Septic suitability in Marion County, IL

Very limited

Marion County, IL: USDA's soil survey calls 98.1% of the county "Very limited" for a septic leach field. Practically, that rules out a simple gravity system for most of the county - 98.1% of it sits in USDA's most-constrained bucket. For scale: 572.538 square miles and 36,437 people call Marion County home.

Before you rely on this for one lot

USDA's survey covers the whole of Marion 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 Marion County, IL

Marion 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.

How Marion County, IL compares

Among the 3,058 rated counties on this site, Marion County, IL ranks 232 most-constrained nationally, and 12 of 101 within Illinois.

Further reading

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