Off-Grid Living in St. Mary's County, Maryland

I've spent a good chunk of time digging through St. Mary's County, Maryland records, and here's my honest read on what it takes to live off-grid there.

Zoning comes from the county, not the state. St. Mary's County has its own Comprehensive Zoning Ordinance, administered by the Department of Land Use and Growth Management. That ordinance includes a Rural Preservation District and Resource Conservation Areas, plus an Annual Growth Policy that caps how many new dwelling units get approved each year in growth and rural areas. What I couldn't find anything on is raw-land camping or informal habitation without an approved dwelling, so if that's your plan, call the county's Land Use office directly and ask before you buy land.

Dwellings and tiny homes are a gray zone. The zoning ordinance explicitly deals with mobile homes: they're allowed in the Rural Preservation District or approved mobile home parks, and in some Residential Neighborhood Conservation areas, but always with a building permit. Tiny homes on foundations or wheels aren't called out as their own category in anything I found, and RVs as year-round primary residences outside a licensed campground aren't confirmed as legal either. Campgrounds themselves are inspected and permitted by the county Health Department's Environmental Health Division.

Building permits are a county process, with the Health Department involved. Any structure with plumbing needs a building permit through Land Use and Growth Management, and the Health Department signs off on water supply and sewage adequacy. If you're not on public water and sewer, expect a perc test before you can build.

Septic is locally administered under Maryland's statewide (COMAR) rules. The county's Environmental Health Division handles septic applications and perc testing. As of a 2016 update, properties outside a 1,000-foot Critical Area buffer no longer need the state's Best Available Technology nitrogen-removal units. Composting toilets are allowed, but the liquid portion is treated as a discharge: if it goes into an existing septic system, your local Health Department oversees that; if it goes straight onto the ground, you'd need a state discharge permit from the Maryland Department of the Environment.

Greywater and rainwater harvesting appear to run on Maryland's state baseline, since I found no county-specific rules layered on top. Rainwater collection looks straightforwardly permitted; greywater reuse is allowed under the state's framework, though it's worth double-checking with the county Health Department in case there's unwritten local practice.

Private wells are well-covered locally. SMCHD certifies well potability for both new construction and replacements. Most of the county still relies on private wells and septic, but if you're near a MetCom (the county's water/sewer utility commission) service line, be aware some agreements require you to hook up to public water or sewer within a set period once it's available, effectively ending well/septic independence for that property.

Full utility disconnection isn't addressed head-on anywhere. It's shaped indirectly through zoning, the building permit process, and MetCom's connection requirements near service areas. If going fully off-grid electrically matters to you, that's a direct question for Land Use and Growth Management, since nothing official spells it out.

Bottom line: St. Mary's County is more zoning-heavy than some rural Maryland counties, and a lot of the finer off-grid details (tiny homes, raw-land living, greywater specifics) simply aren't nailed down in public documents. Call before you commit.