De Witt County, Illinois
A shallow water table limits basements on 87% of De Witt County's mapped land, a higher share than 94% of US counties. Shrink-swell clay limits houses without basements on 69%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list no flood losses here since 2016. 76% of homes were built before 1980, against 50% nationally; the median home dates from 1958.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under De Witt County
| Expansive clay (limits slab homes) | 69.2% |
| High water table (limits basements) | 87.4% |
| Septic fields very limited | 89.5% |
| Clay swell (LEP, by area) | 5.0% |
| High-swell land (LEP 6%+) | 18.0% |
| Mapped soil | 258,760 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Sable | 26% | n/a |
| Catlin | 18% | n/a |
| Ipava | 15% | 100% |
| Birkbeck | 7% | n/a |
| Buckhart | 5% | n/a |
| Senachwine | 3% | n/a |
How we count · survey areas IL039 (2025-08-31)
What the numbers mean here
Clay swell averages a linear extensibility of 5.0% by land area here, and 18% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 69% of the mapped land.
On 87% of De Witt County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 35.51 in, 3.43 in below the 1991-2020 average year of 38.94 in.
USDA rates 90% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 26 of the last 52 weeks; the most was 100% of its area, in 24 weeks, most recently on the March 31, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in De Witt County since 2016.
Rain
| Average year, 1991-2020 | 38.94 in |
| 12 months to August 2026 | 35.51 in (-3.43) |
| 2025 | 27.31 in (-11.63) |
| Wettest year since 1895 | 1990: 53.49 in |
| Driest year since 1895 | 1988: 24.23 in |
| Days with 1 inch or more, normal at CLINTON 1SSW (5 mi away) | 9.7 |
Homes
| Housing units | 7,320 |
| Median year built | 1958 |
| Built before 1980 | 76% |
| Built 2000 or later | 11% |
| Owner-occupied | 79% |
| Median value, owner-occupied | $130,300 |
| Single-family detached | 87% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Piatt County, IL | 20 mi | 57% | 94% |
| McLean County, IL | 22 mi | 54% | 85% |
| Macon County, IL | 22 mi | 57% | 88% |
| Logan County, IL | 25 mi | 45% | 71% |
| Champaign County, IL | 37 mi | 26% | 94% |
| Tazewell County, IL | 39 mi | 33% | 53% |
| Moultrie County, IL | 40 mi | 68% | 89% |
| Woodford County, IL | 45 mi | 49% | 81% |
Sources: USDA SSURGO (August 31, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status