Macoupin County, IL: the USDA septic-suitability picture

Very limited

Macoupin County, IL's SSURGO dominant class comes back "Very limited", covering 89.9% of the county. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 89.9% of the county. For scale: 862.995 square miles and 43,895 people call Macoupin County home.

Before you rely on this for one lot

USDA's survey covers the whole of Macoupin County, IL at once, not any single address. The real answer for one lot is still a site-specific perc test, running about $750-$1,850 (typically near $1,300).

Budgeting for a system in Macoupin County, IL

Macoupin County's soil reading pushes the likely outcome toward an engineered system rather than a conventional one. 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.

Macoupin County's rank among Illinois counties

Among the 3,058 rated counties on this site, Macoupin County, IL ranks 1,273 most-constrained nationally, and 50 of 101 within Illinois.

Further reading

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