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Onslow County, North Carolina

A shallow water table limits basements on 84% of Onslow County's mapped land, a higher share than 91% of US counties. Shrink-swell clay limits houses without basements on 2%.

90.1% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 1,065 flood losses here since 2016, 2% of them in buildings with basements. 26% of homes were built before 1980, against 50% nationally; the median home dates from 1998.

Data as of October 13, 2026 · sources

2%

expansive clay: shrink-swell limits slab homes

84%

high water table: limits basements

90%

in drought, October 13, 2026

26%

of homes built before 1980

Soil under Onslow County

Expansive clay (limits slab homes)1.7%
High water table (limits basements)84.0%
Septic fields very limited80.4%
Clay swell (LEP, by area)1.6%
High-swell land (LEP 6%+)1.7%
Urban land, not rated1.4%
Mapped soil524,934 acres
Soil seriesShare hereSeries nationally: high water table
Baymeade9%n/a
Croatan6%n/a
Rains6%n/a
Muckalee6%n/a
Woodington6%n/a
Torhunta6%n/a
Jones County: 95%Duplin County: 92%Pender County: 94%Craven County: 85%Lenoir County: 88%New Hanover County: 68%Wayne County: 70%Greene County: 83%Onslow County JonesDuplinPenderCravenLenoirNew HanoverWayneGreeneOnslow
Onslow 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 NC133 (2025-08-27)

What the numbers mean here

On 84% of Onslow 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: 42.48 in, 14.62 in below the 1991-2020 average year of 57.10 in.

USDA rates 80% of the land very limited for septic absorption fields.

Drought

90.1% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 48 of the last 52 weeks; the most was 100% of its area, in 26 weeks, most recently on the August 4, 2026 map.

October 21, 2025Share of area in drought, weeklyOctober 13, 2026
Category, October 13, 2026Share of county
D0 abnormally dry or worse100%
D1 moderate drought or worse90.1%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

1,065 flood losses since 2016, $31.6 million paid. The worst year was 2018, with 978. Foundations of the buildings, where recorded: 2% basements, 24% slabs, 14% crawl spaces, 60% elevated. Median water depth outside the building: 19 in.

YearFlood losses
201637
20171
2018978
20194
202014
20212
20226
202313
20247
20253
2026 to date0

Rain

Average year, 1991-202057.10 in
12 months to August 202642.48 in (-14.62)
202548.35 in (-8.75)
Wettest year since 18952018: 84.76 in
Driest year since 18952007: 36.45 in
Days with 1 inch or more, normal at NEW RIVER MCAF (8 mi away)15.6

Homes

Housing units87,354
Median year built1998
Built before 198026%
Built 2000 or later48%
Owner-occupied64%
Median value, owner-occupied$236,400
Single-family detached65%

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
Jones County, NC 20 mi 6% 95%
Duplin County, NC 28 mi 0% 92%
Pender County, NC 28 mi 1% 94%
Craven County, NC 34 mi 9% 85%
Lenoir County, NC 34 mi 2% 88%
New Hanover County, NC 45 mi 6% 68%
Wayne County, NC 50 mi 1% 70%
Greene County, NC 51 mi 0% 83%

Sources: USDA SSURGO (August 27, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status