Licensing & Registration

Plumber certification cards

Certification cards help ensure plumbing is done by qualified plumbers.

State law requires all plumbing work to be performed by plumbers certified by the Department of Labor & Industries (L&I). Plumbers must meet work experience, education and other requirements to attain each level of certification. Plumber certification can be verified here.

L&I encourages plumbers to wear their certification cards on their clothes so customers, contractors and other plumbers can see them up front. At a minimum, plumbers and plumber trainees must have their certification card with them and immediately available for inspection on job sites.

The L&I-issued cards are color-coded to identify the holder’s qualifications and certification level. The certification cards are plastic and the size of a credit card.

Here are examples of the three types of plumber cards and certification levels.

Journey Level Plumber License

Green Stripe Journey Level Plumber (PL01)
Qualified to work in all phases of the plumbing trade, including commercial and residential jobs. The most highly trained and highest certification level for plumbers.


Specialty Plumber License

:Yellow Stripe Specialty Plumber (PL02)
Certified to work in the specific specialty listed on their card. Specialty plumbers have met work experience requirements and passed an examination for their specialty. No supervision required when working in their specialty. Cannot work on commercial sites unless they have an active trainee certificate and are supervised by a journey level plumber.

Plumber specialties include: residential (shown in card); pump and irrigation; limited volume domestic pump; and backflow. Residential specialty plumbers are limited to working in single-family homes, duplexes and apartment buildings that do not exceed three stories.


Plumber trainee

Red Stripe Trainee certificate
Must be supervised by a journey level or a specialty plumber 75% of the trainees’ time on every job site. Plumber trainees have not met the requirements to take a certification exam.


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