Off-Grid Living in Mason County, Washington

I've been digging into what it actually takes to live off-grid in Mason County, Washington, and the short version is: this is not a "no rules" rural county. Mason County has adopted full countywide zoning under Washington's Growth Management Act, codified in Title 17 of the Mason County Code, so where you are (Rural Residential, Resource, Urban Growth Area, etc.) matters for what you can build and do.

Zoning and raw land. You can't just park on unimproved land and call it home. The county reviews development for consistency with its zoning, and while home-based occupations and cottage industries are generally allowed subject to department review, permanent occupancy of raw land without a permitted structure isn't a recognized use under Title 17.

Dwellings, tiny homes, and RVs. Building permits are required for any dwelling, including manufactured and tiny homes, and the county requires you to document your water source and sewage plan as part of that application. If you're thinking about an RV, county septic guidance is blunt: an RV holding tank can be permitted for part-time or seasonal recreational use, but holding tanks cannot serve as the sole sanitation for a full-time residence. Tiny homes on permanent foundations are treated like any other dwelling under the state building code.

Building permits. The Building/Community Development Department administers the state building code locally, and it wants proof of water adequacy (a well report and a clean water sample within the last year, or a signed connection letter for public water) before it issues a permit. If your parcel has wetlands, steep slopes, or a creek nearby, expect a site pre-inspection.

Septic and composting toilets. Mason County Environmental Health runs its own on-site sewage program under county code and state rules (WAC 246-272A). Every occupied structure needs to be tied to an approved sewer or on-site sewage system, but composting and incinerating toilets are explicitly allowed as long as they're on the Washington Department of Health's approved list.

Greywater. You can reuse greywater, but the county only permits it alongside a full, already-approved septic system, and only seasonally. It cannot stand in for septic.

Rainwater. No Mason County-specific restriction turned up in my research; state Ecology policy is the governing framework here, so I'd call this permitted at the baseline level, with local specifics unconfirmed.

Wells. Permit-exempt wells exist, but the county caps usage by Water Resource Inventory Area (WRIA) and requires recording water restrictions on the property title in WRIAs 14, 15, and 22, with different daily gallon caps by WRIA. A private well feeding a home also needs a report and a clean water sample.

Off-grid utilities generally. There's no standalone ban on disconnecting from electric or municipal utilities, but living legally still means clearing the county's septic, water, and building permit hurdles individually. Confirm specifics with the offices below before you commit to a plan.