Septic soil in Surry County, NC, by the numbers
Very limited
84.8% of Surry County, NC's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. A standard gravity system routinely fails on ground like this; the same share of the county falls in USDA's worst absorption-field bucket outright. Surry County, NC is 532.644 square miles with a population of 71,547.
What Surry County's reading doesn't cover
USDA's survey covers the whole of Surry County, NC at once, not any single address. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Surry County will actually do.
What a system would cost here
With 84.8% of Surry County rating "Very 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.
How Surry County, NC compares
Nationally, Surry County, NC is the 1,706-most-constrained of 3,058 rated counties for septic soil. Within North Carolina alone it ranks 33 of 97.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems