Plumber license requirements in Washington.
Washington certifies plumbers at the state level through the Department of Labor & Industries. Everyone starts as a registered plumber trainee; from there you certify either as a journey level plumber or in a specialty such as residential. Certification renews on your birthday and carries a substantial continuing-education requirement.
What Washington requires.
Plumber trainee
The registered entry level. Works under a certified plumber while logging supervised hours toward certification.
Journey level plumber
Full-scope certification. Requires 8,000 hours (about four years) of supervised trainee work, with at least half in commercial or industrial plumbing, plus the journey level exam.
Specialty plumber certificates
Narrower certifications including residential (PL02), residential service, pump and irrigation, domestic well, and backflow assembly tester. The residential specialty requires at least 6,000 hours (three years) under a certified residential or journey level plumber.
Getting the Plumber trainee
- Journey level: 8,000 supervised trainee hours, at least half of them in commercial or industrial plumbing
- Pass the Journey Level Plumber exam with a score of at least 70%
- Residential specialty (PL02): at least 6,000 hours under a certified residential or journey level plumber, limited to single-family homes, duplexes, and apartment buildings up to three stories
Renewal: Certificates renew on your birthday. Journey level, residential specialty, and residential service plumbers must complete at least 24 hours of approved continuing education per three-year certification period — at least 12 hours of plumbing code and at least 4 hours of electrical trade content, with the remaining 8 hours in either trade.
The official board
Washington State Department of Labor & Industries (L&I) — Plumber Certification
Visit the boardVerified 2026-08 against the sources below. Licensing rules change — confirm with the board before relying on this page.
Washington plumbing licensing FAQ.
Do you need a license to do plumbing work in Washington?
Yes. Washington requires plumber certification from the Department of Labor & Industries. You either work as a registered plumber trainee under supervision, or hold a journey level or specialty plumber certificate.
How many hours do you need for a journey level plumber certificate in Washington?
8,000 hours — about four years — of supervised work as a plumber trainee, with at least half of those hours in commercial or industrial plumbing. Then you must pass the Journey Level Plumber exam with at least a 70%.
What is a specialty plumber certificate in Washington?
A narrower certification for a defined type of work: residential (PL02), residential service, pump and irrigation, domestic well, and backflow assembly tester. The residential specialty covers single-family homes, duplexes, and apartments up to three stories and requires at least 6,000 hours of supervised experience.
How do Washington plumbers renew certification?
Renewal falls on your birthday. Journey level, residential specialty, and residential service plumbers need at least 24 hours of approved continuing education for each three-year period — at least 12 hours of plumbing code, at least 4 hours of electrical trade content, and 8 more in either trade.
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