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Water: Public Water Systems

Laboratories & Monitoring

EPA's drinking water standards program has established health based standards for more than 80 contaminants.  Water systems are responsible for conducting monitoring of drinking water to ensure that it is meets all drinking water standards.  To do this, water systems and States use analytical methods developed by  government agencies, universities, and other organizations.  EPA is responsible for evaluating analytical methods developed for drinking water and approves those methods that it determines meet Agency requirements for monitoring organic, inorganic, radionuclide and microbiological contaminants.  Laboratories analyzing drinking water compliance samples must be certified by EPA or the State. 


In addition to setting health based standards, EPA establishes schedules outlining how often water systems must monitor for the presence of contaminants.  The frequency of monitoring is often dependent on the contaminant and the population served by the water system.  Water systems serving large populations generally require more monitoring because of the greater potential impact of violations.  Small water systems can receive variances or exemptions from monitoring in limited circumstances.  EPA has proposed alternatives to standard monitoring requirements and is planning to revise the chemical monitoring regulations through a Chemical Monitoring Reform effort.

  • Unregulated Contaminant Monitoring Rule Revisions, September, 1999
  • -Unregulated Contaminant Monitoring Rule
    This page includes links to the rule, guidance documents, fact sheets, the contaminant candidate list, and the January 1999 direct final rule which suspended UCMR requirements for small systems.

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