Plumber red flags in Washington

License red flags

• The plumber cannot show an L&I plumbing certificate and photo ID. State law requires them to carry both on the job. (RCW 18.106.020)
• A trainee works alone. Trainees need supervision. (RCW 18.106.020)
• A company that employs plumbers has no plumbing contractor license. That has been required since January 1, 2021. (RCW 18.106.020)
• Someone from another outfit shows up to do the work. A licensed or registered contractor may not subcontract plumbing to anyone unlicensed. (RCW 18.106.020(5))
• A handyman offers to "do the plumbing too." Anyone doing plumbing for pay needs a certificate. (RCW 18.106.020)

In Seattle and unincorporated King County, Public Health says the person you pay must be a certified journeyman plumber and a registered contractor or employed by one. (King County)

Permit red flags

• They ask you to pull the permit in your name. L&I lists that as a warning sign. (L&I F625-084-000)
• In Tacoma, a side sewer repair quoted with no mention of a permit. Tacoma requires one for every side sewer repair; clearing roots or a clog needs none. (Tacoma S-205)
• A crew ready to dig in the Tacoma right-of-way without a licensed and bonded contractor. The City requires one there. (Tacoma S-205)

Money and paperwork

These come from L&I's warning list for contractors: (L&I)

• cash only, a large deposit, or full payment before the work is done;
• payment to a personal name instead of the business name;
• no written contract or complete bid;
• a "sign today" special price.

Get the price in writing before work starts. A plumbing contractor posts a $6,000 bond with its license, so ask for the license number on the paperwork. (RCW 18.106.410, read Oct 18, 2026)

Water damage and insurance

• An offer to cover your deductible. A business that makes a regular practice of that is breaking Washington law. (RCW 48.30A.015)
• Pressure to sign an Assignment of Benefits. It lets the contractor deal with your insurer and collect payment without your approval. Call your insurer first. (OIC)

Check before you decide

Plumbing contractors and individual plumbers both show up on L&I Verify. (L&I) The tool also shows bond, insurance and violations. (L&I) More on the two credentials in Washington plumber licenses, explained.