Job 13 of 16
How to check a plumber in Washington
Washington's Department of Labor & Industries certifies plumbers and licenses plumbing contractors, and its Verify tool looks up either by name, license number, workers' comp account or UBI number.
Revised November 4, 2026
How it changes, sheet by sheet
Inside Tacoma there is a second test. Side sewer repairs in the city right-of-way, even on the private part of the line, need a contractor with a Tacoma license and bond.
These sheets are mostly on Pierce County sewer, and the county's customer guide says building sewer work must be done by a Pierce County Registered Sewer Contractor. Ask to see that registration as well.
Backflow testing has its own credential. Fircrest wants an annual test by a certified tester with a copy filed at the city, and Lakewood Water District posts an approved tester list.
Septic has a separate track. Designer and installer work needs a Health Department permit, and a certified professional can do minor repairs, per the department's page. A plumber's certificate does not answer that question.
Septic questions go to Kitsap Public Health, 360-728-2235. Its page says overdue owners should contact a Health District certified pumper or monitoring and maintenance company.
Lakehaven's FAQ says the district does not perform plumbing repairs, so repairs on your side are not the district's. We could not confirm its contractor rules; ask at 253-945-1580.
What does the state require of a plumber?
A certificate, in the person's possession. RCW 18.106.020(1) reads: "No person may engage in or offer to engage in the trade of plumbing without having a journey level certificate, specialty certificate, residential service certificate, temporary permit, or trainee certificate and photo identification in his or her possession."
L&I's plain version on its plumber program page is this: "Only L&I-certified plumbers can legally perform plumbing work on someone else's property. Property owners can perform their own plumbing work on properties they own."
The statute's own wording for the owner's side, RCW 18.106.150(1), is: "Nothing in this chapter shall be construed to require that a person obtain a license in order to do plumbing work at his or her residence or farm or place of business or on other property owned by him or her."
We quote both because they differ in their words, and we add no gloss of our own. Local codes still apply, as the permit page for your place shows.
What does the state require of a firm?
A contractor license as well. L&I says that since July 2021 you must be licensed as a Plumbing Contractor to advertise, offer to do work, submit a bid or perform plumbing work. The requirements include a $6,000 bond or assigned account and $250,000 in liability insurance.
Under RCW 18.106.400(7), the contractor license section does not apply to a person contracting for plumbing work on his or her own residence, unless the work is on a building for rent, sale or lease.
How do you look someone up?
Go to L&I's Verify a Contractor, Tradesperson or Business tool and search by whichever detail you have. L&I's hiring advice says to use it for bonding, insurance and license history, to get at least three written bids, and to get a written contract.
Since the statute has the certificate and photo ID in the person's possession, asking to see them on the job is a fair request. Then search the name in the tool, and search the firm too.
A firm's website is where to find the name and license to look up, and the services it claims to offer. For an example of what to check, from a Pennsylvania firm that is not local and holds no Washington standing you should assume, see a plumbing firm's service page. Central Plumbing & HVAC is run by the same team as this site, and it works in Pennsylvania, not here.
What about help from family?
RCW 18.106.150(6) says nothing restricts a householder assisting or receiving assistance from a friend, neighbor, relative or other person when none of them hold themselves out as engaged in the trade or business of plumbing. That is the statute's limit. We add no other exemption.
Where do complaints go?
To L&I. Its plumber program, 360-902-5207, investigates complaints about plumbers and randomly checks jobsites. When a jurisdiction issues a permit, RCW 18.106.440(2)(b) has it give written notice of license laws and of the potential risk and monetary liability to the homeowner for using an unlicensed plumbing contractor, so read that notice when it comes.
When is a plumber the wrong call?
Some jobs on this site have their own specialists. Septic work on the peninsulas has certified septic companies and health department permits. Backflow assemblies need a certified tester after install, and a side sewer in a city street can bring a separate contractor rule. For gas lines, valves, burners and flues, our advice is a licensed pro, as set out under water heaters and gas.
Check your own address
- Type the firm's name and the plumber's name into L&I's tool, one at a time, and read the bond and insurance lines.
- Ask your city or county permit counter whether the job needs a local contractor registration.
- Get three written bids, as L&I suggests, and a written contract before work starts.
- If unsure about a certificate, call L&I's plumber program and ask.
Source notes
- About the plumber program, Washington L&I. Checked November 4, 2026.
- Licensed plumbing contractor, Washington L&I. Checked November 4, 2026.
- Verify a Contractor, Tradesperson or Business, Washington L&I. Checked November 4, 2026.
- Hiring a contractor, Washington L&I. Checked November 4, 2026.
- RCW 18.106.020. Checked November 4, 2026.
- RCW 18.106.150. Checked November 4, 2026.
- RCW chapter 18.106. Checked November 4, 2026.
- Wastewater resources, City of Tacoma. Checked November 4, 2026.
- Permits, City of Fircrest. Checked November 4, 2026.
- Residential Sewer Customer Guide, Pierce County. Seen only as a search summary on November 4, 2026; confirm on the page.
- Sewer and Septic Services, City of University Place. Seen only as a search summary on November 4, 2026; confirm on the page.
- Utilities, City of Lakewood. Seen only as a search summary on November 4, 2026; confirm on the page.
- Backflow testing documents, Lakewood Water District. Seen only as a search summary on November 4, 2026; confirm on the page.
- Septic operation and maintenance, Tacoma-Pierce County Health Department. Seen only as a search summary on November 4, 2026; confirm on the page.
- Septic information, Kitsap Public Health District. Seen only as a search summary on November 4, 2026; confirm on the page.
- Septic programs, Kitsap Public Health District. Seen only as a search summary on November 4, 2026; confirm on the page.
- Water service FAQ, Lakehaven. Seen only as a search summary on November 4, 2026; confirm on the page.
- Contact, Lakehaven. Seen only as a search summary on November 4, 2026; confirm on the page.