HomeTexasBexar CountySan Antonio
San Antonio, Texas
Inside San Antonio's city limits, shrink-swell clay limits houses without basements on 61% of mapped land, higher than 66% of Texas cities. A shallow water table limits basements on under 1%.
That clay share is above Bexar County's 51%. FEMA's flood data list 235 flood losses since 2016 in the 50 ZIP codes overlapping the city. Of its 612,901 homes, 43% were built before 1980; the median dates from 1985.
Data as of November 3, 2026 · sources · in Bexar County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 50 overlapping ZIPs
of homes built before 1980
Foundation repair in San Antonio
Foundation repair in San Antonio: shrink-swell clay limits slab homes on 61% of San Antonio's mapped land, more than in 66% of Texas cities.
The city requires a permit for the work, and Today's Homeowner (February 25, 2025) puts the average job at $2,965.
About 359,800 of San Antonio's 612,901 homes are detached houses.
| City permit | Required. San Antonio requires a foundation repair permit before work starts and charges a double fee when work starts without one. (City of San Antonio, Development Services Department, read October 2, 2026) |
| Engineer | Repairs must be designed by, or done under the guidance of, a Texas-licensed engineer, who also inspects the work. (City of San Antonio, Development Services Department) |
| Contractor registration | The applicant must be the owner or a residential building contractor licensed by the city. (City of San Antonio, Development Services Department) |
| Drought watering rules | In San Antonio's Stage 3, soaker hoses follow the once-a-week watering day, while hand-held hose watering is allowed any time. (San Antonio Water System) |
| Prices | Today's Homeowner, February 25, 2025 · cost guide ranges compared |
Soil under San Antonio city limits
| Expansive clay (limits slab homes) | 60.6% |
| High water table (limits basements) | under 0.1% |
| Septic fields very limited | 83.1% |
| Clay swell (LEP, by area) | 7.5% |
| High-swell land (LEP 6%+) | 51.6% |
| Mapped soil | 328,254 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Eckrant | 16% | 8% |
| Houston Black | 14% | 91% |
| Lewisville | 13% | n/a |
| Branyon | 9% | 92% |
| Sunev | 5% | n/a |
| Austin | 4% | 93% |
What the numbers mean here
Clay swell averages a linear extensibility of 7.5% by land area here, and 52% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 61% of the mapped land.
Clay shrinks as it dries: 47.4% of Bexar County is in drought on the latest map, and 61% of San Antonio's mapped land has shrink-swell clay.
USDA rates 83% of the land very limited for septic absorption fields.
San Antonio covers 506.7 square miles of land and counts 612,901 housing units, about 1,210 per square mile.
52% of San Antonio's occupied homes are owner-occupied, and the median owner-occupied home is valued at $235,700; 31% of all homes in the city date from 2000 or later.
The largest soil series under San Antonio is Eckrant, on 16% of the mapped land, followed by Houston Black at 14%.
USDA's soil survey maps 328,254 acres inside San Antonio's city limits.
Drought in Bexar County
47.4% of Bexar County is in drought (D1 or worse) on the November 3, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap San Antonio. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78023 | 5% | 8 | $255,650 |
| 78223 | 4% | 2 | $7,160 |
| 78221 | 3% | 10 | $6,906 |
| 78258 | 3% | 6 | $111,585 |
| 78224 | 3% | 4 | $15,305 |
| 78251 | 3% | 4 | $19,443 |
| 78247 | 3% | 3 | $20,071 |
| 78259 | 3% | 12 | $120,019 |
| 78216 | 3% | 7 | $43,890 |
| 78249 | 3% | 2 | $15,782 |
| 78219 | 3% | 10 | $25,047 |
| 78222 | 3% | 2 | $51,613 |
| 78227 | 3% | 4 | $37,068 |
| 78257 | 2% | 0 | $0 |
| 78218 | 2% | 3 | $71,640 |
| 78228 | 2% | 13 | $100,201 |
| 78211 | 2% | 3 | $191,667 |
| 78217 | 2% | 4 | $21,025 |
| 78230 | 2% | 9 | $5,804 |
| 78240 | 2% | 8 | $97,841 |
| 78250 | 2% | 16 | $501,744 |
| 78233 | 2% | 9 | $249,318 |
| 78214 | 2% | 2 | $3,133 |
| 78232 | 2% | 7 | $96,982 |
| 78238 | 2% | 11 | $251,324 |
| 78242 | 2% | 2 | $21,105 |
| 78207 | 2% | 2 | $0 |
| 78210 | 2% | 2 | $0 |
| 78220 | 1% | 0 | $0 |
| 78237 | 1% | 5 | $7,643 |
| 78256 | 1% | 2 | $8,753 |
| 78201 | 1% | 11 | $127,629 |
| 78209 | 1% | 12 | $35,941 |
| 78212 | 1% | 13 | $111,841 |
| 78229 | 1% | 2 | $33,075 |
| 78254 | 1% | 3 | $96,560 |
| 78213 | 1% | 7 | $76,921 |
| 78226 | 1% | 0 | $0 |
| 78234 | 1% | 0 | $0 |
| 78248 | 1% | 2 | $0 |
| 78244 | 1% | 1 | $0 |
| 78202 | 1% | 2 | $0 |
| 78204 | 1% | 0 | $0 |
| 78225 | under 1% | 1 | $1,793 |
| 78235 | under 1% | 0 | $0 |
| 78203 | under 1% | 0 | $0 |
| 78231 | under 1% | 3 | $19,262 |
| 78205 | under 1% | 5 | $92,653 |
| 78208 | under 1% | 0 | $0 |
| 78215 | under 1% | 1 | $78,300 |
Homes in San Antonio
| Housing units | 612,901 |
| Median year built | 1985 |
| Built before 1980 | 43% |
| Built 2000 or later | 31% |
| Owner-occupied | 52% |
| Median value, owner-occupied | $235,700 |
| Single-family detached | 59% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Olmos Park | 2 mi | 65% | 0% |
| Balcones Heights | 3 mi | 52% | 0% |
| Alamo Heights | 4 mi | 43% | 0% |
| Castle Hills | 4 mi | 67% | 0% |
| Terrell Hills | 5 mi | 74% | 0% |
| Leon Valley | 6 mi | 64% | 0% |
| Kirby | 8 mi | 86% | 0% |
| Hill Country Village | 9 mi | 71% | 0% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (November 3, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status