United States
Environmental Protection
Agency
Long Term 2 Enhanced Surface Water
Treatment Rule: A Quick Reference
Guide For Schedule 1 Systems
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.
Public water systems (PWSs) that use surface water or ground water under the direct influence
of surface water (GWUDI).
Schedule 1 systems include PWSs serving 100,000 or more people OR wholesale PWSs that are
part of a combined distribution system in which the largest system serves 100,000 or more
people.
Major Pr ov i s i on s
Control of Cryptosporidium
Source Water
Monitoring
Installation of
Additional
Treatment
Uncovered
Finished Water
Storage Facility
Filtered and unfiltered systems must conduct 24 months of source water monitoring for
Cryptosporidium. Filtered systems must also record source water E. coli and turbidity levels.
Filtered systems will be classified into one of four "Bins" based on the results of their source
water monitoring. Unfiltered systems will calculate a mean Cryptosporidium level to
determine treatment requirements. Systems may also use previously collected data (i.e.,
Grandfathered data).
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.
Bin Classifi cati on F
Cryp tosp oridium
Concentration
(oocysts/L)
< 0.075
0.075 to < 1.0
1.0 to < 3.0
>3.0
Bin
Classification
Bin 1
Bin 2
Bin3
Bin 4
Additional Cryptosporidium Treatment
Required
Conventional
Filtration
No additional
treatment
required
1 log
2 log
2.5 log
Direct
Filtration
No additional
treatment
required
1.5 log
2.5 log
Slog
Slow Sand or
Diatomaceous
Earth Filtration
No additional
treatment required
1 log
2 log
2.5 log
Alternative
Filtration
No additional
treatment
required
(1)
(2)
(3)
(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.
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For additional information
on the LT2ESWTR
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
yourState drinking water
representative.
1 nactivation Requirements for Unfiltered Systems
Cryptosporidium Concentration Required Cryptosporidium
(oocysts/L) Inactivation
< 0.01 2-log
> 0.01 3-log
Critical Deadlines and Requirements
For Drinking Water Systems (Schedule 1)
July 1, 2006
October 2006
December 10, 2006
December 1, 2006
April 1, 2008
September 2008
March 2009
March 2009
April 1, 2009
March 31, 2012
January 1, 2015
April 1, 2015
Systems must submit their:
> Sampling schedule that specifies the dates of sample collection and location of
sampling for initial source water monitoring to EPA electronically; or
> Notify EPAor the state of the systems intent to submit results for grandfathering data;
or
> Notify EPAor the state of the systems intent to provide at least 5.5 log of treatment for
Cryptosporidium. Systems should consult with EPAor their state prior to submitting
this notice.
No later than this month systems must begin 24 months of source water monitoring.
System submit results for first month of source water monitoring.
No later than this date, systems must submit monitoring results for data that they want to
have grandfathered.
No later than this date, systems must notify the EPAor the state of all uncovered treated
water storage facilities.
No later than this month, systems must complete their inital round of source water
monitoring.
No later than this month, filtered systems must report their initial bin classification to the
EPAor the state for approval.
No later than this month, unfiltered systems must report the mean of all Cryptosporidium
sample results to the EPAor the state.
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.
Systems must install and operate additional treatment in accordance with their bin
classification.!
Systems must submit their sampling schedule that specifies the dates of sample collection
and location of sampling for second round of source water monitoring to the state.
> Systems are required to begin conducting a second round of source water monitoring.
> Based on the results, systems must re-determine their bin classification and provide
additional Cryptosporidium treatment, if necessary.
For States
January - June 2006
April 1, 2007
October 5, 2007
January 5, 2008
June 30, 2008
January 5, 2010
December 31, 2012
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 awarding Cryptosporidium treatment credit for primary treatments 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-06-005
www.epa.gov/safewater
June 2006
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