Washington Journey Level Plumber Requirements — Hours, Exam, and Timeline

The Hour Requirement

Washington's journey-level plumber certification (PL01) requires 8,000 hours of supervised work experience accumulated over a minimum of 4 years. That's the baseline — but the total hours alone aren't enough.

At least 4,000 of those 8,000 hours must be specifically in commercial or industrial plumbing installations, performed under the direct on-site supervision of a certified journey-level plumber (PL01). Residential-only experience won't get you to PL01, no matter how many hours you accumulate.

This commercial hour split is the requirement that catches the most people. A trainee who has spent four years exclusively on residential new construction or service work will hit 8,000 total hours but won't qualify for PL01 — they'll need to switch to a contractor that does commercial work and log another 4,000 hours in that scope before they can apply.

If commercial or industrial experience isn't in your plans, the residential specialty (PL02) or residential service (PL04) pathways require fewer hours (6,000 and 4,000 respectively) and don't mandate a commercial split. But those licenses limit your scope to residential work only.

Documenting Your Hours

Every hour that counts toward PL01 must be documented through L&I's affidavit system. Your employer (the plumbing contractor) or apprenticeship-training director must provide a signed, notarized Affidavit of Experience (Form F627-004-000), and you must file it with L&I within 30 days of your annual trainee card renewal date.

Treat the 30-day filing deadline as firm. Hours documented on an affidavit that arrives at L&I after the 30-day window can be denied. A single late filing can erase an entire year of documented work.

The affidavit must be an original, signed, and notarized document. L&I rejects photocopies, faxes, and scanned emails. Forms with whiteout, manual corrections, or inconsistent supervising plumber license numbers get rejected outright. If your supervising plumber's certification number is wrong on the form, L&I bounces it — and if you don't catch the error and resubmit within the 30-day window, those hours are gone.

The Exam

Once L&I approves your hour documentation, you submit the Plumber Certification Application ($202.10) and receive an eligibility letter valid for one year. You then schedule the exam through PSI Services ($80 sitting fee, paid directly to PSI).

The PL01 competency exam is a three-part, closed-book test:

1. General trade knowledge and code — 100 questions, 90-minute time limit
2. Waste and vent sizing drawings — 25 questions, 90-minute time limit
3. Water pipe sizing drawings — 25 questions, 90-minute time limit

You need 70% or higher on each section individually. A 95% on the general section and a 68% on water pipe sizing means you failed the exam — and you retake all three sections, not just the one you missed (unless L&I grants a section waiver based on your scoring pattern, which is rare).

The exam tests against the Uniform Plumbing Code (UPC) and Washington's state amendments. Knowing the UPC alone isn't sufficient — Washington's amendments in WAC 296-400A modify several provisions, and the exam will test those differences.

After Passing

Once you pass all three sections, L&I invoices you for the initial three-year certification fee of $242.70. After payment, L&I mails your physical PL01 trade license card within about 2 weeks.

With an active PL01, you can:

• Work on all phases of plumbing — commercial, industrial, and residential
• Supervise trainees on the jobsite (within the statutory ratios)
• Serve as the designated plumber for a plumbing contractor
• Apply for the master plumber exam after 2 years of active PL01 status

You cannot, however, contract for plumbing work or pull permits as an individual PL01 holder. That requires a separate Plumbing Contractor Registration with L&I — a business-level credential with its own bond, insurance, and registration requirements.

The Realistic Timeline

The minimum timeline from trainee card to PL01 certification is roughly 4.5–5 years:

• Year 1–4: Accumulate 8,000 hours with the required commercial split
• Month 49–50: Complete 16 hours of CE, submit exam application, wait for eligibility letter
• Month 51–52: Schedule and take the PSI exam
• Month 53: Receive PL01 certification

That's the optimistic path — assuming zero affidavit rejections, no hour disputes, no exam retakes, and no gaps in employment. In practice, many plumbers take 5–7 years to reach PL01 due to employer changes, supervision gaps, and the difficulty of accumulating enough commercial hours.

The Washington Plumber License Guide walks through the entire journey-level pathway with checklists for each phase, from your first affidavit filing through your PSI exam registration.

See more Washington guides →