ag/ LT2ESWTR Laboratory Factsheet
WHAT is THE LT2ESWTR?
The U.S. Environmental Protection Agency (EPA) published the Long Term 2 Enhanced Surface Water
Treatment Rule (LT2ESWTR) on January 5, 2006. The goal of the LT2ESWTR is to improve control of
microbial pathogens by identifying water systems whose source water is vulnerable to contamination
by Cryptosporidium and requiring those systems to treat for that greater risk. Key provisions of the
LT2ESWTR include:
• Source water monitoring at public water systems (PWSs) that use surface water or ground water
under the direct influence of surface water (GWUDI).
• Monitoring for Cryptosporidium, E. coli, and turbidity based on system size and filtration type.
• Using Surface water or GWUDI source water monitoring data to categorize the sources
according to four "bin" classifications that have associated treatment requirements. Systems
that avoid filtration will be placed into one of two categories based on source water
monitoring, and will have to meet specified inactivation requirements.
• Using grandfathered data collected before the system must begin Cryptosporidium source
water monitoring, if the data meet rule requirements. Systems may use this data instead of
conducting source water monitoring.
For detailed information regarding source water monitoring, including sampling and shipping
procedures, systems should consult the Source Water Monitoring Guidance Manual For Public Water
Systems For The Final Long Term 2 Enhanced Surface Water Treatment Rule [EPA 815-R06-005
February 2006]), atwww.epa.gov/safewater/disinfection/lt2.
WHICH LABORATORIES MUST SYSTEMS USE?
PWSs must use laboratories or personnel approved for source water monitoring analyses required by
the rule (i.e., Cryptosporidium, E. coli, and turbidity sampling).
• Cryptosporidium analysis: EPA approves laboratories through the Laboratory Quality Assurance
Evaluation Program (the Lab QA Program) to analyze Cryptosporidium. The purpose of the Lab
QA Program is to identify laboratories that can reliably measure the presence of
Cryptosporidium in surface water using the EPA Method 1622 or 1623. A list of commercial,
government, PWS, and university laboratories approved or pending approval to analyze
Cryptosporidium is located at www.epa.gov/safewater/disinfection/lt2/lab aprvlabs.html.
• E. coli analysis: Laboratories must be certified by EPA, the National Environmental Laboratory
Accreditation Conference, or the state to analyze E. coli.
• Turbidity analysis: Analysis must be conducted by a party approved by the state, which usually
means a state-certified operator or a professional engineer. You should consult with your state
for specific state requirements.
Commercial laboratories and other laboratories that accept samples from an outside party may charge
varying rates. Systems may consider contacting multiple laboratories to compare costs. For detailed
information on contracting laboratory services, consult the Source Water Monitoring Guidance Manual
for Public Water Systems for the Final Long Term 2 Enhanced Surface Water Treatment Rule [EPA 815-
R06-005 February 2006], or go online at www.epa.gov/safewater/disinfection/lt2.
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WHAT METHODS MUST LABORATORIES USE?
Laboratories and personnel must use methods approved by EPA for Cryptosporidium, E. coli, and
turbidity, as presented in the following tables.
Approved Methods for E. coli
Standard Methods 9223B (Colilert/Colilert-18)®
Standard Methods 9221B/9221F (LTB-EC-MUG)
Standard Methods 9222D/9222G (mFC-NA-MUG)
Standard Methods 9213D/ EPA Method 1103.1 (mTEC)
EPA Method 1603 Modified mTEC
EPA Method 1604 Ml medium
m-ColiBlue24Broth
Standard Methods 9222B/9222G (mEndo/LES-Endo-
NA-MUG)
Approved Methods for Turbidity
Method 2130 B
Revised Method 180.1
Great Lakes Instrument (GLI) Method 2
Approved Methods for Cryptosporidium
Method 1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA, United States Environmental
Protection Agency, EPA-815-R-05-002. 2005.
Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, United States Environmental Protection
Agency, EPA-815-R-05-001. 2005.
WHEN SHOULD SYSTEMS CONTACT LABORATORIES?
PWSs should contact laboratories to discuss contracts and sampling dates as soon as possible. The
number of samples processed each day will impact the laboratory's capacity. The PWS and the
laboratory must agree on calendar dates for monthly, or more frequent, sample analysis because the
PWS must submit a monitoring schedule no later than 3 months before monitoring begins. Monitoring
start dates are summarized in the following table.
Systems that serve...
At least 100,000 people or part of a combined distribution system
serving at least 100,000 people
50,000 to 99,999 people or part of a combined distribution system
serving at least 50,000 to 99,999 people
10,000 to 49,999 people or part of a combined distribution system
serving at least 10,000 to 49,999 people
Less than 10,000 or part of a combined distribution system serving less
than 10,000 people, and are filtered and monitoring for E. coli
Less than 10,000 or part of a combined distribution system serving less
than 10,000 people, and are monitoring for Cryptosporidium^
Must begin the first round of source
water monitoring...
October 2006
April 2007
April 2008
October 2008
April 2010
1Applies to filtered systems that exceed the E. coli trigger or decide not to monitor for E. coli, and to unfiltered systems.
For additional information, please contact the Safe Drinking Water Hotline at 1-800-426-4791,
send an email to stage2mdbp@epa.gov, or visit www.epa.gov/safewater/disinfection/lt2.
Office of Water (4606)
EPA816-F-06-020
www.epa.gov/safewater/disinfection/lt2
June 2006
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