Off-Grid Living in New Castle, New Hampshire

I'll be upfront: New Castle is about as far from "off-grid friendly" as small New England towns get, and it's worth understanding why before you get attached to any plan here.

New Castle is a tiny coastal island town in New Hampshire, and it is fully zoned. The Town's Zoning Ordinance and Building Code, administered locally through the Building Inspector, Zoning Board of Adjustment, Planning Board, and Conservation Commission, sets out use districts and standard permitted structures: single and two-family homes, garages, workshops, greenhouses, and small accessory sheds. There's a narrow allowance for accessory structures of 80 square feet or less to sit closer to lot lines if they're on a temporary foundation and not hooked up to utilities, but that's a small-shed exception, not a path to living unconnected in a real dwelling. I did not find anything in the ordinance permitting raw-land camping or off-grid occupancy outside of a permitted structure, so I'd treat that as effectively not allowed until the Building Inspector or ZBA tells you otherwise.

Tiny homes on wheels and RVs as year-round residences aren't specifically addressed in the ordinance excerpts I found. Given the town's general expectation that permanent structures connect to water and sewer, I would not assume you can just park an RV and live in it long-term. Ask the Building Inspector's office directly before you buy or move anything onto a lot.

Any construction or renovation goes through the town's Building Inspector, who enforces the adopted building codes plus town zoning, and who decides whether your project also needs sign-off from the ZBA, Conservation Commission, Planning Board, or the Historic District Commission. New Castle's Wetlands Conservation District and its buffer rules, reviewed by the Conservation Commission, add another layer given the island's terrain, so any site near wetlands or shoreline should expect extra scrutiny.

Septic is state-regulated: the NH Department of Environmental Services' Subsurface Systems Bureau must approve any new, replaced, or expanded septic system before installation, and the state rule is that any structure connected to water must be connected to a wastewater system, either sewer or an individual septic system. I did not find a New Castle-specific composting toilet allowance, so assume the state default applies and check with DES and the Building Inspector before relying on one as your only wastewater solution.

Greywater reuse and rainwater harvesting have no New Castle-specific ordinances that I could locate. The Building Code leans on International Residential Code definitions where town rules are silent, which suggests indoor non-potable rainwater use follows the state/IRC baseline, but this isn't spelled out locally, so confirm specifics with the Building Inspector.

Private wells fall under the state's NH Water Well Board, with no town-specific well ordinance found. Because New Castle sits on tidal-influenced ground near the shoreline, well and septic siting may also intersect with the state's Shoreland Water Quality Protection Act, so don't assume a straightforward well permit without checking that overlap.

Bottom line on utilities: living fully disconnected isn't realistic here in practice. The state's water-supply-to-wastewater-system rule, enforced through the town's building permit process, combined with New Castle's restriction on unconnected structures over 80 square feet, points toward permanent dwellings needing full utility connections.