oEPA
United States
Environmental Protection
Agency
For additional information on
theLT2ESWTR
Call the Safe Drinking Water
Hotline at 1-800-426-4791;
visit the EPA web site at
www.epa.gov/safewater/
disinfection/lt2; or contact
your state drinking water
representative.
Long Term 2 Enhanced Surface Water
Treatment Rule: A Quick Reference
Guide For Schedule 4 Systems
Overview of the R
Title
Purposes
General
Description
Utilities
Covered
Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) 71 FR 654, January 5, 2006,
Vol.71, No. 3
Improve public health protection through the control of microbial contaminants by focusing on systems
with elevated Cryptosporidium risk. Prevent significant increases in microbial risk that might otherwise
occur when systems implement the Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2
DBPR).
The LT2ESWTR requires systems to monitor their source water, calculate an average Cryptosporidium
concentration, and use those results to determine if their source is vulnerable to contamination and may
require additional treatment. Filtered systems serving fewer than 10,000 may be eligible to conduct £ Co//
source water monitoring in lieu of Cryptosporidium monitoring.
Public water systems (PWSs) that use surface water or ground water under the direct influence of
surface water (GWUDI).
Schedule 4 systems include PWSs serving fewer than 10,000 people OR wholesale PWSs that are part
of a combined distribution system in which the largest system serves less than 10,000 people.
Control of Cryptosporidium
Source Water
Monitoring
Installation of
Additional
Treatment
Uncovered Finished
Water Storage
Facility
Filtered systems must conduct 12 months of source water monitoring for E. call. If the E. call trigger level
is exceeded, the system must conduct an additional 12 to 24 months of source water monitoring for
Cryptosporidium. Systems may also use previously collected data (i.e., Grandfathered data).
Unfiltered systems must sample their source water for Cryptosporidium at least twice per month for 12
months or once per month for 24 months. Unfiltered systems will calculate a mean Cryptosporidium level to
determine treatment requirements.
Filtered systems providing at least 5.5 log of treatment for Cryptosporidium and Unfiltered systems
providing at least 3-log of treatment for Cryptosporidium and those systems that intend to install this level
of treatment are not required to conduct source water monitoring.
Filtered systems must provide additional treatment for Cryptosporidium based on their bin classification
(average source water Cryptosporidium concentration), using treatment options from the "microbial
toolbox."
Unfiltered systems must provide additional treatment for Cryptosporidium using chlorine dioxide, ozone, or
UV.
Systems with an uncovered finished water storage facility must either:
> Cover the uncovered finished water storage facility; or,
* Treat the discharge to achieve inactivation and/or removal of at least 4-log for viruses, 3-log for
Giardia lamblia, and 2-log for Cryptosporidium.
Disinfection Profiling and Benchmarking
After completing the initial round of source water monitoring any system that plans on making a significant change to their
disinfection practices must:
Create disinfection profiles for Giardia lamblia and viruses;
Calculate a disinfection benchmark; and,
Consult with the state prior to making a significant change in disinfection practice.
Cryptosporidium
Concentration
(oocysts/L)
< 0.075
0.075 to < 1.0
1.0to<3.0
>3.0
Bin
Classification
Binlft
Bin 2
Bin 3
Bin 4
Additional Cryptosporidium Treatment Required
Conventional
Filtration
Direct
Filtration
Slow Sand or
Diatomaceous
Earth Filtration
Alternative
Filtration
No additional treatment required
1 log
2 log
2.5 log
1.5 log
2.5 log
Slog
1 log
2 log
2.5 log
(D
(2)
(3)
ft Systems serving < 10,000 people that are not required to monitor for Cryptosporidium are placed in Bin 1.
(1) As determined by the state (or other primacy agency) such that the total removal/inactivation > 4.0-log.
(2) As determined by the state (or other primacy agency) such that the total removal/inactivation > 5.0-log.
(3) As determined by the state (or other primacy agency) such that the total removal/inactivation > 5.5-log.
Inactivation Requirements for Unfiltered Systems
Cryptosporidium Concentration (oocysts/L)
<0.01
>0.01
Required Cryptosporidium Inactivation
2-log
3-log
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Critical Deadlines and Requirements
For Drinking Water Systems (Schedule 4)
July 1,2008
October 2008
December 1 , 2008
December 10, 2008
April 1,2008
April 1,2009
September 2009
January 1, 2010
April 2010
June 1,2010
June 10, 2010
March 2012
September 2012
September 2012
September 30, 2014
July 1,2017
October 1,201 7
January 1, 2019
April 1,201 9
Systems must submit their:
> Sampling schedule that specifies the dates of sample collection and location of sampling for initial source water
monitoring; or
> Notice to EPA or the state of the system's intent to submit results for grandfathering data; or
> Notice to EPA or the state of the system's intent to provide at least 5.5-log of treatment for Cryptosporidium for
filtered systems or 3-log of treatment for unfiltered systems. Systems should consult with EPA or their state prior to
submitting this notice.
> Notice to EPA or the state of the system's intent to conduct Cryptosporidium monitoring instead of E. coli monitoring.
No later than this month, filtered systems must begin 12 months of bi-weekly source water monitoring for E. coli.
No later than this date, systems must submit E. coli monitoring results for data that they want to have grandfathered.
Systems submit results for first month of £. coli source water monitoring.
No later than this date, systems must notify the EPA or the state of all uncovered treated water storage facilities.
No later than this date, uncovered finished water storage facilities must be covered, or the water must be treated before
entry into the distribution system, or the system must be in compliance with a state approved schedule.
No later than this month, systems that were required to monitor their source water for £. coli complete their inital round
of source water monitoring.
Filtered systems required to monitor for Cryptosporidium must submit their sampling schedule that specifies the dates of
sample collection and location of sampling for source water monitoring.
No later than this month, systems required to conduct Cryptosporidium monitoring must begin 12 or 24 months of source
water monitoring.
No later than this date, systems must submit Cryptosporidium monitoring results for data that they want to have
grandfathered.
Systems submit results for first month of Cryptosporidium source water monitoring.
No later than this month, systems that were required to monitor their source water for Cryptosporidium complete their
inital round of source water monitoring
No later than this month, filtered systems that were required to monitor their source water for Cryptosporidium must
report their initial bin classification to the EPA or the state for approval.
No later than this month, unfiltered systems must report the mean of all Cryptosporidium sample results to the EPA or the
state.
Systems must install and operate additional treatment in accordance with their bin classification or mean
Cryptosporidium level. t
Systems must submit their sampling schedule that specifies the dates of sample collection and location of sampling for
second round of £. coli source water monitoring to the state.
Systems are required to begin conducting a second round of £. coli source water monitoring. Based on the results,
systems must re-determine their bin classification and provide additional treatment, if necessary.
Systems must submit their sampling schedule that specifies the dates of sample collection and location of sampling for
second round of Cryptosporidium source water monitoring to the state.
Systems are required to begin conducting a second round of Cryptosporidium source water monitoring. Based on the
results, systems must re-determine their bin classification (filtered systems) or mean Cryptosporidium level (unfiltered
systems) and provide additional treatment, if necessary.
For States
July - December
2006
April 1,2007
October 5, 2007
January 5, 2008
June 30, 2010
Januarys, 2010
June 30, 2015
States are encouraged to communicate with affected systems regarding LT2ESWTR requirements.
States are encouraged to communicate LT2ESWTR requirements related to treatment, uncovered finished water
reservoirs, and disinfection profiling to affected systems.
States are encouraged to submit final primacy applications or extension requests to EPA.
Final primacy applications must be submitted to EPA, unless granted an extension.
States should begin determining Cryptosporidium treatment credit for primary treatments already in place.
Final primacy revision applications from states with approved 2-year extensions agreements must be submitted to EPA.
States should award Cryptosporidium treatment credit for toolbox option implementation.
t States may allow up to an additional 24 months for compliance for systems making capital improvements.
Office of Water (4606)
EPA816-F-06-008
www.epa.gov/safewater
June 2006
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