Starting November 1, homes on septic in Snohomish County need an inspection and a county report before they can change hands. The Snohomish County Board of Health adopted the ordinance this spring, and it brings the county in line with a new state law making these inspections mandatory statewide.
Even if you’re not planning to sell this year, it’s worth knowing now. Keeping up with routine maintenance and records today makes the inspection simpler whenever you do.
The short answer: Beginning November 1, 2026, any home on septic in Snohomish County must have a full septic inspection by a certified professional within 12 months before closing, with the tank pumped if recommended. The seller then submits a Report of Property Transfer to the Snohomish County Health Department and gives the buyer the reviewed report, maintenance records and seller disclosure at closing.
If you think of septic as a rural issue, it’s worth a second look. The county has roughly 84,000 private septic systems. Many are in unincorporated areas, but plenty are in more populated cities like Lynnwood and Mukilteo, and about 2,800 septic properties change ownership each year.
Here’s what the new rule means for you, whether you’re selling or buying.
What’s changing
Neighboring King, Skagit and Island counties already required septic inspections before a sale. Snohomish County now joins them. Washington will require every septic system to be inspected at sale by February 2027, and this rule is how Snohomish County puts that state requirement into practice locally.
The goal is straightforward: protect water quality, reduce pollution from failing systems, and help buyers avoid inheriting an expensive problem.
What sellers need before closing
Before closing, sellers will need:
- A full septic inspection completed within the past 12 months by a certified septic professional
- Tank pumping, if the inspection report recommends it
- An as-built drawing of the system. If the county doesn’t have one on file, the septic professional creates a site plan during the inspection or pumping
- A Report of Property Transfer (RPT), which the seller submits to the Health Department along with a fee before closing
The Health Department reviews the system’s service history and flags any potential issues. The good news on timing: the inspection can be done up to a year before closing.
What if the inspection finds a problem?
If the county finds deficiencies, the report goes back to the seller with those items noted. If there’s surfacing sewage or another immediate health hazard, county staff will visit the site and may start enforcement with a compliance schedule.
Selling doesn’t make a problem go away. If those hazards aren’t fixed before the sale, the county restarts enforcement with the buyer, who becomes responsible as the new owner. That’s why it pays to know your system’s condition early, before you’re negotiating with a buyer.
What buyers receive
At closing, the seller must give the buyer the county-reviewed RPT, the system’s maintenance records, and the seller disclosure statement required under Washington law. For buyers, that means a clearer picture of the system you’re taking on and its history.
A septic inspection is separate from a general home inspection. Your home inspector typically doesn’t evaluate the septic system itself, so this report fills an important gap.
Timing tips for a smooth sale
- Start early. If you’re thinking about listing in the next year, schedule the inspection before you go on market. You’ll know what you’re working with and won’t be waiting on reports during escrow. Our Seller’s Guide walks through the rest of the prep.
- Watch the 12-month window. The county’s report is valid for 12 months from the date it’s issued, and an expired report can’t be renewed. If your sale takes longer, plan on repeating the process.
- Check for an exemption. Systems installed within the past 12 months are exempt.
- Plan to handle it as the seller. The county puts this requirement on the seller, so sellers should expect to arrange the inspection, any needed pumping and the county filing before closing.
As the Health Department’s environmental health director put it, “If you plan ahead, this requirement won’t slow down a home sale.”
Not sure if your home is on septic?
You can look up records the county has on file for your property through the Health Department’s as-built records search. Your seller disclosure from when you bought, or your utility bills, can also tell you whether you’re on public sewer.
Help with septic costs
The Health Department’s Savvy Septic program offers rebates, grants and expert guidance to help homeowners keep their systems working. If your inspection turns up repairs, it’s worth checking what’s available before you list.
Frequently asked questions
Does Snohomish County require a septic inspection to sell a house?
Yes. As of November 1, 2026, a septic inspection is required before a home on septic can be sold.
How long is a septic inspection good for in Snohomish County?
The inspection must be done within 12 months before the sale, and the county’s Report of Property Transfer is valid for 12 months from the date it’s issued.
Who pays for the septic inspection?
The requirement falls on the seller, who arranges the inspection, any needed pumping and the county filing. As with other costs in a sale, buyers and sellers can negotiate how it’s handled.
Are any homes exempt?
Systems installed within the past 12 months are exempt.
Does this apply in cities, or only rural areas?
Both. Many septic systems are in unincorporated areas, but a large number are in cities like Lynnwood and Mukilteo.
Talk through your options
Every septic property is a little different, and the details can affect your timeline, your negotiation and your bottom line. If you’re thinking about buying or selling a home on septic in Snohomish County, I’m happy to walk you through what to expect and help you plan the timing.
Erin Corwin, Broker | The Corwin Group at Spire One Realty
206-650-7390 | [email protected] | TheCorwinGroup.com
This post is for general information only and is not legal advice. Septic requirements, fees and procedures are set by the Snohomish County Health Department and may change. Confirm current requirements directly with the Health Department at snohd.org before making decisions about a sale or purchase.
Sources: Snohomish County Health Department: Property Transfer Inspection program handout, Report of Property Transfer application, and Health Code Update materials; Snohomish County Health Department news release via the Snohomish County Tribune; Washington Administrative Code, Chapter 246-272A.
