Off-Grid Living in Williamson County, Tennessee

Williamson County, Tennessee is not the place I'd point someone chasing the loosest possible off-grid setup, and I want to be upfront about that. Unlike a lot of rural Tennessee counties that have no zoning at all, Williamson County adopted a comprehensive zoning ordinance (effective January 1, 2013) that covers all unincorporated land, per the Williamson County Planning Department. That means "buy raw land and just live on it" isn't a simple proposition here; zoning districts and land-use rules apply everywhere outside the six incorporated cities (Franklin, Brentwood, Fairview, Nolensville, Spring Hill, Thompson's Station), each of which runs its own separate zoning and building department.

On dwellings, I could not find an official county page that spells out tiny-house-on-wheels or RV-as-permanent-residence rules. Codes Compliance handles mobile home setup and zoning enforcement, but I'd call them directly before assuming anything is allowed.

Building permits are required in unincorporated Williamson County, issued through the county's Building Codes Division, and this county has not opted out of state building code enforcement. Electrical permits, notably, now run through the State of Tennessee's core.tn.gov system rather than the county, as of a 2023 change.

Septic is where Williamson County stands out. It's one of nine Tennessee "contract counties" that runs its own septic permitting program under state authorization instead of deferring fully to TDEC, according to the state Division of Water Resources. The county's own Department of Sewage Disposal Management, overseen by the Williamson County Board of Health, issues Construction Permits for any onsite sewage disposal system. I found no confirmed dry-cabin exemption or waiver for going without a permitted septic system.

Greywater has no county-specific ordinance that I could find; it would fall back to whatever ambiguity exists at the state level, so I'd confirm directly with the Sewage Disposal Management office. Rainwater collection appears unrestricted, inheriting the general state posture of no barrier to collecting or using rainwater, though tying it into household plumbing would trigger a building permit review.

Wells are licensed and regulated at the state level under the Tennessee Water Well Act of 1963, requiring a licensed driller. Tennessee doesn't mandate water testing for private wells, though free test kits have been offered through the state health lab in the past, worth confirming current availability. The county's sewage office also keeps a list of private water-testing labs and soil scientists.

Living disconnected from the electric grid isn't itself prohibited by anything I found, but any habitable structure will still need to clear the county's building and septic permit requirements described above. Bottom line: zoning and septic here are more actively enforced than in many Tennessee counties, so the paperwork side of off-grid living matters more than the "can I do this at all" question.