Construction / Plumber License / Washington
- Washington
- Plumber License
- Journeyman Plumber
- Updated Oct 2026
How to Get Your Washington Plumber License
Washington certifies journeyman plumbers through the Department of Labor & Industries. Here’s the experience you need, how the theory and practical exams work and what it takes to renew.
Last updated October 27, 2026 from Washington State Department of Labor & Industries requirements
Application fee
$202.10
Exam application; plus $84 PSI exam and $242.70 certificate fee
Exam time
Not stated
Theory exam plus two sizing drawings
Time to get license
~4 yrs
8,000 hrs as a trainee, 4,000 of them commercial or industrial
Continuing ed
16 hrs
Each licensing period, before renewal
Overview
Do you need a Washington plumber license?
Yes. To work as a journeyman plumber in Washington you need a plumber certificate from the Department of Labor & Industries. You earn it by logging supervised hours as a trainee and passing the theory and practical exams.
License required when
- You install, alter, repair or renovate potable water systems
- You work on liquid waste systems
- You work on medical gas piping systems inside a building’s footprint
Common exceptions
- Trainees work under the supervision of a certified journey-level plumber while they log hours
- The journeyman scope covers work in the footprint of a building
Penalties for unlicensed work
Our sources don’t list specific fines. Labor & Industries regulates plumber certification and can act against anyone doing plumbing work without the right certificate, so get certified before you work on your own.
Your fast-track Washington plumber license checklist
The Washington application, one page
- 8,000 documented trainee hours
- 4,000 of those hours in commercial or industrial work
- 16 hours of pre-test education
- Exam pre-approval for PSI
- Passing scores on the theory and practical exams
Types
Washington plumber license types and classifications
This page covers the journeyman plumber certificate. You get there by working as a trainee under a certified journey-level plumber.
TRN
Starting out
Plumber trainee
Works under the supervision of a certified journey-level plumber while logging the hours needed for the journeyman exam.
Exam
None
Limit
Supervised work only
JRY
Most common
Journeyman Plumber
Installs, alters, repairs and renovates potable water, liquid waste and medical gas piping systems in the footprint of a building.
Exam
Plumbing Theory + Practical
Limit
Building footprint
Requirements
Washington plumber license requirements, class by class
Everything you need before you can sit for the journeyman exams.
| Requirement | Journeyman Plumber |
|---|---|
| Total experience | 4+ years (at least 8,000 hours) as a trainee under a certified journey-level plumber |
| Commercial or industrial | 2+ years (at least 4,000 hours) |
| Pre-test education | 16 hours of Washington-approved education, at least 4 from the industry-related electrical category |
| Exams | Plumbing Theory and Plumber Practical |
| Exam pre-approval | Required |
| Minimum age | Not stated |
Steps
How to get your Washington plumber license, step by step
- Work as a trainee~4 years
Log at least 8,000 hours under a certified journey-level plumber, with at least 4,000 in commercial or industrial work. - Complete pre-test educationBefore you test
Finish 16 hours of Washington-approved education, at least 4 of them in the industry-related electrical category. - Get approved to testBefore you schedule
Send L&I your exam application with the $202.10 fee. Once you’re approved, PSI emails you; pay the $84 exam fee and book at 855-746-8173 or on the PSI Washington plumbing page. - Pass the theory and practical examsExam day
A 100-question theory exam plus waste and vent and water pipe sizing drawings. - Pay your certificate feeWithin 90 days
Pay L&I the $242.70 certificate fee within 90 days of passing, or you’ll need to reapply and test again. Questions? Call 360-902-5207 or visit the Department of Labor & Industries.
Exam
What to expect on the Washington plumber exam
The journeyman exam has three parts: a written theory section and two sizing drawings. Washington adopted the 2018 Uniform Plumbing Code in 2021 through WAC Chapter 51-56, so study the state amendments too.
Format
Written + sizing drawings
Questions
100 (Part 1)
Passing score
70 correct (Part 1)
Exam vendor
PSI
Scoring & content
- Part 1: 100 questions, 70 correct to pass, listed as closed book
- Part 1 topics: Washington amendments from UPC Chapters 1–10, 15, 16 and 17
- Part 2: waste and vent pipe sizing drawing (Chapter 7 methods)
- Part 3: water pipe sizing drawing (Chapter 6 methods)
- Code: 2018 Uniform Plumbing Code with Washington amendments
Retake policy
- Retake fee: $52 for each portion you retest
- You can’t rebook on the day you test; a retest can be as soon as two days later, if seats are open
- Pre-approval is required before you schedule
- Call PSI at 855-746-8173 with scheduling questions
- Confirm which references are allowed on each part with PSI
Exam references · Varies
Our sources list Part 1 of the Journeyman Plumber exam (Washington amendments) as closed book, while also saying Washington references can be tabbed, highlighted and used during the test. Parts 2 and 3 are pipe-sizing drawings based on Chapters 6 and 7 of the UPC, so check the PSI candidate bulletin for what you can bring in.
| Book | Edition | Use |
|---|---|---|
| Uniform Plumbing Code (UPC) | 2018 | Not stated |
| Washington State Building Code Amendments to the UPC | Not stated | Not stated |
Prep
Best Washington plumber exam prep, compared
We haven’t compared prep courses for this exam yet.
Costs
How much does a Washington plumber license cost?
| Item | Type | Estimate |
|---|---|---|
| L&I exam application | Fixed | $202.10 |
| PSI exam fee | Fixed | $84 (all three portions); $52 per portion to retest |
| Certificate fee (first card, three years) | Fixed | $242.70 |
| Plumber trainee certificate (one year) | Fixed | $60.00 |
| 16 hours of pre-test education | Variable | Varies |
| 2018 Uniform Plumbing Code | Variable | Varies |
| State fees and exams | Exam application, PSI exam and first certificate; excludes trainee certificate, education and code book | $528.80 |
Fees from WAC 296-400A-045 (effective July 1, 2026) and the PSI Washington plumber candidate bulletin, checked October 2026.
Reciprocity
Does Washington accept out-of-state plumber licenses?
Washington has a reciprocity agreement with Idaho. Everyone else applies as a new applicant.
Idaho — reciprocity agreement
Our sources don’t spell out what’s waived, so confirm the terms with L&I before you apply.
All other states — no agreement
Apply as a new applicant: document your hours, complete the pre-test education and pass the exams.
Local
Do Washington cities and counties have their own plumber licensing rules?
Your plumber certificate comes from the state. Cities and counties still handle the job-site side of the work.
State handles
- Trainee and journeyman plumber certificates
- Exam approval, with testing through PSI
- Pre-test and continuing education rules
- State plumbing code amendments
City & county handle
- Plumbing permits
- Inspections
- Local business licenses
Governance
Who regulates plumbers in Washington
Licensing authority
Washington State Department of Labor & Industries
360-902-5207
Oversight responsibilities
- Issues and renews plumber certificates
- Approves applicants to sit for the PSI exams
- Sets pre-test and continuing education requirements
- Manages reciprocity with Idaho
Maintenance
How to renew your Washington plumber license and keep it active
Washington plumbers complete 16 hours of continuing education each licensing period before they renew. Journey-level certificates renew every three years for $242.70. Our sources don’t list a late penalty, so confirm that with L&I.
Renewal cycle
3 years
CE hours
16
Renewal fee
$242.70
Late penalty
Not stated
Renewing your license?
See the Washington CE guide: hours, deadline, required topics and how to renew.
FAQ
Washington plumber license FAQs
How many hours do I need to become a journeyman plumber in Washington?
At least 8,000 hours (4 years) as a trainee under a certified journey-level plumber, with at least 4,000 hours in commercial or industrial work.
What’s on the Washington journeyman plumber exam?
A 100-question theory section on Washington’s Uniform Plumbing Code amendments, plus a waste and vent sizing drawing and a water pipe sizing drawing.
What score do I need to pass?
70 correct out of 100 on the theory section.
Do I need education before I test?
Yes. You need 16 hours of Washington-approved education first, with at least 4 hours in the industry-related electrical category.
Which plumbing code does Washington use?
The 2018 Uniform Plumbing Code, adopted in 2021 through WAC Chapter 51-56, with state amendments.
How much continuing education do Washington plumbers need?
16 hours each licensing period, before renewal.
Does Washington accept out-of-state plumbing licenses?
Washington has a reciprocity agreement with Idaho. Plumbers from other states apply as new applicants.
Sources
Official sources for the Washington plumber license
- Washington L&I, Plumber certification
- PSI, Washington plumbing exams
- Washington State Building Code Council, UPC amendments (PDF)
- WAC Chapter 51-56, Uniform Plumbing Code
- WAC 296-400A-045, Plumbing certificate fees
- PSI, Washington plumber candidate information bulletin (PDF)
Last updated October 27, 2026. Spot something out of date? Tell us.
Exam Insiders is an independent guide and is not affiliated with the Washington State Department of Labor & Industries.