Off-Grid Living in Merrimack, New Hampshire

I've been digging into what off-grid living actually looks like in Merrimack, New Hampshire, and the short version is: this is a fully zoned, fairly buttoned-up suburban-edge town, not a place where you can just buy acreage and do your own thing.

Zoning. Merrimack operates under a comprehensive Zoning Ordinance & Building Code, administered by the town's Planning Board and Zoning Board of Adjustment. The ordinance is district-based, meaning uses are permitted only where they're listed for that district (residential, commercial, industrial, plus overlays like the Aquifer Conservation District, Shoreland Protection District, and Wellhead Protection Areas). Raw-land "just live on it" occupancy outside a listed use isn't permitted. If you're eyeing a parcel, check with the town's Community Development Department before assuming anything is allowed.

Dwellings, tiny homes, RVs. The ordinance has a defined ADU (accessory dwelling unit) pathway that requires Planning Board approval, limits you to one ADU per property, and won't allow an ADU where more than one primary dwelling already exists. I found no town provision permitting RVs or wheeled tiny homes as standalone residences, so treat that as unresolved and ask the Zoning Board directly.

Building permits. New Hampshire has adopted the 2018 ICC codes and the 2020 NFPA NEC 70 electrical code as the state baseline, which Merrimack enforces through its Building Code Enforcement & Inspectional Services division (part of the Fire & Rescue Department). Permits go through the town's OpenGov portal, inspections are required, and the Fire Department issues the Certificate of Occupancy before you can move in.

Septic and composting toilets. Septic design and installation is a state matter under NHDES's Individual Sewage Disposal Systems rules (Env-Wq 1000), required for any structure discharging wastewater with a connected water supply. Locally, Merrimack's sewer ordinance and state law require sewer connection if you're within 200 feet of the sanitary sewer line, though the town does allow a waiver if a licensed subsurface designer inspects your septic system and both the Town Council and NHDES sign off. Privies and composting toilets are allowed under state DHHS guidance, applied by Merrimack's local health officer, so long as they're sited and built so waste doesn't reach groundwater.

Greywater and rainwater. I couldn't find a Merrimack-specific ordinance or state DES rule on household greywater reuse, so this falls back on the general septic/sewer framework, confirm specifics with the town or NHDES. Rainwater harvesting doesn't appear to be separately restricted; it falls under the standard state-adopted building code.

Wells. Well construction is a state program (NH Water Well Board, RSA 482-B); I found no additional Merrimack siting rules on top of that.

Utility disconnection. The 200-foot mandatory sewer connection rule is the main practical constraint near town infrastructure. Outside that radius, I found no additional town mandate forcing water or electric hookups.