How to get a plumbing license in Washington: the official requirements
The Journey Level Plumber (PL01) certificate license, the experience and training it takes, the exam and how to apply, from the Washington State Department of Labor & Industries.
In Washington, the state plumbing license for individual plumbers is issued by the Washington State Department of Labor & Industries. The journey level plumber (PL01) certificate from the Washington State Plumber Certification Program at L&I. You must be certified to work in the plumbing trade in Washington, and a journey level plumber may work in all phases of plumbing construction. Apprentice or trainee registration: Start as a plumber trainee: apply for a plumber trainee certificate, be 16 or older, and work under the direct supervision of a journey level or certified plumber. The trainee certificate is good for 12 months and is renewed with affidavits of experience and continuing education. Experience and training: Four years or more (at least 8,000 hours) working as a plumber trainee under the supervision of a certified journey level plumber, with at least two years (4,000 hours) in commercial or industrial installations. Trainees report supervised hours at least once a year on notarized affidavits of experience. Licensing exam: The Washington state plumber examination, the final step to certification. It is administered by PSI and based on the 2015 Uniform Plumbing Code with Washington amendments; the journey level exam is closed book. How to apply: Once your affidavits of experience and continuing education are approved, apply to L&I for the exam online, by mail with the Plumber Exam Application, or in person at an L&I field office. L&I approves eligibility and sends a letter explaining how to schedule with PSI.
Washington plumbing license requirements
| Requirement | Washington |
|---|---|
| License you apply for | The journey level plumber (PL01) certificate from the Washington State Plumber Certification Program at L&I. You must be certified to work in the plumbing trade in Washington, and a journey level plumber may work in all phases of plumbing construction. |
| Apprentice or trainee registration | Start as a plumber trainee: apply for a plumber trainee certificate, be 16 or older, and work under the direct supervision of a journey level or certified plumber. The trainee certificate is good for 12 months and is renewed with affidavits of experience and continuing education. |
| Experience and training | Four years or more (at least 8,000 hours) working as a plumber trainee under the supervision of a certified journey level plumber, with at least two years (4,000 hours) in commercial or industrial installations. Trainees report supervised hours at least once a year on notarized affidavits of experience. |
| Classroom hours | Not stated in the official source we read. Check with the Washington State Department of Labor & Industries. |
| Licensing exam | The Washington state plumber examination, the final step to certification. It is administered by PSI and based on the 2015 Uniform Plumbing Code with Washington amendments; the journey level exam is closed book. |
| How to apply | Once your affidavits of experience and continuing education are approved, apply to L&I for the exam online, by mail with the Plumber Exam Application, or in person at an L&I field office. L&I approves eligibility and sends a letter explaining how to schedule with PSI. |
| Background check | Not stated in the official source we read. Check with the Washington State Department of Labor & Industries. |
| State fees | L&I fees: exam application $202.10 (non-refundable); journey level certification fee $242.70, invoiced after you pass; plumber trainee certificate $60.00. PSI also charges a scheduling fee, which is not an L&I fee. |
| License term | The certificate renews on your birthdate every 3 years; the first certificate lasts 25 to 37 months depending on your application date and birthdate. |
| Continuing education | Journey level renewals need 24 hours of continuing education: at least 12 hours of Uniform Plumbing Code and at least 4 hours of industry-related electrical. Trainees need at least 8 hours every year to renew. |
Where the official source we read does not state something, the table says so rather than guessing. Fees shown are the licensing authority's own. Fees charged by exam vendors, schools, apprenticeship programs, fingerprint vendors and application portals are not included.
This page covers the plumbing license issued by the state. Cities and counties can have their own registration, permit or license rules; ask the local building department where you will work.
How to get licensed in Washington
- Apply to L&I for a plumber trainee certificate (you must be 16 or older).
- Work at least 8,000 hours (four years) as a trainee under a certified journey level plumber, with at least 4,000 hours in commercial or industrial work.
- File notarized affidavits of experience for your supervised hours at least once a year, and keep your trainee continuing education current.
- Apply to L&I for the journey level exam online or by mail with the $202.10 exam fee.
- After L&I approves you, schedule and pass the PSI exam; L&I then invoices the certification fee.
- Renew every 3 years on your birthdate with 24 hours of continuing education.
Go further
Requirements state by state.
Open →CareerHow to become a plumberThe career path, nationally.
Open →PayPlumber salary in WashingtonWhat plumbers earn.
Open →CareerPlumber career guideThe job, skills and outlook.
Open →ResumePlumber resumeHow to present your hours and licenses.
Open →InterviewPlumber interview questionsWhat hiring managers ask.
Open →Disclosure: TryHired makes HIRED, a paid job-search program, so we have a conflict of interest when we mention it. Everything on this page is free to use without buying anything.
Questions people ask
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How this page is built
Each fact on this page comes from the Washington State Department of Labor & Industries (sources named below), read on the dates shown, with the exact wording we relied on kept on file. Requirements and fees change; the Washington State Department of Labor & Industries's current instructions govern. We re-read each state's sources every six months (next review by May 10, 2027).
- Not legal advice.
- Licensing rules can change. Verify current requirements with the issuing agency.
- Fees shown are the licensing authority's own. Fees charged by exam vendors, schools, apprenticeship programs, fingerprint vendors and application portals are not included.
- This page covers the plumbing license issued by the state. Cities and counties can have their own registration, permit or license rules; ask the local building department where you will work.
- This page covers the individual license named above. Master, contractor, specialty, residential, limited and out-of-state (reciprocity) licenses have their own rules.
- Washington State Department of Labor & Industries, Plumber Certification, official source, read Nov 9, 2026.
- Washington State Department of Labor & Industries, Plumber Trainee, official source, read Nov 9, 2026.
- Washington State Department of Labor & Industries, Get or Renew Your Certification (plumbers), official source, read Nov 9, 2026.
- Washington State Department of Labor & Industries, Plumber Examination, official source, read Nov 9, 2026.
- Washington State Department of Labor & Industries, Plumber Continuing Education, official source, read Nov 9, 2026.
- Washington State Department of Labor & Industries, Plumber Exam Application (F627-008-000, 10-2026), official source, read Nov 9, 2026.