Updated
Does Washington require a septic license?
Washington has no statewide septic installer license; septic contractors are licensed or registered locally. Washington counties certify septic installers; the state licenses designers.
Who licenses septic contractors in Washington?
County health departments (designers licensed by the state).
Washington's septic credentials:
- County certified installer
How to check a septic contractor's license in Washington
- Washington has no public statewide list of septic contractors.
- Ask the contractor for their local license or registration number and which county or town issued it.
- Call that county health department or town office to confirm it is current.
Septic permits in Washington
A contractor license says who may do septic work; a permit authorizes a specific system. In Washington, permits for new systems, replacements and most repairs come from the local health department or the state agency office that covers the property. Ask your installer to pull the permit and include the fee in the quote.
Licensed septic companies in Washington
The Septic Guide lists 34 septic companies and licensed professionals in Washington. This is what we could match as of October 2026, not an official count.
All septic companies in Washington →
Washington septic licensing: common questions
Do you need a license to install septic systems in Washington?
Washington has no statewide septic installer license; septic contractors are licensed or registered locally. Washington counties certify septic installers; the state licenses designers.
Who issues septic licenses in Washington?
County health departments (designers licensed by the state). Washington counties certify septic installers; the state licenses designers.
How do I check a septic contractor's license in Washington?
Washington has no public statewide list of septic contractors. Ask the contractor for their local license or registration number and which county or town issued it. Call that county health department or town office to confirm it is current.
How many licensed septic contractors are in Washington?
The Septic Guide lists 34 septic companies and licensed septic professionals in Washington (data as of October 2026). This counts what we could match; it is not an official total.
Do you need a permit for a septic system in Washington?
New septic systems, replacements and most repairs need a permit before work starts. The permit comes from the local health department or the state agency office that covers your property, and the permit, not the contractor license, is what authorizes a specific job.
Sources: County health departments (designers licensed by the state); state license lists loaded into The Septic Guide. See how we verify licenses.