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Somerset County, New Jersey

A shallow water table limits basements on 44% of Somerset County's mapped land, a higher share than 61% of US counties and the 10th 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 1,118 flood losses here since 2016, 71% of them in buildings with basements. 46% of homes were built before 1980, against 50% nationally; the median home dates from 1982.

Data as of October 13, 2026 · sources

0%

expansive clay: shrink-swell limits slab homes

44%

high water table: limits basements

0%

in drought, October 13, 2026

46%

of homes built before 1980

Soil under Somerset County

Expansive clay (limits slab homes)0.0%
High water table (limits basements)44.1%
Septic fields very limited93.3%
Clay swell (LEP, by area)2.2%
High-swell land (LEP 6%+)0.0%
Mapped soil194,129 acres
Soil seriesShare hereSeries nationally: high water table
Penn18%n/a
Klinesville8%n/a
Neshaminy7%n/a
Rowland6%n/a
Mount Lucas6%n/a
Reaville5%n/a
Middlesex County: 53%Hunterdon County: 31%Union County: 42%Mercer County: 44%Morris County: 53%Essex County: 22%Richmond County: 22%Warren County: 22%Somerset County MiddlesexHunterdonUnionMercerMorrisEssexRichmondWarrenSomerset
Somerset County (heavy outline) and nearby counties, shaded by high water table share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas NJ035 (2025-08-28)

What the numbers mean here

On 44% of Somerset 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: 42.76 in, 6.27 in below the 1991-2020 average year of 49.03 in.

USDA rates 93% 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 40 of the last 52 weeks; the most was 100% of its area, in 34 weeks, most recently on the July 21, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse0%
D1 moderate drought or worse0%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

1,118 flood losses since 2016, $79.8 million paid. The worst year was 2021, with 858. Foundations of the buildings, where recorded: 71% basements, 18% slabs, 5% crawl spaces, 6% elevated. Median water depth outside the building: 28 in.

YearFlood losses
20165
20177
201812
20198
20204
2021858
20227
202323
202422
2025171
2026 to date1

Rain

Average year, 1991-202049.03 in
12 months to August 202642.76 in (-6.27)
202539.85 in (-9.18)
Wettest year since 18952011: 69.31 in
Driest year since 18951965: 29.84 in
Days with 1 inch or more, normal at BOUND BROOK 2W (3 mi away)12.4

Homes

Housing units133,639
Median year built1982
Built before 198046%
Built 2000 or later17%
Owner-occupied74%
Median value, owner-occupied$552,100
Single-family detached58%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

WorkRangeSource
Basement waterproofing, US $3,000 to $10,000 Fixr, February 6, 2026
Sump pump installation, US $800 to $2,000 Fixr, January 31, 2025
Crawl space encapsulation, US $2,000 to $8,000 Fixr, August 29, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Middlesex County, NJ 14 mi 0% 53%
Hunterdon County, NJ 15 mi 0% 31%
Union County, NJ 18 mi 0% 42%
Mercer County, NJ 20 mi 0% 44%
Morris County, NJ 21 mi 0% 53%
Essex County, NJ 25 mi 0% 22%
Richmond County, NY 25 mi 0% 22%
Warren County, NJ 28 mi 0% 22%

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