Plumbers in Washington Must Be Certified by Labor & Industries

Information on the certificates issued by L&I.

Get or renew your certification …


By mail

In person

See also

  • Plumber Training and Continuing Education.
    Find out about plumber exams, fees, training for the Medical Gas Piping Installer Endorsement, and continuing education requirements.
  • Verify a Contractor or Plumber.
    • If the contractor is registered or a plumber is certified, you can search for them in our Verify tool, and any infractions that are associated with that registration or certificate number will appear.

If you have questions, contact:

For more information:

Facts About State Certification for Plumbers (F627-022-000)
— Get an overview of the requirements and process and frequently asked questions.

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