Septic soil in Wilson County, TN, by the numbers
Very limited
In Wilson County, TN, 85.2% of the surveyed land carries a "Very limited" rating for a standard septic drain 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. Wilson County, TN is 571.088 square miles with a population of 169,948.
What Wilson County's reading doesn't cover
This is a countywide, area-weighted figure across every soil survey map unit in Wilson County, TN - never a reading for one specific parcel. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Wilson County will actually do.
What a system would cost here
With 85.2% of Wilson 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.
Where this sits nationally
Nationally, Wilson County, TN is the 1,670-most-constrained of 3,058 rated counties for septic soil. Within Tennessee alone it ranks 35 of 95.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems