&EPA
United States
Environmental Protection
Agency
I
*
Comprehensive Surface Water Treatment Rules Quick
Reference Guide: Systems Using Conventional or Direct
Filtration
r
Overview of the Rules
Title*
Purpose
General
Description
Surface Water Treatment Rule (SWTR) - 40 CFR 141 .70-141 .75
Interim Enhanced Surface Water Treatment Rule (IESWTR) - 40 CFR 141 .170-141.175
Filter Backwash Recycling Rule (FBRR) 40 CFR 141 .76
Long Term 1 Enhanced Surface Water Treatment Rule (LT1 ESWTR) - 40 CFR 1 41 .500-1 41 .571
Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) - 40 CFR 1 41 .700-1 41 .722
Improve public health protection through the control of microbial contaminants, particularly
viruses, Giardia lamblia, and Cryptosporidium.
The Surface Water Treatment Rules:
>• Applies 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."
>• Requires all Subpart H systems to disinfect.
>• Requires Subpart H systems to filter unless specific filter avoidance criteria are met.
>• Applies a treatment technique requirement for control of microbials.
This document provides a summary of federal drinking water requirements; to ensure full compliance, please consult
the federal regulations at 40 CFR 141 and any approved state requirements.
Overview of Requirements
The purpose of this table is to show how the requirements for the IESWTR, FBRR, LT1ESWTR and LT2ESWTR
build on the existing requirements established in the original SWTR.
APPLICABILITY: PWSs that use surface
water or GWUDI (Subpart H systems) that
practice conventional or direct filtration.
Population
Served
Regulated
Pathogens
Residual
Disinfection
Requirements
Source Water
Monitoring
Requirements
and Bin
Classification
Turbidity
Performance
Standards
Disinfection
Profiling and
Benchmarking
Sanitary
Surveys (state
requirement)
Finished
Reservoirs/
Water Storage
Facilities
> 10,000
< 10,000
99.99% (4-log) removal/
inactivation of viruses
99.9% (3-log) removal/
inactivation of Giardia lamblia
99% (2-log) removal of
Cryptosporidium
Entrance to distribution system
(> 0.2 mg/L)
Detectable in the distribution
system
Monitoring to calculate
Cryptosporidium and determine
appropriate bin classification
for each plant required to
monitor
Combined Filter Effluent
Individual Filter Effluent
Systems must profile
inactivation levels and generate
benchmark, if required
CWS**: Every 3 years
NCWS**: Every 5 years
All new facilities constructed
must be covered
Uncovered facilities must be
covered or discharge treated
Final Rule Dates
SWTR
1989
^
^
^
^
^
•/
*
~
Operated by Qualified Personnel as Specified
by State | *
IESWTR
1998
^
For sanitary
survey
provisions only
Regulated
under SWTR
Regulated
under SWTR
^
Regulated
under SWTR
Regulated
under SWTR
^
^
^
^
^
Regulated
under SWTR
LT1 ESWTR
2002
^— ^^^M
^
Regulated
under SWTR
Regulated
under SWTR
*
Regulated
under SWTR
Regulated
under SWTR
*<
*
*
Regulated
under
IESWTR
*
"•
Regulated
under SWTR
LT2ESWTR
2006
•/
*
Regulated
under SWTR
Regulated
under SWTR
Additional
treatment
may be
required
Regulated
under SWTR
Regulated
under SWTR
\/
Regulated
under SWTR,
IESWTR and
LT1 ESWTR
Regulated
under
IESWTR and
LT1 ESWTR
^
Regulated
under
IESWTR
Regulated
under
LT1 ESWTR
\/
Regulated
under SWTR
FBRR
2001
**
*S
Regulated
under SWTR
Regulated
under SWTR
Regulated
under
IESWTR and
LT1 ESWTR
Regulated
under SWTR
Community water system (CWS), Noncommunity water system (NCWS)
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Turbidity
Compliance with turbidity provisions is measured at the Combined Filter Effluent (CFE) and Individual Filter Effluent (IFE). The
CFE turbidity results may mask the performance of an individual filter since the individual filter may have a turbidity spike of a
short duration not detected by 4 hours CFE readings. IFE performance is measured in systems using conventional or direct
filtration. The performance of each individual filter is critical to controlling pathogen breakthrough.
The IESWTR and LT1ESWTR created more stringent CFE turbidity standards and established a new IFE turbidity monitoring
requirement to address Cryptosporidium. These new turbidity standards assure conventional and direct filtration systems will be
able to provide 2-log Cryptosporidium removal. Subpart H systems using the Treatment Performance Toolbox option under the
LT2ESWTR must meet the more stringent CFE and IFE turbidity monitoring levels in order to receive additional Cryptosporidium
log credit.
Turbidity: Monitoring and Reporting Requirements
Turbidity Type and Reporting Requirements (Reports
due by the 10th day of the following month the system
serves water to the public.)
CFE 95% Value
Report total number of CFE measurements and number and
percentage of CFE measurements s 95th percentile limit
CFE Maximum Value
Report date and time of any CFE measurement that
exceeds CFE maximum limit
IFE Monitoring
Report IFE monitoring conducted and any follow-up actions
Monitoring/
Recording
Frequency
At least every 4
hours*
At least every 4
hours*
Monitor
continuously
every 15 minutes
SWTR
As of June
29, 1993
<0.5 NTU
5NTU
Contact state
within 24 hours
None
IESWTR
> 10,000 people
As of January
1, 2002
< 0.3 NTU
1 NTU
Contact state
within 24 hours
LT1ESWTR
< 10,000 people
As of January 1, 2005
< 0.3 NTU
1 NTU
Contact state within 24 hours
Monitor-exceedances require follow-up action. Systems with 2
or fewer filters may monitor CFE continuously in lieu of IFE.
'Monitoring frequency may be reduced by the state to once per day for systems serving fewer than 500 people.
IFE Turbidity: Follow-Up and Reporting Requirements
Condition
2 consecutive
recordings > 0.5 NTU
taken 15 minutes
apart at end of first 4
hours of continuous
filter operation after
backwash/offline:
2 consecutive
recordings > 1 .0 NTU
taken 15 minutes
apart:
2 consecutive
recordings > 1 .0 NTU
taken 15 minutes apart
at the same filter for 3
months in a row:
2 consecutive
recordings > 2.0 NTU
taken 15 minutes apart
at the same filter for 2
months in a row:
IESWTR (> 10,000)
Action
Produce filter
profile within 7
days (if unknown
cause).
Produce filter
profile within 7
days (if unknown
cause).
Conduct filter
self-assessment
within 14 days.
Arrange for
Comprehensive
Performance
Evaluation (CPE)
within 30 days
& submit report
within 90 days.
Report
*• Filter*
>• Turbidity value
>• Date
>• Cause (if known) or
report profile was
produced
>• Filter*
^ Turbidity value
>• Date
>• Cause (if known) or
report profile was
produced
>• Filter*
^ Turbidity value
>• Date
>• Report filter
self-assessment
produced
*• Filter*
^ Turbidity value
>• Date
Submit CPE report
By
10th of the
following month
10th of the
following month
10th of the
following month
10th of the
following month
90 days after
exceedance
LT1ESWTR(<1 0,000)**
Action
Conduct a filter
self-assessment
within 14 days
Systems with 2
filters that monitor
CFE in lieu of
IFE must do both
filters.
Arrange for CPE
within 60 days
& submit CPE
report within 120
days.
Report
>• Filter*
^- Turbidity value
> Date
^- Cause (if known)
Date filter assessment
triggered & completed
Date CPE triggered
Submit CPE report
By
10th of the following
month
10th of the following
month (or within 14
days of filter self-
assessment being
triggered if triggered
in last 4 days of the
month).
10th of the following
month
120 days after
exceedance
** Systems serving fewer than 10,000 people had to begin complying with these requirements beginning January 1, 2005.
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Filter Backwash Recycling Rule
The FBRR applies to Subpart H systems that practice conventional or direct filtration, and recycle spent filter backwash, thickener
suernatant, or liquids from dewatering processes. The FBRR requires systems that recycle to return specific recycle flows through
all processes of the system's existing conventional or direct filtration system or at an alternate location approved by the state.
The FBRR was developed to improve public health protection by assessing and changing, where needed, recycle practices for
improved contaminant control, particularly microbial contaminants. Systems were required to submit recycle notification to the
state by December 8, 2003. By June 8, 2004, systems were required to return recycle flows through the processes of a system's
existing conventional or direct filtration system or an alternate recycle location approved by the state and collect recycle flow
information and retain on file. Any system making capital improvements to modify the recycle return location was given until June
8, 2006, to complete the improvements. All new systems must abide by these requirements.
Disinfection
Disinfection must be sufficient to ensure that the total treatment process (disinfection plus filtration) of the system achieves at
least:
>• 99.9% (3-log) inactivation and/or removal of Giardia lamblia.
>• 99.99% (4-log) inactivation and/or removal of viruses.
Subpart H systems using chlorine dioxide, ozone, or ultraviolet (UV) disinfection may achieve additional Cryptosporidium log credit
by using the Inactivation Toolbox option under the LT2ESWTR. Systems must also comply with the maximum residual disinfectant
level (MRDL) and maximum contaminant level (MCL) requirements specified in the Stage 1 Disinfectants and Disinfection
Byproducts Rule (Stage 1 DBPR) and Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR).
Residual Disinfectant Monitoring and Reporting Requireme
Location
Concentration
Monitoring Frequency
Reporting
(Reports due 10th of the following month)
Entry to distribution
system.
Residual disinfectant concentration cannot be
< 0.2 mg/L for more than 4 hours.
Continuous, but states may allow
systems serving < 3,300 to take
grab samples from 1 to 4 times per
day, depending on system size.
Lowest daily value for each day, the date and
duration when residual disinfectant was
< 0.2 mg/L, and when state was notified of events
where residual disinfectant was < 0.2 mg/L.
Distribution system -
same location as
total coliform sample
location(s).
Residual disinfectant concentration cannot be
undetectable in greater than 5% of samples
in a month, for any 2 consecutive months.
Heterotrophic plate count (HPC) < 500/mL is
deemed to have detectable residual disinfectant.
Same time as total coliform
samples.
Number of residual disinfectant or HPC
measurements taken in the month resulting in
no more than 5% of the measurements as being
undetectable in any 2 consecutive months.
LT2ESWTR Source Water Monitoring and Bin Classification
Bin concentration is calculated by averaging individual sample results from 1 or more years of monitoring (specific procedures
vary by frequency and duration of monitoring).
A combined distribution system (CDS) is an interconnected distribution system consisting of the distribution systems of the
wholesale system and of the consecutive systems that receive finished water from that wholesale system. Under the LT2ESWTR,
wholesale systems in a CDS must comply with the LT2ESWTR based on the population of the largest system in their CDS.
EPA has established four schedule categories based on system size to simplify the discussion of the LT2ESWTR monitoring
requirements. Schedule 1 applies to systems that serve 100,000 or more people or in a CDS that largest system serves 100,000
people. Schedule 2 applies to systems that serve 50,000 to 99,999 people or in a CDS that largest system serves 50,000 to
99,999 people. Schedule 3 applies to systems that serve 10,000 and 49,999 people or in a CDS that largest system serves
10,000 and 49,999 people. Schedule 4 applies to systems that serve less than 10,000 people.
Source water monitoring requirements are as follows:
>• Large systems (> 10,000 people served) must sample for Cryptosporidium, E.coli and turbidity at least monthly for 2 years.
>• Small systems (< 10,000 people served) must initially sample for E.coli at least once every 2 weeks for 1 year. Cryptosporidium
monitoring is only required if E. coli levels are above certain levels based on the water source type.
>• All systems must begin a second round of monitoring 6 years after initial bin classification.
Bin Classification and Additional Treatment Requirements
Bin
Bin1
Bin 2
Bin 3
Bin 4
Cryptosporidium
Bin Concentration
Less than .075 oocysts/ L **
.075 oocysts/L or higher, but less than 1 .0 oocysts/L
1 .0 oocysts or higher, but less than 3.0 oocysts/L
3.0 oocysts or higher
Additional Treatment Requirements*
Conventional Filtration
No additional treatment
1-log treatment***
2-log treatment***
2.5 log treatment***
Direct Filtration
No additional treatment
1 .5-log treatment***
2.5-log treatment***
3-log treatment***
Requirements in addition to those met in full compliance with SWTR, IESWTR, and LT1ESWTR
* Or Subpart H systems not required to monitor for Cryptosporidium
** Removal or inactivation
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Microbial Toolbox: Inactivation Options, Credits and Criteria
The Microbial Toolbox provides a list of the tools that systems can use, and receive treatment credits for, in order to meet
additional treatment requirements of LT2ESWTR. The toolbox provides systems with the flexibility to use any combination of
applicable treatment options as long as the systems are in compliance with design, operational, and performance criteria which
are not detailed in this document. The toolbox options and credits available for Subpart H systems are divided into five categories:
>• Source protection and management: watershed control program (0.5-log), alternative source/intake management (no
prescribed credit).
>• Prefiltration: presedimentation basin with coagulation (0.5-log), two-stage lime softening (0.5-log), bank filtration (0.5- or
1-log).
>• Treatment performance: combined filter performance (0.5-log), individual filter performance (0.5-log), demonstration of
performance (log credit variable).
>• Additional filtration: bag and cartridge filters individual (up to 2-log), bag and cartridge filters in series (up to 2.5-log),
membrane filtration (log credit variable), second stage filtration (0.5-log), slow sand filters (2.5- to 3-log).
>• Inactivation: chlorine dioxide (log credit variable), ozone (log credit variable), UV (log credit variable).
Disinfection Profiling and Benchmarking Requirements
A disinfection profile is the graphical representation of a system's microbial inactivation over 12 consecutive months.
A disinfection benchmark is the lowest monthly average microbial inactivation value. The disinfection benchmark is used as a
baseline of inactivation when considering changes in the disinfection process.
Disinfection Profiling and Benchmarking Requirements
The purpose of disinfection profiling and benchmarking is to allow systems and states to assess whether a change in disinfection practices reduces
microbial protection. Systems must develop a disinfection profile that reflects Giardia lamblia and viruses inactivation, calculate a benchmark
(lowest monthly inactivation) based on the profile, and consult with the state prior to making a significant change to disinfection practices.
Requirement
Affected
Systems:
Begin
Profiling By:
Frequency &
Duration:
States
May Waive
Disinfection
Profiling
Requirements
If:
Disinfection
Benchmark
Must be
Calculated If:
IESWTR
Community water systems (CWS), nontransient
noncommunity water systems (NTNCWS), and
transient noncommunity water systems (TNCWS)
> 10,000.
April 1 , 2000
Daily monitoring for 12 consecutive calendar
months to determine the total logs of Giardia
lamblia inactivation (and viruses, if necessary) for
each day in operation.
TTHM annual average < 0.064 mg/L and HAAS
annual average < 0.048 mg/L:
^ Collected during the same period.
^ Annual average is arithmetic average of the
quarterly averages of 4 consecutive quarters
of monitoring.
>• At least 25% of samples at the maximum
residence time in the distribution system.
>• Remaining 75% of samples at representative
locations in the distribution system.
>• Systems required to develop a disinfection
profile and are considering making a
significant changes in disinfection practice*.
>• Systems must consult the state prior to
making any modifications to disinfection
practices.
LT1ESWTR
CWS and NTNCWS <1 0,000 only.
>• July 1 , 2003, for systems
serving 500-9,999 people.
>• January 1 , 2004, for systems
serving < 500 people.
Weekly inactivation of Giardia
lamblia (and viruses, if necessary),
on the same calendar day each
week over 12 consecutive months.
One TTHM sample < 0.064 mg/L
and one HAAS sample < 0.048
mg/L:
>• Collected during the month of
warmest water temperature;
AND
^ At the maximum residence time
in the distribution system.
Samples must have been collected
after January 1, 1998.
Same as IESWTR, and systems
must obtain state approval prior
to making any modifications to
disinfection practices.
LT2ESWTR
Any CWS, NTNCWS or TNCWS that proposes to
make a significant change in disinfection practice*.
^ Upon completion of initial round of source
water monitoring, AND
>• 1 2 consecutive months prior to making the
proposed change.
At least weekly inactivation of Giardia lamblia and
viruses, for at least 1 year. May use data collected
for profile under IESWTR or LT1 ESWTR.
^ The system has an existing disinfection profile
for both Giardia lamblia and viruses, and
has neither made a significant change to its
treatment practices nor changed sources since
the profile was developed; OR,
^ The system has at least 1 year of existing data
that can be used to complete a disinfection
profile, and has neither made a significant
change to its treatment practice nor changed
sources since the data were collected.
Complete disinfection profile and benchmark for
viruses and Giardia lamblia.
*A significant change in disinfection practice is defined as (1) change in the point of disinfection, (2) change to the type of disinfectant, (3) change to the disinfection
process, or (4) any other modification designated by the state.
Office of Water (4606M)
EPA 816-F-10-074
http://water.epa.gov/drink
August 2010
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