Kendall County, Illinois
A shallow water table limits basements on 85% of Kendall County's mapped land, a higher share than 92% of US counties. Shrink-swell clay limits houses without basements on 26%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 6 flood losses here since 2016. 24% of homes were built before 1980, against 50% nationally; the median home dates from 2001.
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 Kendall County
| Expansive clay (limits slab homes) | 26.1% |
| High water table (limits basements) | 84.7% |
| Septic fields very limited | 98.2% |
| Clay swell (LEP, by area) | 4.9% |
| High-swell land (LEP 6%+) | 13.6% |
| Mapped soil | 206,215 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Drummer | 14% | over 99% |
| Graymont | 13% | n/a |
| Elpaso | 5% | n/a |
| Bryce | 4% | n/a |
| Swygert | 4% | n/a |
| Brenton | 4% | n/a |
How we count · survey areas IL093 (2025-08-31)
What the numbers mean here
Clay swell averages a linear extensibility of 4.9% by land area here, and 14% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 26% of the mapped land.
On 85% of Kendall 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: 41.57 in, 3.79 in above the 1991-2020 average year of 37.78 in.
USDA rates 98% 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 12 of the last 52 weeks; the most was 100% of its area, in 8 weeks, most recently on the June 9, 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
6 flood losses since 2016, $90,991 paid. The worst year was 2019, with 4.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 1 |
| 2019 | 4 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 37.78 in |
| 12 months to August 2026 | 41.57 in (+3.79) |
| 2025 | 30.19 in (-7.59) |
| Wettest year since 1895 | 1902: 51.48 in |
| Driest year since 1895 | 1956: 22.53 in |
| Days with 1 inch or more, normal at AURORA (15 mi away) | 9.2 |
Homes
| Housing units | 46,589 |
| Median year built | 2001 |
| Built before 1980 | 24% |
| Built 2000 or later | 55% |
| Owner-occupied | 84% |
| Median value, owner-occupied | $322,400 |
| Single-family detached | 74% |
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 |
|---|---|---|---|
| Grundy County, IL | 21 mi | 30% | 85% |
| Kane County, IL | 24 mi | 8% | 82% |
| Will County, IL | 25 mi | 24% | 85% |
| DuPage County, IL | 25 mi | 33% | 90% |
| DeKalb County, IL | 27 mi | 28% | 98% |
| LaSalle County, IL | 29 mi | 37% | 84% |
| Kankakee County, IL | 43 mi | 19% | 80% |
| Cook County, IL | 46 mi | 25% | 59% |
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