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Grafton County, New Hampshire

A shallow water table limits basements on 29% of Grafton County's mapped land and the 7th highest of 10 New Hampshire counties. Shrink-swell clay limits houses without basements on 1%.

The soil survey maps 71% of the county's land area; these shares describe the mapped part. 71.3% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 57 flood losses here since 2016, 74% of them in buildings with basements. 48% of homes were built before 1980, against 50% nationally; the median home dates from 1981.

Data as of October 13, 2026 · sources

1%

expansive clay: shrink-swell limits slab homes

29%

high water table: limits basements

71%

in drought, October 13, 2026

48%

of homes built before 1980

Soil under Grafton County

Expansive clay (limits slab homes)1.0%
High water table (limits basements)29.0%
Septic fields very limited87.4%
Clay swell (LEP, by area)1.0%
High-swell land (LEP 6%+)1.0%
Mapped soil775,300 acres
Soil seriesShare hereSeries nationally: high water table
Tunbridge11%n/a
Becket8%n/a
Lyman8%n/a
Peru7%n/a
Marlow7%n/a
Monadnock6%n/a
Orange County: 36%Carroll County: 36%Belknap County: 42%Caledonia County: 49%Sullivan County: 26%Merrimack County: 49%Windsor County: 27%Washington County: 35%Grafton County OrangeCarrollBelknapCaledoniaSullivanMerrimackWindsorWashingtonGrafton
Grafton 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 NH009 (2025-09-10)

What the numbers mean here

On 29% of Grafton 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: 41.12 in, 6.62 in below the 1991-2020 average year of 47.74 in.

USDA rates 87% of the land very limited for septic absorption fields.

Drought

71.3% 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 25 weeks, most recently on the April 7, 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 worse71.3%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

57 flood losses since 2016, $1.0 million paid. The worst year was 2017, with 27. Foundations of the buildings, where recorded: 74% basements, 15% slabs, 6% crawl spaces, 6% elevated. Median water depth outside the building: 11 in.

YearFlood losses
20163
201727
20183
20191
20201
20211
20220
202317
20241
20252
2026 to date1

Rain

Average year, 1991-202047.74 in
12 months to August 202641.12 in (-6.62)
202539.00 in (-8.74)
Wettest year since 18952008: 59.96 in
Driest year since 18952001: 33.87 in
Days with 1 inch or more, normal at GLENCLIFF 2 (5 mi away)8.7

Homes

Housing units51,920
Median year built1981
Built before 198048%
Built 2000 or later21%
Owner-occupied71%
Median value, owner-occupied$344,500
Single-family detached61%

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
Orange County, VT 27 mi 0% 36%
Carroll County, NH 32 mi 2% 36%
Belknap County, NH 35 mi 2% 42%
Caledonia County, VT 40 mi 0% 49%
Sullivan County, NH 43 mi 2% 26%
Merrimack County, NH 44 mi 2% 49%
Windsor County, VT 45 mi 0% 27%
Washington County, VT 46 mi 0% 35%

Sources: USDA SSURGO (September 10, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status