My plan

How to Start a Plumbing Business in Washington

Plumbing is steady, needs-based work: leaks, clogs and water heaters don't wait for a good economy. Most states license plumbers individually, so many owners start after years as a journeyman. Federal rules also limit lead in the pipes and fittings you install for drinking water.

Reviewed November 5, 2026 · Sources linked inline

Washington requirements for this business

  • All construction contractors in Washington, general and specialty, must register with the Department of Labor & Industries (L&I); the application fee is $150.20. [source]
  • Registration requires a continuous surety bond of $30,000 for general contractors or $15,000 for specialty contractors; an assigned bank account can be used instead. [source]
  • You must be certified by the Washington State Plumber Certification Program to work in the plumbing trade; work outside a building, such as water main or sewer connections, is generally exempt. [source]
  • A journey level plumber certificate (PL01) requires at least 8,000 hours as a trainee under a certified journey level plumber, including at least 4,000 hours of commercial or industrial work. [source]
  • A residential plumber certificate (PL02) requires at least 6,000 hours and is limited to single-family dwellings, duplexes, and apartment buildings of up to three stories. [source]

Statewide steps for every Washington business — forming an LLC or registering a business name with the Washington Secretary of State — are on our state licensing directory.

FirstBizGuide is not a government agency: any license or registration fees are paid directly to the agency named in each source. These are the Washington facts we have verified so far, not a complete list. City and county rules vary — check with your local government before opening.

Startup costs

We haven't found a reliable published cost range for this business, so we don't show one. Costs vary widely by market, equipment and whether you buy new or used. Plug your own quotes into the worksheet:

Open the plumbing contractor cost worksheet →

SBA 7(a) loans in this industry

Plumbing, Heating, and Air-Conditioning Contractors (NAICS 238220): 3,358 loans approved in FY2024–FY2026. Median loan $175,000; middle half $63,125–$450,000.

Loan size is not startup cost — these loans also fund acquisitions, real estate and working capital. Full breakdown and caveats →

How much competition is there?

Census industry: Plumbing, Heating, and Air-Conditioning Contractors (NAICS 238220)

In Washington: 2,242 employer establishments (2023) and 1,467 businesses without employees (2024). Nationwide: 111,207 employer establishments (2023) and 189,085 businesses without employees (2024).

See counts for your county → Counts aren't a measure of saturation — see the caveats on the tool page.

Equipment and supplies

  • Drain cleaning machines (drum and sectional)
  • Sewer inspection camera and locator
  • Pipe wrenches, cutters and press or crimp tools
  • Soldering and brazing kit
  • Wet/dry vacuum and water-extraction gear
  • Service van with parts shelving
  • PPE including gloves and eye protection
  • Field service software

Licenses and registration

  • If you form an LLC or corporation, register it with your state; if you use a business name other than your own, file a trade name (DBA) where your state requires it (in some states that's the county).
  • Most states license plumbers, often with apprentice, journeyman and master levels, and some also license the business; check your state plumbing board and your city.
  • Many jobs, such as water heater replacements and new piping, need a permit and inspection from the local building department.
  • Under the Safe Drinking Water Act, pipes, fittings and fixtures installed or repaired in plumbing that provides water for human consumption must be "lead free" — a weighted average of 0.25% lead across wetted surfaces, and 0.2% for solder and flux — with listed exemptions such as non-potable devices, toilets and shower valves. [source]
  • Backflow prevention testing and gas piping often require separate certifications or licenses — ask your state or local water and building authorities.
  • EPA's Renovation, Repair and Painting (RRP) rule names plumbers and electricians among the special trade contractors it covers: firms paid for work that disturbs paint in homes and child-occupied facilities built before 1978 must be certified, even sole proprietorships, unless an exemption such as minor repair (6 square feet or less per room inside, 20 square feet or less outside) applies. [source]
  • Some states run their own lead-based paint (RRP) program instead of EPA; if yours does, certify with the state. [source]
  • Commercial clients and general contractors often ask for a certificate of insurance, a W-9 and proof of license.
  • Get a free Employer Identification Number (EIN) from the IRS if you will hire employees or form an LLC or corporation. Beware of sites that charge for this. [source]
  • To find your state's business registration office, use the SBA's state-by-state registration lookup. [source]

Insurance to consider

  • General liability (water damage is a common claim)
  • Commercial auto for service vans
  • Tools and equipment (inland marine) coverage
  • Workers' compensation once you hire
  • Contractor license bond if your state or city requires one

Get quotes from several carriers or an independent agent; coverage needs depend on your contracts, state and staff.

Financing options

  • SBA 7(a) loans — the SBA's main guaranteed loan program, made through participating lenders. [source]
  • SBA Microloans — smaller loans delivered through nonprofit intermediary lenders. [source]
  • SBA Lender Match — a free tool that connects you with interested SBA lenders. [source]
  • Free counseling from your local SBDC or SCORE chapter can help you build the business plan lenders ask for. [source]

Estimate payments with the loan calculator, then check runway with the cash flow projection.

Ongoing operating expenses

  • Parts and materials (usually billed per job)
  • Fuel and van maintenance
  • Insurance
  • Plumber and helper wages
  • License renewals and continuing education
  • Equipment repair
  • Software subscriptions
  • Marketing

Use the break-even calculator to see how many jobs or sales cover them.

Common mistakes

  • Pricing by the hour without knowing your true cost per hour
  • Skipping permits on water heaters and repipes
  • Installing parts that aren't lead free in drinking-water lines
  • No after-hours or emergency pricing
  • Not documenting job sites with photos

Finding customers

  • Google Business Profile and local service listings
  • Emergency and same-day service positioning
  • Referrals from realtors, home inspectors and property managers
  • Relationships with general contractors and remodelers
  • Follow-up offers for water heater and drain maintenance

Startup checklist

Ticks are saved on this device and appear on My plan.

Compare with other businesses

Sources