Licensed Plumber in Washington: How to Verify Before You Hire

Washington State requires plumbers to be licensed through the Department of Labor & Industries (L&I) before touching any pipe in a home or commercial building. The state issues individual plumber licenses and requires plumbing contractors to carry a separate business registration with a surety bond. Verifying both before you hire protects you from fines, failed inspections, and water damage caused by substandard work.

This guide covers how Washington's plumbing license system works, where to verify credentials, what the different license types mean, and what you risk by hiring unlicensed.

Does Washington State require plumbers to be licensed?

Yes, Washington requires all plumbers performing plumbing work to hold an individual license issued by L&I, and plumbing contractor businesses must also be registered with L&I. Washington issues three individual plumber license levels: Plumber Trainee, Journeyman Plumber, and Master Plumber. Working without these credentials is a gross misdemeanor under Washington law, punishable by fines up to $5,000.

The contractor registration and individual plumber license are separate things. A plumbing business must be registered as a contractor with L&I. The individual doing the work must hold a current Journeyman or Master Plumber license. When you hire a plumbing company, verify both.

Where do I verify a plumber's license in Washington State?

Verify any Washington plumber or plumbing contractor through L&I's free lookup at lni.wa.gov using "Verify a Contractor, Electrician or Plumber." The search returns the license type, current status, expiration date, and for contractors, the bond and insurance status. You can search by name or license number, and the results are available immediately at no charge.

For contractor businesses, the lookup confirms registration, bond status, and liability insurance in a single screen. For individual plumbers, it confirms whether the person holds a current Journeyman or Master Plumber license. Ask any plumber for both numbers — their contractor registration and their individual license — before work begins.

What are the different Washington plumber license types?

Washington issues three individual plumber credentials. A Plumber Trainee is registered to learn under supervision and cannot perform work independently. A Journeyman Plumber is fully licensed to perform plumbing work under the oversight of a Master Plumber. A Master Plumber holds the highest individual credential, can supervise others, and is qualified to pull plumbing permits.

For any residential plumbing project, the company should hold an active contractor registration and have a licensed Master Plumber associated with the business. The crew performing the actual work must hold current individual licenses — Trainee status alone is not sufficient to perform unsupervised plumbing work.

What bond is required for a Washington plumbing contractor?

Washington requires specialty contractors — including plumbing contractors — to carry a $6,000 surety bond as part of their L&I contractor registration. General contractors in Washington must carry a larger $12,000 bond. The specialty contractor bond is verified in real time through the L&I database and must be active at the time work is performed in your home.

The surety bond provides financial recourse if a contractor abandons a job, fails to complete work, or causes property damage without resolution. Combined with the liability insurance requirement, it gives homeowners a financial backstop before civil litigation becomes necessary.

What insurance should a Washington plumbing contractor carry?

Washington requires registered plumbing contractors to carry public liability and property damage insurance as a condition of L&I registration, and the database confirms whether this coverage is current. Plumbing contractors with employees must also maintain workers' compensation coverage through L&I. Water damage from a burst pipe or failed connection can cost tens of thousands of dollars, and a contractor without liability insurance leaves you with no clear recourse.

When you run a contractor lookup on lni.wa.gov, the results show registration, bond, and liability insurance status together. All three should be current and active before you allow any work to begin.

What are the penalties for unlicensed plumbing work in Washington?

Performing plumbing work without proper L&I credentials is a gross misdemeanor in Washington with fines up to $5,000 per violation. L&I can also issue stop-work orders, halting a project mid-construction. Washington has over 120,000 registered contractors across all trades, but enforcement actions against unlicensed operators are routine — particularly when permits get pulled and inspectors identify unlicensed work.

For homeowners, hiring unlicensed plumbers creates serious downstream problems. Unpermitted plumbing work can fail a home inspection, void insurance coverage for water damage claims, and require expensive tear-out to remediate. Only licensed plumbing contractors can pull plumbing permits in Washington.

What should I ask a Washington plumber before hiring?

Ask for the company's L&I contractor registration number and the Master Plumber's individual license number. Verify both at lni.wa.gov to confirm registration is active, bond is current, and liability insurance is on file. Ask whether the scope of work requires a permit and confirm the contractor will pull it before work starts.

Every legitimate Washington plumbing contractor can provide their registration number and the master plumber's license number immediately. Any reluctance to share these numbers is a clear warning sign worth taking seriously.

How does CheckLicensed make plumber verification faster?

Washington's L&I database is thorough but navigating contractor registration and individual plumber lookups separately takes time if you are unfamiliar with the system. CheckLicensed.com delivers a clear, consolidated verification for $0.99 per check — so you can confirm the credentials that matter without working through multiple search screens. Verify any Washington plumber before the first pipe gets touched.