): The Total
Coliform Rule (TCR) and the Surface Water Treatment Rule (SWTR).  The TCR and SWTR provide the
foundation for the M-DBP Cluster and are summarized below.

The TCR covers all public water systems.  Since coliforms are easily detected in water, they are used to
indicate a water system's vulnerability to pathogens in the water. In the TCR, EPA set a MCLG of zero
for total coliforms. EPA also set a MCL for total coliforms.  If more than 5.0 percent of the samples
contain coliforms within a month, water system operators must report this violation to the state and the
public. In addition, sanitary surveys are required every five or ten years (depending on the  quality of the
source water) for every system that collects fewer than five samples per month (typically systems that
serve less than 4,100 people).

EPA issued the SWTR in response to Congress' mandate requiring disinfection, and where necessary,
filtration of systems that  draw their water from surface sources before distribution. The SWTR applies to
all systems that use surface water or ground water under the direct influence of surface water (GWUDI).
The rule sets MCLGs for Legionella, Giardia lamblia, and viruses at zero since any exposure to these
contaminants presents some level of health risk.
                                              PageS

-------
Specifically, the rule requires that a surface water system have sufficient treatment to reduce the source
water concentration of Giardia lamblia and viruses by at least 99.9 percent (3 log) and 99.99 percent (4
log), respectively. A detectable disinfection residual must be maintained throughout the entire
distribution system. For systems that filter, the adequacy of the filtration process is determined by
measuring the turbidity of the treated water since high levels of turbidity often indicate that the filtration
process is not working properly. The goal of the SWTR is to reduce risk to less than one infection per
year per 10,000 people. However, the SWTR does not account for systems with high pathogen
concentrations that, when treated at the levels required under the rule, still may not meet this health goal,
and the rule does not specifically control for the protozoan Cryptosporidium.

In 1990, EPA's Science Advisory Board, an independent panel of experts established by Congress, cited
drinking water contamination as one of the most important environmental risks and indicated that
disease-causing microbial contaminants (i.e., bacteria, protozoa, and viruses) are probably the greatest
remaining health-risk management challenge for drinking water suppliers. Data from the Centers for
Disease Control (CDC)  confirm this concern and indicate that between 1980 and 1994, 379 waterborne
disease outbreaks were reported, with over 500,000 cases of disease. During this period, a number of
agents were implicated as the cause, including protozoa, viruses, bacteria, and several chemicals. Most of
the cases (but not the outbreaks) were associated with surface water, including a single outbreak of
cryptosporidiosis in Milwaukee (over 400,000 cases).

In response to these findings, the SDWA was further amended in 1996 to improve public health
protection by incorporating new data on the adverse health effects of contaminants, the occurrence of
contaminants in public water systems, and the estimated reduction in health risks that would result from
further regulation.  The Act also increased scientific research requirements and emphasized cost-benefit
analyses in the regulatory decision process.

Based on prevailing scientific data, the M-DBP Cluster is intended to control microbial pathogens while
minimizing the public health risk from disinfectants and DBFs. Since multiple threats require multiple
barriers, the IESWTR and Stage 1 DBPR expand on the foundation of the TCR, SWTR, and TTHM
standards to target health risk outliers unaddressed by prior regulations. By targeting these gaps, multiple
threats can be minimized.

The IESWTR builds on the SWTR by adding protection from Cryptosporidium through strengthened
combined filter effluent turbidity performance standards and individual filter turbidity provisions for
filtered systems that serve greater than 10,000 people. For unfiltered systems, Cryptosporidium must be
included in the watershed control requirements.  In addition, the IESWTR builds on the TCR by
requiring sanitary surveys for all public water systems using surface water and ground water under the
direct influence of surface water. The IESWTR also requires covers for all new finished water storage
facilities and includes disinfection benchmark provisions to ensure continued levels of microbial
protection while taking the necessary steps to comply with the DBF standards. Collectively, the SWTR
and IESWTR place stringent treatment requirements on systems using surface water as a source.

By building on the foundation set forth by the original SDWA, the quality of drinking water has
improved and public health protection has increased. The IESWTR and Stage 1 DBF Rules are part of a
series of rules designed to expand on the foundation of prior rulemaking efforts. By encompassing
previously unaddressed health risks from microbials and disinfection byproducts, the M-DBP Cluster
continues to maximize drinking water quality and public health protection.
                                                Page 6

-------
Development of the Rule

The new rules are a product of 6 years of collaboration among the water supply industry, environmental
and public health groups, and local, state, and federal governments. EPA first launched a rule-making
process in 1992 and convened a Regulatory Negotiation (RegNeg) Advisory Committee under the
Federal Advisory Committees Act (FACA), representing a range of stakeholders affected by possible
regulation. The 1996 SDWA Amendments required EPA to develop rules to balance the risks between
microbial pathogens and disinfection byproducts.

In 1997, a similar FACA process was implemented with the Microbial-Disinfectants/Disinfection
Byproducts (M-DBP) Advisory Committee. The M-DBP Committee convened to collect, share, and
analyze new information available since 1994, review previous assumptions made during the RegNeg
process, as well as build consensus on the regulatory implications of this new information. Negotiations
resulted in the following three proposals:

        D       A staged approach to regulation of DBFs (referred to as the Stage 1 and Stage 2 DBPRs)
               incorporating Maximum Contaminant Levels (MCLs), Maximum Residual Disinfectant
               Levels (MRDLs), and treatment technique requirements;

        D       A companion Interim Enhanced Surface Water Treatment Rule (DESWTR) designed to
               improve control of microbial pathogens and prevent inadvertent reductions in microbial
               safety as a result of DBF control  efforts; and,

        D       An Information Collection Rule (ICR) to collect information necessary to reduce many
               key uncertainties prior to subsequent negotiations for the Stage 2 DBPR

Benefits of the Rule

The IESWTR will improve public health by increasing the level of protection from exposure to
Cryptosporidium and other pathogens in drinking water supplies through improvements in filtration at
water systems. According to the risk assessment performed for the Regulatory Impact Analysis, the
IESWTR decreases the likelihood of endemic illness (constant, low-level presence of a disease or
infection) from Cryptosporidium by 110,000 to 463,000 cases annually. Based on these values, the
estimated annual benefits of reducing the illness range from $0.263 billion to $ 1.240 billion per year.
This calculation is based on a valuation of $2,000 per incidence of cryptosporidiosis prevented. The
IESWTR will also reduce the risk of more severe health impacts on sensitive populations, including the
risk of mortality. Additionally, the IESWTR will reduce the likelihood of outbreaks of cryptosporidiosis
and its associated costs by providing a larger margin of safety against such outbreaks hi some systems.
2.  Applicability  and Compliance Dates
The IESWTR applies to public water systems (PWSs) that use surface water or ground water under the
direct influence of surface water (GWUDJ) as a source (also known as subpart H systems) and serve
10,000 or more people. Additionally, it establishes a schedule by which states are required to conduct
sanitary surveys for all subpart H systems.

Subpart H systems serving at least 10,000 people must comply with the turbidity and monitoring
requirements, the primary requirements of the IESWTR, no later than January 1, 2002. However, PWSs
with elevated levels of DBFs (total trihalomethanes—TTHM; and five haloacetic acids—HAAS) are
                                              Page?

-------
required to develop an evaluation of their existing disinfection practices—a disinfection profile—no later
than April 2001.

The timetable for the IESWTR is presented in Table 1. The compliance dates for the associated Stage 1
Disinfectants/Disinfection Byproducts Rule (Stage 1 DBPR) are January 2002 and January 2004. Subpart
H systems that serve 10,000 or more people will have to comply with the provisions of the Stage 1 DBPR
by January 2002. Subpart H systems that serve fewer than 10,000 people and all ground water systems
will have to comply with the provisions of the rule by January 2004.  The rules to provide additional
microbial protection for small subpart H systems (Long Term 1 ESWTR) and ground water systems
(Ground Water Rule) are scheduled to be finalized in Spring/Summer 2001, with compliance required by
Spring/Summer 2004.

                    Table 1: Timetable for the IESWTR Requirements
Date
December 16, 1998
February 16, 1999
February 16, 1999
March 16, 1999
April 16, 1999
December 31, 1999
December 3 1,1999
December 3 1,1999
March 31, 2000
March 31, 2000
April 1,2000
April 1,2000
March 31, 2001
IESWTR Requirement
Rule is published in Federal Register [63 FR 241 69478].
60-day legal challenge period ends.
Construction of uncovered finished water storage facilities is prohibited [40 CFR
141.170(c)].
After this date, TTHM and HAAS monitoring must begin for systems that do not have
ICR or occurrence data and wish to determine if they must develop a disinfection profile
[40 CFR 141.172(a)(2)(iii)].
Systems that have 4 consecutive quarters of HAA5 occurrence data that meet the TTHM
monitoring requirements must submit those data to the state to determine if they must
develop a disinfection profile [40 CFR 141.172(a)(5)(ii)].
TTHM and HAAS data are due for those systems that collected data under the ICR to
determine if they must develop a disinfection profile [40 CFR 141.172(a)(5)(i)].
Systems that elect to profile without conducting 4 quarters of TTHM and HAAS
monitoring must notify the state of their election [40 CFR 141.172(a)(5)(iv)].
Systems that wish to request state approval of "a more representative annual data set"
than the ICR data set to determine if they must develop a disinfection profile must do so
in writing [40 CFR 141.172(a)(5)(v)].
TTHM and HAAS monitoring must be complete for systems determining if they must
develop a disinfection profile [40 CFR 141.172(a)(2)(iii)(A)].
If system is using 3 years of existing operational data to develop the disinfection profile,
the profile generated from these data and a request for state approval must be submitted
[40CFR141.172(b)(3Xi)].
Systems determining if they must develop a disinfection profile must submit their
TTHM andHAA.5 data to the state [40 CFR 141.172(a)(5)(iii)].
Systems must begin developing a disinfection profile if either their annual average
TTHM D 0.064 mg/L or their annual average HAAS D 0.048 mg/L [40 CFR
141.172(b)(2)].
Disinfection profile is complete [40 CFR 141.172(b)(2)].
                                             PageS

-------
Date
March 31, 2001
December 31, 2001
December 3 1,2001
December 31, 2001
January 1,2002
December 2004
December 2006
DESWTR Requirement
After this date, systems that were required to develop a disinfection profile that wish to
make a significant change to their disinfection practice must first calculate a disinfection
benchmark and consult with the state [40 CFR 141.172(c)].
Systems that are not required to filter must comply with the requirements for TTHM in
§141.12 and §141.30 until this date. After this date, systems must comply with the
requirements in Subpart L for TTHM, HAAS, bromate, chlorite, chlorine, chloramines,
and chlorine dioxide [40 CFR 141.71(b)(6)].
Systems that do not meet all of the criteria for avoiding filtration and use
conventional/direct filtration must meet the turbidity requirements of the rule [0.3 NTU
CFE (combined filter effluent) 95 percent of the time, at no time exceed 1 NTU] [40
CFR 141.173].
Alternative technologies for systems that serve at least 10,000 people must remove 99
percent of Cryptosporidium oocysts, and the state must establish alternative turbidity
performance standards that must be met 95 percent of the time and a maximum [40 CFR
141.173(b)].
Systems must comply with the reporting and recordkeeping requirements of 40 CFR
141.175, including turbidity exceptions reporting. Systems must, when appropriate:
• Produce filter profiles or identify obvious reason for poor filter performance.
• Report profile has been produced or identify obvious reason for poor filter
performance.
• Conduct filter self-assessments.
• Have 3rd party CPEs performed.
State must have first round of sanitary surveys completed for Subpart H CWSs [40 CFR
142.16(b)(3)(i)].
State must have first round of sanitary surveys completed for Subpart H NCWSs [40
CFR 142.16(b)(3)(i)].
3.  Summary of Requirements

Disinfection profiling and benchmarking

Surface water or GWUDI systems having average annual TTHM D 0.064 mg/L or annual average HAAS
D 0.048 mg/L must develop a disinfection profile. The disinfection profile is a compilation of daily
measurements of microbial inactivation by disinfection, collected over the period of 1 year. From the
disinfection profile, the PWS calculates the average microbial inactivation potential for each month, and
the lowest monthly average inactivation becomes the disinfection benchmark.

The purpose of these provisions is to provide a process whereby a public water system (PWS) and the
state, working together, assure that there will be no significant reduction hi microbial protection as the
result of disinfection practice modifications designed to meet the more restrictive maximum contaminant
levels (MCLs) for DBPs established in the Stage 1 DBPR. Those PWSs required to develop disinfection
profiles, and that then wish to modify their disinfection practices to meet the new MCLs, must establish
the disinfection benchmark and consult with the state prior to implementing such modifications. In
addition, PWSs must keep the disinfection profile on file for the state to review during their sanitary
surveys. The benchmark does not set a new regulatory floor for disinfection practice, but instead
                                             Page 9

-------
characterizes current practice so that the system, in consultation with the state, can make an informed
decision when implementing a modification.

Cryptosporidium

The IESWTR sets a maximum contaminant level goal (MCLG) of zero for the protozoan
Cryptosporidium. It also establishes a requirement for 2-log (99%) removal of Cryptosporidium for
systems that must currently filter under the 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 in the IESWTR (discussed below). 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 SWTR.

The IESWTR also extends the existing watershed control requirements for unfiltered systems to include
the control of potential sources of Cryptosporidium. Such sources must be included in an unfiltered
system's watershed control plan.

These new provisions, along with the new turbidity requirements, will better protect consumers from
Cryptosporidium and other pathogens.

Strengthened turbidity requirements

The IESWTR includes a series of requirements related to turbidity. These requirements strengthen
current SWTR requirements for combined filter effluent for systems that use  conventional or direct
filtration. The turbidity level of a system's combined filtered water at each plant must be less than or
equal to 0.3 nephelometric turbidity units (NTUs) in at least 95 percent of the measurements taken each
month, and the turbidity level of a system's combined filtered water must at no tune exceed 1 MTU
(under the SWTR, these turbidity requirements are 0.5 NTU and 5 NTU, respectively).

Individual filter monitoring requirements

The IESWTR requires continuous turbidity monitoring for individual filters. The rule requires that
surface water and GWUDI systems that use conventional or direct filtration must conduct continuous
turbidity monitoring (every 15 minutes) on the effluent of each individual filter. PWSs must report
instances of poor filter performance to the state, and,  based on performance triggers, must take prescribed
actions to identify and correct the cause(s). This requirement will allow systems to identify filters whose
poor performance might be masked in a combined filter effluent.

Uncovered finished -water storage facilities

The rule prohibits building any uncovered finished water storage facilities (reservoir, holding tank, or
other storage facility) for which construction begins after February  16, 1999.  This provision will help
limit recontamination of treated water, but does not require that existing uncovered finished water
storage facilities be covered.

Public -water system recordkeeping and reporting requirements

The IESWTR requires PWSs to submit combined filter effluent monitoring and compliance data and
report that they have conducted individual filter turbidity monitoring to states within 10 days after the
end of each month the system serves water to the public. Additionally, PWSs must report to the state if
certain individual filter monitoring trigger levels are exceeded.  In this case, systems must report turbidity
                                              Page 10

-------
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.

Sanitary surveys

The IESWTR requires that the state must conduct sanitary surveys for all PWSs using surface water or
ground water under the direct influence of surface water (GWUDI), regardless of the population served,
no less frequently than every 3 years for community water systems and every 5 years for noncommunity
systems. For community water systems determined by the state in previous sanitary surveys to have
"outstanding performance," successive sanitary surveys may be conducted at up to 5-year intervals.

Unfiltered Systems

The IESWTR requires unfiltered systems to continue to meet the SWTR source water and site-specific
requirements to remain unfiltered.  In addition, unfiltered systems must include Cryptosporidium in their
watershed control programs  and must meet all Stage 1 DBPR MCLs and MRDLs to remain unfiltered.
Like filtered systems, they are subject to disinfection profiling and benchmarking and sanitary surveys.
4.  Additional Information

A series of guidance manuals have been developed to support the Interim Enhanced Surface Water
Treatment Rule and the Stage 1 Disinfectants/Disinfection Byproducts Rule. The manuals will aid EPA,
state agencies and affected public water systems in implementing the two interrelated rules, and will help
to ensure that implementation among these groups is consistent. The manuals are available on EPA's
website at www.epa.gov/safewater/mdbp/implement.htmL  Additional information on ordering these
manuals is provided below.

The manuals for the IESWTR include:

Disinfection Profiling and Benchmarking Guidance Manual (EPA 815-R-99-013)

Objective: To help determine if a disinfection profile (an evaluation of current disinfection practice) is
required and how to do one; when a disinfection benchmark must be determined and how to extract it
from the profile;  and how a public water system uses the benchmark, in consultation with the state, to
protect from microbial risk when the system changes disinfection practice.

Contents: The manual provides detailed information on the following subjects: applicability of the
profiling and benchmarking requirements to public water systems; procedures for generating a
disinfection profile, including example profiles; methods for calculating the disinfection benchmark,
including example calculations; the use of the benchmark in modifying disinfection practices,
communicating with the state, and assessing significant changes to disinfection practices; the
development of the profiling and benchmarking regulations; the significance of the log inactivation
concept and CT values for inactivations achieved by various disinfectants; and the determination of
contact time.
                                              Page 11

-------
Guidance Manual for Compliance with the Interim Enhanced Surface Water Treatment Rule:
Turbidity Provisions (EPA 815-R-99-010)

Objective: The first section provides technical information regarding specific requirements of the
Interim Enhanced Surface Water Treatment Rule relating to turbidity and is intended for experienced
operators and others in the regulated community.  The second section of the document provides
background on concepts surrounding turbidity and serves as a primer for less experienced operators and
individuals.

Contents: The first section contains key regulatory requirements including combined filter effluent
monitoring and individual filter monitoring; recordkeeping and reporting requirements; additional
compliance issues such as compliance schedule, public notification, variances/exemptions, and follow-up
action requirements; approved methods and additional measurement and calibration issues; components
and description of a filter self-assessment; and components and description of a Comprehensive
Performance Evaluation.The second section of the manual includes more basic information on turbidity;
description of the particles (both natural and man-made) which typically contribute to turbidity;
discussion of typical steps in a treatment process and how turbidity is removed or created in each step;
discussion of turbidity in different source waters with an emphasis of how changes in source water effect
turbidity; and basic turbidimeter design.

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

Objective: To provide technical data and engineering information on disinfectants and oxidants that are
not as commonly used as chlorine, so that systems can evaluate their options  for developing disinfection
schemes to control water quality problems such as zebra mussels and Asiatic clams, and oxidation to
control water quality problems associated with iron and manganese.

Contents: The manual discusses six disinfectants and oxidants: ozone, chlorine dioxide, potassium
permanganate, chloramines, ozone/hydrogen peroxide combinations, and ultraviolet light.  A decision
tree is provided to help evaluate which disinfectant(s) is most appropriate given certain site-specific
conditions (e.g., water quality conditions, existing treatment and operator skill). The manual also
contains a summary of existing alternative disinfectants use in the United States and cost estimates for
the use of alternative disinfectants.

Microbial and Disinfection Byproducts Simultaneous Compliance Manual (EPA 815-R-99-015)

Objective: To help public water systems achieve simultaneous compliance with various drinking water
regulations (e.g., Stage 1 Disinfectants and Disinfection Byproducts Rule, Interim Enhanced Surface
Water Treatment Rule, Lead and Copper Rule and the Total Coliform Rule).  The manual discusses
operational problems systems may encounter when implementing these rules.

Contents: The manual provides detailed information on the requirements in the Stage 1 Disinfectants
and Disinfection Byproducts Rule and the Interim Enhanced Surface Water Treatment Rule.

Guidance Manual for Conducting Sanitary Surveys of Public Water Systems:  Surface Water and
Ground Water Under the Direct Influence (GWUDI) (EPA 815-R-99-016)

Objective: The guidance manual provides an overview of how to conduct  a sanitary survey of all water
systems using surface water and ground water under the direct influence of surface water. It is intended
to help state agencies improve their sanitary survey programs where needed.
                                              Page 12

-------
Contents: The manual provides information about the objective and regulatory context of sanitary
surveys. It covers four principal stages of a sanitary survey: planning, including preparatory steps to be
taken by inspectors before conducting the onsite portion; conducting the onsite survey; compiling a
sanitary survey report; and performing follow-up activities.

Uncovered Finished Water Reservoirs (EPA 815-R-99-011)

Objective: To provide information on ways systems can limit water quality degradation in existing
finished water reservoirs.

Contents: The manual provides detailed information on the following subjects: developing and
implementing comprehensive open finished water reservoir management plans based on site-specific
conditions; identifying potential sources of contamination in open finished water reservoirs and potential
mitigation measures; employing different methods to control the degradation of water quality while it
resides in the reservoir; monitoring schemes that can be used to characterize water quality and identify
water quality degradation before it becomes severe and is difficult to correct.
5.  Detailed regulatory requirements

Detailed descriptions of the monitoring and reporting requirements for public water systems (PWSs) are
presented in the following section. The IESWTR applies only to subpart H systems that serve 10,000 or
more people, with the exception of a sanitary survey provision that applies to all subpart H systems (the
state or a third party conducts the sanitary survey). These systems are all required to monitor and report
similar data, with the exception of turbidity exceedance reports that will be prepared as required.

Combined filter effluent turbidity monitoring

The Interim Enhanced Surface Water Treatment Rule (IESWTR) establishes a number of provisions
related to the performance of filters used in drinking water treatment. These provisions include treatment
technique requirements restricting turbidity levels in the combined filter effluent.  These requirements
are designed to decrease risk from waterborne microbial pathogens by limiting levels of particulate
material in finished water.  EPA has used a treatment technique because it is neither technically nor
economically feasible to measure pathogens such as Giardia, Cryptosporidium, and viruses in either the
source water or treated water.
                                              Page 13

-------
Which systems must comply with turbidity requirements for the combined filter effluent under the
EESWTR?
The treatment technique requirements for combined filter effluent turbidity under the IESWTR apply to
public water systems (PWS) that use surface water or ground water under the direct influence of surface
water (GWUDI), serve 10,000 or more people, and are required to filter.

What are the maximum allowable levels of turbidity in the combined filter effluent?
For systems using conventional filtration or direct filtration, the turbidity level of representative samples
of a system's filtered water must be less than or equal to 0.3 NTU in at least 95 percent of the
measurements taken each month, and must never exceed 1 NTU. For slow sand and diatomaceous earth
filtration systems, requirements for turbidity levels in the combined filter effluent remain as specified
under the SWTR (less than or equal to 1 NTU in 95 percent of the measurements taken each month and
never greater than 5 NTU).  For systems using filtration technologies other than conventional, direct,
slow sand, or diatomaceous earth, the systems must demonstrate to the state, using pilot plant studies or
                                              Page 14

-------
CO
us
e>
                                                                                                                                                                                    1

-------
 other means, that the alternative filtration technology in combination with disinfection treatment
 consistently achieves 99.9 percent removal and/or inactivation of Giardia lamblia cysts, 99.99 percent
 removal and/or inactivation of viruses, and 99 percent removal of Cryptosporidium oocysts.  For each
 approval of an alternative filtration technology, the state will set turbidity performance requirements that
 the system must meet at least 95 percent of the time, and that the system may not exceed at any tune, at
 values that consistently achieve these levels of removal'and/or inactivation of Giardia lamblia, viruses,
 and Cryptosporidium.  Failure to meet these requirements is a treatment technique violation.

 What are the monitoring requirements for combined filter effluent turbidity?
 Systems must monitor combined filter effluent turbidity as specified under the SWTR.  This specifies
 that turbidity measurements must be performed on representative samples of the system's filtered water
 every four hours (or more frequently) that the system serves water to the public. A public water system
 may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous
 measurement for accuracy on a regular basis using a protocol approved by the state. For any systems
 using slow sand filtration or filtration treatment other than conventional treatment, direct filtration, or
 diatomacebus earth filtration, the state may reduce the sampling frequency to once per day if it
 determines that less frequent monitoring  is sufficient to indicate effective filtration performance.
 Turbidity must be measured using methods approved by EPA and by a party approved by the state. A
 system that uses lime softening may acidify representative samples prior to analysis using a protocol
 approved by the state. Failure to meet these requirements is a monitoring violation.

 What are the reporting and recordkeeping requirements for turbidity in the combined filter
 effluent?
 The reporting requirements for combined filter effluent  turbidity are unchanged from those established
 under the SWTR, except where reporting levels have been modified to  reflect more stringent turbidity
 requirements established under the ffiSWTR.  Required turbidity measurements must be reported within
 10 days after the end of each month the system serves water to the public.  Information that must be
 reported includes: 1) the total number of filtered water turbidity measurements taken during the month;
 2) the number and percentage of filtered water turbidity measurements taken during the month which are
 less than or equal to the turbidity limits established under the SWTR for diatomaceous earth and slow
 sand filtration systems,  and under the IESWTR for conventional, direct, and alternative filtration
 systems; and 3) the date and value of any turbidity measurements taken during the month which exceed  1
NTU for conventional and direct filtration systems, 5 NTU for slow sand and diatomaceous earth
filtration systems, and the maximum level established by the state for alternative filtration technology
systems. Failure to meet these requirements is a reporting/recordkeeping violation.

                      IESWTR COMBINED FILTER EFFLUENT TURBIDITY
                                 COMPLIANCE REQUIREMENTS
FILTRATION TECHNOLOGY
Conventional filtration
Direct filtration
Diatomaceous earth filtration
Slow sand filtration
Filtration technologies not listed above
95thPERCENTILE
TURBIDITY (NTU)
0.3
0.3
1
1
as determined by the state
MAXIMUM
TURBIDITY (NTU)
1
1
5
5
as determined by the state
                                             Page 16

-------
                                 Combined Filter Effluent Provisions of IESWTR
                            (Applicable to Conventional and Direct Filtration Systems)
Turbidity Performance Requirements
 - Measurements are taken every 4 hours of
representative samples of the systems
filtered water (as required under the SWTR)
- Turbidity must at no time exceed 1 NTU
- Turbidity must be less than or equal to
 0.3 NTU in at least 95 percent of the
measurements taken each month.
                                                             Reporting and Recordkeeoinq Requirements
                                                             Within 10 days after the end of the month, system must
                                                             provide a report of turbidity measurements to the State
                                                             which includes:
                                                             - Total number of measurements taken during the
                                                             month
                                                             - Number and percentage of measurements less than
                                                             or equal to 0.3 NTU
                                                             - Date and value of any measurements taken during
                                                             the month which exceed 1 NTU.
                                         Did System
                                       report all required
                                    information to State within
                                     0 days after the end o
                                         the month?
                                             Did
                                       turbidity exceed
                                      1 NTU at any time?
                                             Was
                                  turbidity less than or equal to
                                     0.3 NTU in at least 95
                                   ercent of the measurements
                            YES  \   taken each month?
                                                  Page 17

-------
                     Alternative Filtration Requirements of the IESWTR
(Filtration Technologies other than conventional, direct, slow sand or diatomaceous earth)
                    Alternative Filtration Technologies
                    System must demonstrate to the State that the alternative filtration technology,
                    in combination with disinfection consistently meets:
                     - 3 log Giardia and 4 log virus
                    removal/inactivation
                     - 2 log Cryptosporidium removal
                                                 Did State
                                           approve the alternative
                                            filtration technology?
                                                                     NO
             Alternative Turbidity Performance Requirements
             The State will set turbidity performance requirements that the system must meet 95 percent of
             the time (95th PERCENTILE)

             The State will set turbidity performance requirements that the system may not exceed at any
             time (MAXIMUM)

             These performance requirements will be set at a level that consistently achieves 3 log Giardia
             removal/inactivation, 4 log virus removal/inactivation and 2 log Cryptosporidium removal
              Reporting and Recordkeeoing Requirements
              Within 10 days after the end of the month, the system must provide a report of turbidity
              measurements to the State which includes:

                 1)Total number of measurements taken during the month
                 2)Numberand percentage of measurements less than or equal to 95TH PERCENTILE
                 3)Date and value of any  measurements taken during the month which exceed MAXIMUM
                      Did system report
                  to State within 10 days after
                    the end of the month?
                        Did turbidity
                exceed State-set MAXIMUM at
                         any time?
                       Was turbidity
                    less than or equal to
               State-set 95TH PERCENTILE in
                  at least 95 percent of the
                  measurements taken each
                          month?
NO
                                                                YES
NO
                                              Page 18

-------
                                       Combined Filter Effluent Provisions of SWTR
                        (Applicable to Systems using Slow Sand and Diatomaceous Earth Filtration)
Turbidity Performance Requirements
Systems must meet the following provisions:

- Measurements are taken every 4 hours of
representative samples of the systems filtered water

- State may reduce the monitoring frequency to once
per day for systems using slow sand or that serve
<500

- Turbidity must at no time exceed 5 NTU

- Turbidity must be less than or equal to 1 NTU in at
least 95 percent of measurements taken each month.
Reporting and Recordkeepinq Requirements
Within 10 days after the end of the month, System
must provide a report of turbidity measurements
to the State which includes:

- Total number of measurements taken during the
month

- Number and percentage of measurements less than
or equal to 1 NTU

- Date and value of any measurements taken during
the month which exceed 5 NTU.
                                          Did System
                                       report all required
                                       information to the
                                      State withinIO days
                                          r the end of the
                                           month?
                                          Did turbidity
                                       exceed 5 NTU at
                                           anytime?
                                       Was turbidity less
                                   than or equal to 1 NTU in at
                                      least 95 percent of th
                                   measurements taken each
                             YES  \       month?
                                                       Page 19

-------
Individual filter turbidity monitoring

The IESWTR establishes a number of requirements related to the performance of filters used in drinking
water treatment. Included in these requirements are provisions mandating that certain systems monitor
the effluent of individual filters.  These provisions are designed to decrease the risk of microbial
pathogen contamination of finished waters by focusing greater attention on the performance of individual
filters.

Which systems are required to monitor individual filters?
The filtration requirements of the IESWTR apply to PWSs that use surface water or GWUDI, serve
10,000 or more people, and are required to filter.  Systems that provide conventional or direct filtration
treatment must monitor individual filters.

What are the monitoring requirements for individual filters?
Systems must  continuously measure the effluent turbidity of each individual filter using a method
approved by EPA, and must record the results every 15 minutes.  If there is a failure in the continuous
turbidity monitoring equipment, the system must conduct grab sampling every four hours in lieu of
continuous monitoring until the turbiditneter is repaired or replaced, and is in violation if the turbidimeter
is not replaced or repaired within five working days  following the failure of the equipment. Failure to
comply with these requirements is a monitoring violation.

What are the reporting and recordkeeping requirements for individual filter monitoring?
Systems required to monitor individual filters must maintain the results of this monitoring for at least 3
years.  Within 10 days after the end of each month, these systems must make a report to the state that
they have conducted individual filter turbidity monitoring.  Systems must report individual filter turbidity
measurements only if the measurements demonstrate any of the following four exceedance conditions:

        1)      Any individual filter that has a measured turbidity level of greater than  1.0 NTU in two
               consecutive measurements taken 15 minutes  apart.  The system must report the filter
               number, the turbidity measurement, and the date(s) on which the exceedance occurred.
               The system must also either identify and report an obvious reason for the exceedance or
               produce a filter profile for the filter within 7 days of the exceedance and report that the
               profile has been produced. (A filter profile is a graphical representation of turbidity or
               total particle counts as a function of time for an entire filter run. A discussion of filter
               profiles is included in EPA's guidance document on turbidity.)

       2)      Any individual filter that has a  measured turbidity level of greater than 0.5 NTU in two
               consecutive measurements taken 15 minutes apart at the end of the first four hours of
               continuous filter operation after the filter has  been backwashed or  otherwise taken
               offline.  The system must report the filter number, the turbidity measurement, and the
               date(s) on which the exceedance occurred. The system must also  either identify and
               report an obvious reason for the exceedance or produce a filter profile for the filter
               within 7 days of the exceedance and report that the profile has been produced.  (A filter
               profile is a graphical representation of turbidity or total particle counts as a function of
               time for an entire filter run.  A  discussion of filter profiles is included in EPA's guidance
               document on turbidity.)

       3)      Any individual filter that 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 three
               consecutive months. The system must report the filter number, the turbidity
               measurement,  and the date(s) on which the exceedance occurred.  The system must
               conduct a self-assessment of the filter within  14 days of the exceedance and report that

                                              Page 20

-------
               the self-assessment was conducted in the monthly report. The self-assessment must
               consist of at least the following components: assessment of filter performance,
               development of a filter profile, identification and prioritization of factors limiting filter
               performance, assessment of the applicability of corrections, and preparation of a filter
               self-assessment report.

        4)      Any individual filter that has a measured turbidity level greater than 2.0 NTU in two
               consecutive measurements taken 15 minutes apart at any time in each of two consecutive
               months.  The system must report the filter number, the turbidity measurement, and the
               date(s) on which the exceedance occurred.  The system must arrange for the conduct of
               a comprehensive performance evaluation (CPE) by the state or a third part approved by
               the state no later than 30 days following the exceedance.  (A CPE is a thorough review
               and analysis of a treatment plant's performance-based capabilities and associated
               administrative, operation and maintenance practices.) The CPE must be completed and
               submitted to the state no later than 90 days following the exceedance.

The turbidity guidance manual has detailed information about filter profiling, filter self-assessments, and
CPEs.  Systems using lime softening may apply to the state for alternative exceedance levels to those
specified above if they can demonstrate that higher turbidity levels in individual filters are due to lime
carryover only and not  due to degraded filter performance.

Failure to comply with  these requirements is a reporting violation. However, the exceedance criteria are
not treatment technique requirements, and systems have not committed a violation solely by
demonstrating any of the exceedance conditions in their individual filters.
                                               Page 21

-------

-------

-------

-------
What ROUTINE MONITORING must I conduct under the IESWTR?

What do I have to REPORT to the State?

IMPORTANT: The information in the table below does not include the requirements for determining
profiling applicability, disinfection profiling, and disinfection benchmarking. Please refer to the section
on Disinfection Benchmarking for these monitoring and sampling requirements.
    Activity
                                     Requirement
 Combined filter
 effluent
 monitoring
All systems must continue to monitor the combined filter effluent at the same location and
frequency as under the S WTR.
 Turbidity
 Monitoring at
 Individual
 Filters
   All systems using conventional filtration treatment or direct filtration must conduct
   continuous turbidity monitoring for each individual filter using an approved method and
   Individual must calibrate turbidimeters using the procedure specified by the manufacturer.
   Systems must record the results of individual filter monitoring every 15 minutes.
   If there is a failure in the continuous turbidity monitoring equipment, the system must
   conduct grab sampling every 4 hours in lieu of continuous monitoring .
 Triggers for
 Turbidity
 Exceptions
 Reporting for
 Individual
 Filters
   For any individual filter that has a measured turbidity level of greater than 1.0 NTU in 2
   consecutive measurements taken 15 minutes apart, the system must report the filter number,
   turbidity measurement, and date of exceedance. The system must produce  a filter profile for
   the filter within 7 days of the exceedance and report that the profile has been produced or
   report the obvious reason for the exceedance.

   For any individual filter that has a measured turbidity level of greater than 0.5 NTU in 2
   consecutive measurements taken 15 minutes apart after the first 4 hours of operation after the
   filter has been backwashed or otherwise taken offline, the system must report the filter
   number, turbidity measurement, and date of exceedance. The system must produce a filter
   profile for the filter within 7 days of the exceedance and report that the profile has been
   produced or report the obvious reason for the exceedance.

   For any individual filter that has a measured turbidity level of greater than 1.0 NTU in 2
   consecutive measurements taken 15 minutes apart in each of 3 consecutive months, the
   system must report the filter number, turbidity measurement, and date of exceedance. The
   system must conduct a self-assessment of the filter within 14 days of the exceedance and
   report that the self-assessment was conducted.

   For any individual filter that has a measured turbidity level of greater than 2.0 NTU in 2
   consecutive measurements taken 15 minutes apart in 2 consecutive months, the system must
   report the filter number, turbidity measurement, and date of exceedance. The system must
   contact the state or 3rd party to conduct a CPE no later than 30 days following the
   exceedance and have the evaluation completed and submitted to the state no later than 90
   days following the exceedance.
Reporting and
Recordkeeping
Individual Filter Data
   Results of individual filter monitoring must be maintained for at least 3 years.
   Individual filter data must be reported only if there has been a turbidity exceedance
Combined Filter Effluent Data Reporting
                   Total number of combined filter effluent turbidity measurements taken during last month that
                   do not exceed the turbidity limits.
                   Date and value of any turbidity measurements taken during the month that exceed 1 NTU for
                   systems using conventional or direct filtration.
                   Turbidity measurements must be reported within 10 days after the end of each month the
                   system serves water to the public.
                                               Page 23

-------

-------
Disinfection profiling and benchmarking

The Interim Enhanced Surface Water Treatment Rule (IESWTR) establishes disinfection benchmarking
as a procedure requiring certain public water systems (PWSs) to evaluate the impact on microbial risk of
proposed changes in disinfection practice. It is designed to help utilities and states work together to
assure that pathogen control is maintained while the provisions of the Stage 1 Disinfectants and
Disinfection Byproducts Rule (Stage 1 DBPR) are implemented. This procedure involves a PWS
charting daily levels of pathogen inactivation for a period of at least one year to create a profile of
inactivation performance.  The PWS then uses this profile to determine a baseline or benchmark of
inactivation against which proposed changes in disinfection practices can be measured. Profiling and
benchmarking is explained in detail in the Disinfection Profiling and Benchmarking Guidance Manual

Who is required to prepare a disinfection profile?
Surface water or GWUDI systems having average annual TTHM D 0.064 mg/L or annual average
HAAS D 0.048 mg/L as a result of data or specific monitoring conducted by March 31, 2000 must
develop a disinfection profile. These levels, equal to 80% of the MCLs established for these compounds
by the Stage 1  DBPR, are intended to include most systems that will modify their disinfection practices
to comply with the Stage 1 DBPR.  To determine  applicability, systems that collected TTHM and HAAS
data under the ICR must use the results of the last 12 months of ICR monitoring unless the state
determines there is a more representative data set. Non ICR systems may either use existing TTHM and
HAAS data, if approved by the state, or must conduct TTHM and HAAS monitoring for four quarters.
This monitoring must be completed before April 2000.  Alternatively, systems can elect to forgo this
monitoring if they construct a disinfection profile.

How are the disinfection profile and benchmark developed?
A disinfection profile consists of a compilation of daily Giardia  lamblia log inactivations (plus virus
inactivations for systems using either chloramines or ozone for primary disinfection) computed over a
period of at least one year through the entire treatment plant.  It is based on daily measurements of
disinfectant residual concentrations), contact time(s), temperature, and pH. A system with more  than
one point of disinfection application must conduct this monitoring for each disinfection segment. The
profile may also be developed using up to 3 years of existing (i.e. grandfathered) data if the state finds
the data acceptable. Systems having less than 3 years of acceptable grandfathered data are required to
conduct one year of monitoring to create the profile. This monitoring must be completed by April 2001.
The disinfection benchmark is equal to the lowest monthly average inactivation level in the disinfection
profile (or average of low  months for multi-year profiles).

How are the disinfection profile and benchmark used?
Any system required to develop a disinfection profile under the IESWTR that decides to make a
significant change to its disinfection practice must calculate its benchmark and consult with the state
prior to and only if making a significant change.  Significant  changes in disinfection practice are defined
as: 1) changes to the point of disinfection; 2) changes to the  disinfectants) used in the treatment plant; 3)
changes to the disinfection process; and 4) any other modification identified by the  state.  As part  of the
consultation process, the system must submit to the state the following information: a description  of the
proposed change; the disinfection profile for Giardia lamblia (and, if necessary, viruses) and benchmark;
and an analysis of how the proposed change will  affect the current levels of disinfection.  In addition, the
state is required to review the disinfection profile  as part of its periodic sanitary survey.
                                               Page 24

-------

-------
                                   Disinfection Profiling and Benchmarking Provisions (1998IESWTR)
                                                                                 Profiling and Benchmarking
                                                                                   provisions do not apply.
Subpart H System
serving 010,000?
                                      System needs to determine whether
                                    Profiling and Benchmarking is required.
                                                                                     as the system
                                                                                collected 4 consecutive
                                                                                   quarters of TTHM
                                                                                 compliance data and
                                                                                   HAAS occurrence
                                                                                       data?
                                                                           Has the State
                                                                        approved the use of
                                                                            this data for
                                                                            applicability
                                                                           eterminationTM
                Did system
          collect TTHM and
            data underthe 1996
           Information Collection
                 ule (ICR)?
     Has the
State determined if
  there is a more
  prasentative d
      set?
                                                                                                                     consecutive quarters of
                                                                                       Has the
                                                                                   system elected to
                                                                                   forgo TTHH/HAA5
                                                                                     monitoring?
                                                                       Apr-Jun  99 quarter and
                                                                                                                    completed no later than
                                       Did
                                     system
                                calculate benchmark
                                    consult with
                                     State?
                                  System must notify State
                                  in writing no later than 12
                                   mos after promulgation
                                        (Dec. '99).
                                                                                                                    the 4 quarters of data to
                                                                                                                    the State by March 2000
                                                                                                                     determine applicability.
                                                                                                                                    Systems must submit data to
                                                                                                                                      State no later than 4 mos
                                                                                                                                     after promulgation (Apr '99)
                                                                                                                                        and use that data to
                                                                                                                                       determine applicability.
                     Did
                    system
                   develop a
                   profile and
                    keep it
                    on fib?
   Has system
 decided to make
significant change
  to disinfection
    radices?
                              System is in compiian
                                 with Profiling and
                                   Benchmarking
                                   requirements.
                                                                                 have annual average of
                                                                   System is in compliance with Profiling and Benchmarking
                                                                                     requirements.
                                                                             Disinfection Profile is not needed.
NOTES
'TTHM and HAAS averages must be taken from same time period.
2Any lab approved under the ICR or using ICR-approved methods may conduct HAAS analyses.
3TTHM and HAAS monitoring must meet same sampling number and location requirements as TTHM in 141.12 and 141.30; and same handling
and analytical requirements as the ICR in 141.142(b)(1).
4System must conduct HAAS monitoring until state approves of the existing data.
5State may also require a more representative data set.
"Disinfection Profile must be kept on file for State to review during Sanitary Survey.
                                                            Page 25

-------

-------