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Plumbers in Washington Must Be Certified by Labor & Industries

Information on the redesigned 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.
  • View Contractor and Plumber Violators.
    You are now able to look up a contractor or plumber in 2 different ways and see any infractions that have been issued to them:
    • If the contractor is registered or a plumber is certified, you can search for them on the main search screen, and any infractions that are associated with that registration or certificate number will appear.
    • Under Lookup a Violator, you can search for individuals or companies that were not registered or certified at the time the infraction was issued.
    If you have questions, contact the Infraction Section:

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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