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Water: Laboratory Certification

Basic Information about Analytical Methods and Laboratory Certification under the Safe Drinking Water Act

Laboratory Role

Laboratories analyze public water systems’ (PWSs) water samples and provide the PWSs with information on the quality of their water.

Water sample types analyzed and purposes of analysis:

  • Source water samples are analyzed to check for contamination and determine general water quality characteristics that influence the treatment processes.
  • Process water samples are analyzed to provide key information relevant to treatment optimization.
  • Finished water samples are analyzed to verify the water meets health-based and aesthetic standards and periodically check for contaminants that are not regulated in drinking water.

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Water System Monitoring Frequency

Monitoring schedules differ according to the type of contaminant, the type of source water used to produce drinking water, and the population served by the public water system. Each regulation outlines the requirements that systems must follow. EPA’s Quick Reference Guides provide a simple overview of the monitoring requirements associated with most regulations.

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Analytical Method

An analytical method is a procedure that determines the concentration of a contaminant in a water sample.

Analytical methods generally describe:

  • How to collect, preserve, and store the sample.
  • Procedures to concentrate, separate, identify, and quantify contaminants present in the sample.
  • Quality control criteria the analytical data must meet.
  • How to report the results of the analysis.

In general, an analytical method:

  • Is applicable to routine analyses of samples.
  • Is suitable for measuring the drinking water contaminant in the concentration range of interest.
  • Provides data with the necessary accuracy and precision to demonstrate compliance or meet monitoring objectives in a wide variety of drinking water matrices.
  • Includes instructions for all aspects of the analysis from sample collection to data reporting.
  • Incorporates appropriate quality control criteria so that acceptable method performance is demonstrated during the analysis of samples.

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Drinking Water Method Developers

EPA obtains analytical methods from a variety of sources. Many methods are developed by EPA or other governmental organizations. Consensus method organizations such as Standard Methods and ASTM, International often provide methods that are suitable for drinking water analyses. Methods may also be developed by university, commercial or public water system laboratories, and by commercial vendors.

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EPA Method Approval Processes

When a monitoring requirement for a contaminant is established, EPA approves at least one analytical method by specifying it in the regulation. Additional methods for the contaminant may be approved by issuing another regulation or by publishing an action in the Federal Register.

Drinking water methods must be approved by EPA before they can be used to analyze samples to meet federal monitoring requirements or to demonstrate compliance with drinking water regulations. New drinking water methods may be submitted to EPA for evaluation under EPA’s Alternate Test Procedure (ATP) program. The ATP program evaluates methods that are alternatives to the test procedures that are listed in the drinking water regulations.

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Laboratory Certification Requirements

Laboratories analyzing drinking water compliance samples must be certified by U.S. EPA or the State. Certified laboratories must successfully analyze proficiency testing samples, use approved methods, and successfully pass periodic on-site audits.

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Water System Sampling Results

Each year by July 1 you should receive in the mail a short report (consumer confidence report or drinking water quality report) from your water supplier that tells where your water comes from and what is in it. You can also contact your local supplier if you have questions about their results of testing. If you want to have your water tested, EPA recommends you use a lab certified by your state.

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Laboratory Fraud

EPA recommends that state laboratory certification programs and certified labs develop fraud detection programs to ensure that the public can have confidence in drinking water analytical results.

If you suspect fraudulent activity related to drinking water analysis, notify:

If the suspected fraud involves EPA staff, programs or contracts, contact EPA’s Office of Inspector General (OIG).

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