Union County, Tennessee
USDA's soil survey flags shrink-swell clay on under 1% of Union County's mapped land and a shallow water table under basements on 5%, 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 5 flood losses here since 2016. 32% of homes were built before 1980, against 50% nationally; the median home dates from 1993.
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 Union County
| Expansive clay (limits slab homes) | 0.4% |
| High water table (limits basements) | 4.7% |
| Septic fields very limited | 79.8% |
| Clay swell (LEP, by area) | 3.2% |
| High-swell land (LEP 6%+) | 0.4% |
| Mapped soil | 158,200 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Clarksville | 21% | under 1% |
| Fullerton | 19% | 0% |
| Berks | 9% | 0% |
| Talbott | 6% | n/a |
| Weikert | 5% | 0% |
| Montevallo | 4% | n/a |
How we count · survey areas TN173 (2025-08-29)
What the numbers mean here
Rain over the 12 months to August 2026: 49.59 in, 3.63 in below the 1991-2020 average year of 53.22 in.
USDA rates 80% of the land very limited for septic absorption fields.
With shrink-swell clay on under 1% and a shallow water table on 5% of the land, the soil survey points to neither problem across most of Union County; 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 22 of the last 52 weeks; the most was 100% of its area, in 7 weeks, most recently on the May 26, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 21.3% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
5 flood losses since 2016, $115,461 paid. The worst year was 2026, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 1 |
| 2021 | 0 |
| 2022 | 1 |
| 2023 | 1 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 1 |
Rain
| Average year, 1991-2020 | 53.22 in |
| 12 months to August 2026 | 49.59 in (-3.63) |
| 2025 | 50.05 in (-3.17) |
| Wettest year since 1895 | 2019: 67.71 in |
| Driest year since 1895 | 2007: 35.95 in |
| Days with 1 inch or more, normal at NORRIS (13 mi away) | 16 |
Homes
| Housing units | 9,831 |
| Median year built | 1993 |
| Built before 1980 | 32% |
| Built 2000 or later | 36% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $204,000 |
| Single-family detached | 73% |
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 |
|---|---|---|---|
| Claiborne County, TN | 18 mi | under 1% | 3% |
| Grainger County, TN | 18 mi | 2% | 3% |
| Campbell County, TN | 20 mi | 0% | 2% |
| Knox County, TN | 21 mi | 0% | 8% |
| Anderson County, TN | 23 mi | 2% | 7% |
| Jefferson County, TN | 27 mi | 0% | 5% |
| Bell County, KY | 32 mi | 0% | 1% |
| Hamblen County, TN | 32 mi | 4% | 7% |
Sources: USDA SSURGO (August 29, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status