Snohomish County, WA · County Septic Guide

Snohomish County Septic Guide: Permits, Inspections & Rules

The Snohomish County Health Department permits every septic system under 3,500 gallons a day in the county. This page covers current fees, inspection schedules, your septic records, and the new sale-inspection rule starting ahead of the statewide one.

Independent research, checked against Snohomish County and Washington State primary sources on July 22, 2026.

General information, not legal advice. Fees and rules change without a posted revision date on some county pages. Confirm current numbers with the Health Department first.

Who Permits Septic Systems Here

The Snohomish County Health Department runs the county's on-site sewage system (OSS) program, through its Land Use Division. Some older links still show its former name, Snohomish Health District.

The county's authority stops at a flow rate. Systems under 3,500 gallons a day fall to the county, under WAC 246-272A and Snohomish County Board of Health Code Chapter 5.55. Systems between 3,500 and 100,000 gallons a day move to the state's Large On-site Sewage System (LOSS) program instead.

Finding your septic records

The county keeps as-built drawings and service history through a third-party portal, OnlineRME, not a page on its own site. Search your property at onlinerme.com. A record, where one exists, shows the system's lot location, install year, and type; the county's As-Built Records page links a checklist to help you read one. If nothing turns up, some systems predate records requirements — email [email protected].

Fees & Inspection Requirements

The county's fee page doesn't print an effective date, but the Board of Health finalized these rates through Ordinance BOH25-08 (effective Nov. 1, 2025) and Ordinance BOH26-03 (2026 adjustments, approved April 14, 2026). Confirm a specific line item before budgeting. (snohd.org — Permits & Fees, fetched July 2026)

Septic permit & fee schedule
ItemFee
Design & application review
Gravity distribution$1,130.00 (2-yr approval)
Pressure distribution$1,130.00 (2-yr approval)
Other DOH-approved system types$1,290.00 (2-yr approval)
Community system$2,170.00, plus $765.00/connection
Product development system$1,400.00, plus $235.00/hr over 6 hrs
Any system over 1,000 gal/dayDoubles the standard review fee
Permits
Standard (non-community systems)$385.00
Redesign, previously disapproved$395.00
Renewal, within 30 days, current code$430.00
Replacement systemCharged as a new application
Specialty, alterations & repairs
Composting toilet (nonresidential)$390.00, plus $235.00/yr monitoring
Holding tank$1,115.00 prelim + $640.00 permit + $470.00/yr
Vault privy$390.00, plus $235.00/yr monitoring
Absorption system alteration$480.00
Tank-only alteration$390.00
Single-family repair$390.00
Complete system alterationBilled as a new system
Repair redesignNo fee

Source: snohd.org/270/Permits-Fees.

How often you need an inspection

WAC 246-272A-0270 makes the homeowner responsible for keeping a system maintained and inspected. The required interval depends on system type, not one countywide number.

Minimum inspection frequency by system type
System typeMinimum inspection frequency
Gravity systemAt least once every 3 years
Low Pressure Distribution (LPD)Annually
LPD with Aerobic Treatment Unit (ATU)Every 6 months for the first 2 years after start-up, then annually
Subsurface Drip System (SSD)30 days after start-up, then annually
SSD with ATU, or OSCAR system30 days after start-up, then every 6 months for 2 years, then annually
Mound or sand filter system6 months after start-up, then annually

Source: Snohomish County Health Department, Septic Monitoring & Maintenance Frequencies. The county's own FAQ page summarizes this as gravity every 3 years, alternative systems annually, unless the manufacturer's product registry listing requires a tighter schedule.

Some system types also require a Declaration of Covenant, an ongoing monitoring agreement recorded against the property (noted on the county's Permit Steps page). The duty to maintain sits with the homeowner, permanently.

Selling or Buying a Home With a Septic System

As of today, July 22, 2026, Snohomish County has no active point-of-sale septic inspection requirement. That changes soon, on a different clock than the statewide rule.

The county's Board of Health has adopted a local ordinance that takes effect November 1, 2026, well before Washington's statewide inspection mandate, which doesn't start until February 1, 2027. See our statewide guide to selling a house with septic for how the two rules relate. (snohd.org/1872/Property-Transfer; news release)

What the new Snohomish County rule requires, starting Nov. 1, 2026:
  • A full inspection before closing, by a certified septic contractor, with any recommended pumping done too.
  • Dated within 12 months of closing. The Report of Property Transfer (RPT) it produces stays valid 12 months.
  • An as-built on file, or a site plan if none exists, before the seller files the RPT application and pays a fee.
  • Systems installed in the past 12 months are exempt.

Stated legal basis: Chapter 5.55 of the Board of Health Code, WAC 246-272A-0270, and Chapter 64.06 RCW, the state's seller disclosure law. The county frames the change as matching neighboring King, Skagit, and Island counties, which already run similar rules. (snohd.org)

Closing before Nov. 1, 2026: no county mandate yet, though a lender or buyer may still ask for one. Closing after: treat it as real, and schedule early, since it has to land within 12 months of closing.

Programs Specific to Snohomish County

Savvy Septic

Savvy Septic is the county's homeowner incentive and education program, at snohd.org/712 (savvyseptic.org redirects there). It offers up to $500 in rebates for workshop attendance, inspections, riser installs, pumping, and minor repairs, plus grants and low-interest financing for low-income households facing a major repair or replacement. From 2023 through 2025 the county paid 1,922 maintenance rebates, about $223,860 combined, plus 15 low-income households helped with a failing-system replacement. Email [email protected].

LakeWise Septic Systems

The county also runs LakeWise Septic Systems, tying the monitoring guidance above to lake-adjacent properties. (snohomishcountywa.gov/2591/LakeWise-Septic-Systems)

How many septic systems are out there

The county's news release on the transfer ordinance puts the number at approximately 84,000 private septic systems countywide, with about 2,800 septic properties changing ownership each year. (snohd.org — Property Transfer news release)

Pumping & installation costs

The fee tables above cover county review and permit charges, not what a contractor bills to pump a tank or install a system — we found no Snohomish-specific numbers for either. See our statewide pumping cost guide and installation cost guide.

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Primary sources

All sources accessed July 22, 2026. General information, not legal advice; rules change over time, sometimes without a posted revision date. Confirm current requirements with the Health Department before you budget or list a property.