Illinois Soil Surveys
The most common soil here is Drummer, on about 4% of the land: a silty clay loam, smooth and slightly sticky. Ipava and Hickory come next.
About 28% of the land drains well, and 55% stays wet for long stretches; groundwater comes within two feet of the surface under 55% of it.
USDA rates 84% of the land very limited for a standard septic drain field, and 70% very limited for homes with basements. That means extra cost or special design, not that it can't be done.
Worth knowing: 12% of the land floods occasionally or more, and bedrock lies within 40 inches under 2% of it.
Soils change over short distances, so look up an address below for the soil at that exact spot and the reasons behind each rating.
The soils you're most likely standing on
The biggest named soils in Illinois, each drawn five feet deep from its official USDA description, in its recorded colors.
Dots mark gravel; white flecks mark lime. Shares are by acres across the survey area, and each mapped patch usually mixes several of these soils.
Illinois has 102 USDA soil survey areas covering a wide range of landscapes and soil conditions. The most common soil order is Alfisols — moderately leached forest soils with a clay-enriched subsoil, making up roughly 54% of surveyed soils. Mollisols — grassland soils with a thick, dark, fertile topsoil rich in organic matter account for another 31%.
In terms of drainage, 31% of Illinois soils are classified as somewhat poorly drained. About 56% of soils have some form of poor drainage, which is important to consider for septic systems and foundations. Drainage class affects everything from septic system design to basement feasibility to garden planning. Use the survey area pages below to see drainage details for specific counties, or look up any address for an exact soil profile.