Which code does the WA plumber exam actually test? 2015 vs 2021 UPC

The short answer

Per L&I's own examination page, Washington's plumber exams are based on the 2015 Uniform Plumbing Code with the state's amendments. That hasn't changed even though Washington adopted the 2021 UPC for installations effective March 2024. If you're preparing for the PL01 right now, the 2015 edition is the one being tested.

How Washington ended up split across two editions

Code adoption and exam development run on different clocks. The State Building Code Council moved Washington's in-force plumbing code to the 2021 UPC in March 2024 — but a licensing exam can't just flip editions overnight. Questions have to be rewritten against the new text and Washington's new amendments, reviewed, and validated before anyone's license can fairly depend on them. Until that process finishes, L&I keeps examining on the 2015 edition.

So the strange-but-true situation stands: a trainee can spend the day installing under the 2021 code and the evening studying the 2015 code — and for exam purposes, the evening is right.

The 2021 rewrite is already underway

This isn't rumor; it's in the minutes. At the April 15, 2025 meeting of L&I's Advisory Board of Plumbers, an active workgroup was reported to be updating the examination to the 2021 UPC. The same discussions have floated expanding the question bank (from roughly 100 to 200 items) and the possibility of a NASCLA-based exam, and earlier transcripts raised a future Spanish-language exam.

The board meets quarterly — third Tuesday of January, April, July, and October, in Tumwater and via Microsoft Teams — and as of July 2026, no switch date has been announced.

What candidates should do

Testing in the next few months? Study 2015. Full stop.

Your exam is written against the 2015 UPC + WAC 51-56. Studying 2021 material "because it's newer" means drilling values and provisions that may differ from what the exam asks. Newer is not correct — matching is correct.

Check what edition your study material is actually built on

Plenty of national prep products are built on the IPC (a different model code entirely) or on a 2021+ UPC edition, and plenty more never say. For this exam, material that doesn't state "2015 UPC + Washington amendments" is a gamble. This cuts both ways: the day the exam switches to 2021, today's 2015 material goes stale too — edition-matching is a permanent habit, not a one-time check.

Watch the primary sources, not the rumor mill

• The Advisory Board of Plumbers page posts meeting information and minutes.
• L&I's email bulletins (via GovDelivery) are how changes like this reach the trade.
• If your test date could straddle an announcement, confirm the tested edition with L&I or PSI before you sit.

Where JourneyWorthy stands on this

JourneyWorthy is built for the actual Washington exam as it exists today — 2015 UPC + WA amendments, closed book, all three portions — with content verified by trade professionals. Every question is cited to its code edition and section, and the content is organized per edition on purpose.

We follow the advisory board's quarterly meetings, and when L&I announces the move to the 2021 UPC, updating our content for the new edition becomes our first priority. Until that announcement, our job — and yours — is the code the exam actually tests.

More free guides