What Washington’s New Septic Inspection Rule Means When You Sell

October 21, 2026    

If you own a home on a septic system in Washington, a change is coming to how your property transfers at closing, and a little planning now will save you time later.

Beginning November 1, 2026, Snohomish County will require sellers of properties served by a septic system (also called an on-site sewage system, or OSS) to complete a set of steps before closing. This is the county’s early rollout of a broader Washington State requirement. The State Board of Health has adopted a rule that makes a Property Transfer Inspection mandatory statewide by February 1, 2027, so counties across Washington are expected to put similar programs in place. Snohomish is simply getting an early start, and more of our local counties will follow.

What sellers in Snohomish County will need to do

Under the new county program, a seller will generally need to:

• Have the full septic system inspected by a certified septic professional within the 12 months before closing.
• Have the tank or tanks pumped if the inspection report recommends it.
• Confirm that an as-built record drawing of the system is on file with the Snohomish County Health Department. If no as-built exists, a certified septic professional will need to create an On-Site Sewage System site plan.
• Complete a Report of Property Transfer (RPT) application and pay the applicable fee. The county cannot accept the RPT or fee before November 1, 2026.

Once the Health Department reviews the RPT, the seller provides the buyer with the reviewed report, the system’s maintenance records, and the seller disclosure statement required under chapter 64.06 RCW. The reviewed RPT is valid for 12 months from the date of acceptance.

There is one notable exemption. Systems installed within the 12 months before the sale are generally exempt from these property transfer requirements.

Why timing matters

Because the inspection, any recommended pumping, and the Health Department review all happen before closing, these steps can affect your transaction timeline. Scheduling the inspection early gives you room to address anything the report turns up and to allow for county review, so your closing stays on track. The seller is responsible for completing and submitting the RPT application. Please note that escrow does not prepare or submit this application on the seller’s behalf.

Looking ahead for the rest of Washington

Snohomish County is first among our local markets, but it will not be the last. With the statewide requirement taking effect February 1, 2027, sellers in King, Pierce, Kitsap, and surrounding counties can expect comparable programs. If you are even thinking about selling in the next year or two, it is worth knowing where your as-built records and maintenance history stand today.

At Ticor Title, we are following these changes closely across the counties we serve so we can keep you informed as each program takes shape. For the current Snohomish County requirements, forms, and FAQs, visit the Snohomish Health Department directly.

Learn More
Property Transfer | Snohomish Health Department — https://www.snohd.org/1872/Property-Transfer

For general informational purposes only. Requirements and county procedures may change. Please consult the Snohomish County Health Department for the most current information.