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Water: Long Term 2 Enhanced Surface Water Treatment Rule

LT2 Rule

Welcome to the Long Term 2 Surface Water Treatment Rule (LT2 Rule) page. On this site you will find links to the rule, fact sheets as well as general information about the history of the rulemaking.

LT2 Rule

The purpose of the rule is to reduce disease incidence associated with Cryptosporidium and other disease-causing microorganisms in drinking water.

The rule will supplement existing regulations by targeting additional Cryptosporidium treatment requirements to higher risk systems. The rule also contains provisions to reduce risks from uncovered finished water storage facilities and to ensure that systems maintain microbial protection as they take steps to reduce the formation of disinfection byproducts. The rule will apply to all systems that use surface water or ground water under the direct influence of surface water.

The LT2 rule was published in the Federal Register on January 5, 2006.

Federal Register (FR) Notices
Fact Sheet

Rule Making History

new For LT2 public meeting materials, visit our Public Meetings page


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new LT2 Round 1 Source Water Monitoring Data

  • Cryptosporidium “cleaned up” data from monitoring under the LT2 Rule (CSV) (7MB)
    This file contains a “cleaned up” version of the Cryptosporidium data collected under Round 1 source water monitoring as required by the LT2 Rule.  A brief description of the data “clean up” process is provided in the document “Preparation of Round 1 LT2 monitoring data for EPA analyses”.  This “cleaned up” dataset also includes a dictionary describing the data fields.
  • E. coli “cleaned up” data from monitoring under the LT2 Rule (CSV) (7MB)
    This file contains a “cleaned up” version of the E. coli and turbidity monitoring data collected under Round 1 source water monitoring as required by the LT2 Rule.  A brief description of the data “clean up” process is provided in the document “Preparation of Round 1 LT2 monitoring data for EPA analyses”.  This “cleaned up” dataset also includes a dictionary describing the data fields.
  • Preparation of Round 1 LT2 monitoring Data for EPA analyses (PDF) (3 pp, 129K)
    This document describes the quality assurance (QA) and quality control (QC) steps that were taken to assess the LT2 Rule Round 1 Cryptosporidium and E. coli source water monitoring raw data.  The document also describes potential data quality concerns.
  • Cryptosporidium raw data from monitoring under the LT2 Rule (CSV)  (13MB)
    This file contains Cryptosporidium data collected under the Round 1 source water monitoring as required by the LT2ESWTR. The data are used by utilities to determine whether additional treatment for Cryptosporidium is needed. Data dictionary included.

  • E. coli raw data from monitoring under the LT2 Rule (CSV)  (17MB)
    This file contains E. coli and turbidity data collected under the Round 1 source water monitoring as required by the LT2ESWTR. The E. coli data are used by small utilities as a screen for Cryptosporidium to determine whether additional treatment and/or monitoring for Cryptosporidium is needed. Data dictionary included.

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LT2 Rule Supporting Documents

The following documents were developed to support the final rule-making: 

Additional Information

  • Quick Reference Guides to LT2 Rule
    These documents provide a simple and straight forward description of the rule, critical deadlines and requirements for drinking water systems and states, and information on monitoring requirements.

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