Washington Plumber License Requirements (2026)

The Washington State Department of Labor and Industries (L&I) certifies plumbers under RCW Chapter 18.106. PL01, the journey level plumber certificate, is qualified for all phases of plumbing construction. The normal path is at least four years and 8,000 hours as a plumber trainee under a certified journey level plumber, including at least 4,000 hours in commercial or industrial installations. The individual PL01 certificate is separate from the plumbing-contractor business license. Since July 2021, a business that advertises, bids, offers, or performs plumbing work must generally hold the Chapter 18.106 plumbing-contractor license and assign a designated certified plumber.

Regulatory Body

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

Eligibility Requirements

Applicants must be at least 16 years old. Applicants must provide a Social Security Number. No Washington residency requirement.

Good moral character

L&I evaluates whether the applicant satisfies the applicable experience, education, examination, application, and renewal requirements. Do not infer an unsupported general-contractor fitness review for this individual certificate.

Background investigation

L&I’s online PL01 application requires a Social Security number and relies on documented experience and credential review; its published certification information does not support a claim of a routine criminal-background check for every applicant.

Experience and Education

At least 4 years of At least four years and 8,000 hours as a plumber trainee under a certified journey level plumber, with at least 4,000 hours in commercial or industrial installations. 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

• Plumber trainee Affidavit of Experience (F627-004-000) filed with L&I at least annually
• Experience documentation required by L&I for the PL01 examination application
• Comparable active out-of-state credential and photo identification for L&I review when applicable

Education substitution

Washington’s published PL01 path is based on trainee experience under a certified journey level plumber. L&I reviews out-of-state credentials or U.S. military experience under its published process; do not claim an unsupported general education substitution.

Exam Requirements

Testing provider or authority: PSI, after L&I processes the PL01 examination application. The following examination requirements cover the pathways described in this guide; follow each part's classification, waiver, and local-scope conditions. Unpublished format details do not remove an examination requirement:

• PL01 Journey Level Plumber examination — PSI — question count: confirm with the authority, timing: confirm with the authority, passing score: confirm in the current candidate bulletin

Examination fee: $202.10 L&I examination-application fee, plus the PSI testing-agency fee set under its contract with L&I.

Retake policy: If an applicant fails, L&I requires a new application and the $202.10 application fee before another PL01 examination attempt.

Insurance and Bonds

The applicant must secure and file a $6,000 surety bond before the L&I will release the license.

General liability

This applies to the separate plumbing-contractor business license, not the individual PL01 certificate: $200,000 public liability plus $50,000 property damage, or $250,000 combined single-limit coverage, with L&I as certificate holder.

Workers' compensation

This applies when operating a plumbing-contractor business with employees: the business application requires its industrial-insurance account information.

Additional financial requirements

This applies to the separate plumbing-contractor business license: a $6,000 continuous plumbing-contractor bond or assigned savings account is required, as is an assigned designated certified plumber.

Fee Schedule

To turn these board fees into a realistic year-one budget — bond premium, liability insurance, and exam prep included — open the cost calculator preloaded for Washington plumber.

Renewal and Continuing Education

The Washington Journey Level Plumber (PL01) must be renewed every 3 years. The fee to renew is presently $243. The current PL01 renewal fee is $242.70. A late renewal is a double fee; after 90 calendar days without renewal fee and/or CE, L&I requires retesting to reinstate.

Continuing education: 24 approved hours for each three-year PL01 renewal: at least 12 Uniform Plumbing Code hours, at least 4 industry-related electrical hours, and 8 additional approved hours in code, electrical, or industry-related plumbing.

Reciprocity

Washington grants no NASCLA reciprocity for this classification.

L&I’s current published PL01 reciprocity information identifies Idaho. Other out-of-state applicants may submit comparable credentials for review but normally must pass the Washington examination.

Weighing more than one jurisdiction? The national hub compares published Plumber license requirements by state — exam, bond, fee, and experience thresholds side by side.

Plumber Licensing in Neighboring States

Contractors working near a state line, or weighing where to qualify first, should compare Washington's requirements against the bordering jurisdictions before committing to an application:

• Idaho Plumber License Requirements — Idaho Journeyman Plumber and Plumbing Contractor
• Oregon Plumber License Requirements — Oregon Journeyman Plumber and Plumbing Business (PB) License

Step-by-Step Application Roadmap

1. Register as a plumber trainee with L&I. L&I trainee registration is required before beginning supervised plumbing work in Washington.
2. Complete and report the required trainee experience. Complete at least 8,000 hours over four or more years, including 4,000 commercial or industrial hours, and file trainee affidavits with L&I at least annually.
3. Apply for the PL01 Journey Level Plumber examination. File the L&I application with the experience documentation and exam fee.
4. Take the approved PSI examination. After L&I processes the $202.10 PL01 examination application, schedule the examination with PSI.
5. Pay the first certificate fee after passing. L&I invoices $242.70 for the first PL01 certificate after successful examination; the certificate expires on the holder’s birthday and then renews every three years.
6. Obtain the plumbing-contractor license when operating a business. A business that contracts for plumbing work needs the separate Chapter 18.106 license, UBI, $6,000 bond or assigned savings, $250,000 liability insurance, and a designated certified plumber.

Application Checklist

Have each of the following squared away before the packet goes to L&I:

• L&I plumber trainee registration
• Documentation of at least 8,000 trainee hours over four years, including 4,000 commercial/industrial hours
• L&I PL01 application with exam fee
• PSI examination completed after L&I approval
• Separate plumbing-contractor license, if contracting for plumbing work
• $6,000 plumbing-contractor bond or assigned savings and $250,000 liability insurance for the business path
• Designated certified plumber and industrial-insurance account as required for the business path

Progress is saved in this browser, so you can return to this checklist while your application is in flight.

Common Filing Mistakes

The errors below are the ones that most frequently cost Washington Plumber applicants time, drawn from the cited board guidance.

Confusing certificate with registration

PL01 is an individual certificate; a business contracting for plumbing work generally needs the separate Chapter 18.106 plumbing-contractor license and designated plumber.

Skipping the trainee registration

Start as a plumber trainee and file affidavits of experience at least annually. L&I relies on its trainee-hour record to determine PL01 examination eligibility.

Missing the commercial or industrial hour requirement

A total of 8,000 hours is not enough for PL01 if fewer than 4,000 were commercial or industrial installations.

Assuming Oregon reciprocity

L&I’s current published journey-level reciprocity is with Idaho. Do not rely on unsupported claims of reciprocal PL01 certification with Oregon or other states.

Letting the certificate lapse

After 90 calendar days without required renewal fee and/or continuing education, L&I requires retesting to reinstate a PL01 certificate.

Study and Reference Materials

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.

• Washington L&I Plumber Certification — Washington L&I. Current PL01 scope, experience, and Idaho-reciprocity guidance.
• WAC 296-400A-045 — Washington State Code Reviser. Current PL01 and plumbing-contractor fee schedule.
• WAC 296-400A-028 — Washington State Code Reviser. Controlling PL01 continuing-education categories and hours.

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 Concrete 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
• Washington Handyman License Requirements
• Washington Pest Control License Requirements
• Washington Septic Contractor License Requirements

Frequently Asked Questions

How many hours of experience does Washington require for a Journey Level Plumber?

PL01 requires at least four years and 8,000 hours as a plumber trainee under a certified journey level plumber. At least 4,000 of the hours must be in commercial or industrial installations.

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?

L&I’s current published reciprocity information identifies Idaho for journey level plumbers. Other out-of-state plumbers can submit comparable credentials for review but normally must pass the Washington examination.

How often does the Washington plumber certificate renew?

Every three years. PL01 renewal requires 24 approved CE hours: at least 12 hours of Uniform Plumbing Code, at least 4 hours of industry-related electrical instruction, and 8 additional approved hours.

Do I need both a plumber certificate and a contractor registration?

A PL01 is an individual certificate. A business that advertises, bids, offers, or performs plumbing work generally needs the separate Chapter 18.106 plumbing-contractor license and a designated certified plumber.

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