What Boone County, IL's soil rates for a septic system

Very limited

Soil across 74.3% of Boone County, IL rates "Very limited" in USDA's septic-absorption-field interpretation. Practically, that rules out a simple gravity system for most of the county - 74.3% of it sits in USDA's most-constrained bucket. Boone County, IL is 280.749 square miles with a population of 53,313.

What Boone County's reading doesn't cover

This is a countywide, area-weighted figure across every soil survey map unit in Boone County, IL - never a reading for one specific parcel. A local percolation test, typically $750-$1,850 (around $1,300 typical), is the only way to know what one lot in Boone County will actually do.

What a system would cost here

With 74.3% of Boone 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.

How Boone County, IL compares

Nationally, Boone County, IL is the 2,318-most-constrained of 3,058 rated counties for septic soil. Within Illinois alone it ranks 75 of 101.

Before you act on this

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