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Environmental Laboratory (NELAP) Accreditation

This page offers information on the Agency's National Environmental Laboratory Accreditation Program (NELAP)


Laboratories are assessed against the provisions of the 2009 TNI NELAP standards.




Don’t miss the early registration deadline for the TCEQ Environmental Trade Fair & Conference, March 17th. The Lab Practices and Data Reporting Track includes the following presentations:

  • Untapped Power of Data Validation
  • The 2016 TNI Laboratory Accreditation Standard: Quality Systems and Microbiology Testing
  • The 2016 TNI Chemistry Standard
  • Root Cause Analysis: Key Elements to Effective Corrective Action
  • Corrective Action Response Guidelines for TCEQ Accredited Laboratories
  • Method Equivalency Under 40 CFR 136.6: What Modifications are Allowed and What Documentation Should Laboratories Have for Assessments
  • Flexible Approaches to Environmental Measurement
  • Common Findings in Microbiology
  • Navigating the Challenges for Analysis of PFAS in Environmental Matrices to Meet TRRP Requirements
  • TCEQ Laboratory Accreditation Program:  What Questions Would You Like to Ask?

A full list of presentations scheduled can be found on the Environmental Trade Fair and Conference webpage. Technical staff will also be available at the TCEQ booth in the exhibit hall to answer questions.


The TCEQ Lab Accreditation Program has issued a revision to the drinking water fields of accreditation for microbiology. The fields have been revised to provide more clarity for the accredited laboratory, to include E. coli as an analyte in addition to total coliforms for presence/absence analyses, and to reflect the Revised Total Coliform Rule (40 CFR 141.851) which went into effect on April 1, 2016. The changes to the drinking water fields of accreditation for microbiology are effective October 15, 2016.

Additional detailed information (PDF)


Subscribe to Laboratory Accreditation Program e-mail updates

Go to this link: Get e-mail updates on your choice of topics.

After entering your e-mail address and personal preferences, mark the Laboratory Accreditation / Environmental Laboratory (NELAC) Accreditation box.


Application, Fields of Accreditation, Checklists, and Procedures

Application (PDF) (Revision 7 - August 2012)

Fields of Accreditation (FoAs) (PDF) (Revision 17 - October 2016)


History of changes to the Fields of Accreditation (PDF)


The current list of accredited laboratories, with links to their scope of accreditation, can be accessed here:

List of Accredited Laboratories (PDF)


The accreditation team uses the 2009 TNI Quality Systems checklist Exit the TCEQ to determine each laboratory's conformance to the elements of this Standard. A copy of the TNI checklist is now available directly from their web page.

Be advised that you must have a copy of the TNI Standard ELV1, Management and Technical Requirements for Laboratories Performing Environmental Analyses before you may download this checklist.


TCEQ (Internal) Accreditation Procedures (PDF)


Accreditation applications in progress (PDF)


For administrative information, please contact our records specialist at 512/239-3754 or e-mail us at


For additional information, including suitable ways to obtain traceability of measurements, or to make a complaint, please contact the program manager at 512/239-1990 or e-mail us at


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Frequently Asked Questions (FAQs)

This is a document addressing frequently asked questions regarding the Texas laboratory accreditation program:

FAQ guides (PDF)


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External Links


The NELAC Institute (TNI) Exit the TCEQ


National Environmental Laboratory Accreditation Program (NELAP) designated proficiency testing providers Exit the TCEQ


NELAP Fields of Proficiency Testing Exit the TCEQ


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Our mailing address is:

Texas Laboratory Accreditation Program
Texas Commission on Environmental Quality
P.O. Box 13087, MC-165
Austin, TX 78711-3087


Our physical address for overnight mail delivery is:

Texas Laboratory Accreditation Program
Texas Commission on Environmental Quality
12100 Park 35 Circle, Bldg B, MC-165
Austin, TX 78753


Rules (Including Fees) and Accreditation Standards

Title 30, Texas Administrative Code, Chapter 25 Exit the TCEQ, Subchapters A and B (for a schedule of fees refer to §25.30)



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