Septic soil in Grenada County, MS, by the numbers
Very limited
Soil across 88.5% of Grenada County, MS rates "Very limited" in USDA's septic-absorption-field interpretation. 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. Grenada County covers 422.113 square miles and counts 20,931 residents.
This is a county figure, not a parcel figure
Nothing about Grenada County, MS's SSURGO figure applies to a specific address - it's a county-wide average. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Grenada County.
System cost, conventional vs. engineered
Given Grenada 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, Grenada County, MS is the 1,422-most-constrained of 3,058 rated counties for septic soil. Within Mississippi alone it ranks 54 of 82.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems