Peoria County, Illinois
A shallow water table limits basements on 37% of Peoria County's mapped land, a higher share than 56% of US counties. Shrink-swell clay limits houses without basements on 29%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 103 flood losses here since 2016, 51% of them in buildings with basements. 70% of homes were built before 1980, against 50% nationally; the median home dates from 1966.
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 Peoria County
| Expansive clay (limits slab homes) | 28.9% |
| High water table (limits basements) | 37.0% |
| Septic fields very limited | 62.1% |
| Clay swell (LEP, by area) | 4.3% |
| High-swell land (LEP 6%+) | 21.7% |
| Mapped soil | 402,680 acres |
How we count · survey areas IL143 (2025-08-31)
What the numbers mean here
Clay swell averages a linear extensibility of 4.3% by land area here, and 22% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 29% of the mapped land.
On 37% of Peoria 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: 39.19 in, 1.07 in above the 1991-2020 average year of 38.12 in.
USDA rates 62% 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 24 of the last 52 weeks; the most was 100% of its area, in 21 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
103 flood losses since 2016, $1.1 million paid. The worst year was 2019, with 46. Foundations of the buildings, where recorded: 51% basements, 11% slabs, 6% crawl spaces, 32% elevated. Median water depth outside the building: 24 in.
| Year | Flood losses |
|---|---|
| 2016 | 10 |
| 2017 | 4 |
| 2018 | 8 |
| 2019 | 46 |
| 2020 | 28 |
| 2021 | 0 |
| 2022 | 3 |
| 2023 | 1 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 2 |
Rain
| Average year, 1991-2020 | 38.12 in |
| 12 months to August 2026 | 39.19 in (+1.07) |
| 2025 | 26.95 in (-11.17) |
| Wettest year since 1895 | 2009: 54.37 in |
| Driest year since 1895 | 1901: 22.31 in |
| Days with 1 inch or more, normal at PEORIA GTR PEORIA AP (9 mi away) | 9.2 |
Homes
| Housing units | 84,930 |
| Median year built | 1966 |
| Built before 1980 | 70% |
| Built 2000 or later | 15% |
| Owner-occupied | 67% |
| Median value, owner-occupied | $158,500 |
| Single-family detached | 72% |
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 |
|---|---|---|---|
| Stark County, IL | 22 mi | 36% | 52% |
| Tazewell County, IL | 23 mi | 33% | 53% |
| Knox County, IL | 25 mi | 41% | 41% |
| Marshall County, IL | 28 mi | 36% | 66% |
| Woodford County, IL | 29 mi | 49% | 81% |
| Fulton County, IL | 32 mi | 24% | 38% |
| Putnam County, IL | 38 mi | 23% | 50% |
| Mason County, IL | 39 mi | 3% | 42% |
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