To learn the plumbing trade in Washington State and become a certified plumber, you must start as a plumber trainee. As a trainee, you will work under the direct supervision of a certified plumber and learn through on-the-job training. Once you have the required experience and education, you can take the plumber exam to become a certified plumber or journey level plumber.
Plumber trainees must report their supervised work hours at least once a year by filing affidavits of experience (F627-004-000) and/or residential service affidavit of experience with L&I. These affidavits report the qualifying, supervised hours a trainee has worked, and who their supervising plumber was. We verify all affidavits and log creditable hours as trainees work toward certification.
Affidavits should be sent in no later than 30 days after your renewal date. Trainees must submit separate, notarized affidavits to report hours worked for each employer, registered contractor, and/or supervising plumber during the previous year.
Trainees may not receive credit for any hours of experience:
If you receive a decision that denies training hours, you can request a reconsideration. There is no fee for filing a request, which must be made within 20 calendar days of the date on the initial denial letter you received. The request must include specific reasons why the denial should be reconsidered along with a copy or photo of the letter you received.
See RCW 18.106.070 (2) and WAC 296-400A-120 (4) for detailed information on affidavits of experience.
It is the trainee’s responsibility to submit each of their affidavits to L&I by their renewal date. To ensure the accuracy of hours reported on affidavits, trainees should keep a personal training log to track their hours. For an example, refer to our sample training log. A trainee’s log is strictly for their record keeping. It is not an acceptable form of documentation for contractors.
Apply to be a plumber trainee
Your plumber trainee certificate is good for 12 months from the date your application is approved.
To apply as a new plumber trainee, you will need:
Note: To apply, you cannot have any outstanding, unpaid infractions with L&I
To apply for a plumber trainee certificate, print the Application for Plumber Trainee Certificate (F627-003-000) and follow the instructions on the form.
You can apply in person at any L&I field office.
We will process your application and mail your plumber trainee certificate within 2-4 weeks.
Renew your plumber trainee certificateTo renew your plumber trainee certificate, you will need:
Note: You cannot renew online if you have any outstanding, unpaid plumbing infractions, or your certificate is suspended.
Department of Labor & Industries
Plumber Certification Program
PO Box 44470
Olympia, WA 98504-4470
Note: Affidavits that are altered or have corrections will be denied. No copied, faxed, or emailed affidavits are accepted.
To renew your existing plumber trainee certificate, print the Plumber, Medical Gas, or Trainee Renewal (F627-019-000) form and follow the instructions on the form.
You can renew in person at any L&I field office.
Verify Your CertificationAfter you have applied for or renewed your certification and/or endorsement, use our Verify a Contractor, Tradesperson or Business tool make sure your record shows your new expiration date.
Washington State
Department of Labor & Industries
Plumber Certification
PO Box 44470
Olympia, WA 98504-4470