Off-grid site report

King County, WA

47.5801, -122.3273 · 36 ft elevation

Read this before you act on anything below. This is my researched starting point for King County, WA, 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 rulesKing County, WA

Zoning & raw-land occupancy

Varies locallyUnincorporated King County is zoned under Title 21A (Rural Area, Agricultural, Forestry, Mining, rural towns, etc.), each with its own permitted-use table and setbacks set by the King County Council. source

Dwellings, tiny homes & RVs

RestrictedKing County requires dwellings, including tiny homes, to have an approved potable water source and wastewater system; RVs are limited to 60 days of temporary camping per year and can't be used as permanent housing or stored on vacant land. source

Building permits & codes

Generally allowedKing County's Department of Local Services Permitting Division administers the state building code locally, using Title 21A density and dimension tables to determine what's allowed. source

Septic & composting toilets

Generally allowedPublic Health - Seattle & King County permits on-site sewage systems under Board of Health Code Title 13, adopting the state WAC with stricter county provisions where applicable; composting toilets need state DOH listing plus a county permit. Rules were updated in 2025 and reviews are currently running slower than usual. source

Greywater reuse

Unclear - verifyNo King County-specific greywater ordinance was located; the state WAC 246-274 framework likely applies through local health jurisdictions, but this isn't confirmed at the county level. Ask Public Health - Seattle & King County directly.

Rainwater harvesting

Generally allowedNo county restriction on non-potable rainwater collection was found; this appears to follow the Washington Department of Ecology's generally permissive statewide stance, though not independently confirmed at the county level.

Private wells & water rights

Varies locallyPermit-exempt wells are allowed but King County Public Health caps domestic use at 950 gallons/day per residence, and any system serving two or more parcels must be permitted as a Group B public water system. source

Living disconnected from utilities

Unclear - verifyNo outright ban on off-grid living, but since a dwelling needs an approved water and septic system to be permitted for occupancy, full utility disconnection is effectively conditioned on that permitting process.

Open the full county page with sources →

Sun30-year normals

Peak-sun hours, annual average: 3.8 hrs/day
Worst month (sizes an off-grid array): 1.6 hrs/day
Yearly output per 1 kW of panels: 1,069 kWh

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Weather1991-2020

Precipitation: 38 in/yr
Snowfall: 5 in/yr
Heating degree days: 4,370 (moderate)
Frost-free season: Mar 6 to Nov 25

How far help isstraight-line

Hospital Navos West Seattle Campus: 3.6 mi
Fire station Seattle Fire Department: 1.4 mi
Hardware store Chown: 0.4 mi
Grocery La Esperanza Mercado y Carniceria: 0.7 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 98134).

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 21, 2026; agencies update their layers on their own schedules. Planning data, not a survey or legal advice.