Off-grid site report
Contra Costa County, CA
37.7770, -121.9639 · 472 ft elevationRead this before you act on anything below. This is my researched starting point for Contra Costa County, CA, 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 rulesContra Costa County, CA
Zoning & raw-land occupancy
RestrictedContra Costa County has countywide zoning districts under its Ordinance Code; there's no recognized use for occupying land without a permitted structure conforming to the zoning district. Local level: county Department of Conservation and Development. source
Dwellings, tiny homes & RVs
RestrictedCounty ordinance covers RV/boat storage (with screening rules) but not habitation; living full-time in an RV or trailer isn't established as permitted, and Code Enforcement investigates complaints. Not confirmed whether temporary RV occupancy during construction is allowed. source
Building permits & codes
RestrictedDCD's ePermits Center handles building/grading permits statewide-code based, but Environmental Health sign-off is required upfront for any project with a septic system or well. Small sheds under a set footprint are exempt unless utilities are added. source
Septic & composting toilets
RestrictedContra Costa Health's Environmental Health Land Use Program runs septic (OWTS) permitting through site/soil evaluation, perc testing, design, and construction permit steps, with a set minimum well-to-septic distance. Composting toilets are not clearly addressed; confirm with Environmental Health. source
Greywater reuse
Generally allowedNo county-specific greywater ordinance was found beyond the state Plumbing Code framework, so it appears to default to California's statewide greywater rules.
Rainwater harvesting
Generally allowedNo county-specific restriction was found; rooftop rainwater harvesting appears to follow the state's Rainwater Capture Act baseline with no added county permitting layer.
Private wells & water rights
RestrictedContra Costa Health issues well permits and requires a licensed C-57 driller approved for the county, a plot plan, a four-hour pump test for minimum yield, and a coliform bacteriological test; reactivated wells need fresh bacteriological testing. source
Living disconnected from utilities
Unclear - verifyNo county ordinance directly addresses full off-grid utility disconnection; it's governed indirectly through building habitability review and zoning/code enforcement, so status is unclear and best confirmed with DCD.
Sun30-year normals
- Peak-sun hours, annual average
- 5.9 hrs/day
- Worst month (sizes an off-grid array)
- 3.8 hrs/day
- Yearly output per 1 kW of panels
- 1,678 kWh
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Weather1991-2020
- Precipitation
- 25 in/yr
- Snowfall
- 1 in/yr
- Heating degree days
- 3,242 (moderate)
How far help isstraight-line
- Hospital
Menlo Park Surgical Hospital - 24.3 mi
- Fire station
ACFD Station 18 - 7.4 mi
- Hardware store
Dublin Plumbing Supply - 5.3 mi
- Grocery
Nob Hill Foods - 1.2 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 94570).
Size a solar systemHeat loss & insulationFirewood per winterRainwater harvestGarden sizePanel tilt
Looking at a specific parcel in Contra Costa County, CA?The rules above are the jurisdiction. The land check runs the parcel itself: flood zone, soils and septic suitability, wetlands, slope, access, climate, and these verdicts, from a parcel number or coordinates.
Check a parcel →Share or save this report:New report
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.
New here, or not sure where this fits? Start here walks through the whole thing in order.