Snohomish County, WA
Selling a home with a septic system in Snohomish County
Updated · Prepared by the Plumb Right Now editorial team
Short answer
Starting November 1, 2026, anyone selling a property with a septic system in Snohomish County must, before closing, have a full inspection by a certified septic contractor within the past 12 months, pump the tank if the report recommends it, file a site plan if the Health Department has no as-built record, and submit a Report of Property Transfer application with its fee. Systems installed within the past 12 months are exempt.
What Snohomish County handles
From November 1, 2026, sellers of a property with a septic system must have a full inspection by a certified septic contractor completed within the 12 months before closing. [1]
If the Health Department has no as-built record of the system, a certified septic contractor must complete an On-Site Sewage System Site Plan, and the seller files a Report of Property Transfer application with a fee. [1]
Under state rule WAC 246-272A-0270, gravity septic systems should be inspected every 3 years and alternative systems every year unless the manufacturer specifies otherwise. [2]
Seller's checklist
- Book a full inspection with a certified septic contractor; it can be done up to a year before closing.
- Pump the tank if the inspection report recommends it.
- Check whether an as-built drawing is on file with the Health Department; if not, have the contractor draw a site plan.
- Submit the Report of Property Transfer application and fee online; it can't be filed before November 1, 2026.
Who this affects
Rural and lakeside parts of the county, including many homes around its lakes, rely on septic. Most homes in Everett are on city sewer and aren't affected; inside the house, a sewer smell or slow drains are still a plumbing job, not a septic one.
Common questions
When does Snohomish County's septic sale rule start?
November 1, 2026; applications can't be submitted before then.
How recent must the septic inspection be for a Snohomish County sale?
Completed within 12 months before closing.
Who can do the inspection for a Snohomish County home sale?
A certified septic contractor.
What if there's no as-built for my septic system in Snohomish County?
A certified septic contractor completes an On-Site Sewage System Site Plan.
Is a new septic system exempt from the Snohomish County sale rule?
Yes, if it was installed within the past 12 months.
Do I have to pump the tank before selling in Snohomish County?
Only if the inspection report recommends it.
How often should a gravity septic system be inspected in Washington?
Every 3 years under WAC 246-272A-0270; alternative systems every year.
Who files the Report of Property Transfer in Snohomish County?
The seller, online, with the associated fee.
Can the septic inspection be done well before listing?
Yes, up to a year before closing, which leaves time for any repairs.
Do Everett homes need a septic inspection to sell?
Only if the property is on septic; most Everett homes are on city sewer.
Cities and services in Snohomish County
- Plumbing services in EverettEverett is a port and aerospace city north of Seattle, with early 1900s homes near downtown and post-war neighborhoods to the south. Its water comes f…
- Backflow Testing in WashingtonWashington's cross-connection rule: assemblies tested at installation, after repair or relocation and every year, by a state-certified Backflow Assembly Tester.
- Plumbing in WashingtonStatewide code, licensing and climate for Washington.
Other Washington counties
- Septic system inspections in King CountyKing County septic rules: gravity systems inspected every 3 years, pressure, mound and sand filter systems every year, and the report your maintainer files.
- Pierce County septic Report of System Status for home salesSelling a Pierce County home on septic: pump and inspect, apply for a Report of System Status, the Health Department's field visit, and the 12-month validity.
- Septic permits in Spokane County and the aquiferSpokane County septic rules: permits from Spokane Regional Health District, a licensed designer for any permitted work, and protection of the aquifer.
Sources (2)
- Snohomish County Health Department, Property Transfer · checked 2026-10-06
- Snohomish County Health Department, Septic FAQs · checked 2026-10-06