Carroll County, IL's soil, for a septic absorption field

Somewhat limited

51% of Carroll County, IL's surveyed soil comes back "Somewhat limited" in USDA's own SSURGO data, the county's dominant condition for a septic absorption field. It's a soil condition contractors work around routinely, with a bigger field or added fill, rather than one that forces an engineered system outright. Carroll County, IL is 445.406 square miles with a population of 15,444.

What Carroll County's reading doesn't cover

USDA's survey covers the whole of Carroll County, IL at once, not any single address. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Carroll County will actually do.

What a system would cost here

With 51% of Carroll County rating "Somewhat 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, Carroll County, IL is the 2,943-most-constrained of 3,058 rated counties for septic soil. Within Illinois alone it ranks 101 of 101.

Before you act on this

How this rating is built, and its real limits · How a percolation test actually works