Off-grid site report

McHenry County, IL

42.2652, -88.4323 · 932 ft elevation

Read this before you act on anything below. This is my researched starting point for McHenry County, IL, not legal advice and not a guarantee. Rules change, and the deciding facts on any specific parcel (setbacks, perc results, overlay districts, deed restrictions, road frontage) live at the county or town office, not in any database. Before you buy land or build, confirm the current rules directly with the local zoning and health offices - the sources on this page tell you exactly who to call.

The local rulesMcHenry County, IL

Zoning & raw-land occupancy

Varies locallyMcHenry County zoning and land use rules only apply in unincorporated areas, handled by the county's Planning, Zoning and Land Use Division under the Unified Development Ordinance. If your parcel sits inside a city or village like McHenry, Woodstock, Crystal Lake, or Algonquin, that municipality's own zoning code controls instead, so you need to check which jurisdiction you're in first. source

Dwellings, tiny homes & RVs

Unclear - verifyI could not find an official McHenry County document setting a minimum habitable floor area or a specific rule on RVs as permanent residences. This would need direct confirmation from the county's Planning & Development Department, and again municipalities may differ.

Building permits & codes

Generally allowedBuilding permits are required for construction in unincorporated McHenry County, and as of January 1, 2023 the county reviews new permit applications against the 2021 ICC codes and 2020 NEC. Small accessory structures of 150 square feet or less, outside floodplain or wetlands, may be exempt from a permit, but anything larger needs one from Planning and Development. source

Septic & composting toilets

Generally allowedA permit from the McHenry County Department of Health is required to install, modify, repair, or abandon any septic system, and only IDPH-licensed contractors may do that work. Aerobic treatment units are allowed if they discharge to a compliant subsurface system, surface-discharging systems are banned, and holding tanks are restricted to limited temporary situations; composting toilets aren't specifically addressed at the county level, so check with the Health Department or IDPH. source

Greywater reuse

Unclear - verifyI found no official McHenry County or Illinois rule specifically addressing residential greywater reuse separate from septic and holding-tank rules. Call the county Health Department's Environmental Health Division to ask how greywater is treated under the private sewage ordinance.

Rainwater harvesting

Unclear - verifyNo McHenry County ordinance or Illinois EPA rule specifically authorizing or restricting rain barrels or cisterns turned up in this research. This is worth a direct call to county Planning & Development or the Health Department before you build a system.

Private wells & water rights

Generally allowedA well permit is required from the McHenry County Department of Health to construct, repair, modify, or abandon a private water well, and the county is entirely reliant on groundwater for drinking water. As a private well owner, you're responsible for testing your own water quality, and the county lab offers testing for coliform bacteria and nitrates. source

Living disconnected from utilities

Unclear - verifyThere's no standalone McHenry County rule I found that directly prohibits or permits disconnecting from grid electricity or municipal water and sewer. In practice it's controlled indirectly: your dwelling still needs to meet the adopted 2021 ICC building code and have an approved water supply and wastewater system, both of which require the permits described above.

Open the full county page with sources →

Sun30-year normals

Peak-sun hours, annual average: 4.6 hrs/day
Worst month (sizes an off-grid array): 2.8 hrs/day
Yearly output per 1 kW of panels: 1,333 kWh

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Weather1991-2020

Precipitation: 36 in/yr
Snowfall: 31 in/yr
Heating degree days: 6,908 (cold)
Frost-free season: Apr 29 to Oct 8

How far help isstraight-line

Hospital Mercyhealth Hospital and Physician Clinic: 8.2 mi
Fire station Woodstock Fire & Rescue Station 1: 3.5 mi
Hardware store Ziegler's Ace Hardware: 6.0 mi
Grocery Supermercado El Sol: 3.6 mi

From OpenStreetMap. Road miles will be longer, often much longer in hill country.

Plan this spot

These open with this location's real numbers already filled in (ZIP 60098).

Size a solar system Heat loss & insulation Firewood per winter Rainwater harvest Garden size Panel tilt

Sources: US Census Bureau geocoder; NLR PVWatts v8 (solar); NOAA NCEI 1991-2020 climate normals (nearest station) or Open-Meteo (ZIP-centroid) for weather; Open-Elevation; OpenStreetMap contributors. Public data retrieved Aug 22, 2026; agencies update their layers on their own schedules. Planning data, not a survey or legal advice.