dEPA
    United States
    Environmental Protection
    Agency
Comprehensive Surface Water Treatment Rules
Quick Reference Guide: Systems Using Slow Sand,
Diatomaceous Earth, or Alternative Filtration
                         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
          Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) - 40 CFR
          141.500-141.571
           Improve public health protection through the control of microbial contaminants, particularly
           viruses, Giardia, 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 ajj 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.	
Overview of Requirements
The purpose of this table is show how the requirements for the IESWTR and LT1 ESWTR build on
the existing requirements established in the original SWTR.
APPLICABILITY: PWSs that use surface water or
ground water under the direct influence of surface
water (Subpart H) that practice slow sand,
diatomaceous earth or alternative filtration.
Population Served
Regulated
Pathogens
Residual
Disinfectant
Requirements
Turbidity
Performance
Standards
Disinfection Profiling
& Benchmarking
Sanitary Surveys
(state requirement)
>1 0,000
< 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
Combined Filter Effluent - Slow
Sand and Diatomaceous Earth
Combined Filter Effluent -
Alternative
Systems must profile inactivation
levels and generate benchmark, if
required
CWS: Every 3 years
NCWS: Every 5 years
Covered Finished Reservoirs/Water Storage Facilities
(new construction only)
Operated by Qualified Personnel as Specified by State
Final Rule Dates
SWTR
1989
/
/
/
^

,/
/
V
V
~

^
IESWTR
1998
V
N/A (except for
sanitary survey
provisions)
Regulated under
SWTR
Regulated under
SWTR
V
Regulated under
SWTR
Regulated under
SWTR
Regulated under
SWTR
^
V
^
^
Regulated under
SWTR
LT1 ESWTR
2002
^
Regulated under
SWTR
Regulated under
SWTR
^
Regulated under
SWTR
Regulated under
SWTR
Regulated under
SWTR
^
^
Regulated under
IESWTR
^
Regulated under
SWTR
                        (CWS) Community Water System    (NCWS) Non-community Water System

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Turbidity

Turbidity is measured as Combined Filter Effluent (CFE) for slow sand, diatomaceous earth, and alternative filtration. The
CFE 95th % value and CFE maximum value for slow sand and diatomaceous earth were not lowered in the IESWTR and
LT1ESWTR since these filtration technologies are assumed to provide 2-log Cryptosporidium removal with the turbidity
limits established by SWTR. Alternative filtration technologies (defined as filtration technologies other than conventional,
direct, slow sand, or diatomaceous earth) must demonstrate to the state that filtration and/or disinfection achieve 3-log
Giardia and 4-log virus removal and/or inactivation. The IESWTR and LT1 ESWTR also require alternative filtration technolo-
gies to demonstrate 2-log Cryptosporidium removal.
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.)
Slow Sand & Diatomaceous
Earth
Alternative
x Membranes
x Cartridges
x Other
CFE 95%
CFE Max
CFE 95%
CFE Max
Monitoring/
Recording
Frequency
At least every
4 hours*
At least every
4 hours*
At least every
4 hours*
At least every
4 hours*
SWTR
As of June
29, 1993
<1 NTU
5NTU
<1 NTU
5 NTU
IESWTR
>1 0,000 people
As of January 1, 2002
Regulated under SWTR
Regulated under SWTR
Established by state
Established by state
LT1 ESWTR
< 10,000 people
As of January 1,2005
Regulated under SWTR
Regulated under SWTR
Established by state
(not to exceed 1 NTU)
Established by state
(not to exceed 5 NTU)
*Monitoring frequency may be reduced by the state to once per day for systems using slow sand or alternative filtration.  Monitoring
frequency may be reduced by the state to once per day for systems serving 500 or fewer people regardless of type of filtration used.
 CFE  Turbidity:  Reporting Requirements
 Report to State:
     SWTR Measurements
    IESWTR Measurements
  LT1 ESWTR Measurements**
                    Total number of monthly
                    measurements
                               Total number of monthly
                               measurements
                              Total number of monthly
                              measurements
 Within 10 days after
 the end of the month:
Number and percent less than or
equal to designated 95th percent!le
turbidity limits
Number and percent less than or
equal to designated 95th percentile
turbidity limits
Number and percent less than or
equal to designated 95th percentile
turbidity limits
                    Date and value exceeding 5 NTU
                               Date and value exceeding 5 NTU
                               for slow sand and diatomaceous
                               earth or maximum level set by
                               state for alternative filtration
                              Date and value exceeding 5 NTU
                              for slow sand and diatomaceous
                              earth or maximum level set by state
                              for alternative filtration
 Within 24 hours:
Exceedances of 5 NTU for CFE
Exceedances of 5 NTU for slow
sand and diatomaceous earth or
maximum CFE level set by state
for alternative filtration
Exceedances of 5 NTU for slow
sand and diatomaceous earth or
maximum CFE level set by state for
alternative filtration
  Systems serving fewer than 10,000 people must begin complying with these requirements beginning January 1, 2005.

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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.


Cryptosporidium must be removed by filtration and no inactivation credits are currently given for disinfection. Systems
must also comply with the maximum residual disinfectant level (MRDL) requirements specified in the Stage 1 Disinfectants/
Disinfection Byproducts Rule (Stage 1 DBPR).
 Residual  Disinfectant  Monitoring  and  Reporting  Requirements
      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
or fewer persons 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.

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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  Under
 IESWTR  & LT1ESWTR
 The purpose of disinfection profiling and benchmarking is to allow systems and states to assess whether a change in disinfection
 practices creates a microbial risk. Systems should develop a disinfection profile that reflects Giardia lamblia inactivation (systems
 using ozone or chloramines must also calculate inactivation of viruses), 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
                 IESWTR
                    LT1ESWTR
 AFFECTED SYSTEMS:
Community, non-transient non-community, and
transient systems.
     Community and non-transient non-community
     systems only.
 BEGIN PROFILING BY:
April 1,2000
     >  July 1, 2003 for systems serving 500-9,999
       people.
     >  January 1, 2004 for systems serving fewer than
       500 people.
 FREQUENCY &
 DURATION:
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.
     Weekly inactivation of Giardia lamblia (and
     viruses, if necessary), on the same calendar day
     each week over 12 consecutive months.
 STATES MAY WAIVE
 DISINFECTION
 PROFILING
 REQUIREMENTS IF:
TTHM annual average <0.064 mg/L and HAA5
annual average <0.048 mg/L:
>  Collected during the same period.
>  Annual average is arithmetic average of the
   quarterly averages of four 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.
     One TTHM sample <0.064 mg/L and one HAA5
     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.
 DISINFECTION
 BENCHMARK MUST BE
 CALCULATED IF:
Systems required to develop a disinfection profile
and are considering any of the following:
>  Changes to the point of disinfection.
>  Changes to the disinfectant(s) used.
>  Changes to the disinfection process.
>  Any other modification identified by the state.

Systems must consult the state prior to making any
modifications to disinfection practices.
                                                                     Same as IESWTR, and systems must obtain state
                                                                     approval prior to making any modifications to
                                                                     disinfection practices.
      Office of Water (4606)
          EPA816-F-04-002
www.epa.gov/safewater
August 2004

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