LT2ESWTR Source Water Monitoring for Systems Serving At Least 10,000 People 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 LT2ESWTR improves control of microbial pathogens. The LT2ESWTR requires source water monitoring at public water systems (PWSs) that use surface water or ground water under the direct influence of surface water (GWUDI) (i.e., Subpart H PWSs). Based on system size and filtration type, systems need to monitor for Cryptosporidium, E. coli, and turbidity.

WHAT IS THE PURPOSE OF SOURCE WATER MONITORING?

Source water monitoring data will be used to categorize the source water Cryptosporidium concentration into one of four “bin” classifications that have associated treatment requirements. The LT2ESWTR provides other options for systems to comply with the initial source water monitoring requirements:

Submit data from Cryptosporidium samples collected before the system must begin source water monitoring (i.e., Grandfathered), and the data must meets certain requirements.

Filtered systems may skip source water monitoring and commit to provide a total of at least 5.5- log of treatment for Cryptosporidium, equivalent to meeting the treatment requirement of Bin 4. Unfiltered systems skip source water monitoring and commit to provide a total of at least 3-log Cryptosporidium inactivation, which is equal to meeting the treatment requirements for unfiltered systems with a mean Cryptosporidium concentration of greater than 0.01 oocysts/L. Systems that decide to skip monitoring and provide maximum treatment must notify the state in writing.

A second round of source water monitoring will follow 6 years after the system makes its initial bin determination. Grandfathering is not available for the second round of source water monitoring.

 

Note: E. coli and turbidity data may not be grandfathered unless the system is also grandfathering corresponding Cryptosporidium data.

WHAT ARE THE INITIAL SOURCE WATER MONITORING REQUIREMENTS?

 

The source water monitoring requirements of the LT2ESWTR apply to all Subpart H PWSs. You are subject to initial source water monitoring requirements if you do not have existing monitoring data that meets grandfathering requirements. For more information on source water monitoring requirements, see EPA’s 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), available at www.epa.gov/safewater/disinfection/lt2/compliance.html.

Prior to beginning initial source water monitoring, you must submit a sampling schedule that specifies the calendar dates when you will collect the required source water samples. The samples must be evenly spaced throughout the monitoring period (e.g., monthly on the 15th of each month). However, the schedule may be altered to take into account holidays, weekends, or other events. All the samples must be taken within a 5-day window (i.e., you can take the sample up to 2 days before or 2 days after

the date indicated in the schedule). In addition, you must submit a description of the intended sampling location in relation to the source and any treatment processes, as well as a description of any points of chemical addition, and filter backwash recycle.

 

FILTERED SYSTEMS SERVING AT LEAST 10,000 PEOPLE – You must collect Cryptosporidium,

  1. coli and turbidity samples at least monthly for 24 months.

 

UNFILTERED SYSTEMS SERVING AT LEAST 10,000 PEOPLE – You must sample for Cryptosporidium

at least monthly for 24 months.

 

Alternately, you may notify the EPA or the state that you elect not to conduct source water monitoring and commit to providing the maximum treatment of 5.5 log removal or inactivation for filtered systems or 3-log inactivation for unfiltered systems.

WHEN MUST I COMPLY WITH THE MONITORING REQUIREMENTS?

 

The system compliance schedule is based on the population served by your system. A PWS must conduct monitoring based on the requirements of the largest system in the combined distribution system. The interconnected wholesale/consecutive systems relationships have been determined by the state.

 

Systems that serve… > 100,000 people

(Schedule 1) 1

50,000 to 99,999

people (Schedule 2) 1

10,000 to 49,999

people (Schedule 3) 1

Submit: Sample Schedule and Sample Location Description July 1, 2006 January 1, 2007 January 1, 2008
Must begin the first round of source water monitoring by… October 2006 April 2007 April 2008
Submit Grandfathered Data (if applicable) December 1, 2006 June 1, 2007 June 1, 2008
Submit Bin Classification (Filtered) or Mean Cryptosporidium Level (Unfiltered) March 2009 September 2009 September 2010
Comply with additional LT2ESWTR treatment technique requirements2 April 1, 2012 October 1, 2012 October 1, 2013
Must begin the second round of source water monitoring by… April 2015 October 2015 October 2016

1 Your schedule is defined by the largest system in your combined distribution system.

2 State may allow up to an additional 2 years for capital improvements to comply with the treatment technique.

 

WHAT IS A BIN CLASSIFICATION?

 

FILTERED SYSTEMS SERVING AT LEAST 10,000 PEOPLE – You will be classified into a “bin” based on the results of your source water monitoring. Your bin classification determines whether further treatment for Cryptosporidium is required. A second round of source water monitoring is required 6 years after your initial bin classification and may affect your bin classification.

 

 

For systems that are:

Mean Cryptosporidium

Concentration1

 

Bin Classification

…required to monitor for Cryptosporidium < 0.075 oocysts/L Bin 1
from 0.075 to < 1.0 oocysts/L Bin 2
from 1.0 to < 3.0 oocysts/L Bin 3
> 3.0 oocysts/L Bin 4

1 Samples must be analyzed by an approved laboratory and use EPA method 1622 or 1623.

 

ADDITIONAL TREATMENT REQUIREMENTS FOR FILTERED SYSTEMS – Additional treatment is required if the bin classification is a 2, 3, or 4. Refer to the table below for the additional Cryptosporidium treatment requirements.

 

Bin Classification If the system uses the following filtration treatment in full compliance with existing requirements, then the additional Cryptosporidium treatment requirements are…
Conventional filtration treatment (including softening)  

Direct filtration

Slow sand or diatomaceous earth filtration Alternative filtration technologies
Bin 1 No additional treatment No additional treatment No additional treatment No additional treatment
Bin 2 1-log treatment 1.5-log treatment 1-log treatment (1)
Bin 3 2-log treatment 2.5-log treatment 2-log treatment (2)
Bin 4 2.5-log treatment 3-log treatment 2.5-log treatment (3)
  • As determined by the state such that the total Cryptosporidium removal and inactivation is at least 0-log.
  • As determined by the state such that the total Cryptosporidium removal and inactivation is at least 0-log.
  • As determined by the state such that the total Cryptosporidium removal and inactivation is at least 5-log.

For information on the toolbox options that can be used to achieve additional log removal requirements, see the Long Term 2 Enhanced Surface Water Treatment Rule Toolbox Guidance Manual (draft version anticipated late 2006).

 

UNFILTERED SYSTEMS SERVING AT LEAST 10,000 PEOPLE – You must calculate an arithmetic mean of all Cryptosporidium samples concentrations required. Following completion of the second round of source water monitoring, you must provide a level of inactivation for Cryptosporidium based on the arithmetic mean of your Cryptosporidium sample concentrations.

 

 

For systems that are:

Mean Cryptosporidium

Concentration1

 

Cryptosporidium inactivation

Unfiltered < 0.01 oocysts/L 2-log
> 0.01 oocysts/L 3-log

1 Samples must be analyzed by an approved laboratory and use EPA method 1622 or 1623.

 

ARE YOU CONSIDERING MAKING A CHANGE TO YOUR DISINFECTION PRACTICES?

 

After completing the initial round of source water monitoring, systems that plan to make a significant change to their disinfection practice must notify the state, develop disinfection profiles, and calculate disinfection benchmarks for Giardia lamblia and viruses. To develop a profile and benchmark, PWSs must monitor at least weekly for a period of 12 consecutive months to determine the total log inactivation for Giardia lamblia and viruses. The disinfection benchmark is an indicator of disinfection effectiveness and depends upon the inactivation of Giardia lamblia or viruses. The benchmark is determined by calculating the average daily inactivation value for each of 12 consecutive months. The lowest monthly average becomes the disinfection benchmark. If the PWS has data from more than 1 year, the benchmark is the average of the lowest monthly average value for each of the years. A PWS may use grandfathered data that is substantially equivalent to develop the disinfection profiles for Giardia lamblia and viruses. The Long Term 1 Enhanced Surface Water Treatment Rule (LT1ESWTR) Disinfection Profiling and Benchmarking Technical Guidance Manual (EPA 816-R-03-004, May 2003), provides guidance for developing a disinfection profile and benchmark. EPA has developed two tools for systems to determine their disinfection profile and calculate the benchmark at the following website: http://www.epa.gov/safewater/mdbp/lt1eswtr.html.

ADDITIONAL GUIDANCE MATERIALS

 

The following guidance document addresses the source water monitoring requirements for the LT2ESWTR:

 

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) – Provides surface water systems, laboratories, states, and Tribes with a review of the source water monitoring provisions. The source water monitoring guidance manual provides direction to the systems on how, where and when to monitor, how to report the data, how to submit “grandfathered” data (e.g., previously collected data), and how the data can be evaluated and used to determine risk bin classification.

 

For additional guidance on implementing the LT2ESWTR, you may refer to the following existing and future EPA materials:

LT2ESWTR Quick Reference Guides (Schedules 1 – 3) On-line Microscopy Training Module

On-line Sample Collection Module

Microbial Laboratory Guidance Manual for the Final Long Term 2 Enhanced Surface Water Treatment Rule (EPA 815-R06-006 February 2006)

Membrane Filtration Guidance Manual (EPA 815-R-06-009 November 2005)

Membrane Filtration Guidance Manual: Overview and Summary Factsheet (www.epa.gov/safewater/disinfection/lt2/pdfs/guide_lt2_membranefiltration_fs_final.pdf)

Ultraviolet Disinfection Guidance Manual and Workbook (final version anticipated mid-2006)

Simultaneous Compliance Guidance Manual for Stage 2 Rules (draft version anticipated mid-2006)

Long Term 2 Enhanced Surface Water Treatment Rule Toolbox Guidance Manual (draft version anticipated late 2006)

For additional information, please contact the Safe Drinking Water Hotline at 1-800-426-4791, send an email to [email protected], or visit www.epa.gov/safewater/disinfection/lt2.

Office of Water (4606)                 EPA 816-F-06-017                  www.epa.gov/safewater/disinfection/lt2        June 2006