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Nov. 19, 2007

Drinking Water Monitoring per the UCMR2 Rule

Author: Dr. Kim Baughman

The Unregulated Contaminant Monitoring Rule 2 (UCMR2), published in the Federal Register on January 4, 2007, took effect in January of 2008.  This regulation is part of the Environmental Protection Agency’s (EPA) response to the Safe Drinking Water Act (SDWA), which requires the EPA to identify up to 30 contaminants every five years that are not currently regulated.  Results will be used to evaluate the rate of contamination throughout the country and can be used to set future standards.

There are 25 contaminants in the UCMR2 study.  These include insecticides and herbicides and their degradants, explosives, flame retardants, and nitrosamines.  There are actually two separate lists.  List 1 includes 10 contaminants, which are determined by two analytical methods.  All public water systems (PWS’s) that serve more than 10,000 people and 800 PWS’s serving fewer than 10,000 people are required to sample for the 10 compounds on List 1.  This must be performed on a quarterly basis over a 12-month period between January 2008 and December 2010.

List 2 contains an additional 15 contaminants, which are determined by three analytical methods.  Monitoring for these compounds is required by PWS’s serving more than 100,000 people and 800 systems serving fewer than 100,000 people.

The EPA issued four new methods for this program (521, 527, 529, and 535). A fifth method, 525.2, is also used for the analyses.  Laboratory approval occurs directly through the EPA, and is achieved by demonstrating the capability and proficiency directly to the agency.  Full laboratory participation is more limited than in most drinking water programs because two of the instruments required, Gas Chromatograph/Mass Spectrometer/Mass Spectrometer (GC/MS/MS) and Liquid Chromatograph/Mass Spectrometer/Mass Spectrometer (LC/MS/MS), are not standard equipment in many environmental laboratories.

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