Buncombe County, NC's soil, for a septic absorption field

Very limited

Soil across 91.3% of Buncombe County, NC rates "Very limited" in USDA's septic-absorption-field interpretation. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 91.3% of Buncombe County's land. Buncombe County covers 656.49 square miles and counts 279,210 residents.

This is a county figure, not a parcel figure

Two lots a mile apart in Buncombe County can carry different soil, even though they share one countywide rating. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Buncombe County.

System cost, conventional vs. engineered

Given Buncombe 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.

Where this sits nationally

Nationally, Buncombe County, NC is the 1,129-most-constrained of 3,058 rated counties for septic soil. Within North Carolina alone it ranks 17 of 97.

Further reading

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