Mason, Ohio
Inside Mason's city limits, a shallow water table limits basements on 41% of mapped land, the 5th-highest of 13 cities in Warren County. Shrink-swell clay limits houses without basements on 4%.
That water-table share is below Warren County's 51%. USDA doesn't rate the 30% of mapped land classed as urban land, so these shares are floors. FEMA's flood data list 4 flood losses since 2016 in ZIP code 45040 overlapping the city. Of its 13,866 homes, 22% were built before 1980; the median dates from 1996.
Data as of October 13, 2026 · sources · in Warren County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 1 overlapping ZIP
of homes built before 1980
Basement waterproofing in Mason
Basement waterproofing in Mason: a shallow water table limits basements on 41% of Mason's mapped land, and the ZIP code overlapping Mason logged 4 FEMA flood losses since 2016.
In Warren County, 42% of the 24 flood-loss buildings with a recorded foundation type had basements.
About 9,600 of Mason's 13,866 homes are detached houses.
Soil under Mason city limits
| Expansive clay (limits slab homes) | 4.3% |
| High water table (limits basements) | 40.8% |
| Septic fields very limited | 65.0% |
| Clay swell (LEP, by area) | 4.3% |
| High-swell land (LEP 6%+) | 1.8% |
| Urban land, not rated | 30.4% |
| Mapped soil | 12,476 acres |
What the numbers mean here
On 41% of Mason's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 65% of the land very limited for septic absorption fields.
Drought in Warren County
0% of Warren 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 Mason. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 45040 | 92% | 4 | $12,708 |
Homes in Mason
| Housing units | 13,866 |
| Median year built | 1996 |
| Built before 1980 | 22% |
| Built 2000 or later | 40% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $426,200 |
| Single-family detached | 69% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| South Lebanon | 4 mi | 9% | 25% |
| Lebanon | 6 mi | 16% | 27% |
| Maineville | 7 mi | 3% | 77% |
| Loveland | 7 mi | 9% | 23% |
| Monroe | 7 mi | 27% | 41% |
| Montgomery | 8 mi | 5% | 8% |
| Sharonville | 8 mi | 2% | 9% |
| Morrow | 9 mi | 11% | 16% |
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