What Jefferson County, WA's soil rates for a septic system

Very limited

98% of Jefferson County, WA's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. Practically, that rules out a simple gravity system for most of the county - 98% of it sits in USDA's most-constrained bucket. Jefferson County covers 1,803.728 square miles and counts 33,944 residents.

This is a county figure, not a parcel figure

USDA's survey covers the whole of Jefferson County, WA at once, not any single address. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Jefferson County.

System cost, conventional vs. engineered

Given Jefferson County's rating, plan for the engineered-system range rather than the conventional one. The engineered-system range, $10,000-$40,000 (mound or aerobic treatment), is the more realistic number to plan around, against $3,000-$8,000 for a conventional system on the rare lot that passes.

Jefferson County's rank among Washington counties

Nationally, Jefferson County, WA is the 250-most-constrained of 3,058 rated counties for septic soil. Within Washington alone it ranks 3 of 39.

Related guides

How this rating is built, and its real limits · Conventional vs. engineered septic systems