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Union County, New Jersey

A shallow water table limits basements on 42% of Union County's mapped land, a higher share than 60% of US 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 1,879 flood losses here since 2016, 83% of them in buildings with basements. 78% of homes were built before 1980, against 50% nationally; the median home dates from 1956.

Data as of October 13, 2026 · sources

0%

expansive clay: shrink-swell limits slab homes

42%

high water table: limits basements

0%

in drought, October 13, 2026

78%

of homes built before 1980

Soil under Union County

Expansive clay (limits slab homes)0.0%
High water table (limits basements)42.1%
Septic fields very limited62.3%
Clay swell (LEP, by area)1.8%
High-swell land (LEP 6%+)0.0%
Urban land, not rated33.5%
Mapped soil67,500 acres
Soil seriesShare hereSeries nationally: high water table
Boonton16%n/a
Haledon13%n/a
Amwell3%n/a
Neshaminy3%n/a
Hasbrouck3%n/a
Birdsboro2%n/a
Essex County: 22%Richmond County: 22%Hudson County: 32%Middlesex County: 53%Somerset County: 44%Morris County: 53%Kings County: 17%New York County: 2%Union County EssexRichmondHudsonMiddlesexSomersetMorrisKingsNew YorkUnion
Union 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 NJ039 (2025-08-28)

What the numbers mean here

On 42% of Union 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: 44.66 in, 3.51 in below the 1991-2020 average year of 48.17 in.

USDA rates 62% 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 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

1,879 flood losses since 2016, $67.3 million paid. The worst year was 2021, with 1,398. Foundations of the buildings, where recorded: 83% basements, 11% slabs, 1% crawl spaces, 5% elevated. Median water depth outside the building: 16 in.

YearFlood losses
20168
20177
201823
201926
20205
20211,398
202210
202352
202417
2025306
2026 to date27

Rain

Average year, 1991-202048.17 in
12 months to August 202644.66 in (-3.51)
202538.93 in (-9.24)
Wettest year since 18952011: 69.22 in
Driest year since 18951965: 29.67 in
Days with 1 inch or more, normal at CRANFORD (1 mi away)13.8

Homes

Housing units212,385
Median year built1956
Built before 198078%
Built 2000 or later13%
Owner-occupied57%
Median value, owner-occupied$529,200
Single-family detached50%

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
Essex County, NJ 9 mi 0% 22%
Richmond County, NY 11 mi 0% 22%
Hudson County, NJ 13 mi 0% 32%
Middlesex County, NJ 16 mi 0% 53%
Somerset County, NJ 18 mi 0% 44%
Morris County, NJ 19 mi 0% 53%
Kings County, NY 19 mi 0% 17%
New York County, NY 19 mi 0% 2%

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