Off-Grid Living in Washington County, Oregon

I've been digging into Washington County, Oregon for folks who want to live off-grid, and the short version is: it's doable, but the path runs through permits, not around them. This is unincorporated county land I'm describing here, once you cross into Hillsboro, Beaverton, Forest Grove, or any of the other dozen-plus cities, their own municipal code takes over and can be stricter or looser.

Zoning. Washington County's Community Development Code (CDC) sets the rules outside city limits. Rural Residential zones generally carry a 5-acre minimum lot size, while urban unincorporated residential land runs much smaller. Farm and forest land falls under the county's Exclusive Farm Use zone, which implements the state's Goal 3 rules. None of this bans off-grid living outright, but building a dwelling almost always requires an approved permit first.

Dwellings, tiny homes, RVs. This is where I'd slow down if I were you. The county is explicit that a tiny house on wheels counts as an RV, and living in an RV full-time is prohibited except through a narrow health-hardship permit process outside the urban growth boundary, and even that requires physician documentation and limits you to one RV and one trailer per lot. A foundation-built tiny home that meets Appendix Q of the residential code is treated as a normal dwelling and goes through standard permitting instead.

Building permits. The county enforces the Oregon state building code under its home rule authority, through its own Building Services division. There's no off-grid carve-out I found, but there is an Alternate Materials & Methods (AMM) review path for non-standard systems like unconventional power or water setups.

Septic. Washington County's own Environmental Health department issues septic permits directly (a number of Oregon counties instead route through a DEQ agent, but this one handles it itself), covering new installs, repairs, and alterations, under the state's OAR 340-071 wastewater rule. If sewer is available to the property, you're required to connect to it instead. Composting toilets specifically weren't addressed anywhere I could find, so confirm with Environmental Health directly.

Greywater and rainwater. I couldn't find county-specific rules for either. Assume Oregon DEQ's statewide tiered greywater program applies, and that rooftop rainwater collection falls under general building code review if it's plumbed into the house.

Wells. Wells are permitted, but Washington County sits over parts of a state-designated Critical Groundwater Area and several Groundwater Limited Areas, where the state Water Resources Commission has restricted basalt aquifer pumping to domestic/stock use on tracts of 10+ acres. Well construction itself is governed by state OWRD rules, not the county.

Bottom line on utilities. Nothing bans disconnecting from the grid for a properly permitted stick-built or manufactured home with an approved septic system and legal water source. The real obstacle is the RV/tiny-home-on-wheels ban, which rules out the cheapest, fastest off-grid setups many people picture.