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Nantucket County, Massachusetts

A shallow water table limits basements on 16% of Nantucket County's mapped land. Shrink-swell clay limits houses without basements on 0%.

63.9% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 58 flood losses here since 2016, 7% of them in buildings with basements. 43% of homes were built before 1980, against 50% nationally; the median home dates from 1984.

Data as of October 13, 2026 · sources

0%

expansive clay: shrink-swell limits slab homes

16%

high water table: limits basements

64%

in drought, October 13, 2026

43%

of homes built before 1980

Soil under Nantucket County

Expansive clay (limits slab homes)0.0%
High water table (limits basements)16.2%
Septic fields very limited70.0%
Clay swell (LEP, by area)1.4%
High-swell land (LEP 6%+)0.0%
Mapped soil37,075 acres
Soil seriesShare hereSeries nationally: high water table
Evesboro35%n/a
Plymouth8%n/a
Riverhead6%n/a
Hooksan4%n/a
Freetown2%n/a
Swansea2%n/a
Barnstable County: 19%Dukes County: 17%Plymouth County: 51%Bristol County: 63%Newport County: 66%Bristol County: 38%Washington County: 38%Kent County: 34%Nantucket County BarnstableDukesPlymouthBristolNewportBristolWashingtonKentNantucket
Nantucket 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 MA019 (2025-09-05)

What the numbers mean here

On 16% of Nantucket 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: 26.64 in, 17.04 in below the 1991-2020 average year of 43.68 in.

USDA rates 70% of the land very limited for septic absorption fields.

Drought

63.9% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 49 weeks, most recently on the September 22, 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 worse63.9%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

58 flood losses since 2016, $965,246 paid. The worst year was 2018, with 35. Foundations of the buildings, where recorded: 7% basements, 30% slabs, 33% crawl spaces, 30% elevated. Median water depth outside the building: 16 in.

YearFlood losses
20164
20174
201835
20193
20203
20212
20225
20231
20240
20250
2026 to date1

Rain

Average year, 1991-202043.68 in
12 months to August 202626.64 in (-17.04)
202528.65 in (-15.03)
Wettest year since 18951972: 59.47 in
Driest year since 18951965: 26.90 in
Days with 1 inch or more, normal at EDGARTOWN (23 mi away)12.9

Homes

Housing units12,594
Median year built1984
Built before 198043%
Built 2000 or later24%
Owner-occupied72%
Median value, owner-occupied$1.6 million
Single-family detached79%

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
Barnstable County, MA 29 mi 0% 19%
Dukes County, MA 32 mi 0% 17%
Plymouth County, MA 58 mi 0% 51%
Bristol County, MA 60 mi 0% 63%
Newport County, RI 63 mi 0% 66%
Bristol County, RI 68 mi 0% 38%
Washington County, RI 79 mi 0% 38%
Kent County, RI 81 mi 0% 34%

Sources: USDA SSURGO (September 5, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status