Washington Plumber License Requirements — Every Level from Trainee to Master
The License Levels
Washington's plumbing licensing system runs through L&I (Department of Labor & Industries) under RCW 18.106 and WAC 296-400A. There are seven distinct individual certification categories, each with different hour requirements, scope of work, and fees. Here's the full progression:
Plumber Trainee (PT00/PT31) — the entry point. No experience needed, no exam. You register with L&I, get a trainee card, and start logging supervised hours.
Residential Specialty Plumber (PL02) — residential work in buildings up to three stories. Requires 6,000 hours over at least 3 years.
Residential Service Plumber (PL04) — service, repair, and replacement work on existing residential systems. Requires 4,000 hours over at least 2 years.
Pump and Irrigation Specialty (PL03/PL03A) — water acquisition and irrigation systems. PL03 requires 4,000 hours; PL03A (domestic well specialty) requires 2,000 hours.
Journey-Level Plumber (PL01) — the full-scope license covering commercial, industrial, and residential work. Requires 8,000 hours over at least 4 years, with at least 4,000 hours in commercial or industrial work.
Master Plumber — the administrative and business credential. Requires an active PL01 for at least 2 years before you can apply for the master exam.
What the Trainee Card Requires
To start, you need:
- Be at least 16 years old
- Complete the Plumber Trainee Application (Form F627-003-000)
- Pay the $60 application fee
- Affiliate with a licensed plumbing contractor that employs certified journey-level or specialty plumbers to supervise your work
No exam, no prior experience. L&I processes the application and mails your physical trainee card within 2–4 weeks. Once you have the card, you can start working — but only under direct supervision of a certified plumber.
The trainee card renews annually ($60), and you need 8 hours of approved continuing education per renewal cycle.
Journey-Level (PL01) Requirements in Detail
PL01 is the license most plumbers aim for, and its requirements are the most involved:
Experience: 8,000 hours of supervised work over a minimum of 4 years. At least 4,000 of those hours must be in commercial or industrial installations under direct on-site supervision of a certified journey-level plumber.
CE: 16 hours of approved continuing education, including at least 4 hours of industry-related electrical (IRE) training, completed before your exam application.
Application: Submit the Plumber Certification Application with the $202.10 exam application fee to L&I. L&I reviews your hour documentation and issues an eligibility letter (processing takes 2–3 weeks).
Exam: Three-part, closed-book exam administered by PSI Services. 100 general trade knowledge questions (90 minutes), 25 waste and vent sizing drawing questions (90 minutes), and 25 water pipe sizing drawing questions (90 minutes). You need 70% or higher on all three sections individually. If you fail any section, you retake all three.
Post-exam fee: $242.70 for the initial three-year certification.
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The Total Cost Breakdown
The licensing costs add up across the years it takes to reach journeyman status:
| Fee | Amount |
|---|---|
| Trainee card application | $60 |
| Trainee annual renewals (4 years) | $240 |
| CE courses (varies by provider) | $200–$600 |
| Exam application fee | $202.10 |
| PSI exam sitting fee | $80 |
| Initial 3-year certification | $242.70 |
| Total minimum to PL01 | ~$1,025–$1,425 |
That's the state fees alone. If you're going through a formal apprenticeship program (CITC, UA Local), tuition adds $1,000–$1,500 per quarter. Self-directed trainees avoid tuition but need to source their own CE courses.
If you plan to start a plumbing business after getting certified, add the contractor registration ($148.10), designated plumber assignment ($53.20), surety bond ($6,000 face value — annual premium varies), and general liability insurance ($250,000 minimum coverage).
How to Apply
L&I handles all individual plumber certifications through its Plumbing Program. The application process:
- Download the correct form — trainee, exam, or renewal — from L&I's plumber certification page
- Complete all fields using your personal information (not your employer's — a common mistake that delays processing)
- Submit with the correct fee — L&I accepts online payments for renewals, but initial applications may require a check or money order
- Wait for processing — L&I operates first-come, first-served. Exam applications take 2–3 weeks; trainee cards take 2–4 weeks
For exam applicants, L&I issues an eligibility letter valid for exactly one year. Once you have the letter, you contact PSI directly to schedule your exam date and pay the separate PSI sitting fee.
The Washington Plumber License Guide maps every step from trainee application through master plumber certification, including the forms, fees, and deadlines at each level.
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