Off-grid site report
Williamson County, TX
30.5333, -97.6142 · 656 ft elevationRead this before you act on anything below. This is my researched starting point for Williamson County, TX, 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 rulesWilliamson County, TX
Zoning & raw-land occupancy
Varies locallyWilliamson County has no countywide zoning and mainly regulates subdivision platting under state law (LGC Chapter 212). Cities within the county apply their own zoning and platting rules inside their limits and extraterritorial jurisdiction (ETJ), overriding the county baseline there.
Dwellings, tiny homes & RVs
Unclear - verifyNo confirmed countywide minimum dwelling size or tiny-home ban for unincorporated land; county rules mostly touch RVs for flood-evacuation planning. Deed restrictions/HOAs often control instead, and cities may have their own dwelling standards. source
Building permits & codes
Generally allowedPer the county's FAQ (citing Local Government Code Sec. 233), Williamson County does not require unincorporated-area residential construction to follow any building code, though floodplain, driveway, and septic permits still apply and cities/ETJs may impose their own codes. source
Septic & composting toilets
Generally allowedSeptic (OSSF) systems are permitted and administered by the Williamson County Engineer's Office under TCEQ authority (30 TAC Ch. 285), requiring an Authorization to Construct, inspections, and a final License to Operate; extra TCEQ Edwards Aquifer Protection Plan approval is needed in the recharge zone. source
Greywater reuse
Unclear - verifyNo standalone county greywater ordinance was found; it appears to be handled within the same OSSF/TCEQ permitting framework. Not confirmed as a distinct process, so ask the County Engineer's OSSF office directly. source
Rainwater harvesting
Generally allowedNo Williamson County ordinance restricting rainwater harvesting was found; the state baseline of allowing/encouraging rainwater collection appears to apply, with subdivision review only checking water-supplier letters where a district serves the lot.
Private wells & water rights
Generally allowedNo groundwater conservation district currently covers Williamson County, so Texas's rule of capture generally applies to private wells; a 2023-2024 push to join the Clearwater Underground Water Conservation District was rejected by that district's board. Plats combining wells and septic must show a 100-foot sanitary easement around the well and a 50-foot setback from property lines, per the County Engineer's subdivision rules. source
Living disconnected from utilities
Generally allowedBecause unincorporated Williamson County has no residential building code requirement, there's no evident county mandate to connect to electric or municipal water/sewer; floodplain and driveway permits still apply where relevant, and cities may set stricter utility rules within their limits. source
Sun30-year normals
- Peak-sun hours, annual average
- 5.4 hrs/day
- Worst month (sizes an off-grid array)
- 4.2 hrs/day
- Yearly output per 1 kW of panels
- 1,514 kWh
JFMAMJJASOND
Weather1991-2020
- Precipitation
- 36 in/yr
- Snowfall
- 0 in/yr
- Heating degree days
- 1,949 (mild)
- Frost-free season
- Mar 7 to Nov 24
How far help isstraight-line
- Hospital
Saint David's North Austin Medical Center - 10.0 mi
- Fire station
Austin Fire Station 28 - 9.4 mi
- Hardware store
SouthernCarlson - 4.7 mi
- Grocery
Hill Country Grocery - 3.5 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 78634).
Size a solar systemHeat loss & insulationFirewood per winterRainwater harvestGarden sizePanel tilt
Looking at a specific parcel in Williamson County, TX?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 21, 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.