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

Very limited

Soil across 76% of Union County, IL rates "Very limited" in USDA's septic-absorption-field interpretation. This is the reading that pushes a project toward an engineered system rather than a conventional one, and it covers 76% of Union County's land. Union County covers 413.412 square miles and counts 16,886 residents.

This is a county figure, not a parcel figure

This is a countywide, area-weighted figure across every soil survey map unit in Union County, IL - never a reading for one specific parcel. A site-specific perc test, usually $750-$1,850, is what a health department will actually require before permitting a lot in Union County.

System cost, conventional vs. engineered

Given Union County's rating, plan for the engineered-system range rather than the conventional one. 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.

Union County's rank among Illinois counties

Nationally, Union County, IL is the 2,238-most-constrained of 3,058 rated counties for septic soil. Within Illinois alone it ranks 72 of 101.

Related guides

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