Washington Plumber License Requirements (2026)
By Gabriel Giner, Editor · Reviewed 2026-04-16 · CLR Editorial Review Desk
The Washington State Department of Labor and Industries (L&I) certifies plumbers and registers plumbing contractors statewide under RCW Chapter 18.106. Washington issues several plumber certificate classifications, with PL01 (Journey Level Plumber) being the broadest. Working as a plumber in Washington requires both an individual certificate and a plumbing contractor business registration. Trainees work toward certification through an L&I-registered apprenticeship that documents 8,000 hours of supervised plumbing work over at least four years.
The Licensing Authority
Authority over this credential rests with Washington State Department of Labor and Industries (L&I), which issues and polices it under Revised Code of Washington Chapter 18.27 (Contractors); Chapter 19.28 (Electricians); Chapter 18.106 (Plumbers). L&I registers contractors statewide, certifies individual electricians and plumbers, administers prevailing wage, and conducts complaint investigations.
- Official portal: https://lni.wa.gov/licensing-permits/contractors/
- Address: 7273 Linderson Way SW, Tumwater, WA 98501
- Phone: (360) 902-5226
Baseline Eligibility
The applicant must be at least 18 years of age and possess a valid Social Security Number. No Washington residency requirement.
Good moral character
L&I conducts a fitness review on every applicant. Prior contractor judgments and L&I infractions are reviewed individually.
Background investigation
L&I screens for unpaid contractor judgments and prior L&I plumbing infractions.
Experience and Education Requirements
At least 4 years of 8,000 hours of supervised plumbing work over at least four years under a certified Journey Level Plumber has to be evidenced and confirmed. Retain payroll, tax, project, or supervisor records, since the board may audit the experience claimed.
Accepted proof of experience or eligibility
- L&I plumber trainee hours affidavits signed by each supervising journey-level plumber
- L&I-registered apprenticeship completion certificate (where applicable)
- W-2 statements, pay stubs, or 1099 records covering the qualifying period
Education substitution
L&I-registered apprenticeship programs document hours toward the 8,000-hour requirement.
The Licensing Examination
International Code Council (ICC) under contract to L&I administers the required examination. Each part below must be passed before the license will issue:
- PL01 Journey Level Plumber Examination — Uniform Plumbing Code, Washington plumbing rules (WAC 296-400A), business and law — 80 questions, 240 minutes, passing score 70%
Examination fee: $84.50 examination fee paid to ICC at scheduling.
Retake policy: Failed examinations may be re-taken by paying a new $84.50 fee. Each application remains valid for two years.
Financial Security and Insurance
The applicant must secure and file a $6,000 surety bond before the L&I will release the license.
General liability
Plumbing contractor registration requires $250,000 per occurrence and $200,000 property damage (or $250,000 combined single limit) general liability insurance.
Workers' compensation
Washington workers compensation is administered by L&I under RCW Title 51. Plumbing contractors with employees must open an L&I workers compensation account.
Additional financial requirements
$6,000 specialty contractor surety bond required for plumbing contractor business registration.
Fee Schedule
| Fee | Amount |
|---|---|
| Application (non-refundable) | $90 |
| Examination | $84 |
| Initial license | $95 |
| Renewal (every 2 years) | $95 |
License Renewal
The Washington Journey Level Plumber (PL01) must be renewed every 2 years. The fee to renew is presently $95. Washington plumber certificates renew every two years.
Continuing education: 16 hours of L&I-approved continuing education each two-year renewal cycle, including UPC code updates.
Downloadable Asset
2026 Washington Plumber License Roadmap (PDF) — a printable step-by-step checklist for the application process.
Download the PDF roadmap →Reciprocity Map
Washington grants no NASCLA reciprocity for this classification.
| Reciprocal State | Accepted Exam | Conditions |
|---|---|---|
| Oregon | Trade exam waived | Bilateral L&I–Oregon BCD reciprocity for active journey level plumbers. |
| Idaho | Trade exam waived | Bilateral L&I–Idaho DOPL reciprocity. |
Washington maintains bilateral plumber reciprocity agreements with neighboring western states. Reciprocal applicants must still pass the Washington-specific exam portion covering WAC 296-400A.
Weighing more than one jurisdiction? The national hub compares Plumber license requirements in every state — exam, bond, fee, and experience thresholds side by side.
The Licensing Roadmap
- Register as a plumber trainee with L&I. L&I trainee registration is required before beginning supervised plumbing work in Washington.
- Complete 8,000 hours of supervised work. Hours must be documented and signed by a certified Journey Level Plumber. Most applicants complete this through an L&I-registered apprenticeship over at least four years.
- Apply for the PL01 Journey Level Plumber examination. File the L&I application with the experience documentation and exam fee.
- Pass the ICC examination at 70%. Score 70% or better on the 80-question exam covering the Uniform Plumbing Code and Washington plumbing rules.
- Receive the PL01 certificate. L&I issues the individual certificate after the exam is passed. The certificate must be renewed every two years with continuing education.
- Register the plumbing contractor business (if self-employed). Post the $6,000 bond, obtain the $250,000 liability insurance, and pay the L&I contractor registration fee.
Preparation Resources
These materials are drawn from the regulator's own citations and the references applicants commonly use to prepare. CLR receives no compensation for listing them.
- Uniform Plumbing Code (Washington-adopted edition) — IAPMO. Primary technical reference. Open-book at the ICC test center.
- WAC Chapter 296-400A (Washington Plumbing Rules) — Washington L&I. Required for the Washington-specific exam portion.
- RCW Chapter 18.106 (Plumbers) — State of Washington. Licensing law.
Before Filing: A Checklist
Have each of the following squared away before the packet goes to L&I:
- ☐ L&I plumber trainee registration
- ☐ Documentation of 8,000 hours of supervised plumbing experience
- ☐ L&I PL01 application with exam fee
- ☐ ICC examination pass certificate at 70%+
- ☐ Plumbing contractor business registration (if self-employed) with $6,000 bond
- ☐ $250,000 general liability insurance certificate
- ☐ L&I workers compensation account (if any employees)
Common Application Pitfalls
The errors below are the ones that most frequently cost Washington Plumber applicants time, drawn from the cited board guidance.
Confusing certificate with registration
Individuals need a certificate; businesses need a registration. Self-employed plumbers need both.
Skipping the trainee registration
L&I trainee registration is required before beginning supervised plumbing work. Hours worked without trainee registration do not count.
Studying the wrong code
Washington uses the Uniform Plumbing Code, not the International Plumbing Code. Candidates from IPC states often study the wrong reference.
Missing the WAC 296-400A portion
Reciprocal applicants who skip studying WAC 296-400A routinely fail the Washington-specific portion of the exam.
Letting the certificate lapse
A lapsed individual certificate cannot be used to perform plumbing work. Reinstatement requires fees and may require continuing education catch-up.
Other Washington Trade Licenses
Looking at a different trade? CLR also publishes these Washington licensing guides:
- Washington General Contractor License Requirements
- Washington Electrician License Requirements
- Washington HVAC Technician License Requirements
- Washington Roofing Contractor License Requirements
- Washington Painting Contractor License Requirements
- Washington Landscaping Contractor License Requirements
- Washington Masonry Contractor License Requirements
- Washington Carpentry Contractor License Requirements
- Washington Solar Installer License Requirements
- Washington Low-Voltage Technician License Requirements
- Washington Fire Sprinkler Contractor License Requirements
- Washington Home Inspector License Requirements
- Washington Pool Contractor License Requirements
Answers to Common Questions
How many hours of experience does Washington require for a Journey Level Plumber?
8,000 hours of supervised plumbing work over at least four years under a certified Journey Level Plumber. Most applicants complete this through an L&I-registered apprenticeship.
What plumbing code does Washington use?
Washington has adopted the Uniform Plumbing Code (UPC) as the basis for state plumbing rules, with Washington-specific amendments in WAC 296-400A.
Does Washington reciprocate plumber credentials?
Yes. L&I maintains bilateral plumber reciprocity agreements with Oregon and Idaho. Reciprocal applicants must still pass the Washington-specific exam portion.
How often does the Washington plumber certificate renew?
Every two years. Renewal requires 16 hours of L&I-approved continuing education.
Do I need both a plumber certificate and a contractor registration?
Yes if you operate as a self-employed plumber. The certificate authorizes you to perform plumbing work; the contractor registration authorizes the business to bid and contract.
Primary Sources
Regulatory requirements on this page are drawn from the official board, statute, and exam-provider materials listed below.
- Washington Department of Labor & Industries
- L&I Contractor Registration
- RCW Chapter 18.27 — Contractors
- RCW Chapter 19.28 — Electricians
- RCW Chapter 18.106 — Plumbers
Verified 2026-04-16 · Next scheduled review 2026-07-15