Delaware County, Ohio
A shallow water table limits basements on 84% of Delaware County's mapped land, a higher share than 92% of US counties. Shrink-swell clay limits houses without basements on 23%.
None of the county is in drought on the November 3, 2026 Drought Monitor map. FEMA's flood data list 25 flood losses here since 2016. 20% of homes were built before 1980, against 50% nationally; the median home dates from 2000.
Data as of November 3, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, November 3, 2026
of homes built before 1980
Soil under Delaware County
| Expansive clay (limits slab homes) | 22.5% |
| High water table (limits basements) | 84.5% |
| Septic fields very limited | 91.0% |
| Clay swell (LEP, by area) | 4.5% |
| High-swell land (LEP 6%+) | 1.4% |
| Urban land, not rated | 1.7% |
| Mapped soil | 292,672 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Pewamo | 22% | 99% |
| Blount | 19% | over 99% |
| Glynwood | 15% | over 99% |
| Bennington | 13% | 99% |
| Cardington | 7% | 99% |
| Centerburg | 3% | over 99% |
How we count · survey areas OH041 (2025-08-27)
What the numbers mean here
Clay swell averages a linear extensibility of 4.5% by land area here, and 1% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 23% of the mapped land.
On 84% of Delaware 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: 45.48 in, 4.68 in above the 1991-2020 average year of 40.80 in.
USDA rates 91% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the November 3, 2026 map. No part of the county was in drought in the last 52 weeks.
| Category, November 3, 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
25 flood losses since 2016, $298,560 paid. The worst year was 2020, with 9.
| Year | Flood losses |
|---|---|
| 2016 | 8 |
| 2017 | 3 |
| 2018 | 0 |
| 2019 | 2 |
| 2020 | 9 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 0 |
| 2025 | 1 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 40.80 in |
| 12 months to August 2026 | 45.48 in (+4.68) |
| 2025 | 35.90 in (-4.90) |
| Wettest year since 1895 | 2011: 55.09 in |
| Driest year since 1895 | 1934: 21.77 in |
| Days with 1 inch or more, normal at WESTERVILLE (11 mi away) | 8.2 |
Homes
| Housing units | 86,269 |
| Median year built | 2000 |
| Built before 1980 | 20% |
| Built 2000 or later | 51% |
| Owner-occupied | 79% |
| Median value, owner-occupied | $445,500 |
| Single-family detached | 74% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Delaware County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Ashley | 28% | 98% | 704 |
| Delaware | 23% | 72% | 17,726 |
| Galena | 8% | 80% | 522 |
| Ostrander | 4% | 86% | 317 |
| Powell | 12% | 71% | 5,669 |
| Shawnee Hills | 6% | 94% | 361 |
| Sunbury | 15% | 92% | 3,030 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Union County, OH | 19 mi | 25% | 97% |
| Morrow County, OH | 20 mi | 9% | 87% |
| Franklin County, OH | 21 mi | 12% | 71% |
| Marion County, OH | 23 mi | 40% | 92% |
| Licking County, OH | 31 mi | 1% | 69% |
| Knox County, OH | 32 mi | under 1% | 65% |
| Madison County, OH | 34 mi | 36% | 94% |
| Crawford County, OH | 40 mi | 3% | 93% |
Sources: USDA SSURGO (August 27, 2025) · US Drought Monitor (November 3, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status