How to get a plumbing license in Washington

Journeyman level 8,000 hours on the job + state exam What's a journeyman?

Licensing office Washington State Department of Labor & Industries (L&I), Plumber Certification Program · 360-902-5207 [1]

The license pathway in Washington

1. 1

   Plumber trainee

   • 8 hours of approved continuing education each year
   • $60.00
   • Yearly; 8 hours CE

   Your first certificate. It lets you learn the trade under the direct supervision of a certified plumber. Each year you report your hours on notarized affidavits of experience. [2][6][10]

2. 2

   Residential service plumber (PL04)

   • 4,000 hours on the job
   • 2 years of experience
   • Yes, PSI; 65 questions, 90 minutes, closed book, 70% to pass
   • $202.10 exam application; $242.70 certificate
   • Every 3 years; 24 hours CE

   Service, repair and replacement of existing fixtures and piping in single-family homes and duplexes, plus drain cleaning and leak repairs in any residential building. Your first 2,000 hours must be under a journey level or residential specialty plumber. [1][3][6][7][9]

3. 3

   Residential specialty plumber (PL02)

   • 6,000 hours on the job
   • 3 years of experience
   • 16 hours CE before testing
   • Yes, PSI; same three-part closed-book format as journey level, residential version
   • $202.10 exam application; $242.70 certificate
   • Every 3 years; 24 hours CE

   Plumbing in single-family homes, duplexes and apartment buildings up to three stories. You need 6,000 hours over at least 3 years under a residential specialty or journey level plumber. [1][3][6][7][9]

4. 4

   Journey level plumber (PL01)

   • 8,000 hours on the job
   • 4 years of experience
   • 16 hours CE before testing, at least 4 industry-related electrical
   • Yes, PSI; 100 code questions plus waste-and-vent and water sizing drawings; closed book; 70% on each part
   • $202.10 exam application; $84 PSI; $242.70 certificate
   • Every 3 years; 24 hours CE (at least 12 code, 4 electrical)

   Qualified for all phases of plumbing construction. You need 8,000 hours over at least 4 years under a certified journey level plumber, with 4,000 hours of commercial plumbing. [1][3][4][6][7][9]

5. 5

   Medical gas piping installer endorsement (MG01)

   • At least 32 hours in an L&I-approved medical gas course
   • Yes, PSI; 100 questions, open book (NFPA 99C)
   • $74.30 application; $166.90 endorsement
   • Every 3 years with an affidavit of continuity

   An add-on for journey level plumbers who work on medical gas and medical vacuum piping, such as oxygen and nitrous oxide systems. [1][7][9]

6. 6

   Plumbing contractor license

   • $148.10 per 2-year license
   • Every 2 years

   The business license. Since July 1, 2021 all contract plumbing work must be done by a licensed plumbing contractor, which needs a $6,000 bond, $250,000 in general liability insurance and a certified plumber designated to L&I. [6][10][16][17]

Who needs a plumber certificate in Washington

You must be certified by L&I's Plumber Certification Program to work in the plumbing trade in Washington. The trade covers water supply and distribution pipes, fixtures and traps, drainage and vent pipes, medical gas and vacuum systems, and water heaters.

Except for domestic pump and pump and irrigation systems, you don't need a certificate to install plumbing outside a building, such as a water line connected to a city main or a sewer connection. Property owners can do plumbing work on property they own. [1][5]

The certificate ladder

Trainee. Everyone starts with a plumber trainee certificate. You work under the direct supervision of a certified plumber, renew every year with 8 hours of continuing education, and report your hours on notarized affidavits of experience.

Residential service (PL04). At least 2 years and 4,000 hours; the first 2,000 under a journey level or residential specialty plumber.

Residential specialty (PL02). At least 3 years and 6,000 hours under a residential specialty or journey level plumber. Covers single-family homes, duplexes and apartment buildings up to three stories.

Journey level (PL01). At least 4 years and 8,000 hours under a certified journey level plumber, including 4,000 hours of commercial plumbing. Before testing for journey level, residential specialty or domestic pump certificates you need 16 hours of continuing education, at least 4 of them industry-related electrical training.

Washington also has pump and irrigation (PL03), domestic well (PL03A) and backflow (PL30) specialties. Pump and well work also requires an electrical certificate. A journey level plumber can add a medical gas endorsement (MG01) after a 32-hour approved course.

Trainees in an approved apprenticeship or a technical school plumbing program can apply for an endorsement ($43.30) that lets them work without direct on-site supervision during the last six months of their required experience. [1][2][3][6]

The exam

L&I approves you to test, and PSI gives the exam at testing centers. L&I's exam page and PSI's bulletin say the exams are based on the 2015 Uniform Plumbing Code (UPC) with the amendments adopted by the Washington State Building Code Council. The state plumbing code itself has been the 2021 edition of the UPC since March 15, 2024 (WAC 51-56-003), so ask L&I which edition to study.

The journey level and residential specialty exams are closed book (some code tables are provided) and have three parts: 100 code and trade-knowledge questions, a waste and vent sizing exercise on a building drawing, and a water pipe sizing exercise. PSI allows 90 minutes for each part, and you need 70% on each. If you fail any part, PSI's bulletin says you retake all three, though L&I may waive a part based on earlier attempts.

Your L&I approval is good for one year. To retest, you send a new application with another $202.10 fee and wait at least 14 days after the failed attempt. Find testing details in PSI's Plumbing Examinations Candidate Information Bulletin. [4][7][8]

Fees and renewal

L&I's fees (rule effective July 1, 2026):

• Plumber trainee certificate: $60.00 a year.
• Exam application (journey level, residential specialty, residential service or backflow): $202.10.
• Journey level, residential specialty or residential service certificate: $242.70 for 3 years.
• Medical gas endorsement: $74.30 application, $166.90 certificate.
• Plumbing contractor license: $148.10 per 2 years.

PSI charges $84 for the three-part exam and $52 per part for retests.

Certificates renew every 3 years on your birthday. Journey level and residential plumbers need 24 hours of continuing education, with at least 12 hours of plumbing code and 4 hours of industry-related electrical. Late renewal costs double, and if you go more than 90 days past your renewal date you must retest. [6][7][9][10]

Union and open-shop apprenticeships in Washington

Washington has union and non-union registered apprenticeship programs; joining a union is your choice. Find them in L&I's Apprenticeship Registration and Tracking System (ARTS) and apply directly to each program.

The Seattle Area Plumbers, Housing Plumbers, Pipefitters, HVAC-Service Controls Technician/Refrigeration Mechanics and Marine Pipefitters Apprenticeship Committee, a joint committee with UA Local 32, runs a 10,000-hour plumber apprenticeship. Applicants must be 18, have a high school diploma or GED, show math readiness, pass a drug test and hold a driver's license.

The Construction Industry Training Council of Washington (CITC) runs a 10,000-hour plumber apprenticeship statewide, with at least 216 hours of classroom instruction a year. Applicants must be 18 with a diploma or GED, a year each of algebra and geometry, and a score of 50 or higher on the Scheig Utility Worker test.

Your apprenticeship hours count toward your trainee experience only while you hold an active Washington trainee certificate. [11][12][13][14]

If you're licensed in another state

Idaho. L&I lists reciprocal certification with Idaho for journey level plumbers. Email a copy of your active Idaho journey level card and a government photo ID to plumbers@Lni.wa.gov. The reciprocity application fee is $202.10. Under L&I's rule you must live in the state that licensed you when you apply.

Other states. All other plumbers must pass the Washington exam. Send a copy of your out-of-state license (or documents showing U.S. military experience) and photo ID for review. Hours worked for out-of-state employers or in other states' apprenticeship programs don't count toward a Washington certificate.

While you wait to test, a current out-of-state license holder can get a one-time 120-day temporary permit for $100.30. [4][6][9][15]

Plumbing contractor license

A 2020 law (SB 6170) created a separate plumbing contractor license. Since July 1, 2021, all contract plumbing work must be done by a licensed plumbing contractor, and general contractors can't bid on or advertise plumbing work unless they also hold this license or subcontract the plumbing.

To apply you need a UBI business number from the Department of Revenue, a $6,000 plumbing contractor surety bond (or assignment of savings), general liability insurance of $250,000 combined single limit (or $200,000 public liability and $50,000 property damage), and a certified plumber designated to L&I as your company's plumber. The license runs 2 years. L&I's rule sets the fee at $148.10 plus $53.20 to designate your plumber; L&I's how-to page still shows $139.10 for renewals, so check the current amount. [6][10][16][17]

Steps to get licensed in Washington

1. Get a plumber trainee certificate

   Apply with L&I online, by mail or in person. You must be 16 or older; the fee is $60 and the certificate lasts a year. [2][6]

2. Work under a certified plumber

   Get hired by a plumbing contractor or join a registered apprenticeship. Keep a personal log of your hours. [2][11]

3. Report your hours and renew every year

   Send notarized affidavits of experience for each employer within 30 days after your renewal date, and complete 8 hours of continuing education each year. [2][18]

4. Reach 8,000 hours and 16 hours of pre-exam training

   Journey level needs 8,000 hours over at least 4 years, including 4,000 commercial hours, plus 16 hours of continuing education with at least 4 hours of industry-related electrical training. [3]

5. Apply to L&I for the exam

   Once L&I has approved your affidavits and education, apply online or by mail with the $202.10 fee. Approved applications are good for one year. [4][6]

6. Schedule and pass the PSI exam

   Pay PSI ($84 for the three-part exam) and schedule. After you pass, L&I invoices the $242.70 certificate fee, which you must pay within 90 days. [7][9][19]

Where to get the hours

Programs that train plumbers in or for Washington, from their own official pages. Listed by type, not ranked.

• State program

  L&I Apprenticeship Registration and Tracking System (ARTS)

  L&I's database of every registered apprenticeship program in Washington, union and non-union. Apply directly to the programs you're interested in. [11]

• Union

  Seattle Area Plumbers, Pipefitters and HVAC apprenticeship committee (UA Local 32)

  Joint committee with United Association Local 32. Its Plumber apprenticeship runs 10,000 hours; a Housing Plumber track runs 6,000 hours. Applicants must be 18 with a diploma or GED. [12]

• Other

  Construction Industry Training Council of Washington (CITC), Plumber

  A state-approved 10,000-hour plumber apprenticeship covering all four regions of Washington. Applicants must be 18 with a diploma or GED and pass the Scheig Utility Worker test. [13]

• State program

  Recognized apprenticeship preparation programs

  Short programs, recognized by the Washington State Apprenticeship and Training Council, that have agreements with apprenticeship sponsors. Some are run by school districts and colleges. [20]

Licensed in another state?

Questions people ask