Simpson County's SSURGO septic rating

Very limited

Simpson County, MS: USDA's soil survey calls 91.2% of the county "Very limited" for a septic leach 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. The county spans 589.165 square miles, home to 25,597 people.

What this number does and doesn't tell you

Nothing about Simpson County, MS's SSURGO figure applies to a specific address - it's a county-wide average. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.

Simpson County: conventional vs. engineered cost

91.2% of Simpson County carrying a "Very limited" reading changes the realistic budget here. 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.

How Simpson County, MS compares

Among the 3,058 rated counties on this site, Simpson County, MS ranks 1,148 most-constrained nationally, and 47 of 82 within Mississippi.

Further reading

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