New Snohomish County Septic Requirements Start November 1, 2026: What Home Sellers Need to Know
If you own a home with a septic system in Snohomish County — especially if selling that home might be somewhere on your radar — there is an important change coming that you need to know about.
Beginning November 1, 2026, new septic system requirements will apply to property transfers in Snohomish County.
The Snohomish County-Camano Association of REALTORS® (SCCAR) recently sent its members an important update outlining the new requirements and encouraging real estate professionals to start preparing their clients now.
And this isn’t just another minor paperwork change. If you’re selling a property on septic, this is something you’re going to want to address early in the process.
So, What’s Changing?
Beginning November 1, sellers of properties with septic systems will have additional steps that must be completed as part of the property-transfer process.
According to the SCCAR release, sellers will need to have a full septic system inspection performed by a certified septic professional within 12 months prior to closing. If pumping is recommended as part of that inspection, the septic tank or tanks will need to be pumped.
The seller will also need to deal with the property’s septic records and submit a Report of Property Transfer (RPT) application, along with the applicable fee, to the Snohomish County Health Department.
At the time of the property transfer, the buyer must receive the Health Department-reviewed RPT, septic maintenance records and the required seller disclosure.
One important timing issue: the RPT application itself cannot be submitted until November 1, 2026.
There’s Another Big Requirement: The Septic As Build
This is one of the pieces I think Snohomish County homeowners really need to pay attention to.
As part of the new property-transfer process, the seller will need to verify that an as build record for the septic system is on file with the Snohomish County Health Department.
What’s an as build?
In simple terms, a septic as build is the record showing where the septic system and its major components are actually located on the property. It can be extremely important when inspecting, maintaining, repairing or replacing a septic system.
And here’s where this new requirement could become particularly important for owners of older homes:
What happens if there isn’t an as build on file?
According to the SCCAR release, if no as build is available, a certified septic professional will need to complete an On-Site Sewage System Site Plan as part of the process.
That means the existence — or nonexistence — of your septic records is something worth figuring out before you’re approaching a closing date.
For sellers, this adds one more item to the pre-listing checklist:
Do we have the septic as build, and does Snohomish County have it on file?
If the answer is no, that’s something I’d rather discover while we’re preparing the home for sale than when a buyer, lender, title company or septic professional is waiting on documentation.
Why Is Snohomish County Doing This?
The change isn’t happening in a vacuum.
Snohomish County’s new program brings the County into compliance with Washington State requirements for septic inspections during property transfers. The stated goals are pretty straightforward: identify failing or deficient septic systems, protect water quality and give buyers better information about the septic system they’re inheriting when they purchase a property.
There are approximately 84,000 private septic systems in Snohomish County, and thousands of properties with septic systems change ownership each year.
So, yes, this is going to affect a lot of real estate transactions.
What Does This Mean If You’re Thinking About Selling?
This is probably the most important part.
Don’t wait until you’re a week or two away from closing to start thinking about your septic system.
SCCAR is specifically advising REALTORS® to encourage sellers to begin the process early — ideally before the property is listed or early in the transaction — because these additional requirements could affect transaction timing.
That makes sense.
If you’re preparing a Snohomish County home for sale and it’s on septic, checking the septic records and understanding the condition of the system should become part of the pre-listing conversation.
That includes asking several questions early:
- When was the septic system last inspected?
- Does the system need to be pumped?
- Is an as build on file with Snohomish County?
- If there isn’t an as build, will a septic professional need to prepare an On-Site Sewage System Site Plan?
- Are there maintenance or repair issues that should be addressed before going under contract?
The last thing anybody wants is to discover a septic issue — or missing septic documentation — when the moving truck is practically packed and closing is right around the corner.
What Happens If the Inspection Finds a Problem?
Finding a deficiency doesn’t necessarily mean the sale of the property comes to a screeching halt.
The purpose of the new process is to identify problems, protect public health and make sure the parties involved in the transaction understand the condition of the septic system.
If deficiencies are discovered, they may need to be documented or addressed depending upon the circumstances.
That’s another reason I would much rather have my sellers know about a potential problem before we’re deep into a transaction.
Is Anyone Exempt?
There is an important exemption.
According to SCCAR, septic systems that were installed within the previous 12 months are exempt from the property-transfer inspection requirement.
My Takeaway for Snohomish County Homeowners
Real estate transactions already have plenty of moving parts. Adding another required inspection, County review and septic-record requirement means homeowners with septic systems should simply plan a little further ahead.
If you’re considering selling a home in Snohomish County after November 1, 2026, and the property has a septic system, this needs to be part of the conversation from the beginning.
Find out what records exist.
Find out whether Snohomish County has an as build for your septic system.
Understand the inspection requirements.
And give yourself enough time to deal with any surprises.
In real estate, surprises are occasionally fun when they’re competing offers.
They’re considerably less fun when they’re underground and connected to a septic tank.
If you’re thinking about selling a home in Snohomish County — whether that’s in Monroe, Snohomish, Lake Stevens, Arlington, Marysville, Mill Creek, Edmonds, Mukilteo or elsewhere in the county — Team NSRG can help you understand how these new requirements fit into the overall selling process and help you prepare before your property hits the market.
Source: Snohomish County-Camano Association of REALTORS®, “Important Update: New Septic Requirements Begin November 1,” September 14, 2026. The Association states that sellers must verify that an as build record is on file with the Snohomish County Health Department and, when no as build is available, have a certified septic professional complete an On-Site Sewage System Site Plan.
Snohomish County Health Department Property Transfer information: https://www.snohd.org/1872/Property-Transfer
