Off-grid site report

Mason County, WA

47.1965, -122.9134 · 0 ft elevation

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

Zoning & raw-land occupancy

Varies locallyMason County has countywide zoning under Title 17 MCC; permanent occupancy of raw unimproved land without a permitted structure is not a recognized use, and requirements vary by zone. source

Dwellings, tiny homes & RVs

Varies locallyDwellings including tiny homes need standard building permits with water/sewer documentation; full-time living in an RV on a holding tank is not authorized by county septic guidance.

Building permits & codes

Generally allowedMason County Building/Community Development administers the state building code and requires proof of water adequacy and septic approval before permitting; parcels near critical areas may need a site pre-inspection.

Septic & composting toilets

Generally allowedMason County Environmental Health regulates on-site sewage under county code and state WAC 246-272A; composting and incinerator toilets are allowed if on the state Department of Health's approved list. source

Greywater reuse

RestrictedGreywater reuse is permitted by the county only alongside a full approved septic system and only seasonally; it cannot replace septic.

Rainwater harvesting

Generally allowedNo Mason County-specific restriction was found; state Department of Ecology policy is the governing baseline statewide.

Private wells & water rights

Varies locallyPermit-exempt wells are allowed but capped by Water Resource Inventory Area, with fee and title-recording requirements in WRIAs 14, 15, and 22 per county code implementing state law. source

Living disconnected from utilities

Unclear - verifyThere's no standalone county ban on disconnecting from utilities, but occupancy still requires meeting the county's separate septic, water, and building permit approvals. source

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: 1,040 kWh

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Weather1991-2020

Precipitation: 50 in/yr
Snowfall: 11 in/yr
Heating degree days: 5,384 (moderate)
Frost-free season: Apr 29 to Oct 14

How far help isstraight-line

Hospital Mason General Hospital: 9.6 mi
Fire station Central Mason Fire Station: 5.3 mi
Hardware store Washington Home Center: 8.9 mi
Grocery POD Market: 8.8 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 98506).

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.