Washington · Plumbing licensing · official-source guide
Washington licenses plumbing twice through Labor and Industries. The individual holds a certificate of competency by grade, from journey level down to residential service and the specialties. The business holds a separate plumbing contractor license under chapter 18.106 RCW, which takes a six thousand dollar bond, liability insurance and a full-time designated certified plumber.
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Washington regulates plumbing through the Department of Labor and Industries, and it does it twice. The individual is certified under chapter 18.106 RCW, the plumbers chapter. The business is licensed as a plumbing contractor under the same chapter, in a group of sections added later. L and I's plumbing page states that it certifies plumbing professionals and ensures they meet state requirements, and that it regulates more than 6,000 plumbers, 4,000 plumber trainees and 600 medical gas installers. The business side has a feature that catches contractors coming from other trades. Under RCW 18.106.400, as of July 1, 2021 it is unlawful for any person, firm, partnership, corporation or other entity to advertise, offer to do work, submit a bid, or perform any work under the chapter without being licensed as a plumbing contractor. The same section then says contractors licensed under the chapter are not required to be registered under chapter 18.27 RCW, the general contractor registration statute. L and I's own page on the change says specialty plumbing registration under the old system stopped being valid on July 1, 2021, and that a general contractor may not offer, advertise or bid on projects requiring plumbing work unless it also holds a plumbing contractor license. So a plumbing firm in Washington runs on a plumbing contractor license, not a specialty contractor registration, and the firm must employ a full-time individual holding the matching certificate of competency.
WAC 296-400A-010 lists the certificate types by code. PL01 journey level plumber may work on all phases of plumbing projects including residential, commercial and industrial worksites. PL02 residential specialty plumber covers installation, maintenance and repair of all phases of plumbing for residential structures, which the statute defines as single family dwellings, duplexes and multiunit buildings not exceeding three stories. PL04 residential service plumber is limited to single family dwellings and duplexes and may only repair or replace previously existing fixtures, piping and fittings that are outside the interior wall or above the floor. The statute adds that a residential service plumber may perform plumbing work as needed to do drain cleaning, may repair leaks on any pipe, fitting or fixture from the leak to the next serviceable connection, and may not perform plumbing for new construction of any kind. PL30 backflow specialty plumber covers maintenance and repair of backflow assemblies, where maintenance and repair means cleaning and replacing internal parts and does not include installing or replacing assemblies. PL03 pump and irrigation specialty plumber and PL03A limited volume domestic pump specialty plumber cover domestic water pumping systems, with PL03A restricted to systems not exceeding one hundred gallons per minute. PT00 and PT31 are plumber trainee cards. Medical gas is separate and absolute: under RCW 18.106.020 no person may engage in or offer to engage in medical gas piping installation without a journey level certificate plus a medical gas piping installer endorsement and photo identification in their possession.
The statute sets the outline and the rule sets the numbers. RCW 18.106.040 says a journey level applicant must show completion of a course of study in the plumbing trade in the armed services or at a school accredited by the workforce training and education coordinating board, or four or more years of experience under the direct supervision of a certified journey level plumber. WAC 296-400A-121 makes that concrete: you may take the journey level examination after completing 8,000 hours and not less than four years of documented training, which must include 4,000 hours of commercial plumbing experience under direct supervision of a certified journey level plumber. The residential specialty examination comes after 6,000 hours and not less than three years of documented training. The residential service examination comes after 4,000 hours and not less than two years, where the first year and 2,000 hours must be under direct supervision of a certified journey level or residential specialty plumber and the second year and 2,000 hours may be under a residential service plumber. For the limited volume domestic pump specialty the requirement is one year and 2,000 hours of practical experience on pumping systems not exceeding one hundred gallons per minute, and for the unrestricted version it is 4,000 hours but not less than two years. That experience may be accrued at the same time as the electrical experience required by RCW 19.28.191. Backflow is different again: eligibility requires written evidence of a valid backflow assembly tester certification administered and enforced by the Department of Health.
Washington puts classroom training in front of the examination rather than after it. RCW 18.106.070 states that the training to become a certified plumber must include not less than 16 hours of classroom training established by the director with the advice of the advisory board, and that it must include electrical wiring safety, grounding, bonding and other related items plumbers need to know. WAC 296-400A-121 repeats the requirement as a testing gate: individuals must complete 16 hours of continuing education with a minimum of four hours of industry related electrical training before testing for journey level, domestic pump or residential specialty plumber certification. Anyone certified before January 1, 2003 is deemed to have received that classroom training. The examination schedule is fixed rather than on demand. WAC 296-400A-121 states that examinations are held the first Thursday of every month unless that date falls on a holiday, and that applications must be submitted and received by the plumbing certification program office two weeks before the next scheduled date. An applicant who fails must wait at least until the next scheduled examination date and location, and must work under the direct supervision of a certified plumber on an active trainee card until they pass and the certificate is issued. Failure to reschedule or appear on the scheduled date forfeits the examination fee. WAC 296-400A-020 adds that the certification issuance fee must be paid within ninety days of notification of passing, or the applicant has to sit the examination again.
Every apprentice and every person learning the trade must hold a plumbing training certificate from the department, renewed annually, and at renewal the holder gives the department a list of employers in the plumbing construction industry for the previous year and the hours worked for each. Supervision means a journey level, residential service or appropriate specialty plumber is on the same jobsite as the trainee for a minimum of 75 percent of each working day. RCW 18.106.070 adds a remote option with three conditions that all have to be met: the trainee has more than 2,000 hours of training, the supervising plumber is no more than forty miles from the jobsite, and the scope of work is residential service plumbing in a residential structure limited to the scope of the residential service plumber. Supervision is then given by mobile phone or similar device in a manner allowing both audio and visual direction. Ratios run until December 31, 2028 as follows: not more than three trainees, each on a separate residential structure jobsite performing residential service plumbing in a like-in-kind manner, for every certified specialty or journey level plumber working as a specialty plumber; not more than one trainee on any one jobsite for every certified journey level plumber working at journey level; not more than one trainee per certified residential service plumber; and not more than three trainees on a residential construction jobsite performing plumbing installation per certified specialty or journey level plumber working as a specialty plumber. After December 31, 2028 the cap becomes two trainees per certified plumber on any residential structure jobsite. Medical gas trainees require one hundred percent supervision on a one to one ratio.
Sourcesapp.leg.wa.gov
RCW 18.106.400 sets out what the application must state: the name and address of the applicant, with the names of the individuals comprising a firm or partnership or the managing officials of a corporation; the location of the place of business and the name the business trades under; the employer social security or tax identification number; evidence of workers compensation coverage for employees working in Washington; the employment security department number; and the state excise tax registration number. A unified business identifier may substitute for the last three where the applicant will not employ employees in Washington. The condition the firm lives or dies by is in subsection 4: to obtain a plumbing contractor license the applicant must employ a full-time individual who currently possesses a valid journey level plumber's certificate of competency, or a specialty plumber's certificate of competency in the specialty for the scope of work performed, and no individual may serve as the certified plumber for work exceeding the scope of their certificate. WAC 296-400A-011 calls that person the designated certified plumber and says the designated plumber's certificate defines the scope of work the company may perform. Lose that person and the license is at risk: RCW 18.106.430 lets the department suspend, revoke or civilly penalise a license where the plumbing contractor does not employ a full-time individual holding the matching certificate. The contractor also has two standing duties, to ensure all plumbing work complies with the certification laws and rules, and to ensure all plumbing work is performed by properly licensed and certified individuals.
The plumbing contractor bond is smaller than the general contractor bond and it is easy to budget the wrong one. RCW 18.106.410 requires each applicant for a plumbing contractor license to file a surety bond in the sum of six thousand dollars, issued by a surety insurer meeting chapter 48.28 RCW, naming the state of Washington as obligee, continuous, and cancellable only on written notice to the director. WAC 296-400A-012 confirms six thousand dollars and adds that where a contractor has up to three final judgments involving a residential single family dwelling in the previous five years, the department may require up to three times the normal amount, shown in the rule as $18,000.00. An assigned savings account may be filed instead of the bond. RCW 18.106.420 sets the insurance: at licensing and at each renewal the applicant must furnish insurance or financial responsibility in the form of an assigned account in the amount of fifty thousand dollars for injury or damage to property, one hundred thousand dollars for injury or damage including death to any one person, and two hundred thousand dollars for injury or damage including death to more than one person. L and I states the accepted equivalents on its own pages as $200,000 in public liability and $50,000 property damage, or $250,000 combined single limit, with L and I listed as certificate holder. For comparison, a firm registering under chapter 18.27 instead posts $30,000 as a general contractor or $15,000 as a specialty contractor under RCW 18.27.040, against the same insurance figures in RCW 18.27.050.
Sourcesapp.leg.wa.gov 1app.leg.wa.gov 2app.leg.wa.gov 3lni.wa.gov 4lni.wa.gov 5app.leg.wa.gov 6app.leg.wa.gov 7
WAC 296-400A-045 is the fee rule. It prices the plumbing contractor license at $148.10 for each issuance, renewal or reregistration, states the registration is valid for two years from the date of issuance, renewal or reregistration, and prices initial identification or change in designated plumber at $53.20. Reinstatement of a plumbing contractor license is $74.00 in the same table. L and I's own plumber licensing page instead lists the plumbing contractor application at $148.10, designated plumber assignment at $53.20, renewal at $139.10 and reinstatement at $69.50. Both are department sources and both are reported here rather than one being chosen. On the individual side the rule prices an examination application for journey level, residential specialty, residential service or backflow certification at $202.10, with the note that exam administration is normally performed by a state authorized contractor whose fees are set by contract and are additional. A reciprocity application is $202.10. A trainee certificate is $60.00 for one year or when hours are updated. A temporary permit good for one hundred twenty days is $100.30. A journey level, residential specialty or residential service certificate renewal or first card, covering three years, is $242.70. The domestic pump equivalent is $242.80 and the backflow assembly maintenance and repair equivalent is $167.40. A medical gas endorsement application is $74.30 and its renewal or first card is $166.90. Reinstatement is $324.50 for residential and journey level certificates, $186.60 for backflow and $486.00 for domestic pump. Replacement of any certificate is $27.20, an unsupervised trainee endorsement is $43.30, and inactive status is $43.30.
Sourcesapp.leg.wa.gov 1lni.wa.gov 2
A certificate of competency is renewed every three years, on or before the birthdate of the holder. RCW 18.106.070 conditions renewal on paying the fee and, during the past three years, completing twenty four hours of continuing education approved by the department with the advice of the advisory board, including four hours related to electrical safety. WAC 296-400A-028 breaks the same total down further: a minimum of twelve hours of plumbing code and a minimum of four hours of electrical trade related classes from the currently adopted Washington state plumbing and electrical codes, with the remaining eight hours being plumbing or electrical trade related. For the domestic pump specialty the twenty four hours may mix electrical and plumbing with a minimum of twelve hours in plumbing. Plumber trainees complete at least eight hours per year. Backflow specialty plumbers are exempt from continuing education under the rule. The statute also allows up to four hours of approved behavioral health and wellness training to count toward the total, covering destigmatising behavioral health and supporting wellness, recognising signs of distress, suicide prevention, substance use disorder awareness and prevention, and peer support and connecting to resources. Miss the renewal date and the fee doubles. Go ninety days past the renewal date and the statute requires you to retake the examination and pay the examination fee again. No credit is given for the same approved course taken more than once in a renewal cycle, and none at all for a course the department has not approved.
RCW 18.106.155 lets the director grant a certificate of competency without examination to an applicant who is a registered journey level or specialty plumber in another state whose requirements for registration are at least substantially equivalent to Washington's, and which extends the same privileges of reciprocity to Washington plumbers. WAC 296-400A-070 spells out how that works in practice and adds conditions most applicants have not read. You may be eligible to work in Washington without examination if you hold a current plumbers certificate or license from another state, that state has a current reciprocal agreement with L and I, and you pay the reciprocity application fee plus the certificate fee in the fee rule. Then the restrictions. Reciprocity agreements cannot be used to take the Washington competency examination instead of the examination in your home state. Reciprocity application is only allowed for applicants applying work experience toward certification that was obtained in states with which the department has an agreement. An applicant for a reciprocal certificate must be a resident of the state in which they hold the certificate at the time they apply. And a certificate by reciprocity must not be granted to an individual who already resides in Washington at the time of application. That last pair rules out the common case of a plumber who moves first and applies afterwards. The rule does not publish the list of agreement states and instead directs applicants to contact the plumber's certification clerk at the department's Tumwater headquarters.
RCW 18.27.100 is the advertising statute and it is unusually specific. All advertising and all contracts, correspondence, cards, signs, posters, papers and documents that show a contractor's name or address must show the name or address as registered. All advertising that shows the contractor's name or address must show the contractor's current registration number. The number may be omitted in an alphabetized listing of registered contractors stating only name, address and telephone number, and the statute provides that signs on motor vehicles and on-premises signs do not count as advertising for this purpose. All materials used to directly solicit business from retail customers who are not businesses must show the current registration number. A contractor may not use a false or expired registration number in purchasing or offering to purchase an advertisement. Advertising by airwave transmission is outside the number requirement but is inside the subpoena provision, which lets the director subpoena an advertising seller for the name, address and telephone number the purchaser gave. Subsection 4 forbids advertising that you are bonded and insured on the strength of the bond and insurance the chapter already requires. Penalties run up to ten thousand dollars. WAC 296-200A-400 sets the ladder: for violations of subsections 1 through 4, $250 first, $750 second, $2,250 third, $5,000 fourth and $10,000 for each additional. For falsifying a registration number to solicit business or pose as a contractor, or falsifying an application, it starts at $2,000 and reaches $10,000. L and I states the duty plainly on its own registration page: when you advertise, solicit bids or offer to perform work, you must always include your contractor registration number.
Sourcesapp.leg.wa.gov 1app.leg.wa.gov 2app.leg.wa.gov 3lni.wa.gov 4
RCW 18.27.114 requires a disclosure statement before work starts on any contracting project for the repair, alteration or construction of four or fewer residential units or accessory structures where the bid or contract price totals one thousand dollars or more, and on any commercial building where the price totals one thousand dollars or more but less than sixty thousand dollars. The form is prescribed in the statute in lower case and upper case twelve point and bold type. It opens by naming the contractor's registration number, the bond or deposit posted with the state and its amount, and the expiration date of the registration, then warns in capitals that the bond or deposit might not be sufficient to cover a claim, that the customer may withhold a contractually defined percentage as retainage, and that the property may be liened. The customer signs to acknowledge receipt. The contractor must retain the signed copy for a minimum of three years and produce it to the department on request, and must notify the customer if the registration expires or is revoked or suspended before the contract ends. The commercial consequence is the one to remember: no contractor subject to the section may bring or maintain a lien claim under chapter 60.04 RCW without alleging and proving that the customer was given the disclosure statement. Failure to comply is an infraction. WAC 296-200A-300 adds a narrow carve out for service work, stating that a service company is not required to execute a disclosure statement before receiving payment for a service call unless a bid or contract is in place, and that an annual service contract may be disclosed at signing.
Washington is one of the few states that requires the credential to be worn rather than merely carried. RCW 18.106.020 says no person may engage in or offer to engage in the trade of plumbing without a journey level certificate, specialty certificate, residential service certificate, temporary permit or trainee certificate and photo identification in their possession, and directs the department to establish by rule a requirement that the person also wear and visibly display the certificate or permit. WAC 296-400A-024 is that rule. The certificate must be immediately available for examination at all times. The individual must also have government issued photo identification in their possession. To work in the plumbing trade, an individual must possess, wear and visibly display on the front of the upper body a current, valid plumber certificate of competency, medical gas endorsement or plumber trainee card. Three exceptions are written into the rule. The certificate may be worn inside the outer layer of clothing when outer protective clothing such as rain gear, arc flash or welding gear is required, and it may be worn inside protective clothing so that it becomes visible when the protective layer comes off. The rule states directly that a cold weather jacket or similar apparel is not protective clothing. The certificate may also be worn inside the outer layer when working in an attic or crawl space, or when operating equipment where wearing it would pose an unsafe condition. The legislature's stated intent was to address the underground economy in construction and level the playing field for honest contractors.
Both chapters treat a violation as an infraction and both multiply it. RCW 18.106.020 says each day in which a person, firm or corporation advertises, offers to do work, submits a bid or performs any work in the trade of plumbing in violation of the chapter, or employs a person in violation of it, is a separate infraction, and each worksite is a separate infraction. Notices of infraction may be issued to three parties at once: the person engaging in or offering to engage in the trade in violation, the contractor in violation, and the contractor's employee who authorised the work assignment. It is unlawful for anyone required to be licensed under chapter 18.106 or registered under chapter 18.27 to subcontract to or use anyone not licensed under chapter 18.106 for plumbing work. RCW 18.106.270 sets the money: a minimum of one hundred dollars for an individual's first infraction, a minimum of five hundred dollars for a contractor's first infraction, and a maximum not exceeding five thousand dollars for a second or subsequent infraction. An administrative law judge may not waive, reduce or suspend the penalty. Until January 1, 2027 three infractions within a thirty six month period can bring suspension for up to two years on the recommendation of the advisory board of plumbers; from January 1, 2027 the trigger becomes five or more infractions determined by final order within a five year period, suspended by the department. RCW 18.27.200 mirrors this for contractor registration, and expressly makes a plumbing contractor's violation of RCW 18.106.320 an infraction under chapter 18.27. That section requires quarterly reporting of all plumbing trainee hours, attestation of supervision and ratio, and the names and certification numbers of supervising plumbers, with a penalty of up to five thousand dollars for failing to maintain adequate records.
Sourcesapp.leg.wa.gov 1app.leg.wa.gov 2app.leg.wa.gov 3app.leg.wa.gov 4
Seattle does not issue its own plumbing permits. Public Health Seattle and King County runs the Plumbing and Gas Piping Program and issues permits in Seattle, Clyde Hill and unincorporated King County, with other King County cities handled by their own building departments. The program's guidance on hiring says it is against the law to hire unregistered contractors or to fail to get the necessary permits and inspections, that all contractors who perform work, advertise or submit bids must be registered with L and I and must post a bond and carry general liability insurance, and that where you are paying for plumbing work the installer is required to be certified and to be a registered contractor or employed by one. Fees effective January 1, 2026 are a plumbing or backflow permit at $137 plus $27 per fixture, a gas piping or medical gas permit at $137 plus $27 per outlet, plan review at $273 per hour, inspection outside regular hours at $410 per hour, a requested site visit with no permit at $273, permit renewal at $68, an administrative fee for permit modification, correction or refund processing at $41, re-inspection at $137, and an Already Built Construction permit at $273 plus $55 per fixture or outlet for work done without permit fees paid. Two program notices matter to schedulers. Permits are required for replacement water heaters starting July 1, 2026, in most cases as an over the counter plumbing permit. And since March 22, 2021 a plumbing permit, a gas piping permit and a backflow device permit must be obtained for each townhome constructed under one roof. State law backs the counter: RCW 18.106.440 forbids any city, town or county from issuing a plumbing permit without verifying the contractor's license, requires the plumbing contractor license number to be printed on the permit, and requires written notice to the applicant about the monetary liability of using an unlicensed plumbing contractor.
Sourceskingcounty.gov 1kingcounty.gov 2kingcounty.gov 3cdn.kingcounty.gov 4app.leg.wa.gov 5app.leg.wa.gov 6app.leg.wa.gov 7
L and I runs one public tool at secure.lni.wa.gov/verify, and it is the same tool cities are told to use. Searches run by business name, contractor or tradesperson license number, workers compensation account or Washington unified business identifier. The results show whether a business has an active contractor registration, whether it has an active and paid to date workers compensation account covering any employees, safety violations, lawsuits against its surety bond and other information. Because Washington splits the credential in two, a customer checking a plumbing company should check the company and the individual. The company appears as a plumbing contractor license under chapter 18.106. The person doing the work appears as a certificate of competency with a grade, and the grade is what limits the scope. A PL04 residential service plumber on a new construction job is outside their certificate no matter who employs them. WAC 296-400A-165 requires a city, town or county to verify the licensure of the plumbing contractor before issuing a plumbing permit, and WAC 296-400A-170 says it may do so by checking the department's contractor registration internet website or by calling the department. That means the permit record itself carries a verified license number, which is a second place a customer or a general contractor can look. L and I's plumbing program can be reached at 360-902-5207 or Plumbers at Lni.wa.gov.
Sourcessecure.lni.wa.gov 1app.leg.wa.gov 2app.leg.wa.gov 3app.leg.wa.gov 4lni.wa.gov 5
These are common details other guides publish about Washington, but we could not verify them from the agency source. Confirm them directly before relying on them.
Yes, and at two levels. The Department of Labor and Industries certifies the individual plumber by grade under chapter 18.106 RCW, and licenses the business as a plumbing contractor under the same chapter. L and I states that it regulates more than 6,000 plumbers, 4,000 plumber trainees and 600 medical gas installers.
No. RCW 18.106.400 states that contractors licensed under chapter 18.106 are not required to be registered under chapter 18.27 RCW. L and I adds that a general contractor may not offer, advertise or bid on projects requiring plumbing work unless it also holds a plumbing contractor license.
A continuous surety bond of six thousand dollars under RCW 18.106.410, naming the state of Washington as obligee. An assigned savings account may be filed instead. Where a contractor has up to three final judgments involving a residential single family dwelling in the previous five years, the department may require $18,000.00.
RCW 18.106.420 requires fifty thousand dollars for injury or damage to property, one hundred thousand dollars for injury or damage including death to any one person, and two hundred thousand dollars for more than one person. L and I states the accepted equivalents as $200,000 public liability with $50,000 property damage, or $250,000 combined single limit.
PL01 journey level, PL02 residential specialty, PL04 residential service, PL30 backflow specialty, PL03 pump and irrigation specialty, PL03A limited volume domestic pump specialty, and PT00 and PT31 trainee cards. Medical gas piping requires a journey level certificate plus a medical gas piping installer endorsement.
WAC 296-400A-121 requires 8,000 hours and not less than four years of documented training, including 4,000 hours of commercial plumbing experience under the direct supervision of a certified journey level plumber. Residential specialty takes 6,000 hours over not less than three years, and residential service takes 4,000 hours over not less than two years.
Every three years, on or before the holder's birthdate, with twenty four hours of department approved continuing education. The rule requires a minimum of twelve hours of plumbing code and a minimum of four hours of electrical trade related classes. Backflow specialty plumbers are exempt from continuing education.
Only with states holding a current agreement with L and I, and with two conditions that rule out many applicants. The applicant must be a resident of the state where the certificate is held at the time of application, and a reciprocal certificate must not be granted to someone already residing in Washington. The rule does not publish the agreement list.
Yes. RCW 18.27.100 requires all advertising showing a contractor's name or address to show the current registration number, and all materials used to directly solicit business from non-business retail customers to show it. Signs on motor vehicles and on-premises signs are excluded. L and I instructs contractors to always include the number when advertising, soliciting bids or offering to perform work.
WAC 296-200A-400 sets the ladder for violations of RCW 18.27.100 subsections 1 through 4 at $250 for a first final violation, $750 second, $2,250 third, $5,000 fourth and $10,000 for each additional. Falsifying a registration number to solicit business starts at $2,000. The statutory maximum is ten thousand dollars.
RCW 18.106.270 sets a minimum of one hundred dollars for an individual's first infraction and five hundred dollars for a contractor's first, with a maximum not exceeding five thousand dollars for a second or subsequent infraction. Each day and each worksite is a separate infraction, and the penalty cannot be waived or reduced by an administrative law judge.
Through L and I's verify tool at secure.lni.wa.gov/verify, searching by business name, license number, workers compensation account or UBI. It shows active contractor registration, workers compensation status, safety violations and lawsuits against the surety bond. Check the company license and the individual certificate grade separately.
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