Septic suitability in Tishomingo County, MS
Very limited
Tishomingo County, MS's SSURGO dominant class comes back "Very limited", covering 80.7% of the county. Practically, that rules out a simple gravity system for most of the county - 80.7% of it sits in USDA's most-constrained bucket. The county spans 424.297 square miles, home to 18,553 people.
What this number does and doesn't tell you
Nothing about Tishomingo 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.
Tishomingo County: conventional vs. engineered cost
80.7% of Tishomingo 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.
Tishomingo County's rank among Mississippi counties
Among the 3,058 rated counties on this site, Tishomingo County, MS ranks 2,004 most-constrained nationally, and 67 of 82 within Mississippi.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems