Plumber Trainee

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 specialty or journey level plumber.

Getting Started

Plumber trainees must:

  • Apply for a plumber trainee certificate.
  • Be 16 or older.
    • For information about minors working on construction sites, contact Employment Standards.
  • Work under the direct supervision of a journey level or specialty plumber.
  • Get the required number of years and hours of experience to qualify for the state plumber examination.
  • Have an electrical trainee card if working in the pump and irrigation or domestic pump trade.
  • Take 8 hours of approved continuing education instruction yearly to renew their certificate.
    • For questions about continuing education requirements, call the Plumber Certification Program at 306-902-5207 or email plumbers@Lni.wa.gov.

Reporting your hours of experience

Plumber trainees must report their supervised work hours at least once a year by filing affidavits of experience (F627-004-000) 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 they are not properly supervised.
  • From incorrectly completed affidavits of experience.
  • While their certificate is expired or inactive.
  • If they have outstanding penalties.
  • While working for out-of-state employers.
  • From out-of-state trainee or apprenticeship programs.

See RCW 18.106.070 (2) and WAC 296-400A-120 (4) for detailed information on affidavits of experience.

Tracking your hours 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:

  • Your Social Security number.
  • An electronic payment: We accept Visa, MasterCard, Discover, and American Express credit or debit cards. We also accept electronic checks (E-Check) – a one-time withdrawal from your checking account.
  • Required Fees.
    • $45.20 for your plumber trainee certificate.

Note: To apply, you cannot have any outstanding, unpaid infractions with L&I

Apply by mail

To apply for a plumber trainee certificate, print the Application for Plumber Trainee Certificate (F627-003-000) and follow the instructions on the form.

Apply in person

You can apply in person at any L&I field office.

What L&I will do

We will process your application and mail your plumber trainee certificate within 2-4 weeks.

Renew your plumber trainee certificate

To renew your plumber trainee certificate, you will need:

  • An active or expired certificate (not suspended or cancelled).
  • Your 12-digit certificate number.
  • Your Social Security number.
  • An electronic payment: We accept Visa, MasterCard, Discover, and American Express credit or debit cards. We also accept electronic checks (E-Check) – a one-time withdrawal from your checking account.
  • Required Fees.
    • $45.20 for your plumber trainee certificate renewal.
  • The required documents on file with L&I.
    • Affidavits of experience.
    • Proof of continuing education.
      • 8 hours of approved continuing education is required each year.
      • Within a two-year period you must take a minimum of 8 hours of plumbing code training and 4 hours of industry-related electrical (IRE) training. The other 4 hours may be from any category: plumbing code, IRE, or industry-related plumbing (IRP).

Note: You cannot renew online if you have any outstanding, unpaid plumbing infractions, or your certificate is suspended.

Affidavits of experience

Mail you original, notarized affidavits of experience (F627-004-000) to:

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.

Renew by mail

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.

Renew in person

You can renew in person at any L&I field office.

Verify Your Certification

Verify your certification

After 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.