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Water: ucmr2

Unregulated Contaminant Monitoring Rule 2 (UCMR 2)

The second Unregulated Contaminant Monitoring Rule (UCMR 2) was published on January 4, 2007. The UCMR 2 required monitoring for 25 contaminants using five analytical methods during 2008-2010. EPA, the States, laboratories and public water systems (PWSs) participated in UCMR 2.

Federal Register Notice

The UCMR design divides contaminants into three types of monitoring. Similarly to UCMR 1, UCMR 2 included both Assessment Monitoring and a Screening Survey.

  • Assessment Monitoring uses common analytical method technologies used by drinking water laboratories. For UCMR 2, all PWSs serving more than 10,000 people and 800 representative PWSs serving 10,000 or fewer people were required to monitor for the 10 List 1 contaminants during a 12-month period from January 2008 through December 2010.
  • Screening Survey monitoring uses specialized analytical method technologies not as commonly used by drinking water laboratories. All PWSs serving more than 100,000 people, 320 representative PWSs serving 10,001-100,000 people and 480 representative PWSs serving 10,000 or fewer people were required to monitor for 15 List 2 contaminants during a 12-month period from January 2008 through December 2010.
  • Pre-Screen Testing uses newer method technologies not as commonly used by drinking water laboratories. UCMR 2 did not include List 3 contaminants.

EPA paid for the analysis of all samples from systems serving 10,000 or fewer people. Additionally, EPA coordinated a Laboratory Approval Program for the contaminants. UCMR 2 required laboratories have EPA approval to analyze PWS samples.


  • Basic Information – Basic information and audience specific fact sheets outlining various aspects of the regulation
  • Methods & Contaminants – List of contaminants and corresponding analytical methods
  • Laboratories – Information describing the Laboratory Approval Program
  • Reporting – Information on reporting requirements, data elements and the electronic reporting system, Safe Drinking Water Accession and Review System (SDWARS)

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