Short definition
A licensed plumber is a tradesperson who has completed required apprenticeship hours and passed the WA L&I licensing exam to install, repair, and maintain plumbing systems. WA L&I licenses individuals in seven tiers — journey-level (PL01) plus six specialty tiers — distinct from the plumbing contractor registration that licenses the business.
What it is
WA’s plumber certification tiers:
- Journey Level (PL01) — full scope; 8,000+ hours apprenticeship, with 4,000+ in commercial / industrial. State exam.
- Residential (PL02) — single-family, duplex, 3-story-or-fewer apartments only. 6,000+ hours.
- Residential Service (PL04) — repair / replacement of existing fixtures. 4,000+ hours (first 2,000 under direct supervision).
- Pump & Irrigation (PL03) — water acquisition / irrigation equipment. 4,000+ hours.
- Domestic Well (PL03A) — wells under 100 gpm. 2,000+ hours.
- Medical Gas (MG01) — journey-level plus 32 hours medical-gas-specific training.
- Backflow Assembly Tester (PL30) — separate test track for annual backflow tests.
All tiers require at least 32 hours of continuing education per renewal cycle. Renewal is paid annually; the license card stays valid for the renewal period.
A registered plumbing trainee can work under direct supervision of a journey-level plumber while accumulating hours toward eventual certification. Trainees register with L&I.
Why it matters to a homeowner
Tier matters for scope. A “PL02 Residential” plumber working on a 4-story commercial building is acting outside their license. A PL04 Residential Service plumber doing a whole-house repipe is also outside scope — repipe is journey-level (PL01) work. Verify the tier matches the project at secure.lni.wa.gov/verify.
A handyman offering plumbing work isn’t legal. Under RCW 18.106 the work needs a plumber license. The “handyman exemption” is a myth. The only exemption that applies is RCW 18.106.150 — homeowner doing work on their own owner-occupied residence (not rental, not for-sale, not for-lease) — and even there, permits and inspections still apply.
When you’ll encounter this term
- An L&I Verify portal search for a plumber’s name.
- A plumbing contractor’s qualifying-plumber line on L&I records.
- A plumbing apprenticeship admission packet.
- A bid that lists the assigned journey-level plumber by name and license number.
Common variants and not the same as
- Licensed plumber vs. licensed plumbing contractor. Plumber is the individual; contractor is the business. A homeowner hires a contractor; the contractor must employ a journey-level plumber as the qualifying plumber on file.
- Licensed plumber vs. general contractor. General contractors register under RCW 18.27. Plumbing contractors register under RCW 18.106. Different statutes.
- Specialty vs. journey-level. PL04 specialty plumbers can swap fixtures and do residential service; PL01 journey-level covers full new construction and major remodels.
Washington note
WA’s tier system differs from many other states (Oregon, California, etc.). The tier matters for scope of work. L&I Verify is the single source of truth — Yelp and Google ratings are not verification of licensure.
A door-to-door plumber offering “free water test” should be verified at the L&I portal before any work. Door-to-door plumbers are higher-risk for scam patterns. Use the WA RCW 63.14.154 cooling-off right (3 business days to cancel) if you signed something on the spot.