Selling a Home With a Septic System in Snohomish or King County (2026)

Short answer: Starting November 1, 2026, if you sell a home on a septic system in Snohomish County, you have to complete a Report of Property Transfer with the Snohomish County Health Department before closing. That means a full inspection by a certified septic contractor within the past 12 months, pumping if the inspection report recommends it, a site plan if no as-built drawing is on file, and an online application with a fee. King County already requires a time-of-sale inspection and a recorded maintenance notice. In both counties, the paperwork is easier to finish before you list than after you’re under contract.

What changes in Snohomish County on November 1, 2026

The Snohomish County Board of Health adopted Ordinance BOH26-02, which adds chapter 5.60 to the county’s Board of Health Code with a November 1, 2026 effective date. The Health Department says the county is carrying out a new state requirement that all septic systems be inspected when properties are sold, and that all counties must have a program in place by February 2027. The state rule, WAC 246-272A-0270, requires a third-party inspection at property transfer beginning February 1, 2027.

The Health Department lays out three steps for sellers, all due before closing:

1. Inspection and records. Get a full septic system inspection by a certified septic contractor within the past 12 months. If the report recommends pumping, have the tank or tanks pumped. Check whether an as-built drawing is on file on the Health Department’s As-Built Records page. If there isn’t one, have a certified septic contractor complete an On-Site Sewage System Site Plan instead. The department specifically says not to hire a septic designer for this. If the as-built exists but is wrong, the inspection report has to note the discrepancies.
2. Report of Property Transfer. Submit the Report of Property Transfer (RPT) application online and pay the fee. The application can’t be submitted before November 1, 2026. The Health Department reviews the application and your septic records, then sends the RPT back with or without deficiencies noted.
3. Hand-off to the buyer. At transfer, give the buyer the reviewed RPT, your septic maintenance records, and the seller disclosure statement required by chapter 64.06 RCW.

The reviewed RPT is valid for 12 months from the date it’s accepted. The only exemption the Health Department lists is a system installed within the past 12 months. The department also notes that other parties in a sale, such as lenders, can require septic inspections on their own, separate from the county rule.

Snohomish County and King County side by side

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Based on: Snohomish County Health Department Property Transfer page and Seller Checklist (revised 9/3/26); Public Health – Seattle & King County sales and transfers page and Time of Sale flowchart; King County Board of Health Code 13.60.030. Check the county pages for the current fee and any changes before you list.

What happens if the inspection finds a problem

In Snohomish County, deficiencies are written on the RPT. If they include surfacing sewage or another immediate health hazard, the Health Department will also make a site visit and may start enforcement with a compliance schedule for the current owner. Repairs have to meet WAC 246-272A-0270 and chapter 5.55 of the county Board of Health Code. Once repairs are done, you can ask the department to re-issue the RPT showing the deficiencies were corrected (email SHD-EHQ@snoco.org).

The department says it has no right or intention to prohibit property sales. But if a deficiency under enforcement isn’t fixed before closing, enforcement resets with the buyer, who becomes responsible as the new owner. Expect buyers and their lenders to read the RPT closely.

King County’s Time of Sale flowchart works the same way in practice. A maintainer can make minor repairs during the inspection or a follow-up visit, such as replacing broken risers, lids, baffles or control floats. For a larger repair or a replacement, the chart says the seller and buyer negotiate who will correct the deficiency, and that a needed repair doesn’t prevent the transfer.

Who pays for a repair is a negotiation, and your purchase agreement and any inspection addendum decide the deadlines. Our guides to contingencies and what a home inspection covers cover how those pieces fit together.

The septic questions on the seller disclosure

Washington’s seller disclosure statement (RCW 64.06.020) has a sewer and on-site sewage section. If your home is on septic, you’ll be asked:

• whether a permit was issued for the system and it was approved after construction;
• when it was last pumped, and when and by whom it was last inspected;
• whether there are defects in how it operates;
• how many bedrooms the system was approved for;
• whether all plumbing fixtures, including the laundry drain, are connected to it;
• whether there have been changes or repairs;
• whether the system, including the drainfield, is entirely within the property’s boundaries; and
• whether it needs monitoring and maintenance more than once a year.

The inspection report, the as-built or site plan, and your pumping receipts answer most of these. Pull them together before you fill out the form. RCW 64.06.020 currently has two versions on the Legislature’s site: one marked effective until January 1, 2027, and one effective January 1, 2027. The questions quoted here appear in both. If your listing runs across the new year, confirm which form you’re using when the disclosure is delivered.

If the home also has a private well

The Washington State Department of Health says private well owners are responsible for testing their own water. It also says that in most counties, the county health or planning department or the buyer’s lender may require the seller to provide water-sampling results when a home with a private well is sold, and it suggests calling the local health or planning department for the requirements. For ongoing care, the department recommends testing every year for coliform bacteria and nitrate.

The disclosure form’s water section asks whether the well is shared and whether there are written agreements, whether there’s an easement for access to or maintenance of the water source, and whether the supply has been adequate year-round during your ownership. If your well serves a neighbor too, find the agreement now.

A seller’s checklist for a septic property

1. Look up your system’s records: the Snohomish County As-Built Records page, or King County’s records at onlinerme.com (search the property and look under Application History).
2. Gather pumping, inspection and repair receipts.
3. Book the inspection with a certified contractor or maintainer before you list, so a problem shows up while you still have time to fix it or price it in.
4. Pump the tank if the report recommends it (required before closing in Snohomish County).
5. Snohomish County: submit the RPT online, with a site plan if needed. King County: record the 22U notice if it isn’t already on title.
6. Give the buyer the reviewed report, maintenance records and the seller disclosure.

For help with costs in Snohomish County, the Health Department’s Savvy Septic program offers cost help for inspections, pumping, riser installation and minor repairs on residential properties after you complete a free online Septic Care Workshop, and lists Craft3, a nonprofit lender, for major permitted repairs. Check the program page for current amounts.

FAQ

Do I need a septic inspection to sell my house in Snohomish County?

Yes, starting November 1, 2026. Before closing, the seller needs a full inspection by a certified septic contractor within the past 12 months, pumping if the report recommends it, and a Report of Property Transfer submitted to the Snohomish County Health Department with the fee. The only exemption the Health Department lists is a system installed within the past 12 months.

How long is a Snohomish County Report of Property Transfer good for?

The Health Department says the reviewed Report of Property Transfer is valid for 12 months from the date it’s accepted. The inspection behind it also has to be from within the past 12 months.

Can the health department stop my sale if the septic system has problems?

The Snohomish County Health Department says it has no right or intention to prohibit property sales. Deficiencies are noted on the report. If they include surfacing sewage or another immediate health hazard, the department will also visit and may start enforcement with the current owner, and if that isn’t resolved before the sale, enforcement resets with the buyer.

What if there’s no as-built record for my septic system?

In Snohomish County, don’t hire a septic designer to draw one. Have a certified septic contractor complete the Health Department’s On-Site Sewage System Site Plan, ideally at the time of the inspection, and submit it with your Report of Property Transfer application.

Does King County require a septic inspection when you sell?

Yes. Public Health – Seattle & King County requires an inspection by a certified on-site system maintainer before title transfers, unless a waiver applies. The seller also records a Notice of On-site Sewage System Operation and Maintenance Requirements with the King County Recorder’s Office if one isn’t already on title, and gives the buyer a copy before closing.

Talk it through with a local agent

Peter Kim and Odigo Real Estate Club can help you line up the inspection, records and disclosure before your septic property goes on the market, and price it against real closed sales, with 25+ years combined experience, 593+ closings, and 122 five-star Zillow reviews. See our home selling services or request a property valuation.

Odigo Real Estate Club · REAL Brokerage, WA #112064 · 16108 Ash Way, Suite 201, Lynnwood, WA 98087 · (425) 409-3823 · Mon–Sat 9 AM–6 PM, closed Sunday

Sources

• Snohomish County Health Department, Property Transfer (septic requirements starting Nov 1, 2026) (seller steps, 12-month inspection, pumping if recommended, site plan if no as-built, RPT valid 12 months, exemption, enforcement and re-issue, no intention to prohibit sales, Savvy Septic program and Craft3), https://www.snohd.org/1872/Property-Transfer , accessed Oct 30, 2026.
• Snohomish County Health Department, Seller Checklist, Report of Property Transfer (revised 9/3/26) (three seller steps; application can’t be submitted until Nov 1, 2026), https://www.snohd.org/DocumentCenter/View/15953 , accessed Oct 30, 2026.
• Snohomish County Health Department, Property Transfer Requirements for Septic Systems handout (revised 5/13/26) (seller and buyer responsibilities; enforcement resets with the buyer), https://www.snohd.org/DocumentCenter/View/15098/Property-Transfer-Handout , accessed Oct 30, 2026.
• Snohomish County Health Department, Properties with Septic Systems, Overview for Homebuyers (revised 7/27/26) (buyer responsibility if hazards aren’t fixed before sale; inspection frequency), https://www.snohd.org/DocumentCenter/View/15950/Properties-with-Septic-Systems---Homebuyer-Overview , accessed Oct 30, 2026.
• Snohomish County Health Department, As-Built Records (searching septic records and as-builts), https://www.snohd.org/159/As-Built-Records , accessed Oct 30, 2026.
• Snohomish County Health Department, Savvy Septic program page (county cost help for inspection, pumping and minor repairs; residential only; workshop requirement), https://www.snohd.org/714/Rebates , accessed Oct 30, 2026.
• Snohomish County Board of Health Code, Chapter 5.60 (added by Ordinance BOH26-02, Nov 1, 2026 effective date) (county code chapter for septic requirements in real estate transactions), https://snohomish.boardofhealth.codes/SCBHC/5.60 , accessed Oct 30, 2026.
• Washington State Legislature, WAC 246-272A-0270 (owner responsibilities; records and disclosure at transfer; third-party inspection at transfer beginning Feb 1, 2027), https://app.leg.wa.gov/wac/default.aspx?cite=246-272A-0270 , accessed Oct 30, 2026.
• Public Health – Seattle & King County, Sales and transfers of properties with on-site sewage/septic systems (inspection by certified maintainer before transfer, waivers, 10-business-day review, recorded 22U notice, buyer’s program fee), https://kingcounty.gov/en/dept/dph/health-safety/environmental-health/on-site-sewage-systems/sales-transfers , accessed Oct 30, 2026.
• Public Health – Seattle & King County, Responsibilities at the Time of Sale for Properties with Septic Systems (flowchart) (minor repairs, negotiation of larger repairs, repair need doesn’t prevent transfer, copy of report to buyer), https://cdn.kingcounty.gov/-/media/king-county/depts/dph/documents/health-safety/environmental-health/oss/tos-flowchart.pdf?hash=FF52364C2DF68D2128F3E2328C4DD1A4&rev=80950ad6d21a4749bc902814c86be662 , accessed Oct 30, 2026.
• King County Board of Health, Code Title 13, section 13.60.030, Operation and maintenance at time of sale (time-of-sale inspection, site sketch when no record drawing, records to buyer), https://cdn.kingcounty.gov/-/media/king-county/depts/dph/documents/about-public-health/board-of-health/boh-code-title-13.pdf?rev=9112cb2aacbe499c835b21d2ad08bf92 , accessed Oct 30, 2026.
• Washington State Legislature, RCW 64.06.020 (seller disclosure statement form, including the title, water and sewer/on-site sewage system questions; version effective until Jan 1, 2027 and version effective Jan 1, 2027), https://app.leg.wa.gov/RCW/default.aspx?cite=64.06.020 , accessed Oct 30, 2026.
• Washington State Department of Health, Testing Your Water (well owners responsible for testing; county or lender may require seller’s results; yearly coliform and nitrate testing), https://doh.wa.gov/community-and-environment/drinking-water/contaminants/testing-your-water , accessed Oct 30, 2026.

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