The Septic Rule Starts November 1. If You Are Selling This Autumn, It Already Applies to You.
Snohomish County will require sellers of properties with septic systems to complete new property-transfer requirements before closing starting November 1. If you list in October, you may already be inside it, because there is a good chance you will be closing in November or later.
If your place is on a septic system and you are thinking about selling, this one is worth ten minutes of your time.
The Snohomish County Board of Health has adopted an ordinance requiring septic systems to be inspected as part of the property-transfer process. It takes effect November 1, 2026. The Health Department announced it back in April and said it would spend the summer and fall doing outreach to realtors, contractors and homeowners. That outreach has not reached my office yet, which is most of the reason I am writing this now.
There is one important exception: if the septic system was installed within the previous 12 months, the inspection requirement does not apply.
Why this matters in September
November 1 sounds far away. It is not, because the date that counts is the day you close, not the day you list.
Take a listing in the first week of October and you can very easily be closing in November. A three-week close happens, but it is not the safe assumption. So a seller who lists this month or next can already be affected by the new rule without having done anything wrong.
The good news is that the timing works in your favour if you move early. The required inspection needs to have been completed within the 12 months before closing. Get it done early enough and it can cover your sale well into next year.
What the rule actually requires
Straight from the Health Department, the seller is responsible for completing the property-transfer requirements before closing.
The septic inspection
A certified septic contractor has to perform a full inspection of the system within the previous 12 months.
If the inspection recommends pumping, the tank or tanks also have to be pumped by a certified contractor.
The records
The Health Department wants an as-built drawing of the septic system on file.
If there is no as-built, a certified septic contractor has to prepare an On-Site Sewage System Site Plan instead.
The Report of Property Transfer
The seller submits a Report of Property Transfer application to the Health Department and pays the required fee. The county reviews the application along with the inspection and septic records.
At closing, the seller provides the buyer with the Health Department-reviewed Report of Property Transfer, the septic maintenance records and the seller disclosure statement.
The Report of Property Transfer is valid for 12 months from the date the Health Department accepts it.
Again, there is an exemption when the septic system itself was installed within the previous 12 months.
This is not Snohomish County inventing something out of nowhere. Washington's statewide on-site sewage rules require property-transfer inspections statewide beginning February 1, 2027. Snohomish County is putting its program into effect three months earlier, on November 1, 2026. King, Skagit and Island counties already have property-transfer septic requirements of their own.
How many of us this hits
The Health Department counts roughly 84,000 private septic systems in Snohomish County, with about 2,800 septic properties changing hands in a typical year.
If you picture that as a rural problem, look again. Plenty of those systems sit in unincorporated ground north and east of Arlington, which is where I spend most of my time, but septic systems are not limited to rural acreage. Older neighbourhoods inside and around cities can have them too, and plenty of people living there rarely think about what is buried in the yard.
If you are selling
Do this in whatever order suits you, but do the first one early.
Book the inspection now, not at listing
A failed inspection found before the house goes on the market is a problem you can schedule around. The same problem found in escrow becomes part of a live transaction with deadlines, a buyer and a lender already involved.
That is a much worse time to discover it.
Find out what you actually have
The Health Department keeps an online database of septic records by property. It will tell you what type of system is on your ground and whether an as-built is already on file.
Ten minutes, no cost.
Look at the rebates before you spend
The county's Savvy Septic program currently offers rebates for qualifying inspections, pumping, risers and certain minor repairs. There are also grants of up to $30,000 for qualifying low-income homeowners dealing with major repairs, replacement or sewer connection.
Read the eligibility rules before spending the money. Some programs will not reimburse work that was already completed, and the grant program does not apply to a property that is already undergoing a sale.
If you are buying
You are the person this rule is meant to protect.
The Health Department's stated reasons include making sure buyers know the condition of the septic system they are acquiring, protecting water quality and finding failing systems before they become somebody else's buried surprise.
What changes for you is that the information should now arrive as part of the property-transfer process rather than only because you thought to ask for it.
Read the report properly.
A system can pass an inspection and still be old. A system can be functioning today and still have components you should budget for. "Passed inspection" and "will never cost me money" are two completely different sentences.
What I am not going to tell you
What it costs.
I have seen numbers quoted for septic work in this county that range from a few thousand dollars for relatively limited work to well past thirty thousand for a full replacement on difficult ground, and the honest answer is that it depends entirely on your soil, your site, the type of system and what is already there.
Anyone who gives you a confident replacement number over the phone without seeing the property is guessing.
Get a certified septic professional out and get a real number. That is the only version worth acting on.
The part I would actually worry about
Not the rule.
The queue.
There are thousands of septic-property sales in this county every year and a finite number of certified contractors who can perform the work. I do not know what the wait will look like as November 1 approaches, and neither does anyone else.
What I do know is that deadlines and limited appointment calendars have never been a particularly good combination.
Booking early gives you room.
The bottom line
Starting November 1, 2026, sellers of Snohomish County properties with septic systems generally have to complete the new property-transfer requirements before closing. That means more than simply ordering an inspection. It also means making sure the records are in place, submitting the Report of Property Transfer and getting the accepted report to the buyer.
A septic system installed within the previous 12 months is exempt from the inspection requirement.
If you are on septic and thinking about selling in the next year, start with the records and inspection before the transaction has a clock running on it. The goal is to turn a possible surprise into paperwork you already have.
Sources: Snohomish County Health Department Property Transfer requirements, revised September 3, 2026; Snohomish County Health Department Savvy Septic program; Washington State Department of Health Chapter 246-272A WAC property-transfer requirements. This is general information about a rule change, not legal advice.
Have a question about this? Call or text me at 425-346-7143, or send a message. I answer my own phone.
