Off-Grid Living in Johnson County, Tennessee

I've been digging into what it actually takes to live off-grid in Johnson County, Tennessee, and the short version is: this is one of the more permissive counties I've researched, but there's a sharp line between unincorporated Johnson County and the Town of Mountain City that you absolutely need to know which side of.

Zoning. Johnson County itself is almost entirely unincorporated, and the only true municipality is Mountain City, the county seat, which runs its own zoning map and ordinance for in-town property. For land outside town limits, the Johnson County Planning Commission is your contact, and I'd call them directly, (423) 727-9696, before assuming anything. Notably, the Planning Commission has adopted a new rule (effective March 2, 2026) requiring documented water access for any subdivision of land, so if you're splitting or buying subdivided acreage, that's now in play at the county level.

Dwellings and permits. Here's the headline: Johnson County government states plainly that it does not currently require a building permit for most structures. The only two things the county asks for on new construction or additions are a septic permit and an electric permit. There's no county Certificate of Occupancy process beyond that. That's a genuinely light-touch regulatory environment for tiny homes, cabins, or owner-built structures, though I couldn't confirm any specific ordinance addressing RVs or tiny-house occupancy standards, so treat that as an open question with the Planning Commission. Cross into Mountain City, though, and it flips: building permits are required inside town limits, fees are due before a permit is issued, and the town follows the 2018 International Residential Code, available for review at City Hall.

Septic and water. Septic is the real trigger point countywide, since it's one of the county's only two structural requirements. Septic permitting in this part of Tennessee has moved to the state level, applications now go through TDEC directly rather than the county health department. I did not find any county-specific composting-toilet exemption, so that inherits Tennessee's general standard, worth confirming with TDEC. Greywater and rainwater harvesting have no Johnson County or Mountain City ordinance that I could locate, meaning they likely fall back to whatever the state's baseline plumbing code allows, largely unenforced in a rural setting like this.

Wells and utilities. Private wells follow the state's general well construction framework through a licensed driller; there's no separate county well-permitting office I could find. Since the county doesn't require electric hookup or a building permit, going off-grid on power looks unregulated at the county level, but you still need that septic permit for any habitable structure. Mountain City's requirements, again, are stricter and permit-based.

Bottom line: unincorporated Johnson County is refreshingly light on paperwork, septic and electric permits are the real gates, but always verify current rules with the Planning Commission since local policy (like the 2026 water-access rule) is clearly still evolving.