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Delaware County, Pennsylvania
A shallow water table limits basements on 22% of Delaware County's mapped land. Shrink-swell clay limits houses without basements on under 1%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 462 flood losses here since 2016, 51% of them in buildings with basements. 79% of homes were built before 1980, against 50% nationally; the median home dates from 1957.
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 Delaware County
| Expansive clay (limits slab homes) | under 0.1% |
| High water table (limits basements) | 22.3% |
| Septic fields very limited | 84.5% |
| Clay swell (LEP, by area) | 1.8% |
| High-swell land (LEP 6%+) | under 0.1% |
| Urban land, not rated | 5.7% |
| Mapped soil | 107,668 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Glenelg | 20% | 0% |
| Glenville | 10% | n/a |
| Manor | 7% | n/a |
| Neshaminy | 7% | n/a |
| Pineyneck | 5% | n/a |
| Wheaton | 5% | n/a |
How we count · survey areas PA045 (2025-09-05)
What the numbers mean here
On 22% 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: 39.10 in, 7.89 in below the 1991-2020 average year of 46.99 in.
USDA rates 85% 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 42 of the last 52 weeks; the most was 100% of its area, in 13 weeks, most recently on the July 7, 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
462 flood losses since 2016, $17.2 million paid. The worst year was 2020, with 268. Foundations of the buildings, where recorded: 51% basements, 24% slabs, 3% crawl spaces, 22% elevated. Median water depth outside the building: 25 in.
| Year | Flood losses |
|---|---|
| 2016 | 9 |
| 2017 | 5 |
| 2018 | 77 |
| 2019 | 37 |
| 2020 | 268 |
| 2021 | 35 |
| 2022 | 0 |
| 2023 | 8 |
| 2024 | 14 |
| 2025 | 7 |
| 2026 to date | 2 |
Rain
| Average year, 1991-2020 | 46.99 in |
| 12 months to August 2026 | 39.10 in (-7.89) |
| 2025 | 37.66 in (-9.33) |
| Wettest year since 1895 | 2018: 66.83 in |
| Driest year since 1895 | 1965: 30.71 in |
| Days with 1 inch or more, normal at PHILADELPHIA INTL AP (10 mi away) | 10.9 |
Homes
| Housing units | 229,715 |
| Median year built | 1957 |
| Built before 1980 | 79% |
| Built 2000 or later | 8% |
| Owner-occupied | 70% |
| Median value, owner-occupied | $332,200 |
| Single-family detached | 44% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Philadelphia County, PA | 15 mi | 0% | 5% |
| Gloucester County, NJ | 19 mi | 2% | 34% |
| Chester County, PA | 19 mi | under 1% | 21% |
| Montgomery County, PA | 20 mi | under 1% | 44% |
| Salem County, NJ | 24 mi | 2% | 54% |
| Camden County, NJ | 24 mi | under 1% | 44% |
| New Castle County, DE | 27 mi | 2% | 34% |
| Bucks County, PA | 33 mi | under 1% | 52% |
Sources: USDA SSURGO (September 5, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status