Proficiency Testing

Welcome to the Environmental Laboratory Accreditation Program’s Proficiency Testing (PT) webpage.

Proficiency Testing Requirement
Once per year laboratories are required to obtain an “Acceptable” PT score for each Field of Accreditation (FOA) the laboratory is applying or accredited for.

Proficiency Testing Timing

  • PTs for initial and amendment applications must be completed before the application is submitted.
  • PTs for renewal applications must be completed during the second year of the laboratory’s certificate before the application due date. Annual PTs are due before the end of the first year of a laboratory’s certificate.

Proficiency Testing Reporting 
The analyte, method, and matrix reported in a PT study must match the analyte, method, and matrix in ELAP’s FOA tables. 

If on the first attempt, a laboratory receives a “Not Acceptable” score for a Field of Accreditation, then within forty-five (45) days of receiving notification of the result, the laboratory must:

  1. Notify the ELAP Monitoring Unit of the “Not Acceptable” score by emailing at,
  2. Investigate and document the root cause of the failure,
  3. Take corrective action,
  4. Achieve an acceptable score in a subsequent Proficiency Testing study for that Field of Accreditation, and
  5. Notify ELAP at of the “Acceptable” score.

If on the second attempt, a laboratory receives a “Not Acceptable” score for the same FOA, the laboratory shall:

  1. Be automatically suspended for the FOA upon receiving the result from the provider per CCR Section 64802.15(j). This suspension occurs automatically; the laboratory will not receive a suspension notice from ELAP.
  2. Immediately cease reporting of results for regulatory purposes for that FOA
  3. Notify ELAP at of the “Not Acceptable” result within three days;
  4. Notify affected clients of second “Not Acceptable” result by registered mail, email with return receipt, or electronic signature document;
  5. Investigate and document the root cause of the failure and take corrective action within 30 days

Use these cautionary tales to avoid making common proficiency testing mistakes. The five most common reasons that laboratories are denied or lose accreditation for not meeting PT requirements are:

  • Not performing a PT – With the many demands that laboratories face, it is easy to forget to complete all your PT’s. However, because PTs are required for accreditation, planning ahead is important to avoid denial or loss of accreditation. ELAP recommends laboratories develop a proficiency testing plan for support.
  • Misreporting a method – The method reported in a PT study must match the method for which the laboratory is seeking accreditation or seeking to maintain accreditation.  For example, a common PT reporting error is shown here:

Field of Accreditation 101.01 – SM 9215 B – Heterotrophic Bacteria

Reported as “SM 9215”


The laboratory did not report the method version, and it does not match the ELAP FOA form.

Reported as “SM 9215 B”


The method name and version exactly match the ELAP FOA form.


  • Wrong matrix – Laboratories often perform only one PT and mistakenly believe it will apply to FOAs in more than one matrix. Be sure to perform the right type of study.
    • Drinking water FOAs require a “water supply” (WS) or “drinking water” study
    • Non-potable and ambient water FOAs require a “water pollution” (WP) or “wastewater” study
    • Hazardous waste FOAs require a “soil” or “hazardous waste” study
  • Outside of required timeframe – To meet the ELAP PT requirements, it is important that laboratories understand the two-year accreditation cycle and when they need to perform their PTs within that cycle.
    • Annual PTs – Must be completed during the first year of the laboratory’s certificate.
    • Renewal PTs- Must be completed during the second year of the laboratory’s certificate before the application due date

  • Not checking with all providers for available PTs – Not all providers will offer the same products, and some laboratories may find that more than one provider is needed to obtain every PT they need. This requires some research and planning on behalf of the laboratory. 

Visit ELAP’s Frequently Asked Questions (FAQs) webpage for more questions and answers.