Off-grid site report
Mercer County, MO
40.5114, -93.5322 · 1,083 ft elevationRead this before you act on anything below. This is my researched starting point for Mercer County, MO, 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 rulesMercer County, MO
Zoning & raw-land occupancy
Unclear - verifyNo countywide Mercer County zoning ordinance or planning department was found; Missouri law requires voter approval for counties like Mercer to adopt zoning, and none was confirmed. Any land-use rules would exist only inside incorporated towns like Princeton.
Dwellings, tiny homes & RVs
Unclear - verifyNo Mercer County rule on tiny homes, minimum dwelling size, or RV residency was found, consistent with there being no countywide zoning or building code.
Building permits & codes
Varies locallyMissouri has no statewide building code and Mercer County has not adopted one countywide; the City of Princeton does issue its own building permits and inspections, but only within city limits. source
Septic & composting toilets
RestrictedThe Missouri DHSS sets statewide minimum standards for onsite wastewater systems and generally requires a permit before construction or repair; the Mercer County Health Department is the local agency that issues these permits. source
Greywater reuse
Unclear - verifyNo Mercer County or Missouri state rule specifically addressing greywater reuse was found; ask the Mercer County Health Department directly.
Rainwater harvesting
Generally allowedNo Mercer County ordinance restricting rainwater collection was found, so the general state allowance for landowners to collect rainwater appears to apply.
Private wells & water rights
RestrictedNo Mercer County-specific well ordinance exists; well construction and repair fall under Missouri's statewide Water Well Drillers Act and DNR Well Construction Rules.
Living disconnected from utilities
Generally allowedNo Mercer County ordinance prohibits living without utility hookups; the state baseline allowing private water and septic systems appears to apply, though septic still requires Health Department permitting.
Sun30-year normals
- Peak-sun hours, annual average
- 4.9 hrs/day
- Worst month (sizes an off-grid array)
- 3.2 hrs/day
- Yearly output per 1 kW of panels
- 1,404 kWh
JFMAMJJASOND
Weather1991-2020
- Precipitation
- 37 in/yr
- Heating degree days
- 5,641 (cold)
- Frost-free season
- Apr 18 to Oct 15
How far help isstraight-line
- Hospital
Decatur County Hospital - 20.0 mi
- Fire station
Mercer Fire Station - 0.0 mi
- Hardware store
Hardware Hank's - 19.5 mi
- Grocery
Justino's Market - 8.3 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 64661).
Size a solar systemHeat loss & insulationFirewood per winterRainwater harvestGarden sizePanel tilt
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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.