McLean County, IL: the USDA septic-suitability picture

Very limited

USDA puts McLean County, IL at "Very limited" for septic absorption fields, the dominant reading across 90.7% of the county's soil. Expect the ground itself to work against a plain gravity system; USDA's strictest bucket alone covers 90.7% of the county. The county spans 1,183.248 square miles, home to 172,069 people.

What this number does and doesn't tell you

McLean County's rating is an average across the whole county, not a promise about any one lot inside it. Budget $750-$1,850 for a real perc test on any specific parcel - that's the only figure a permit application accepts.

McLean County: conventional vs. engineered cost

90.7% of McLean 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.

How McLean County, IL compares

Among the 3,058 rated counties on this site, McLean County, IL ranks 1,192 most-constrained nationally, and 45 of 101 within Illinois.

Further reading

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