Plumbers in Washington must be certified by Labor & Industries

Get or renew your certification...

Online

• Plumber (or backflow) Trainee.
• Journeyman Plumber (residential or backflow specialties).
• Medical Gas Endorsement.
• Well Drillers License.

Please note: New applications and renewals submitted online between the hours of 6 p.m. and 3 a.m. may not be updated for up to 48 hours.

By mail

• Print the below application for the plumber certification examination, the medical gas piping installer endorsement or reciprocal certification.
• Plumber Certification Application. (281 KB PDF)

In person

• At any L&I field office.

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 two different ways and see any infractions that have been issued to them. 1) If the contractor is registered or a plumber is certified you may search for them on the main search screen, and any infractions that are associated with that registration or certificate number will be displayed. 2) Under Lookup a Violator you may 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 - E-mail: sayb235@lni.wa.gov - Phone: 360-902-5205.

For more information:

Facts About State Certification for Plumbers (69 KB PDF)
- Get an overview of the requirements and process and frequently asked questions.