Off-Grid Living in Snohomish County, Washington

I've been digging through Snohomish County's code and the county's own guidance pages to figure out what off-grid living actually looks like here, and the honest answer is: it depends heavily on where in the county your parcel sits. Snohomish is one of the few Washington counties with true countywide zoning, so unlike places with patchwork or no zoning, almost everything here traces back to a specific zone under SCC Title 30.

Zoning. The county's Planning & Development Services (PDS) office administers rural zones (like Rural-5 Acre or Rural Diversification) and resource zones (Forestry, Agriculture-10, Mineral Conservation) that each carry different minimum lot sizes and permitted uses. There's no single "off-grid friendly" designation, so I'd treat every parcel as its own case and confirm buildable rights with PDS before assuming anything.

Dwellings and RVs. Under county code, an RV is defined as transient, temporary living quarters, not a permanent dwelling, so parking one long-term as your only home outside an approved park isn't confirmed as legal. Mobile and manufactured homes are permitted, but oddly split: Washington State Labor & Industries (L&I) inspects the factory-built structure itself, while PDS only handles the foundation and land use. Foundation-built tiny homes meeting the state's IRC Appendix Q rules get treated like any standard dwelling.

Building permits. PDS runs the state building code locally. Small non-habitable structures (roughly under 400 sq ft in rural zones, under 200 sq ft in urban zones) can skip a building permit, but they still must meet setback and environmental rules, so "no permit needed" doesn't mean "no rules apply."

Septic and greywater. The Snohomish County Health Department (SCHD) issues septic/OSS permits under both state WAC rules and the county Board of Health code. Any home without public sewer access needs an approved system. Greywater reuse appears to run through the same statewide WAC framework via SCHD, but I couldn't find a distinct county greywater ordinance, so I'd call SCHD directly before building one.

Rainwater. The county explicitly permits commercial rooftop rainwater harvesting systems, and residential rainwater catchment is encouraged as a stormwater best practice. If you want rainwater as your household's drinking supply, though, that pulls you into SCHD's treatment and testing requirements and the county's building-permit water-verification process.

Wells and water rights. This is the trickiest piece. Since the state's Hirst decision and the 2018 legislative fix (RCW 90.94), the county restricts new permit-exempt wells inside unincorporated Urban Growth Areas, and rules otherwise vary by Water Resource Inventory Area. Well siting still needs county review before the Washington Department of Ecology handles construction approval.

Utilities generally. There's no ordinance banning off-grid power that I found, but PDS building permits require proof of an adequate potable water source (public system, well, or approved rainwater catchment) plus an approved septic system if you're not on public sewer. So going off-grid for electricity looks straightforward; going off-grid for water and waste still runs through county approval.