Washington (WA) Plumbing Code & Permit Rules
Uniform Plumbing Code (2021) · Updated 2026-05-31
Data: State plumbing boards, ICC, IAPMO, EPA Last verified: 2026-05-31
Washington has some of the strictest plumbing regulations in the country. A licensed plumber is required for most work, annual backflow testing is mandatory, and seismic strapping is required for water heaters. Homeowners should budget for professional plumbing services and compliance costs.
Plumbing Code
Washington follows the Uniform Plumbing Code (2021 edition).
Key Regulations
| Regulation | Status | Details |
|---|---|---|
| Plumbing Code | UPC (2021) | Uniform Plumbing Code |
| Homeowner DIY | Not allowed | Licensed plumber required in most cases |
| Water Heater Permit | Required | Seismic strapping required in seismic hazard zones; licensed plumber required |
| Backflow Testing | Annual, required | |
| Seismic Strapping | Required | Water heater restraint |
DIY Plumbing in Washington
Washington requires a licensed plumber for most plumbing work. Licensed plumber required in most cases
While this increases costs, it ensures:
- Work meets current code requirements
- Proper permitting and inspection
- Warranty and liability protection
- Safe connections to water and sewer systems
Backflow Prevention
Washington requires annual backflow testing to protect the public water supply from contamination. Testing must be performed by a Certified tester.
Non-compliance penalty: Water service may be shut off if testing is not completed on schedule.
Water Conservation Requirements
Washington has state-specific water conservation mandates. State water conservation standards tied to building codes
Lead Service Line Replacement
Washington has an active lead service line replacement program. Following EPA Lead and Copper Rule 2021
Data Sources
- Washington state plumbing board and licensing agency
- International Code Council (ICC)
- IAPMO
- EPA Safe Drinking Water Act
Updated as regulations change.
Need a licensed plumber in Washington?
Plumbing regulations vary by city. Connect with a licensed professional who knows your local code requirements.
Find a Licensed Plumber →Frequently Asked Questions
What plumbing code does Washington follow?
Washington follows the Uniform Plumbing Code (2021 edition).
Can I do my own plumbing work in Washington?
No, Washington requires a licensed plumber for most plumbing work.
Do I need a permit to replace a water heater in Washington?
Yes, Washington requires a permit for water heater replacement. A licensed plumber is required for the installation.
Is backflow testing required in Washington?
Yes, Washington requires annual backflow testing.
Does Washington require seismic strapping for water heaters?
Yes, Washington requires seismic strapping for water heaters. This typically involves two metal straps securing the water heater to the wall to prevent toppling during an earthquake.