Mercer County, Ohio
A shallow water table limits basements on 95% of Mercer County's mapped land, a higher share than 98% of US counties and the 10th highest of 88 Ohio counties. Shrink-swell clay limits houses without basements on 37%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 18 flood losses here since 2016. 59% of homes were built before 1980, against 50% nationally; the median home dates from 1974.
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 Mercer County
| Expansive clay (limits slab homes) | 37.2% |
| High water table (limits basements) | 95.1% |
| Septic fields very limited | 95.6% |
| Clay swell (LEP, by area) | 5.0% |
| High-swell land (LEP 6%+) | 8.4% |
| Mapped soil | 302,969 acres |
How we count · survey areas OH107 (2025-09-02)
What the numbers mean here
Clay swell averages a linear extensibility of 5.0% by land area here, and 8% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 37% of the mapped land.
On 95% of Mercer 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: 39.23 in, 0.12 in below the 1991-2020 average year of 39.35 in.
USDA rates 96% 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 20 weeks, most recently on the March 3, 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
18 flood losses since 2016, $353,965 paid. The worst year was 2019, with 16.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 1 |
| 2018 | 0 |
| 2019 | 16 |
| 2020 | 1 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 39.35 in |
| 12 months to August 2026 | 39.23 in (-0.12) |
| 2025 | 31.69 in (-7.66) |
| Wettest year since 1895 | 2003: 53.20 in |
| Driest year since 1895 | 1963: 23.91 in |
| Days with 1 inch or more, normal at CELINA 3 NE (6 mi away) | 8.2 |
Homes
| Housing units | 18,103 |
| Median year built | 1974 |
| Built before 1980 | 59% |
| Built 2000 or later | 19% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $210,600 |
| Single-family detached | 81% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Mercer County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Burkettsville | 47% | over 99% | 93 |
| Celina | 23% | 67% | 4,970 |
| Chickasaw | 19% | 93% | 161 |
| Coldwater | 29% | over 99% | 1,600 |
| Fort Recovery | 16% | 95% | 695 |
| Mendon | 16% | 98% | 260 |
| Montezuma | 24% | 92% | 73 |
| Rockford | 27% | 98% | 463 |
| St. Henry | 25% | over 99% | 932 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Jay County, IN | 21 mi | 60% | 96% |
| Auglaize County, OH | 21 mi | 29% | 94% |
| Adams County, IN | 22 mi | 45% | 97% |
| Van Wert County, OH | 22 mi | 64% | 99% |
| Shelby County, OH | 26 mi | 24% | 94% |
| Darke County, OH | 28 mi | 26% | 96% |
| Allen County, OH | 32 mi | 31% | 93% |
| Randolph County, IN | 32 mi | 25% | 94% |
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