Licensing Guides
Washington Plumbing License: How to Become a Plumber in Washington
Plumbing, WA
Joanne Bratton
Table of Contents
Benefits of Getting a Plumbing Contractors License in Washington
How Much Does It Cost to Get a Plumbing Contractor License in Washington?
How Long Does it Take to Get a Plumbing Contractors License in Washington?
Does My Washington Plumbing Contractors License Work in Any Other State?
What Are the Reciprocity Requirements for a Plumbing License in Washington?
What Are the Penalties for Unlicensed Plumbing Work in Washington?
You can’t rush through the training it takes to become a plumber, but time and effort leads to a career that is long-lasting, lucrative, and fulfilling. Almost every state requires plumbers to be licensed because it’s complicated work that affects the health and safety of our society.
According to the U.S. Bureau of Labor Statistics ,there are 504,500 plumbers nationwide, and Washington employs 12,210 of them. The national number is projected to grow 5% from 2024 to 2034, adding 44,000 to the ranks across the country. In Washington, according to CareerOneStop, the U.S. Department of Labor’s job search website, the projected growth rate is higher at 10% for plumbers, pipefitters, and steamfitters.
Contractors struggle to find skilled tradesmen like plumbers, electricians, and HVAC or mechanical professionals while the demand for them continues to grow. According to the Associated General Contractors of America, construction employment in Washington in July 2025 totaled 214,700, a decrease of 9,600 (-4%) from July 2024 and a decrease of 8,800 (-4%) from February 2020.
If you get the training you need, you should have a variety of jobs to choose from when you’re ready.
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Licensing requirements for plumbers vary from state to state and, in some cases, from locality to locality. Washington has statewide standards for working in the plumbing business beginning at the plumber trainee level.
Plumbing License Requirements for Plumbers in Washington
Is a license required for plumbers in Washington? Yes. It is mandated from the beginning.
The Washington State Department of Labor and Industries (L&I) certifies plumber trainees, journey level plumbers, specialty plumbers, and plumbing contractors. The specialty plumber certifications include residential plumbing, residential service plumbing, pump and irrigation, domestic well, and backflow assembly tester.
L&I also offers combination plumbing and electrical gas licenses and a medical gas endorsement for medical gas piping installers.
Types of Plumbing Licenses in Washington
What are the types of plumber licenses in Washington? There are seven types of plumbing certifications and one type of contractor license.
Plumber Trainee Certification — An individual learning the plumbing trade who works under the direct supervision of a certified plumber.
Journey Level Plumber Certification (PL01) — An individual qualified to work on plumbing systems in all phases of plumbing construction.
Residential Plumbing Certification (PL02) — This specialty license is limited to the installation, maintenance, and repair of plumbing in single-family dwellings, duplexes, and apartment buildings three stories or less.
Residential Service Plumbing Certification (PL04) — This specialty license is for the service, repair, or replacement of previously existing fixtures, piping, and fittings that are outside the interior wall or above the floor in single-family dwellings and duplexes.
Pump and Irrigation Certification (PL03) — This specialty license is limited to the installation, maintenance, and repair of equipment used to acquire, treat, store, or move water suitable for drinking or irrigation purposes.
Domestic Well Certification (PL03A)— This specialty license is limited to the installation, maintenance, and repair of equipment that is used to acquire, treat, store, or move drinking or irrigation water using a pump not exceeding 100 gallons per minute or 7.5 horsepower, single phase.
Backflow Assembly Tester Certification (PL30) — A specialty license limited to the maintenance and repair of existing backflow prevention assemblies within a building. This does not include installing or replacing backflow prevention assemblies.
Plumbing Contractor — A person who engages in, offers, or advertises plumbing work as a business or employs a person to perform plumbing work.
Each license has specific requirements.
LICENSE REQUIREMENTS:
Be at least 16 years old.
Work under the direct supervision of a journey level or certified plumber.
Apply for plumber trainee certification with the L&I.
Pay the $56.40 certification fee.
To renew your plumber trainee certificate, each year:
Complete eight hours of continuing education.
Submit an affidavit of experience to report supervised work hours.
Pay the $56.40 certification fee.
Continue working as a plumber trainee and meeting continuing education requirements until you’ve completed at least four years (8,000 hours) of experience.
Journey Level Plumber Certification
Be at least 18 years old.
Complete at least four years (8,000 hours) as a plumber trainee working under the supervision of a certified journey level plumber. At least two years (4,000 hours) must be spent working in commercial or industrial installations.
Submit an exam application to the L&I and pay the $189.80 application fee.
Once your application is approved, pass the journey level plumber exam. The exam costs $80.
Pay the $227.90 certification fee.
Residential Plumbing Certification
Be at least 18 years old.
Complete at least three years (6,000 hours) working in the specialty under supervision of a certified residential or journey level plumber.
Submit an exam application to the L&I and pay the $189.80 application fee.
Once your application is approved, pass the residential specialty plumbing exam. The exam costs $80.
Pay the $227.90 certification fee.
Residential Service Plumbing Certification
Be at least 18 years old.
Complete at least two years (4,000 hours) working as a plumber trainee under the supervision of a journey level, residential specialty, or residential service certified plumber. The first year (at least 2,000 hours) must be spent working under the direct supervision of only a journey level or residential specialty plumber.
Submit an exam application to the L&I and pay the $189.80 application fee.
Once your application is approved, pass the residential service plumbing exam. The exam costs $50.
Pay the $227.90 certification fee.
Pump and Irrigation Certification
Be at least 18 years old.
Complete at least two years (4,000 hours) working in the specialty under supervision of an appropriate certified plumber. You must also obtain electrical certification.
Submit an exam application to the L&I and pay the $189.80 application fee.
Once your application is approved, pass the residential service plumbing exam. The exam costs $50.
Pay the $228 certification fee.
Complete at least one year (2,000 hours) working in the specialty under supervision of an appropriate certified plumber. You must also obtain electrical certification.
Submit an exam application to the L&I and pay the $189.80 application fee.
Once your application is approved, pass the residential service plumbing exam. The exam costs $50.
Pay the $228 certification fee.
Backflow Assembly Tester Certification
Obtain your Backflow Assembly Tester Certification (BAT) issued by the Washington State Department of Health.
Submit an exam application to the L&I and pay the $189.80 application fee.
Once your application is approved, pass the residential service plumbing exam. The exam costs $50.
Pay the $157.20 certification fee.
Corporations, Limited Partnerships, Limited Liability Partnerships, or Limited Liability Companies first register with the Washington Secretary of State.
Apply for a business license with the Washington State Department of Revenue.
Obtain a surety bond or assigned savings account in the amount of $6,000.
Obtain a $250,000 certificate of general liability insurance.
Assign your designated plumber who has a plumber certification with L&I.
Submit a notarized plumbing contractor application to the L&I.
Pay the $139.10 license fee.
Steps to Get a Plumbing Contractor License in Washington
To become a plumber trainee, be at least 16 years old.
Work under the direct supervision of a journey level or certified plumber.
Apply for plumber trainee certification with the L&I. Pay the $56.40 certification fee.
Each year, complete eight hours of continuing education and submit an affidavit of experience to report supervised work hours, until you’ve completed at least four years (8,000 hours) of experience. For the journey level certification, at least two years (4,000 hours) must be spent working in commercial or industrial installations.
Once you’ve completed the required experience, submit an exam application to L&I and pay the $189.80 application fee.
Once your application is approved, pass the journey level plumber exam. The exam costs $80.
Pay the $227.90 fee for your three-year journey level certification.
To become a plumbing contractor, register your business with the Washington Secretary of State (depending on your business structure) and the Washington Department of Revenue.
Obtain a $6,000 surety bond or assigned savings account.
Obtain a $250,000 certificate of general liability insurance.
Apply for the contractor license with L&I.
Pay the $139.10 license fee for the two-year license.
Benefits of Getting a Plumbing Contractors License in Washington
There are many benefits to obtaining your Washington plumbing license:
Most importantly, Washington requires plumber trainees, journeyman plumbers, specialty plumbers, and plumbing contractors to hold a state license to legally perform any plumbing work.
A Washington state plumber license is proof of your experience and skill.
Only licensed plumbing contractors can operate a business and advertise services, obtain commercial insurance, pull building permits and pass inspections, and bid on public and government projects.
Having a license protects your company and customers.
A license gives you a competitive advantage in the job market and increases your earning potential as you acquire more experience.
What Is the Mean Wage for a Plumber in Washington?
The annual mean wage for a plumber in Washington is $87,360, according to the U.S. Bureau of Labor Statistics. However, that salary can increase as you acquire more experience. A plumbing salary database, shared with ServiceTitan by Payscale.com, projects the median plumber salary will increase nationally in 2025 by 3.65% for entry-level workers, and 3.55% for both intermediate and senior level plumbers. In Washington those salary projections are:
Entry (<2 years): $57,700
Intermediate (2-4 years): $75,000
Senior (4-7 years): $81,300
Salaries vary widely depending on the city where you work and other factors like education, certifications, additional skills, and the number of years you have spent in your profession.
What Business Owners Need to Know
Getting the most out of a plumbing technician, no matter where they are in their licensing journey, takes work. ServiceTitan’s cloud-based, all-in-one plumbing software gives technicians and business owners the technology they need to do the work efficiently, and the data they need to do it smartly.
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Location-specific service history, including recorded calls, accessible from the mobile app.
Required forms that ensure every job is done right, driving consistency.
The ability to build multi-option proposals with photos, on-site, in minutes.
Sales presentations that make conversations with customers easier and drive up the average ticket.
Mobile payment acceptance, eliminating lost checks and increasing cash flow.
To learn more, schedule a demo with a product expert today.
How Much Does It Cost to Get a Plumbing Contractor License in Washington?
The cost to get started as a plumbing apprentice in Washington is fairly low. It costs $56.40 to register as a plumber trainee every year. Apprenticeship program costs vary depending on the program you choose. Program fees cover course instruction, textbooks, and materials. Your employer or union typically will absorb these costs.
To become a journey level plumber, you’ll pay a $189.80 exam application fee to the Department of Labor and Industries and $80 to PSI to take the exam. Your three-year journey level certificate costs $227.90.
Plumbing contractors pay additional business-related costs. Contractors must obtain a $6,000 surety bond or assigned savings account and a $250,000 certificate of general liability insurance. The two-year license costs $139.10.
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How to Get a Plumbing License in Washington
Becoming a plumbing professional in Washington isn’t fast, but it is straightforward.
COMPLETE APPRENTICESHIP/WORK EXPERIENCE: To become a plumber trainee, you’ll work under the direct supervision of a journey level or certified plumber. Apply for the plumber trainee certification with the L&I online; download, complete and mail a paper application; or apply in person at an L&I office. Pay the $56.40 certification fee. To renew plumber trainee certification, each year you’ll need to submit proof of completing eight hours of continuing education, submit an affidavit of experience, and pay the $56.40 certification fee, until you’ve completed at least four years (8,000 hours) of experience.
APPLY FOR JOURNEY LEVEL CERTIFICATION: To be eligible for the journey level exam, at least two years (4,000 hours) of your four-year training must be spent working in commercial or industrial installations. To become a journey level plumber, apply for the exam online; download, complete and mail a paper application; or apply in person at an L&I office. Pay the $189.80 exam application fee.
PASS JOURNEY LEVEL EXAM: Once your application is approved, pass the journey level plumber exam with PSI. The exam costs $80. PSI provides a candidate information bulletin with detailed exam information. Once you’ve passed the exam, pay the $227.90 journey level certification fee.
APPLY FOR SPECIALTY CERTIFICATION: If you’re seeking specialty certification, you’ll follow a similar process to the one listed above. Once you meet experience requirements, apply for the exam online; download, complete and mail a paper application; or apply in person at an L&I office. Pay the $189.80 exam application fee. PSI exam costs range from $50 to $80, depending on the specialty. Once you pass the exam, pay the certification fee to L&I.
CONTRACTOR REQUIREMENTS: Depending on your business structure, first register your business with the Washington Secretary of State. You also must apply for a business license with the Washington State Department of Revenue. You’ll need to obtain a surety bond or assigned savings account in the amount of $6,000 and obtain a $250,000 certificate of general liability insurance. Plumbing contractors must assign a designated plumber who has a plumber certification with L&I and submit a notarized application with the $139.10 license fee.
The Department of Labor and Industries provides a FAQ page with answers to commonly asked licensing questions.
How Long Does it Take to Get a Plumbing Contractors License in Washington?
It takes a minimum of four years of experience to obtain your journeyman level plumber certification in Washington, depending on your training program requirements. To obtain a journey level certification, plumber trainees must complete at least four years (8,000 hours) of experience, with at least two of those years (4,000 hours) spent working in commercial or industrial installations.
The great news is that as a plumber trainee, you earn a wage from the very beginning and compensation increases each year as you acquire more training and knowledge. Your salary increases when you become a licensed plumber. As a plumbing contractor, you can own your own plumbing business, be your own boss and grow your business as much as you want. The sky’s the limit!
Washington Plumber Training Programs and Schools
Plumbers are responsible for more than just fixing leaks or clogs. They design, install, and renovate systems that carry liquids or gasses. In addition to mechanics, they must know and follow plumbing code.
Since the state of Washington requires plumbing professionals to begin their career journey as a plumber trainee, you may not choose to get a postsecondary degree. Several plumbing training programs and apprenticeship opportunities exist in Washington.
Trade Schools/Community Colleges
Trade schools or community colleges offering plumbing training courses include:
Apprenticeship
Plumbing apprenticeship opportunities include:
Program Prerequisites: For most apprenticeship plumbing programs, you need to be at least 18 years old and have a high school diploma or GED certificate.
On-the-Job Experience: While on the job, you will need to use good customer service skills, possess mechanical capability, pay attention to detail, and be physically fit. The job typically includes hours of walking, standing, and working in tight spaces, and includes some heavy lifting.
For more detailed information about plumbing school options, check out our Ultimate Guide to Plumbing Schools in Washington.
Washington Plumbing Contractor Licensing Exam Details
Those applying for journey level or specialty plumbing certification must first submit an exam application to the L&I. After application approval, schedule, take, and pass the appropriate plumbing exam administered by PSI.
Journeyman exam: The journeyman exam costs $80. The exam is closed book and consists of three parts:
Part 1: Journey level code and general trade knowledge (100 questions and a 90-minute time limit).
Part 2: Waste and vent journey level drawings (25 questions and a 90-minute time limit).
Part 3: Water sizing journey level drawings (25 questions and a 90-minute time limit).
Residential specialty exam: The residential specialty exam costs $80. The exam is closed book and consists of three parts:
Part 1: Residential code and general trade knowledge (100 questions and a 90-minute time limit).
Part 2: Waste and vents residential drawings (25 questions and a 90-minute time limit).
Part 3: Water sizing residential drawings (25 questions and a 90-minute time limit).
Residential service plumber exam: The residential service exam costs $50. The exam is closed book, has 65 questions, and a 90-minute time limit.
Domestic pump or pump and irrigation exam: The domestic pump or pump and irrigation exam costs $50. The exam is open book, has 45 questions, and a 90-minute time limit.
Backflow exam: The backflow exam costs $50. The exam is closed book, has 55 questions, and a 90-minute time limit.
PSI provides a candidate information bulletin with detailed exam information.
Who Issues Plumbing Contractors Licenses in Washington?
The Washington State Department of Labor and Industries certifies plumber trainees, journey level plumbers, specialty plumbers, and plumbing contractors.
The plumber certification division may be reached by phone at (360) 902-5207 or by email at Plumbers@Lni.wa.gov. The mailing address is:
Washington State Department of Labor & Industries Plumber Certification PO Box 44470 Olympia, WA 98504-4470
The L&I also has a contact page with a list of office locations.
Does My Washington Plumbing Contractors License Work in Any Other State?
No, although Washington has a reciprocal agreement with Idaho for journey level plumbers. This means those with a Washington journey level plumbing license applying for an Idaho license will not need to take an examination if they tested for their current license and can show proof of four years of schooling and on-the-job training, according to the state’s reciprocal licensing requirements.
What Are the Reciprocity Requirements for a Plumbing License in Washington?
Washington has a reciprocal certification agreement with Idaho for journey level plumbers. This means those with an Idaho journey level plumbing license may be exempt from taking the Washington plumber exam. The applicant will still need to apply for the license, meet licensing requirements, and pay required fees.
In addition, plumbers with journey level licenses from another state may be considered for a reciprocal license if the state has comparable experience and licensing requirements.
Plumbing Certifications
Other certifications can help you demonstrate your proficiency to potential employers and clients. National Inspection Testing and Certification (NITC), International Association of Plumbing and Mechanical Officials (ASSE Certifications), and other professional certifications are not required but may make you a more attractive hire to prospective employers or can increase your marketability to customers.
Other Requirements Unique to Washington
Washington plumbing regulations and laws may be found in Washington Administrative Code and the Revised Code of Washington.
In Washington, plumbers must visibly display their plumber certification identification on the front of their upper body and it must be immediately available for examination at all times.
Are There Plumbing Scholarships in Washington?
Yes, there are several plumbing or trade school scholarships in Washington. Scholarship opportunities or scholarship directories include:
Plumbing, Heating, and Cooling Contractors Association (PHCC) Educational Foundation
Washington State Fair Foundation — Fair Chance “Trade School” Scholarship and the Ren Martin Trade School/Career Training Endowment Scholarship
Washington State Opportunity Scholarship — Career & Technical Scholarship
Be sure to check with your high school or area community organizations for local scholarships.
How Can Someone Verify My Plumbing License in Washington?
Potential clients or employees may verify your Washington tradesperson, contractor, or business license by visiting the Department of Labor and Industries’ verification page. Use the verify tool to search by:
Name
Tradesperson/contractor license number
Workers’ compensation account
Washington Unified Business Identification (UBI) number
When Can a Plumbing License Be Suspended in Washington?
A suspended plumber’s license means the plumber is temporarily prohibited from legally practicing their trade. In Washington, a plumbing license may be suspended or revoked for many reasons, including:
Providing a false statement in the certificate or license application.
Practicing fraud, misrepresentation, or bribery in securing a certificate, license, or endorsement.
Violating state laws and regulations.
As a plumbing contractor, failing to employ a person with a valid journey level plumber’s certificate of competency or specialty plumber’s certificate of competency in the specialty for the scope of work performed.
Note: The information above should not be considered legal advice. For specific information, refer to the Revised Code of Washington.
What Are the Penalties for Unlicensed Plumbing Work in Washington?
Working as a plumber or contractor in Washington without the appropriate license is illegal. Individuals working without a license are subject to the following fines:
First infraction: $100
Second infraction: $200
Third infraction: $500
Fourth infraction: $1,000
Fifth infraction: $2,000
Sixth infraction: $4,000
Seventh and each additional infraction: Not more than $5,000
Contractors are subject to the following fines:
First infraction: $500
Second infraction: $1,000
Third infraction: $2,000
Fourth infraction: $4,000
Fifth and each additional infraction: Not more than $5,000
For the monetary penalties, each day a person is in violation is considered a separate infraction, and each job site at which a person is in violation is considered a separate infraction.
In addition, any individual or plumbing contractor who acquires three infractions within a 36-month period may have their certificate, license, endorsement, or registration suspended for a period of up to two years, according to state law.
Continuing Education
Those with plumbing certifications must complete 24 hours of continuing education before license renewal. This includes journey level plumbers, residential, residential service, pump and irrigation, and domestic well certifications.
Of the 24-hour continuing education renewal requirement, a minimum of 12 hours must be plumbing code and a minimum of four hours must be industry-related electrical (IRE). The remaining eight hours may be from code, IRE, or industry-related plumbing (IRP). L&I provides a list of approved continuing education courses on its continuing education page.
Plumber certificates expire every three years on the certificate holder’s birthday. Renew online, by mail, or in person at an L&I office.
Renewal fees are as follows:
Journey level, residential, and residential service: $227.90
Pump and irrigation and domestic well: $228
Backflow assembly tester: $157.20
Plumbing contractor licenses expire every two years on the date of issuance. Contractors may renew online, by mail upon receiving a renewal card, or in person at an L&I office. License renewal fee is $139.10. For more information, visit the contractor renewal page.
Resources
You can stay up to date on all plumbing industry news in several ways:
Check top plumbing blogs, including ServiceTitan’s blog.
Read about the latest industry trends.
Listen to top plumbing podcasts like ServiceTitan’s Toolbox for the Trades podcast.
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