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Certification of Laboratories for Drinking Water

Learn About Laboratory Certification for Drinking Water

On this page:

Laboratory role

Certified laboratories use approved methods to analyze drinking water compliance samples from public water systems (PWSs). This provide the PWSs with reliable information on the quality of their water. The laboratory results are used to monitor PWS compliance with health-based and aesthetic standards.

Laboratories must:

  • Be certified by EPA or the state to analyze drinking water samples for compliance monitoring
  • Successfully analyze proficiency testing (PT) samples at least annually for each method and analyte for which they desire certification
  • Use approved methods
  • Pass periodic on-site audits

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Proficiency testing studies

Many states use PT providers accredited by the American Association for Laboratory Accreditation (A2LA) or the American National Standards Institute (ANSI)-American Society for Quality (ASQ) National Accreditation Board/ACLASS.

State certification programs may:

  • Require laboratories to participate in a specific PT program or permit participation in any accredited PT study
  • Elect to serve as PT study providers themselves
  • Require PWSs to have their PT results sent directly to the state by the PT study provider
  • Increase the frequency of PT studies

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Laboratory integrity

EPA recommends that state laboratory certification programs and certified labs develop standard operating procedures for consistently producing drinking water analytical results that are reliable.

Developing standard operating procedures:

  • Deters fraud
  • Helps ensure appropriate practices
  • Helps maintain the integrity of drinking water analytical results

If you suspect fraudulent or inappropriate activity related to drinking water analysis, contact your state, your EPA region, or EPA’s Office of Enforcement and Compliance Assurance.

If the suspected fraud involves laboratories that do business with EPA, contact EPA’s Office of Inspector General.

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