Want to be a plumber, or move your license to another state? Pick a state below. You'll see the license levels, the hours, who gives the test, which code book the test uses (often not the one in the field), and how to find an apprenticeship.
Every fact links to the official board page, rule or bulletin it came from, checked Nov. 10, 2026. Starting states: WA, OR, ID, CA, MT. More states are coming, and we add each one only after checking its official sources.
Washington
Washington calls it a certificate, and you need one to work in the plumbing trade at all. Almost everyone starts as a plumber trainee.
Licensing agency: Dept. of Labor & Industries (L&I), Plumber Certification Program
License levels and required hours
- Plumber trainee: the starting point for every level. Source: L&I trainee page
- Journey level (PL01): at least 8,000 hours (four years) as a trainee under a certified journey-level plumber. At least 4,000 of those hours must be commercial or industrial. Source: L&I Plumber Certification
- Residential (PL02): at least 6,000 hours (three years) in the specialty, for single-family homes, duplexes and apartments up to three stories. Source: L&I
- Residential service (PL04): at least 4,000 hours (two years), with the first 2,000 under direct supervision of a journey-level or residential plumber. Source: L&I
- Also: pump & irrigation (PL03, 4,000 hours, also needs electrical certification), domestic well (PL03A, 2,000 hours), backflow (PL30), and medical gas (MG01, journey level plus 32 hours of approved training). Source: L&I
The exam
Given by PSI. First submit your experience affidavits and finish your continuing education. The L&I application fee is $202.10, plus a PSI scheduling fee. Journey-level and residential exams are closed book, with three parts: 100 code questions, a waste-and-vent sizing exercise, and a water-pipe sizing exercise. L&I says some tables are provided with the exam. Source: L&I Plumber Examination
Code book on the exam vs. the code in the field
- On the exam
- 2015 edition, with WA amendments
L&I says its exams are based on the 2015 Uniform Plumbing Code and Washington amendments. Source: L&I Plumber Examination - In the field
- 2021 edition, with WA amendments
WAC 51-56-003 adopts the 2021 UPC (effective March 15, 2024), with some chapters and sections left out. Source: WAC 51-56-003
Heads up: the exam edition and the field code are different editions here. Study the exam edition, but work to the field code.
Getting into an apprenticeship
Out-of-state trainee or apprentice hours don't count toward Washington certification. Source: L&I
- Union route: plumber and pipefitter apprenticeships run by United Association (UA) local training committees. Find one through the United Association.
- Non-union (merit shop) route: registered programs through Associated Builders and Contractors (ABC) chapters and other sponsors.
- Any registered program: search the U.S. Department of Labor's Apprenticeship Job Finder.
Check that your state recognizes a program for licensing before you sign up.
Reciprocity
Idaho only, for journey-level plumbers. Other out-of-state plumbers must pass the Washington exam, and can apply for a one-time 120-day temporary permit ($100.30) while they wait. Source: L&I
Statewide or local?
Statewide. L&I certifies plumbers for the whole state. Plumbing contractors need a separate L&I contractor license. Source: L&I licensing requirements
Oregon
Oregon licenses journeyman plumbers through the Building Codes Division. The hours are split evenly between commercial and residential work.
Licensing agency: Building Codes Division (BCD), Dept. of Consumer & Business Services
License levels and required hours
- Journeyman plumber (JP): qualify one of three ways: (1) finish a registered 4-year apprenticeship; (2) 576 classroom hours plus 3,850 commercial and 3,850 residential on-the-job hours; or (3) 7,700 commercial and 7,700 residential hours while holding a similar license elsewhere. Source: Oregon License Directory: Journeyman Plumber Source: BCD application 440-2571
- License fee: $100. Renews every three years on April 1, with 24 hours of continuing education. Source: Oregon License Directory
The exam
4 hours, 64 questions, open book. After approval, BCD mails a letter of authorization and a list of approved exam materials. The application lists test sites in Bend, Eugene, Hermiston, Klamath Falls, Ontario, Pendleton, Portland, Roseburg, Salem and White City. Source: Oregon License Directory Source: BCD application 440-2571
Code book on the exam vs. the code in the field
- On the exam
- Not stated on BCD's public pages
BCD sends the approved-materials list after you're approved. Check it before you buy a book. Source: Oregon License Directory - In the field
- 2026 Oregon Plumbing Specialty Code (based on the 2024 edition)
The 2026 OPSC took effect Oct. 1, 2026, based on the 2024 UPC. Source: BCD Plumbing Code Program
We couldn't confirm the exam edition from an official page, so confirm it before you buy a book.
Getting into an apprenticeship
State-registered programs: Oregon BOLI Apprenticeship and Training.
- Union route: plumber and pipefitter apprenticeships run by United Association (UA) local training committees. Find one through the United Association.
- Non-union (merit shop) route: registered programs through Associated Builders and Contractors (ABC) chapters and other sponsors.
- Any registered program: search the U.S. Department of Labor's Apprenticeship Job Finder.
Check that your state recognizes a program for licensing before you sign up.
Reciprocity
Oregon has reciprocity agreements for journeyman plumbers. See BCD's list of states. Source: BCD Reciprocal licenses
Statewide or local?
Statewide. BCD issues the journeyman plumber license for the whole state. Source: BCD
Idaho
Idaho gives you two roads to journeyman: apprentice hours plus school, or twice the hours. The exam is open book.
Licensing agency: Idaho Plumbing Board, Division of Occupational and Professional Licenses (DOPL)
License levels and required hours
- Apprentice: registered with the state. Source: IDAPA 24.39.20
- Journeyman certificate of competency: pass the exam, plus either 8,000 hours as an apprentice and 576 hours of a board-approved course, or 16,000 hours of plumbing experience. You can sit for the exam once you've finished the 576 hours or the 16,000 hours. Source: IDAPA 24.39.20
- Specialty journeyman: separate certificates for areas like appliances and water pumps, each with its own hours. Source: IDAPA 24.39.20
The exam
Given by PSI. Open book, 70% to pass. Permanent tabs only. Source: Idaho Plumbing Candidate Information Bulletin (dated Nov. 1, 2024)
Code book on the exam vs. the code in the field
- On the exam
- 2015 edition plus the 2017 Idaho State Plumbing Code
The PSI bulletin lists the 2015 UPC and the 2017 Idaho State Plumbing Code as allowed references. Source: PSI bulletin - In the field
- 2015 edition, with Idaho amendments
Idaho's current rules adopt the 2015 UPC as the Idaho State Plumbing Code, with amendments. Source: IDAPA 24.39.20.600
Here the exam edition and the field code match.
Getting into an apprenticeship
Apprentices register with DOPL. Approved courses are set by the board. Source: IDAPA 24.39.20
- Union route: plumber and pipefitter apprenticeships run by United Association (UA) local training committees. Find one through the United Association.
- Non-union (merit shop) route: registered programs through Associated Builders and Contractors (ABC) chapters and other sponsors.
- Any registered program: search the U.S. Department of Labor's Apprenticeship Job Finder.
Check that your state recognizes a program for licensing before you sign up.
Reciprocity
Washington lists Idaho as its only reciprocal state for journey-level plumbers. Source: WA L&I We haven't verified Idaho's full list yet.
Statewide or local?
Statewide. DOPL issues plumbing certificates for the whole state. Source: DOPL
California
California is the odd one out. We didn't find a statewide journeyman plumber certificate on the state's official pages. The state-issued plumbing credential is the CSLB C-36 plumbing contractor license.
Licensing agency: Contractors State License Board (CSLB)
License levels and required hours
- C-36 Plumbing Contractor: you need at least four years of journey-level experience (or foreman, supervisor, contractor or owner-builder) in the class to qualify for the exam. Apprentices, trainees and helpers don't count as journey level, but finishing an apprenticeship does. Source: CSLB: Qualifying Experience
- Working as an employee: state rules for plumber employees aren't covered here. Ask your city or county building department about local requirements.
The exam
CSLB licensing exams. See CSLB's step-by-step guide. Source: CSLB: Get Licensed to Build
Code book on the exam vs. the code in the field
- On the exam
- Not published by CSLB here
We didn't find a code edition for the C-36 exam on CSLB's public pages. - In the field
- 2025 California Plumbing Code (based on the 2024 edition)
The 2025 Title 24 codes took effect Jan. 1, 2026. The state points to the 2024 UPC for Part 5, the California Plumbing Code. Source: CA Building Standards Commission
We couldn't confirm the exam edition from an official page, so confirm it before you buy a book.
Getting into an apprenticeship
State-approved programs: DIR Division of Apprenticeship Standards.
- Union route: plumber and pipefitter apprenticeships run by United Association (UA) local training committees. Find one through the United Association.
- Non-union (merit shop) route: registered programs through Associated Builders and Contractors (ABC) chapters and other sponsors.
- Any registered program: search the U.S. Department of Labor's Apprenticeship Job Finder.
Check that your state recognizes a program for licensing before you sign up.
Reciprocity
Not published on the pages we checked.
Statewide or local?
Plumbing contractors are licensed statewide by CSLB. Local permits and inspections are handled by cities and counties.
Montana
Montana wants five years of legally obtained experience or a finished apprenticeship, then two exams: written and practical.
Licensing agency: Montana Board of Plumbers, Dept. of Labor & Industry
License levels and required hours
- Journeyman plumber: at least 7,500 hours of experience over at least five years, or a completed registered apprenticeship. Some engineering schooling and steam-fitting experience can count for up to two years. Source: MT journeyman application
- Master plumber: four years as a licensed journeyman. Source: MT exam information sheet
The exam
Scheduled through IAPMO after the board approves you. Written exam: 100 questions, open book, 3 hours. Practical exam: three virtual diagrams, 2½ hours. Bring your own code book with factory tabs. Source: MT exam information sheet (rev. Jan. 2023)
Code book on the exam vs. the code in the field
- On the exam
- 2021 edition, as amended
The exam sheet (revised Jan. 2023) says both exams use the 2021 UPC as amended plus the board's statutes and rules. Source: MT exam information sheet The field code has since moved to the 2024 edition, so ask the board which edition your exam uses now. - In the field
- 2024 edition, effective Sept. 26, 2026
Montana's Building Codes program lists the 2024 UPC as effective Sept. 26, 2026. Source: Montana Current Codes
Heads up: the exam edition and the field code are different editions here. Study the exam edition, but work to the field code.
Getting into an apprenticeship
State-registered programs: Montana Registered Apprenticeship.
- Union route: plumber and pipefitter apprenticeships run by United Association (UA) local training committees. Find one through the United Association.
- Non-union (merit shop) route: registered programs through Associated Builders and Contractors (ABC) chapters and other sponsors.
- Any registered program: search the U.S. Department of Labor's Apprenticeship Job Finder.
Check that your state recognizes a program for licensing before you sign up.
Reciprocity
Not published on the pages we checked.
Statewide or local?
Statewide. The Board of Plumbers licenses plumbers for the whole state. Source: MT Board of Plumbers
What book to study
Buy the edition your exam uses, not just the newest one. Pick a state above to switch this list.
Washington: exam: 2015 edition, with WA amendments; field code: 2021 edition, with WA amendments.
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Oregon: exam: Not stated on BCD's public pages; field code: 2026 Oregon Plumbing Specialty Code (based on the 2024 edition).
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Idaho: exam: 2015 edition plus the 2017 Idaho State Plumbing Code; field code: 2015 edition, with Idaho amendments.
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California: exam: Not published by CSLB here; field code: 2025 California Plumbing Code (based on the 2024 edition).
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Montana: exam: 2021 edition, as amended; field code: 2024 edition, effective Sept. 26, 2026.
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Check the edition year on every listing before you buy.
Quick math
Need pipe fall or water-heater recovery? Try our plumbing calculators. They use plain formulas, not code tables.