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District of Columbia, District of Columbia

USDA's soil survey flags shrink-swell clay on 0% of District of Columbia's mapped land and a shallow water table under basements on 9%, both below the national shares of 15% and 29%. None of the county is in drought on the October 13, 2026 Drought Monitor map.

FEMA's flood data list 230 flood losses here since 2016, 83% of them in buildings with basements. 69% of homes were built before 1980, against 50% nationally; the median home dates from 1958.

Data as of October 13, 2026 · sources

0%

expansive clay: shrink-swell limits slab homes

9%

high water table: limits basements

0%

in drought, October 13, 2026

69%

of homes built before 1980

Soil under District of Columbia

Expansive clay (limits slab homes)0.0%
High water table (limits basements)8.7%
Septic fields very limited43.4%
Clay swell (LEP, by area)2.1%
High-swell land (LEP 6%+)0.0%
Urban land, not rated35.5%
Mapped soil44,160 acres
Soil seriesShare hereSeries nationally: expansive clay
Manor6%n/a
Sassafras5%n/a
Christiana3%n/a
Chillum3%n/a
Muirkirk variant2%n/a
Brandywine2%n/a
Arlington County: 0%Alexandria city: 3%Falls Church city: 0%Prince George's County: 1%Fairfax County: 6%Fairfax city: 2%Montgomery County: 1%Howard County: 1%District of Columbia ArlingtonAlexandria cityFalls Church cityPrince George'sFairfaxFairfax cityMontgomeryHowardDistrict of Columbia
District of Columbia (heavy outline) and nearby counties, shaded by expansive clay share.under 10%10-25%25-40%40-60%60%+

How we count · survey areas DC001 (2025-09-09)

What the numbers mean here

Rain over the 12 months to August 2026: 32.49 in, 12.03 in below the 1991-2020 average year of 44.52 in.

With shrink-swell clay on 0% and a shallow water table on 9% of the land, the soil survey points to neither problem across most of District of Columbia; conditions still vary lot by lot.

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 33 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 worse100%
D1 moderate drought or worse0%
D2 severe or worse0%
D3 extreme or worse0%
D4 exceptional0%

Flood losses since 2016

230 flood losses since 2016, $2.0 million paid. The worst year was 2020, with 63. Foundations of the buildings, where recorded: 83% basements, 11% slabs, 2% crawl spaces, 5% elevated. Median water depth outside the building: 5.5 in.

YearFlood losses
201614
201727
201841
201923
202063
202118
202210
202312
20248
20255
2026 to date9

Rain

Average year, 1991-202044.52 in
12 months to August 202632.49 in (-12.03)
202536.23 in (-8.29)
Wettest year since 18952018: 67.32 in
Driest year since 18951930: 19.85 in
Days with 1 inch or more, normal at NATL ARBORETUM DC (3 mi away)11.4

Homes

Housing units361,014
Median year built1958
Built before 198069%
Built 2000 or later24%
Owner-occupied42%
Median value, owner-occupied$737,100
Single-family detached11%

What repairs cost

Published ranges from cost guides, not quotes. More sources, and where they disagree.

WorkRangeSource
Foundation repair, US $2,200 to $8,200 Fixr, January 27, 2026
Pier-and-beam repair, US $2,000 to $15,000 Fixr, January 27, 2026
Foundation inspection, US $300 to $600 Fixr, January 31, 2025

Nearby counties

PlaceDistanceExpansive clayHigh water table
Arlington County, VA 5 mi 0% 3%
Alexandria city, VA 7 mi 3% 44%
Falls Church city, VA 9 mi 0% 13%
Prince George's County, MD 10 mi 1% 46%
Fairfax County, VA 15 mi 6% 33%
Fairfax city, VA 16 mi 2% 10%
Montgomery County, MD 19 mi 1% 19%
Howard County, MD 25 mi 1% 24%

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