Off-Grid Living in Custer County, Montana

Custer County, Montana (seat: Miles City) is one of the more workable rural counties in the state for off-grid living, but "workable" doesn't mean unregulated. I've dug through the county's own zoning resolution and wastewater rules, and here's the honest picture.

Zoning. Custer County has adopted a countywide zoning resolution, administered by the Planning and Zoning office. Farming, ranching, one residential dwelling, and accessory buildings are allowed by right in all districts; anything else needs a Special Use Permit or Planned Unit Development approval. Setbacks scale with parcel size, from fifty feet on larger parcels down to a surveyed ten feet on very small lots. If you're eyeing raw land, call Planning and Zoning before you buy to confirm what's allowed on that specific parcel.

Dwellings, tiny homes, RVs. The county's Homeowner's Packet covers RVs stored (unoccupied) on land, and mobile home moves require sign-off from the County Treasurer's office beforehand. I did not find a Custer County-specific ordinance addressing tiny houses on wheels. Montana's state building code framework allows counties to adopt IRC Appendix Q/AQ for tiny houses, but I could not confirm Custer County has done so, so treat that as unclear and confirm directly with the county.

Building codes. Here's a notable one: Custer County has not adopted a countywide building code. Height limits (thirty feet from finished grade) apply, and state electrical, plumbing, and septic codes fill the gap. You still need a zoning permit before building, administered by the Zoning Administrator.

Septic and composting toilets. The county runs its own On-Site Wastewater Treatment System (OWTS) rules, on top of state DEQ standards. Cesspools and seepage pits are flatly banned. Any structure with piped water must connect to an approved wastewater system or public sewer. Variances go through the county Board of Health, with state DEQ appeal rights.

Greywater. No standalone county greywater exemption exists; greywater must ultimately flow into a compliant wastewater treatment system per the state's subsurface wastewater rules the county has adopted.

Rainwater harvesting. I found no county ordinance on this at all, so it defaults to Montana's general state framework, generally fine for basic rooftop, non-potable collection.

Wells and water rights. Well permitting itself is a state DNRC/DPHHS function, not county. The county's OWTS rules do require well setbacks (around one hundred feet) and sometimes water testing during subdivision review. The state is clear that private well water quality is the homeowner's own responsibility.

Utility disconnection. There's no explicit county mandate to hook up to the electrical grid. But occupancy does hinge on having an approved wastewater system if there's piped water, so full "off-grid" living still runs through the septic/OWTS rules above.

Bottom line: Custer County leaves a lot of room (no building code, generous by-right uses) but is strict about wastewater. Confirm zoning district specifics and any tiny-house questions directly with the county before committing.