Washington Plumbing Licensing and How to Verify a Contractor

Who licenses plumbers in Washington

Washington is state-level on both counts - L&I certifies individual plumbers and separately registers contractor businesses - so a plumbing company should hold a current plumber certification and an active contractor registration with bond and liability insurance, leaving only permitting to local government.

The authority is Washington State Department of Labor & Industries (L&I). Its public register is at https://secure.lni.wa.gov/verify/.

The same license and permit rules apply in all 68 Washington cities and towns covered here, and to every job listed under all plumbing services.

License classes in Washington

How to verify a contractor before work starts

• Ask for the license number and the exact registered name it is held under.
• Check that name against the company on the estimate, the invoice and the vehicle.
• Check the status is current, not expired, suspended or revoked.
• Ask for a certificate of insurance issued to your address, not a policy number read out on a call.
• For gas, sewer, water-heater or repiping work, ask which permit is being pulled and by whom.

Which plumbing code applies

2021 Uniform Plumbing Code including Appendices A, B, I and M, adopted by WAC 51-56-003, effective March 15, 2024 Washington is a Uniform Plumbing Code state: WAC 51-56-003 adopts the 2021 edition of the UPC together with Appendices A, B, I and M only. The selected appendix list is itself a state amendment, so an appendix that applies in another UPC state may not be in force here, and the State Building Code Council publishes the Washington amendments separately.

Permits

Permits are issued by local building departments, even though the plumbing code, the plumber certification and the contractor registration behind the work are all state-level.

Complaints

The L&I verify service is unusually informative for consumers: for one business it shows contractor registration status, active tradesperson certifications, whether workers' compensation premiums are paid to date, safety citations, construction violations and any lawsuits filed against the contractor's surety bond, and L&I is also the agency that receives complaints.

PlumberWashington is not a licensed contractor

PlumberWashington is an independently operated referral service. PlumberWashington is not a plumbing contractor, holds no contractor license, employs no plumbers and performs no plumbing work. Every job arranged through this site is performed by an independent, separately licensed professional who contracts directly with the homeowner.

Consumer protection

Contractor registration under RCW 18.27 requires a surety bond and liability insurance, and the L&I verify tool discloses lawsuits filed against a contractor's bond - an unusually useful consumer signal that most states do not publish.