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Middlesex County, New Jersey
A shallow water table limits basements on 53% of Middlesex County's mapped land, a higher share than 69% of US counties and the 7th highest of 21 New Jersey counties. Shrink-swell clay limits houses without basements on 0%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 1,021 flood losses here since 2016, 67% of them in buildings with basements. 57% of homes were built before 1980, against 50% nationally; the median home dates from 1974.
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 Middlesex County
| Expansive clay (limits slab homes) | 0.0% |
| High water table (limits basements) | 52.8% |
| Septic fields very limited | 84.1% |
| Clay swell (LEP, by area) | 2.0% |
| High-swell land (LEP 6%+) | 0.4% |
| Urban land, not rated | 13.5% |
| Mapped soil | 205,900 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Sassafras | 9% | n/a |
| Woodstown | 7% | n/a |
| Boonton | 4% | n/a |
| Fallsington | 4% | n/a |
| Keyport | 4% | n/a |
| Downer | 3% | n/a |
How we count · survey areas NJ023 (2025-08-28)
What the numbers mean here
On 53% of Middlesex 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: 42.52 in, 5.17 in below the 1991-2020 average year of 47.69 in.
USDA rates 84% 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 39 of the last 52 weeks; the most was 100% of its area, in 25 weeks, most recently on the July 28, 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
1,021 flood losses since 2016, $52.1 million paid. The worst year was 2021, with 712. Foundations of the buildings, where recorded: 67% basements, 20% slabs, 6% crawl spaces, 7% elevated. Median water depth outside the building: 18 in.
| Year | Flood losses |
|---|---|
| 2016 | 8 |
| 2017 | 7 |
| 2018 | 38 |
| 2019 | 18 |
| 2020 | 9 |
| 2021 | 712 |
| 2022 | 7 |
| 2023 | 38 |
| 2024 | 16 |
| 2025 | 163 |
| 2026 to date | 5 |
Rain
| Average year, 1991-2020 | 47.69 in |
| 12 months to August 2026 | 42.52 in (-5.17) |
| 2025 | 39.45 in (-8.24) |
| Wettest year since 1895 | 2011: 65.29 in |
| Driest year since 1895 | 1965: 28.92 in |
| Days with 1 inch or more, normal at NEW BRUNSWICK 3 SE (2 mi away) | 13.1 |
Homes
| Housing units | 317,979 |
| Median year built | 1974 |
| Built before 1980 | 57% |
| Built 2000 or later | 17% |
| Owner-occupied | 64% |
| Median value, owner-occupied | $462,900 |
| Single-family detached | 52% |
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 |
|---|---|---|---|
| Somerset County, NJ | 14 mi | 0% | 44% |
| Union County, NJ | 16 mi | 0% | 42% |
| Richmond County, NY | 16 mi | 0% | 22% |
| Monmouth County, NJ | 17 mi | under 1% | 40% |
| Mercer County, NJ | 19 mi | 0% | 44% |
| Essex County, NJ | 25 mi | 0% | 22% |
| Hudson County, NJ | 27 mi | 0% | 32% |
| Kings County, NY | 28 mi | 0% | 17% |
Sources: USDA SSURGO (August 28, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status