L&I Plumber Licensing in Washington: What Homeowners Need to Know

Washington State requires plumbers to hold specific licenses issued and regulated by the Department of Labor and Industries (L&I). Understanding what these licenses mean — and how to verify them — helps homeowners hire qualified plumbers and protect themselves from unqualified contractors. Here’s what you need to know about Washington plumber licensing.

Washington State Plumber License Types

L&I issues three levels of individual plumber licenses:

1. Plumber’s Apprentice License
– Entry-level — working under supervision
– Enrolled in an apprenticeship program
– Cannot work independently; must work under a journeyman or master plumber

2. Journeyman Plumber License
– Can perform all plumbing work
– Can supervise apprentices
– Cannot run a plumbing business as the qualifying individual (requires Master)
– Requires completion of apprenticeship + licensing exam

3. Master Plumber License
– Highest individual license level
– Required to operate a plumbing contracting business (must be the qualifying agent)
– May design plumbing systems and pull permits
– Requires additional experience and examination beyond journeyman

For homeowners: When hiring a plumbing company, the company should have a licensed Master Plumber as the qualifying agent. The technicians who perform work may be journeymen or apprentices working under supervision.

Plumbing Contractor Registration

In addition to individual licenses, plumbing businesses must hold a contractor’s license with L&I.

Washington State’s Contractors Registration Act requires plumbing contractors to:
– Register as a contractor with L&I (separate from individual plumber licenses)
– Carry liability insurance (minimum $100,000 general liability)
– Carry workers’ compensation insurance (for employees)
– Have a Master Plumber as the qualifying agent or designated supervising plumber

The contractor registration number is distinct from the individual plumber’s license number. Both should be verifiable.

How to Verify a Washington Plumber’s License

The L&I Contractor Lookup tool:

Go to: secure.lni.wa.gov/verify (or search “Washington contractor license lookup”)

You can search by:
– Business name
– License/registration number
– Individual plumber’s name

What the lookup shows:
– Whether the license is active or expired
– License type and level
– Expiration date
– Business address
– Insurance status
– Any violations or disciplinary actions

Do this before hiring any plumber. An unlicensed plumber cannot legally pull permits; their work may not be covered by homeowners insurance; and there’s no regulatory accountability if something goes wrong.

Why Licensing Matters for Homeowners

Insurance protection:
Licensed contractors are required to carry liability insurance. If a licensed plumber damages your property, their insurance covers it. An unlicensed contractor has no required coverage — you may have no recourse for damage they cause.

Permit-pulling authority:
Only licensed contractors can pull building permits in Washington. If a plumber says permits aren’t required for work that actually needs them — or proposes to do work without a permit — that’s either an unlicensed contractor or a dishonest licensed one.

Code knowledge:
Washington plumber licensing requires examination on plumbing codes. A licensed plumber knows current code requirements. An unlicensed worker may install systems that don’t meet code, creating problems at inspection or property sale.

Accountability:
L&I can investigate complaints against licensed contractors, impose fines, suspend or revoke licenses, and take legal action. There’s no regulatory recourse against an unlicensed contractor through L&I.

Red Flags That May Indicate an Unlicensed Plumber

• Cannot provide a Washington contractor registration number or license number
• Asks to be paid entirely in cash with no written contract
• Proposes to skip permits for work that requires them
• Cannot explain which level of license they hold
• Offers prices significantly below all other quotes (often reflecting lack of insurance overhead)
• Has no L&I lookup result for their stated business name

How Washington Plumber Apprenticeships Work

The standard path to a journeyman plumber license in Washington:

1. Register as an apprentice with an L&I-approved apprenticeship program
2. Complete 4–5 years of on-the-job training under a journeyman or master plumber
3. Complete required classroom training (typically 150–160 hours per year)
4. Pass the journeyman plumber examination
5. Apply for journeyman license through L&I

To become a Master Plumber:
1. Hold a journeyman plumber license
2. Complete additional experience requirements (typically 2 years as a journeyman, depending on the specific pathway)
3. Pass the master plumber examination

The experience requirement explains the “years of experience” that professional plumbers describe — it reflects not just time in the field but the formal apprenticeship and licensing pathway.

Owner-Performed Plumbing in Washington

Washington State allows homeowners to perform plumbing work on their own primary residence.

This is called the “owner-builder” exemption. Requirements:
– You must own the property (or be purchasing under a real estate contract)
– It must be your primary residence
– You must perform the work yourself (not hire others to do it)
– Work must still meet code and pass inspection
– You can pull an owner-builder permit for this work

What this doesn’t mean:
– Homeowners cannot hire unlicensed workers to do the work under the owner-builder exemption
– Homeowners doing their own work must still pull permits for required work
– The work must still be inspected and meet code

Practical note: For complex plumbing work (water heater, sewer lateral, repipe), hiring a licensed plumber is usually the right choice — the code knowledge, experience, and accountability are worth the cost.

FAQ

Q: How do I verify a plumber is licensed in Washington State?
A: Use the L&I Contractor Lookup at secure.lni.wa.gov/verify. Search by business name or license number. Confirm the license is active, the type of license, and whether there are any disciplinary actions.

Q: What are the plumber license levels in Washington State?
A: Three levels: Plumber’s Apprentice (entry-level, works under supervision), Journeyman Plumber (can perform all plumbing work, supervise apprentices), Master Plumber (highest level, required to operate a plumbing contractor business).

Q: Does a plumber need to be licensed to pull permits in Seattle?
A: Yes — only licensed contractors can pull plumbing permits in Seattle (SDCI). Unlicensed contractors cannot legally pull permits; work done without permits creates complications for homeowners at insurance claim time and property sale.

Q: What insurance is a licensed Washington plumber required to carry?
A: Washington contractor registration requires minimum $100,000 general liability insurance and workers’ compensation insurance for employees. This protects homeowners if the contractor causes damage.

Q: Can I do my own plumbing without a license in Washington?
A: Yes, on your own primary residence under the owner-builder exemption. You must perform the work yourself (not hire unlicensed workers), still pull required permits, and have work inspected. For complex work, hiring a licensed plumber is typically safer and more practical.