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Monmouth County, New Jersey

A shallow water table limits basements on 40% of Monmouth County's mapped land, a higher share than 58% of US counties. 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 557 flood losses here since 2016, 45% of them in buildings with basements. 57% of homes were built before 1980, against 50% nationally; the median home dates from 1975.

Data as of October 13, 2026 · sources

<1%

expansive clay: shrink-swell limits slab homes

40%

high water table: limits basements

0%

in drought, October 13, 2026

57%

of homes built before 1980

Soil under Monmouth County

Expansive clay (limits slab homes)0.4%
High water table (limits basements)40.1%
Septic fields very limited88.9%
Clay swell (LEP, by area)1.9%
High-swell land (LEP 6%+)0.5%
Urban land, not rated6.0%
Mapped soil309,566 acres
Soil seriesShare hereSeries nationally: high water table
Freehold14%n/a
Evesboro8%n/a
Atsion6%n/a
Tinton6%n/a
Collington5%n/a
Klej4%n/a
Middlesex County: 53%Richmond County: 22%Kings County: 17%Union County: 42%Mercer County: 44%Ocean County: 57%Queens County: 15%Hudson County: 32%Monmouth County MiddlesexRichmondKingsUnionMercerOceanQueensHudsonMonmouth
Monmouth 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 NJ025 (2025-08-28)

What the numbers mean here

On 40% of Monmouth 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: 40.69 in, 6.91 in below the 1991-2020 average year of 47.60 in.

USDA rates 89% 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 16 weeks, most recently on the July 28, 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

557 flood losses since 2016, $9.0 million paid. The worst year was 2023, with 163. Foundations of the buildings, where recorded: 45% basements, 23% slabs, 21% crawl spaces, 12% elevated. Median water depth outside the building: 8 in.

YearFlood losses
201618
201726
2018103
201921
202011
202168
202231
2023163
202434
202517
2026 to date65

Rain

Average year, 1991-202047.60 in
12 months to August 202640.69 in (-6.91)
202539.59 in (-8.01)
Wettest year since 18952018: 66.48 in
Driest year since 18951965: 29.04 in
Days with 1 inch or more, normal at NEW BRUNSWICK 3 SE (19 mi away)13.1

Homes

Housing units270,415
Median year built1975
Built before 198057%
Built 2000 or later16%
Owner-occupied76%
Median value, owner-occupied$606,100
Single-family detached66%

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 17 mi 0% 53%
Richmond County, NY 19 mi 0% 22%
Kings County, NY 26 mi 0% 17%
Union County, NJ 27 mi 0% 42%
Mercer County, NJ 29 mi 0% 44%
Ocean County, NJ 30 mi under 1% 57%
Queens County, NY 30 mi 0% 15%
Hudson County, NJ 31 mi 0% 32%

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