Madison County, Ohio
A shallow water table limits basements on 94% of Madison County's mapped land, a higher share than 98% of US counties. Shrink-swell clay limits houses without basements on 36%.
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. 55% of homes were built before 1980, against 50% nationally; the median home dates from 1976.
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 Madison County
| Expansive clay (limits slab homes) | 36.1% |
| High water table (limits basements) | 93.7% |
| Septic fields very limited | 97.4% |
| Clay swell (LEP, by area) | 5.0% |
| High-swell land (LEP 6%+) | 13.2% |
| Mapped soil | 299,206 acres |
How we count · survey areas OH097 (2025-09-02)
What the numbers mean here
Clay swell averages a linear extensibility of 5.0% by land area here, and 13% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 36% of the mapped land.
On 94% of Madison 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: 45.03 in, 4.44 in above the 1991-2020 average year of 40.59 in.
USDA rates 97% 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 1 of the last 52 weeks; the most was 5.2% of its area, on the October 21, 2025 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, $93,737 paid. The worst year was 2017, with 3.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 3 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 2 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 40.59 in |
| 12 months to August 2026 | 45.03 in (+4.44) |
| 2025 | 38.91 in (-1.68) |
| Wettest year since 1895 | 2011: 56.27 in |
| Driest year since 1895 | 1934: 24.14 in |
| Days with 1 inch or more, normal at MARYSVILLE (22 mi away) | 9 |
Homes
| Housing units | 16,519 |
| Median year built | 1976 |
| Built before 1980 | 55% |
| Built 2000 or later | 20% |
| Owner-occupied | 78% |
| Median value, owner-occupied | $250,100 |
| Single-family detached | 80% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Madison County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| London | 36% | 97% | 4,970 |
| Midway | 10% | 97% | 87 |
| Mount Sterling | 31% | 91% | 756 |
| Plain City | 38% | 90% | 1,612 |
| South Solon | 37% | 88% | 163 |
| West Jefferson | 38% | 93% | 1,718 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Clark County, OH | 20 mi | 17% | 59% |
| Franklin County, OH | 21 mi | 12% | 71% |
| Fayette County, OH | 24 mi | 37% | 96% |
| Pickaway County, OH | 25 mi | 19% | 72% |
| Champaign County, OH | 26 mi | 13% | 83% |
| Union County, OH | 28 mi | 25% | 97% |
| Greene County, OH | 30 mi | 8% | 68% |
| Delaware County, OH | 34 mi | 23% | 84% |
Sources: USDA SSURGO (September 2, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status