- No dollar exemption is stated. The contractor license rule does not apply to plumbing on your own home, unless the building is for rent, sale or lease.
- A journey level (PL01) certificate takes four years or more (at least 8,000 hours) as a plumber trainee under a certified journey level plumber, with at least 4,000 hours on commercial or industrial work. Residential (PL02) takes 3 years (6,000 hours). The contracting business must employ a full-time certified journey level or specialty plumber.
- Plan for a trade exam.
- A $6,000 surety bond with the State of Washington named as obligee.
- The plumbing contractor license expires 24 months after it is issued. Plumber certificates renew every three years on your birthdate, with 24 hours of approved continuing education, including 4 hours on electrical safety.
Do you need a state license in Washington?
Washington licenses plumbing work at the state level through the Washington State Department of Labor and Industries (L&I), Plumber Certification Program. Below is what the board asks for, in the order you will run into it.
No dollar exemption is stated. The contractor license rule does not apply to plumbing on your own home, unless the building is for rent, sale or lease.
Washington license types for plumbing work
Washington splits the work into 6 licenses. Pick the one that matches the jobs you take, since working outside its scope is the same as working without one.
| License | What it covers |
|---|---|
| Plumbing contractor license | The business license needed to advertise, bid or do plumbing work |
| Journey level plumber (PL01) | All phases of plumbing construction |
| Residential (PL02) | Plumbing in single-family homes, duplexes and apartment buildings up to three stories |
| Residential service (PL04) | Service, repair and replacement of existing fixtures and piping in single-family homes and duplexes, plus drain cleaning and leak repair |
| Pump and irrigation (PL03) and domestic well (PL03A) | Water pump, treatment and irrigation equipment; these also need electrical certification |
| Backflow (PL30) | Maintenance and repair of existing backflow assemblies inside a building |
Steps to get licensed in Washington
- Get a plumber trainee certificate from L&I and work under a certified plumber.
- Log your hours: at least 8,000 for journey level (PL01), with 4,000 on commercial or industrial work.
- Apply to L&I for the exam, pass it, and get your certificate.
- Buy a $6,000 surety bond and the required liability insurance, and set up workers' comp if you have employees.
- Apply to L&I for the plumbing contractor license, naming the full-time certified plumber, and pay the $148.10 fee.
- Renew the contractor license every 24 months and your certificate every three years with 24 hours of continuing education.
Experience and other requirements
Experience. A journey level (PL01) certificate takes four years or more (at least 8,000 hours) as a plumber trainee under a certified journey level plumber, with at least 4,000 hours on commercial or industrial work. Residential (PL02) takes 3 years (6,000 hours). The contracting business must employ a full-time certified journey level or specialty plumber.
The license to apply for. Plumbing contractor license, plus a journey level (PL01) or specialty plumber certificate.
Washington plumbing exams
Trade exam. Yes. Journey level and specialty plumbers must pass an L&I certification exam. A state-authorized testing contractor normally gives the exam, and its fee is on top of the L&I fee.
Business and law exam. The official pages we read do not say. Check with the board (official site).
What it costs in Washington
The board lists 5 fees along the way. These are the state's own numbers. Insurance, any bond, exam prep and your business registration come on top.
| Fee | Amount |
|---|---|
| Plumbing contractor license, each issuance or renewal (two years) | $148.10 |
| Naming or changing the designated plumber | $53.20 |
| Exam application, journey level or residential | $202.10 |
| Journey level or residential certificate, first card or renewal (three years) | $242.70 |
| Trainee certificate | $60.00 |
Insurance and bond
Insurance. Liability insurance, or an assigned account, of $50,000 for property damage, $100,000 for injury or death to one person, and $200,000 for injury or death to more than one person. You also show workers' compensation coverage for employees working in Washington.
Bond. A $6,000 surety bond with the State of Washington named as obligee.
Renewal and licenses from other states
Renewal. The plumbing contractor license expires 24 months after it is issued. Plumber certificates renew every three years on your birthdate, with 24 hours of approved continuing education, including 4 hours on electrical safety.
Reciprocity. Washington has reciprocal certification with Idaho for journey level plumbers. Other out-of-state plumbers can present a comparable license, or equivalent U.S. military experience, for consideration.
Good to know in Washington
- A licensed plumbing contractor does not also have to register as a construction contractor under chapter 18.27 RCW.
- Everyone doing plumbing must carry their certificate or permit and photo ID on the job.
- Medical gas piping needs a journey level certificate plus a medical gas endorsement, which takes at least 32 hours of approved training.
- Certificates are not needed for plumbing outside a building, such as sewer or water main connections, except pump and irrigation work.
After you are licensed
The license lets you take the work. Getting the work is the next job.
- Register the business. If you work under a name other than your own, register it where your state asks (often the Secretary of State, sometimes the county), and keep the name the same on your license, your truck and your invoices.
- Claim your Google Business Profile. It is the listing people see when they search for a plumber near them. Fill in your service area, hours and real photos of your work.
- Put up a website that shows the license. Customers look for it before they call. Koira builds a contractor website for you and keeps it current.
- See where you stand. The free Koira report checks how your business shows up in search and on maps against shops near you.
Where this comes from
Every fact on this page comes from the Washington State Department of Labor and Industries (L&I), Plumber Certification Program and the official pages below, checked October 8, 2026. Fees and rules change, so confirm with the board before you file.
More for your trade: how plumbing companies run on Koira.