Short definition
A plumbing contractor is a licensed business entity that installs, repairs, and maintains plumbing systems — distinct from the individual plumber. In WA, plumbing contractors register with L&I under RCW 18.106 with a $6,000 surety bond, $250,000 general liability insurance, and a designated journey-level or specialty plumber on staff.
What it is
Required to operate as a plumbing contractor in WA (verified live from L&I, 2026-04-30):
- Plumbing Contractor License application (notarized)
- $6,000 surety bond (Washington Plumbing Bond) — or assigned savings account
- General liability insurance at $250,000 combined per occurrence, with L&I as certificate holder
- Designated journey-level or specialty plumber assigned to the business per RCW 18.106.400(4)
- License duration of 24 months
- Application fee approximately $141.10
L&I removed the “construction contractor specialty plumbing” category effective July 1, 2024 — businesses must register as a plumbing contractor under RCW 18.106 specifically.
WA runs a two-track system. General Contractors (GC) register under RCW 18.27 (Contractors chapter). Plumbing Contractors (PC) register under RCW 18.106 (Plumbers chapter). A General Contractor doing plumbing work directly — not subcontracting — would also need a PC license. Most GCs subcontract plumbing work to a PC.
Why it matters to a homeowner
The bond and insurance are your customer protection. A $6,000 bond covers smaller damage claims; the $250,000 liability is the bigger backstop. A “very cheap” quote from an unregistered “plumber” is cheaper specifically because they’re not paying the bond, insurance, or workers’ comp. The hidden risk: if they damage your home or injure themselves, your homeowner’s policy may not cover it.
Five scam-prevention angles:
“We’re a plumbing company” without verification
Run the company name on L&I Verify. Should show: active plumbing contractor registration, active bond, active workers’ comp account, designated journey-level plumber on file. Any expired or missing item means they’re not legally a plumbing contractor in WA.
“We sub out the plumbing”
Legitimate model. The general contractor must use a registered plumbing contractor. As the homeowner, you have the right to know the subcontractor’s name and license number. Verify the subcontractor’s license, not just the GC’s.
“Our license is in the name of [different person]”
The qualifying plumber assigned to the contractor must be on staff with active certification. If they “left last month” or are “currently inactive,” the contractor’s authority to do plumbing work is compromised. L&I Verify shows the qualifying plumber’s name and status.
Insurance certificate naming the wrong entity
The Certificate of Insurance must use the contractor’s exact business name. Mismatched names mean the policy may not cover the work being performed. L&I must be listed as a certificate holder for general liability.
Workers’ comp avoided by 1099 misclassification
WA L&I scrutinizes plumber misclassification. A worker injured on a residential job whose contractor classified them as a 1099 may have a personal-injury claim against the homeowner. Verify the contractor has WA workers’ comp on the Verify portal.
When you’ll encounter this term
- A bid letterhead listing a contractor registration number.
- An L&I Verify search returning a contractor with bond, insurance, and qualifying-plumber details.
- A bond claim filing if a contractor causes damage and won’t pay.
- A side-sewer project requiring a Seattle SPU or Tacoma Permits registered side-sewer contractor.
Common variants and not the same as
- Plumbing contractor vs. licensed plumber. Contractor is the business; plumber is the individual.
- Plumbing contractor vs. general contractor. Different statutes (RCW 18.106 vs. RCW 18.27).
- Plumbing contractor vs. handyman. Handymen cannot perform plumbing work in WA; the “handyman exemption” myth covers many things but not plumbing under RCW 18.106.
Washington note
WA’s two-track system (PC plus GC) is unusual nationally — many states bundle plumbing into general-contractor licensing. The dual track means more verification per project but stronger consumer protection.
Side-sewer work in Seattle requires a separately registered side-sewer contractor through SPU. Tacoma maintains a similar list through Tacoma Permits. A single major project — for example, a remodel with structural work plus plumbing plus a sewer connection — may require all three registrations: plumbing contractor (RCW 18.106), general contractor (RCW 18.27), and side-sewer contractor (SPU).
If a contractor finishes work and disappears: file a bond claim with L&I. The $6,000 limit is modest, but it’s real recourse.