As of July 2021, you must be licensed as a Plumbing Contractor with L&I to advertise, offer to do work, submit a bid, or perform plumbing work. Only licensed plumbing contractors may employ certified plumbers to work on plumbing jobs.

To become a licensed plumbing contractor in Washington, you must:

Note: An applicant must wait until their plumbing contractor license is active, before they engage in any plumbing work.

Licensed plumbing contractors who perform non-plumbing construction work can also register as a general or specialty contractor under Chapter 18.27 RCW.

General contractors

General contractors who undertake a construction project that includes some plumbing, may solicit a bid from a plumbing contractor to perform the plumbing work.

General contractors who wish to perform plumbing work must also be licensed as a plumbing contractor under Chapter 18.106 RCW. Licensing requires a separate bond from their contractor registration bond.