Washington Plumbing License Requirements: Complete 2026 Guide

Official-source review: August 25, 2026

Washington plumbing license: Washington requires both certified plumbers and a separately licensed plumbing contractor. PL01 is the unrestricted journey-level individual route; the company must hold the plumbing contractor credential and assign a designated certified plumber.

What the Washington plumbing license covers

Washington requires both certified plumbers and a separately licensed plumbing contractor. PL01 is the unrestricted journey-level individual route; the company must hold the plumbing contractor credential and assign a designated certified plumber.

• PL01 potable water, fixtures, traps, drainage, venting and water-heater systems.
• Certified employees working for a Licensed Plumbing Contractor.
• Medical gas only with the additional MG01 endorsement.
• Local plumbing permits and inspections.

Assembly testing is explained in the Washington backflow tester guide.

Washington plumbing license requirements at a glance

Do not treat this table as an approval notice. The agency, certification organization or local jurisdiction makes the final eligibility decision and may request additional evidence.

How to complete the Washington plumbing license process

1. Confirm the correct credential and scope.
2. Complete required training and experience.
3. Pass the required examination.
4. Submit the application and fees.
5. Complete business licensing, bond and insurance requirements.
6. Obtain permits and renew on time.

Keep copies of every experience certificate, examination result, bond or insurance filing and payment receipt. Names and business entities should match across the application and supporting documents.

Important Washington rules and boundaries

• PL01 certification does not replace the plumbing contractor business license.
• General construction contractors cannot advertise or perform plumbing without the plumbing contractor credential.
• Backflow testing and repair have additional BAT and PL30 rules.
• Work outside buildings and utility connections can be treated differently under statute.

Washington may separate the credential held by a worker from the contractor license held by the business, while preserving local authority over permits and inspections. Confirm every applicable layer before bidding, advertising or beginning regulated work.

Washington plumbing license cost and renewal

Add training, examination, bond, equipment and local permitting costs.

Renew by the published deadline and retain all supporting records.

Government charges are only part of the expected cost. Training, examination preparation, fingerprints, surety premiums, insurance, equipment calibration and local permits can add to the total.

Washington plumbing license checklist

• Confirm that this credential matches the exact work you will perform.
• Check whether the applicant is an individual, sole owner or separate business entity.
• Collect experience and training records before submitting the application.
• Use the current official form and fee schedule.
• Complete every required examination or approved certification route.
• File bonds, insurance and fingerprints when applicable.
• Check county, city, water supplier and building-permit rules.
• Save the expiration date and renewal requirements.

Frequently asked questions

Is this credential statewide?

Yes; local permits and inspections remain separate.

Is an exam required?

Washington journey-level plumber examination administered through PSI after L&I approves experience.

When does it renew?

Individual PL01 every three years on the birthday; plumbing contractor credential renews separately.

Are local approvals separate?

Yes.

Official sources used

• L&I plumber certification
• L&I plumber examination
• L&I plumbing contractor
• L&I certification and renewal fees