What Madison County, IN's soil rates for a septic system
Very limited
96.2% of Madison County, IN's surveyed soil comes back "Very limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 96.2% of Madison County's land. Madison County, IN is 451.921 square miles with a population of 134,222.
What Madison County's reading doesn't cover
Madison County's rating is an average across the whole county, not a promise about any one lot inside it. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Madison County will actually do.
What a system would cost here
With 96.2% of Madison 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.
Madison County's rank among Indiana counties
Nationally, Madison County, IN is the 491-most-constrained of 3,058 rated counties for septic soil. Within Indiana alone it ranks 32 of 90.
Related guides
How this rating is built, and its real limits · Conventional vs. engineered septic systems