Miami County, Ohio
A shallow water table limits basements on 81% of Miami County's mapped land, a higher share than 90% of US counties. Shrink-swell clay limits houses without basements on 18%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 11 flood losses here since 2016. 64% of homes were built before 1980, against 50% nationally; the median home dates from 1971.
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 Miami County
| Expansive clay (limits slab homes) | 18.1% |
| High water table (limits basements) | 81.4% |
| Septic fields very limited | 97.6% |
| Clay swell (LEP, by area) | 4.5% |
| High-swell land (LEP 6%+) | 3.7% |
| Mapped soil | 262,221 acres |
How we count · survey areas OH109 (2025-09-02)
What the numbers mean here
Clay swell averages a linear extensibility of 4.5% by land area here, and 4% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 18% of the mapped land.
On 81% of Miami 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: 44.40 in, 3.23 in above the 1991-2020 average year of 41.17 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 2 of the last 52 weeks; the most was 59.5% of its area, on the October 14, 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
11 flood losses since 2016, $226,432 paid. The worst year was 2017, with 4.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 4 |
| 2018 | 1 |
| 2019 | 3 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 1 |
| 2026 to date | 2 |
Rain
| Average year, 1991-2020 | 41.17 in |
| 12 months to August 2026 | 44.40 in (+3.23) |
| 2025 | 39.78 in (-1.39) |
| Wettest year since 1895 | 2011: 56.15 in |
| Driest year since 1895 | 1934: 25.33 in |
| Days with 1 inch or more, normal at PLEASANT HILL (7 mi away) | 9 |
Homes
| Housing units | 47,226 |
| Median year built | 1971 |
| Built before 1980 | 64% |
| Built 2000 or later | 18% |
| Owner-occupied | 73% |
| Median value, owner-occupied | $229,100 |
| Single-family detached | 79% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Miami County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Bradford | 9% | 86% | 754 |
| Casstown | 0% | 37% | 118 |
| Covington | 15% | 44% | 1,106 |
| Fletcher | 9% | 99% | 235 |
| Laura | 6% | 97% | 178 |
| Ludlow Falls | 3% | 16% | 65 |
| Piqua | 14% | 72% | 9,311 |
| Pleasant Hill | 29% | 37% | 562 |
| Potsdam | 24% | 100% | 90 |
| Tipp City | 18% | 56% | 4,419 |
| Troy | 13% | 61% | 11,733 |
| West Milton | 21% | 38% | 2,287 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Shelby County, OH | 20 mi | 24% | 94% |
| Montgomery County, OH | 21 mi | 17% | 65% |
| Darke County, OH | 21 mi | 26% | 96% |
| Champaign County, OH | 25 mi | 13% | 83% |
| Clark County, OH | 25 mi | 17% | 59% |
| Greene County, OH | 31 mi | 8% | 68% |
| Preble County, OH | 31 mi | 17% | 86% |
| Logan County, OH | 34 mi | 26% | 81% |
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