PSI Plumbing Exam Washington — Scheduling, Format, and What to Expect

The plumbing competency exam is the final gate between you and your Washington PL01 or PL02 certification. L&I does not administer the exam directly — it is proctored by PSI Services LLC, and the scheduling, fees, and logistics run through PSI's own system, separate from your L&I application.

Before You Can Schedule

You cannot contact PSI until L&I issues your examination eligibility letter. That letter comes only after L&I has reviewed and approved your exam application ($202.10 fee), verified your hour affidavits, and confirmed your 16 hours of continuing education (including 4 hours of industry-related electrical training). L&I processes applications first-come, first-served, typically within two to three weeks.

The eligibility letter is valid for exactly one year. If you do not schedule and pass the exam within that window, you must reapply and pay the application fee again.

The Three-Part Exam Format

The Washington plumbing exam consists of three separate sections, each scored independently:

1. General trade knowledge and code — 100 questions, 90-minute time limit. Covers the Uniform Plumbing Code, Washington state amendments, and general plumbing theory.
2. Waste and vent sizing — 25 questions with drawing-based problems, 90-minute time limit. You interpret DWV system drawings and calculate pipe sizes.
3. Water pipe sizing — 25 questions with drawing-based problems, 90-minute time limit. Similar format to the DWV section but focused on supply-side calculations.

You must score at least 70% on each section individually. Passing two out of three does not count — if you fail any single section, you fail the entire exam.

Scheduling and Fees

Once you have your eligibility letter, contact PSI at 855-340-3910 or through their online scheduling portal. The exam sitting fee is $80 for PL01 and PL02, or $50 for PL04 (residential service). This fee is paid directly to PSI, not to L&I.

If you need to reschedule, you must give PSI at least two business days' notice. Rescheduling with less than two days' notice forfeits the fee, and you must pay again.

Retake Rules

If you fail, the default rule is that you must retake all three sections — even the ones you passed. However, L&I may grant a section waiver based on your specific scoring pattern, allowing you to retake only the failed section(s). This is not automatic; you must contact L&I's Plumbing Program to request the waiver and provide your exam scores.

The applicable PSI sitting fee is due for each retake.

After Passing

PSI transmits your results to L&I. L&I then issues an invoice for the initial three-year certification fee — $242.70 for PL01, PL02, or PL04. After payment, L&I mails your physical trade license card within approximately two weeks.

For a complete pre-exam checklist covering eligibility, CE requirements, and the full fee schedule, the Washington Plumber License Guide walks through every step from application to certification.

See more Washington guides →