Washington · plumber licensing · verified July 2026
Washington plumber license requirements
The short answer
As of July 2026, Washington requires state certification for plumbers through the Department of Labor & Industries (L&I). Journey level (PL01) certification requires at least 8,000 supervised hours (4,000 in commercial/industrial work), with lower-hour specialty tiers for residential (6,000), residential service (4,000), pump & irrigation (4,000), domestic well (2,000), and backflow work; trainees register annually and report hours by affidavit. Since July 1, 2021 plumbing contracting businesses must also hold a Licensed Plumbing Contractor registration with a designated certified plumber.
Do you need a license to work as a plumber in Washington?
Washington licenses plumbers statewide, so one credential is valid across the whole state.
Washington has reciprocal journey level certification with Idaho only; out-of-state plumbers with comparable licenses or U.S. military equivalent experience may apply to test. 07-2026).
What licenses does Washington issue?
The Washington State Department of Labor & Industries (L&I), Plumber Certification Program issues the credentials below for this trade. Boards often list further classes for specialties and business licenses; these are the ones this page covers.
Hours are what each class asks for on its own terms. Where a senior class shows fewer than a journeyman, the board is counting time served after the earlier license rather than from the start; the prerequisite column says which.
| License | On-the-job hours | Classroom hours | Exam |
|---|---|---|---|
| Plumber Trainee | not published | not published | No |
| Journey Level Plumber (PL01) | 8,000 | not published | Yes |
| Residential Plumber (PL02) | 6,000 | not published | Yes |
| Residential Service Plumber (PL04) | 4,000 | not published | Yes |
| Specialty certifications: Pump & Irrigation (PL03), Domestic Well (PL03A), Backflow (PL30), Medical Gas endorsement (MG01) | 4,000 | not published | Yes |
| Licensed Plumbing Contractor (business license, effective July 1, 2021) | not published | not published | No |
Source: Washington State Department of Labor & Industries (L&I), Plumber Certification Program (lni.wa.gov). Verified July 2026.
Journey Level Plumber (PL01): 8,000 supervised trainee hours, including at least 4,000 hours commercial/industrial
Residential Plumber (PL02): 6,000 supervised hours
Residential Service Plumber (PL04): 4,000 hours; first 2,000 hours under direct supervision
Specialty certifications: Pump & Irrigation (PL03), Domestic Well (PL03A), Backflow (PL30), Medical Gas endorsement (MG01): Varies by specialty (see description)
How many hours do you need in Washington?
Washington requires 8,000 hours of on-the-job experience for a Journey Level Plumber (PL01) license. At a 40-hour week the on-the-job portion is roughly 4 years of full-time work.
What exam does Washington require?
Journey Level / Residential Plumber examination (3 parts: 100-question UPC trade knowledge; waste & vent sizing; water pipe sizing). Administered by PSI (administered for L&I; L&I application approval required first). Exam fee $202.1.
Specialty exams: Residential Service, Domestic Pump, Pump & Irrigation, Medical Gas. Administered by PSI (administered for L&I). Exam fee $202.1.
Source: examination page (lni.wa.gov). Verified July 2026.
How much does a Washington plumber license cost?
Washington sets its fees per license class rather than as one figure for the trade, so no single total would be true of every applicant. The published items are below exactly as the board sets them.
- Renewal fee (recurring)$242.7
How often do you renew, and what continuing education is required?
Renewal period: 3 years for certified plumbers (journey level, residential, residential service, pump & irrigation, domestic well, backflow), renewing on the holder's birthdate; plumber trainee certificate renews every 12 months
Continuing education: Certified journey level and residential specialty plumbers: 24 hours per renewal cycle (minimum 12 hours Uniform Plumbing Code + minimum 4 hours industry-related electrical; remaining 8 hours flexible), effective July 1, 2021. Trainees: 8 hours annually (within a 2-year period at least 8 hours plumbing code and 4 hours electrical-related). Domestic pump & irrigation: 24 hours per 3-year cycle. Backflow specialty: no CE, renewal requires an active Backflow Assembly Tester (BAT) card.
Source: renewal requirements (lni.wa.gov). Verified July 2026.
How does the apprenticeship route work?
Trainees register with L&I ($60/year) and accumulate supervised hours reported via notarized affidavits of experience filed at least annually; 8,000 hours qualifies for the journey level exam. Participation in an L&I-approved Washington plumbing apprenticeship program is captured on the exam application (apprenticeship ID). Hours worked unsupervised, on an expired certificate, or out of state do not count.
Which states does Washington have license reciprocity with?
Washington appears in 1 published reciprocal licensing agreement for this trade, covering ID. Boards write these as agreements between two states rather than as a one-way list, and some publish the list while their counterpart does not, so this counts every agreement naming Washington from either side. Recognition is never automatic: the board you apply to decides, and most require the original license to have been earned by examination and to be in good standing.
How does Washington compare to neighboring states?
Requirements stop at the state line, which matters if you live near one or expect to move. Here is what the neighboring states ask of the same trade.
| State | Journeyman hours | Licensing model |
|---|---|---|
| Washington | 8,000 | Statewide |
| Idaho | 8,000 | Statewide |
| Oregon | 7,700 | Statewide |
Source: state licensing boards. Verified July 2026.
How does Washington compare nationally?
21 states publish an explicit hour figure for this trade, and they range from 4,000 to 12,000 hours. Washington's 8,000 hours is what 9 of them ask, making it the standard rather than an outlier; 9 states ask less and 3 ask more. The full comparison is on the hours by state table.
Sources and verification
Every fact on this page traces to one of these
- L&I - Plumber Certification (experience requirements by certification type)
- L&I - Plumber Trainee
- L&I - Plumber Examination
- L&I - Plumbing Continuing Education
- L&I - New Plumbing Licensing Requirements (Licensed Plumbing Contractor, eff. 7/1/2021)
- L&I Plumber Exam Application form F627-008-000
- L&I - Get or Renew Your Certification (3-year birthdate cycle, renewal fees)
Last verified July 2026, independently re-verified before publication. Found an error? Report it and it will be corrected and logged on the corrections page.
Other states with published requirements for this trade: West Virginia, Wisconsin, Wyoming, Alabama, Alaska, Arizona.
Price the whole path with the license cost estimator, or weigh earning against paying for school with the apprenticeship comparison. Back to plumbers overview.
Licensing requirements change between our verification sweeps. This page is informational only, so confirm current requirements with Washington State Department of Labor & Industries (L&I), Plumber Certification Program before making decisions. Not legal advice.