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

Somewhat limited

Soil across 50.5% of Benton County, WA rates "Somewhat limited" in USDA's septic-absorption-field interpretation. It's a soil condition contractors work around routinely, with a bigger field or added fill, rather than one that forces an engineered system outright. Benton County, WA is 1,700.128 square miles with a population of 218,190.

What Benton County's reading doesn't cover

Two lots a mile apart in Benton County can carry different soil, even though they share one countywide rating. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Benton County will actually do.

What a system would cost here

With 50.5% of Benton County rating "Somewhat limited", a standard gravity system is not a safe assumption here. 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.

Benton County's rank among Washington counties

Nationally, Benton County, WA is the 2,941-most-constrained of 3,058 rated counties for septic soil. Within Washington alone it ranks 39 of 39.

Before you act on this

How this rating is built, and its real limits · How a percolation test actually works