Septic suitability in Walla Walla County, WA

Very limited

USDA puts Walla Walla County, WA at "Very limited" for septic absorption fields, the dominant reading across 78.7% of the county's soil. That reading means a conventional system is a poor bet here - 78.7% of Walla Walla County lands in the strictest "very limited" bucket USDA uses. For scale: 1,270.033 square miles and 62,068 people call Walla Walla County home.

Before you rely on this for one lot

USDA's survey covers the whole of Walla Walla County, WA at once, not any single address. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).

Budgeting for a system in Walla Walla County, WA

Walla Walla County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. Conventional systems run $3,000-$8,000 where they pass; where they don't, engineered alternatives (mound or aerobic treatment, whichever the health department requires) run $10,000-$40,000 - budget toward the higher figure until a perc test says otherwise.

Where this sits nationally

Among the 3,058 rated counties on this site, Walla Walla County, WA ranks 2,108 most-constrained nationally, and 34 of 39 within Washington.

Further reading

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