Loudoun County, Virginia
A shallow water table limits basements on 31% of Loudoun County's mapped land, a higher share than 50% of US counties. Shrink-swell clay limits houses without basements on 8%.
None of the county is in drought on the October 13, 2026 Drought Monitor map, after 36.6% a week earlier. FEMA's flood data list 30 flood losses here since 2016. 13% of homes were built before 1980, against 50% nationally; the median home dates from 2002.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Loudoun County
| Expansive clay (limits slab homes) | 8.0% |
| High water table (limits basements) | 31.1% |
| Septic fields very limited | 88.4% |
| Clay swell (LEP, by area) | 3.0% |
| High-swell land (LEP 6%+) | 13.3% |
| Mapped soil | 334,045 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Purcellville | 15% | n/a |
| Catoctin | 7% | n/a |
| Tankerville | 7% | n/a |
| Eubanks | 6% | n/a |
| Middleburg | 5% | n/a |
| Albano | 3% | n/a |
How we count · survey areas VA107 (2025-09-04)
What the numbers mean here
On 31% of Loudoun 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: 31.00 in, 11.48 in below the 1991-2020 average year of 42.48 in.
USDA rates 88% 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 51 of the last 52 weeks; the most was 100% of its area, in 38 weeks, most recently on the August 4, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 86.4% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
30 flood losses since 2016, $89,804 paid. The worst year was 2018, with 14.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 1 |
| 2018 | 14 |
| 2019 | 2 |
| 2020 | 5 |
| 2021 | 1 |
| 2022 | 4 |
| 2023 | 2 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 42.48 in |
| 12 months to August 2026 | 31.00 in (-11.48) |
| 2025 | 31.37 in (-11.11) |
| Wettest year since 1895 | 2018: 62.05 in |
| Driest year since 1895 | 1930: 20.43 in |
| Days with 1 inch or more, normal at WFO STERLING (11 mi away) | 11.5 |
Homes
| Housing units | 147,003 |
| Median year built | 2002 |
| Built before 1980 | 13% |
| Built 2000 or later | 57% |
| Owner-occupied | 78% |
| Median value, owner-occupied | $743,800 |
| Single-family detached | 51% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Clarke County, VA | 19 mi | 31% | 15% |
| Jefferson County, WV | 20 mi | 37% | 14% |
| Montgomery County, MD | 24 mi | 1% | 19% |
| Manassas Park city, VA | 24 mi | 0% | 16% |
| Fairfax city, VA | 24 mi | 2% | 10% |
| Manassas city, VA | 25 mi | 0% | 26% |
| Fauquier County, VA | 25 mi | 6% | 28% |
| Fairfax County, VA | 26 mi | 6% | 33% |
Sources: USDA SSURGO (September 4, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status