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Union, Ohio
Inside Union's city limits, a shallow water table limits basements on 50% of mapped land. Shrink-swell clay limits houses without basements on 18%.
That water-table share is below Montgomery County's 65%. FEMA's flood data list 7 flood losses since 2016 in the 2 ZIP codes overlapping the city. Of its 3,035 homes, 52% were built before 1980; the median dates from 1979.
Data as of October 13, 2026 · sources · in Montgomery County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 2 overlapping ZIPs
of homes built before 1980
Basement waterproofing in Union
Basement waterproofing in Union: a shallow water table limits basements on 50% of Union's mapped land, and the 2 ZIP codes overlapping Union logged 7 FEMA flood losses since 2016.
In Montgomery County, 65% of the 48 flood-loss buildings with a recorded foundation type had basements.
About 2,300 of Union's 3,035 homes are detached houses.
Soil under Union city limits
| Expansive clay (limits slab homes) | 17.9% |
| High water table (limits basements) | 49.6% |
| Septic fields very limited | 91.5% |
| Clay swell (LEP, by area) | 4.8% |
| High-swell land (LEP 6%+) | 6.6% |
| Urban land, not rated | 2.1% |
| Mapped soil | 5,485 acres |
What the numbers mean here
Clay swell averages a linear extensibility of 4.8% by land area here, and 7% 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 50% of Union's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 92% of the land very limited for septic absorption fields.
Drought in Montgomery County
0% of Montgomery County is in drought (D1 or worse) on the October 13, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap Union. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 45322 | 53% | 6 | $27,666 |
| 45377 | 44% | 1 | $0 |
Homes in Union
| Housing units | 3,035 |
| Median year built | 1979 |
| Built before 1980 | 52% |
| Built 2000 or later | 26% |
| Owner-occupied | 81% |
| Median value, owner-occupied | $169,200 |
| Single-family detached | 77% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Clayton | 2 mi | 15% | 84% |
| Englewood | 3 mi | 24% | 66% |
| West Milton | 4 mi | 21% | 38% |
| Phillipsburg | 5 mi | 28% | 100% |
| Vandalia | 7 mi | 11% | 73% |
| Ludlow Falls | 7 mi | 3% | 16% |
| Potsdam | 7 mi | 24% | 100% |
| Brookville | 7 mi | 30% | 96% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status