EPA Develops Microbial Laboratory Guidance Manual For LT2 Rule

On Feb. 27, EPA announced on its Web site the release of a guidance manual that provides information regarding analytical methods required for analysis of Cryptosporidium and E. coli samples under the Long Term 2 Enhanced Surface Water Treatment Rule (LT2 Rule).

The guidance manual also has information on other LT2 rule requirements for sample collection and analysis, analytical methods, recordkeeping and data reporting. It also provides information regarding laboratory quality control, the EPA Laboratory Quality Assurance Evaluation Program, and vendor suppliers.

The LT2 Rule was developed to improve control of microbial pathogens in drinking water, including specifically the protozoan Cryptosporidium, and to address risk trade-offs between control of microbial pathogens and control of disinfection byproducts. The LT2 Rule requires public water systems (PWSs) that use surface water or groundwater under the direct influence of surface water to monitor their source water (influent water prior to treatment plant) for Cryptosporidium, E. coli and turbidity for a limited period. Detailed guidance for sample collection during the LT2 Rule, and procedures for sample collection, documentation and shipment, are provided in the Source Water Monitoring Guidance Manual for Public Water Systems for the Long Term 2 Enhanced Surface Water Treatment Rule (see end of article for link to access the document).

According to the microbial laboratory guidance, two types of Cryptosporidium data are collected under the LT2 Rule: Cryptosporidium occurrence data from the analysis of field samples, and method performance data from the analysis of matrix spike (MS) samples. The use of occurrence data from field samples is discussed in section 1.3.1 of the document; the use of method performance data from MS samples is discussed in section 1.3.2. Section 1.4 of the manual discusses the collection of E. coli and turbidity data.

All laboratories analyzing Cryptosporidium and E. coli samples for the LT2 Rule should adhere to defined quality assurance (QA) procedures to ensure that analytical data generated under the rule are scientifically valid and are of known and acceptable quality, according to the document. Detailed quality control (QC) requirements and recommendations specific to Cryptosporidium and E. coli analyses are discussed in sections 3 and 4 of this manual, respectively.

The document -- Microbial Laboratory Guidance Manual for the Final Long Term 2 Enhanced Surface Water Treatment Rule -- and other LT2 compliance help documents can be accessed at http://www.epa.gov/safewater/disinfection/lt2/compliance.html.

This article originally appeared in the 03/01/2006 issue of Environmental Protection.

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