Off-grid site report

Washington County, OR

45.5583, -122.9218 · 194 ft elevation
Read this before you act on anything below. This is my researched starting point for Washington County, OR, 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 rulesWashington County, OR

Zoning & raw-land occupancy
Varies locallyWashington County's Community Development Code sets a 5-acre minimum in Rural Residential zones and smaller minimums in urban unincorporated residential zones; farm/forest land follows the county's Exclusive Farm Use zone implementing state Goal 3. Incorporated cities use their own codes instead. source
Dwellings, tiny homes & RVs
RestrictedFoundation-built tiny homes meeting Appendix Q are treated as standard dwellings, but a tiny house on wheels is classified as an RV, and living full-time in an RV is prohibited except under a limited health-hardship permit outside the urban growth boundary. source
Building permits & codes
RestrictedWashington County enforces the Oregon state building code through its own Building Services division; no county-specific off-grid exemption was found, though an Alternate Materials & Methods review exists for non-standard systems. source
Septic & composting toilets
Generally allowedWashington County Environmental Health directly issues septic permits for new systems, repairs, and alterations under state DEQ wastewater rules (OAR 340-071); properties with sewer access must connect to it instead. Composting toilets are not confirmed and should be asked about directly. source
Greywater reuse
Unclear - verifyNo Washington County-specific greywater rule was found; the state DEQ's tiered greywater program likely applies, with county Environmental Health as the local contact. Confirm directly, not confirmed at the county level.
Rainwater harvesting
Unclear - verifyNo county ordinance restricting rooftop rainwater harvesting was found. Plumbing a cistern into a house would fall under general county building code review, but this is not confirmed in detail.
Private wells & water rights
RestrictedWells are permitted under state OWRD rules, but parts of Washington County lie within a Critical Groundwater Area and Groundwater Limited Areas where the state Water Resources Commission restricts basalt aquifer pumping to domestic/stock use on tracts of 10 acres or more. source
Living disconnected from utilities
RestrictedNothing bans off-grid power or water for a permitted, code-compliant dwelling with approved septic and water source, but the ban on full-time RV/tiny-home-on-wheels living narrows the practical options, per the county's current planning FAQ. source

Open the full county page with sources →

Sun30-year normals

Peak-sun hours, annual average
4.0 hrs/day
Worst month (sizes an off-grid array)
1.7 hrs/day
Yearly output per 1 kW of panels
1,120 kWh
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Weather1991-2020

Precipitation
48 in/yr
Snowfall
10 in/yr
Heating degree days
4,832 (moderate)
Frost-free season
Mar 26 to Nov 19
Design low
24 °F

How far help isstraight-line

Hospital
none within range
Fire station
Portland Fire & Rescue
12.4 mi
Hardware store
Ace Hardware
2.7 mi
Grocery
Fred Meyer
1.0 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 97124).

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.