Bexar County, Texas
Shrink-swell clay limits houses without basements on 51% of Bexar County's mapped land, a higher share than 91% of US counties. A shallow water table limits basements on under 1%.
60.7% of the county is in drought on the September 22, 2026 Drought Monitor map, up from 32.1% a week earlier. FEMA's flood data list 275 flood losses here since 2016, 2% of them in buildings with basements. 36% of homes were built before 1980, against 50% nationally; the median home dates from 1990.
Data as of September 22, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, September 22, 2026
of homes built before 1980
Soil under Bexar County
| Expansive clay (limits slab homes) | 50.8% |
| High water table (limits basements) | under 0.1% |
| Septic fields very limited | 85.4% |
| Clay swell (LEP, by area) | 6.6% |
| High-swell land (LEP 6%+) | 42.2% |
| Mapped soil | 804,601 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Eckrant | 15% | 8% |
| Houston Black | 10% | 91% |
| Lewisville | 8% | n/a |
| Brackett | 6% | 0% |
| Wilco | 6% | n/a |
| Branyon | 6% | 92% |
How we count · survey areas TX029 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 6.6% by land area here, and 42% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 51% of the mapped land.
Clay shrinks as it dries: 60.7% of the county is in drought on the latest map, and 51% of Bexar County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 29.13 in, 2.23 in below the 1991-2020 average year of 31.36 in.
USDA rates 85% of the land very limited for septic absorption fields.
Drought
60.7% of the county is in drought (D1 or worse) on the September 22, 2026 map. Part of the county was in drought in 52 of the last 52 weeks; the most was 100% of its area, in 36 weeks, most recently on the June 2, 2026 map.
| Category, September 22, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 60.7% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
275 flood losses since 2016, $3.9 million paid. The worst year was 2016, with 68. Foundations of the buildings, where recorded: 2% basements, 86% slabs, 8% crawl spaces, 4% elevated. Median water depth outside the building: 5 in.
| Year | Flood losses |
|---|---|
| 2016 | 68 |
| 2017 | 17 |
| 2018 | 42 |
| 2019 | 18 |
| 2020 | 5 |
| 2021 | 63 |
| 2022 | 3 |
| 2023 | 9 |
| 2024 | 9 |
| 2025 | 30 |
| 2026 to date | 11 |
Rain
| Average year, 1991-2020 | 31.36 in |
| 12 months to August 2026 | 29.13 in (-2.23) |
| 2025 | 20.96 in (-10.40) |
| Wettest year since 1895 | 1919: 51.42 in |
| Driest year since 1895 | 1954: 12.85 in |
| Days with 1 inch or more, normal at SAN ANTONIO INTL AP (7 mi away) | 9.4 |
Homes
| Housing units | 820,780 |
| Median year built | 1990 |
| Built before 1980 | 36% |
| Built 2000 or later | 39% |
| Owner-occupied | 59% |
| Median value, owner-occupied | $262,200 |
| Single-family detached | 64% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Bexar County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Alamo Heights | 43% | 0% | 3,701 |
| Balcones Heights | 52% | 0% | 1,552 |
| Castle Hills | 67% | 0% | 1,744 |
| China Grove | 60% | 0% | 463 |
| Converse | 85% | 0% | 10,676 |
| Elmendorf | 11% | under 1% | 826 |
| Grey Forest | 56% | 0% | 353 |
| Helotes | 53% | 0% | 3,100 |
| Hill Country Village | 71% | 0% | 299 |
| Hollywood Park | 52% | 0% | 1,408 |
| Kirby | 86% | 0% | 3,046 |
| Leon Valley | 64% | 0% | 5,110 |
| Live Oak | 46% | 0% | 6,955 |
| Olmos Park | 65% | 0% | 975 |
| San Antonio | 61% | under 1% | 612,901 |
| Sandy Oaks | 0% | 0% | 2,256 |
| Selma | 60% | 0% | 4,387 |
| Shavano Park | 54% | under 1% | 1,422 |
| Somerset | 10% | under 1% | 696 |
| St. Hedwig | 54% | under 1% | 791 |
| Terrell Hills | 74% | 0% | 1,962 |
| Universal City | 63% | 0% | 8,440 |
| Von Ormy | 43% | 0% | 431 |
| Windcrest | 81% | 0% | 2,505 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Comal County, TX | 30 mi | 19% | under 1% |
| Wilson County, TX | 32 mi | 36% | 2% |
| Guadalupe County, TX | 36 mi | 52% | 8% |
| Kendall County, TX | 36 mi | 23% | 0% |
| Medina County, TX | 36 mi | 33% | under 1% |
| Atascosa County, TX | 39 mi | 34% | under 1% |
| Bandera County, TX | 48 mi | 17% | 0% |
| Hays County, TX | 52 mi | 14% | under 1% |
Sources: USDA SSURGO (September 4, 2025) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status