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Castroville, Texas
Inside Castroville's city limits, shrink-swell clay limits houses without basements on 60% of mapped land, the 3rd-highest of 5 cities in Medina County. A shallow water table limits basements on under 1%.
That clay share is above Medina County's 33%. FEMA's flood data list 8 flood losses since 2016 in ZIP code 78009 overlapping the city. Of its 1,310 homes, 44% were built before 1980; the median dates from 1984.
Data as of October 13, 2026 · sources · in Medina County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 1 overlapping ZIP
of homes built before 1980
Foundation repair in Castroville
Foundation repair in Castroville: shrink-swell clay limits slab homes on 60% of Castroville's mapped land, more than in 65% of Texas cities.
About 1,100 of Castroville's 1,310 homes are detached houses.
| Who designs the repair | The ASCE Texas Section's repair guidelines say a Texas-licensed engineer should evaluate the foundation and design the repair (2022 guidelines) |
| Prices | Cost guide ranges compared |
Soil under Castroville city limits
| Expansive clay (limits slab homes) | 59.7% |
| High water table (limits basements) | 0.2% |
| Septic fields very limited | 67.0% |
| Clay swell (LEP, by area) | 7.8% |
| High-swell land (LEP 6%+) | 59.7% |
| Mapped soil | 2,306 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Knippa | 33% | n/a |
| Divot | 9% | n/a |
| Sabenyo | 7% | n/a |
| Atco | 7% | n/a |
| Monteola | 6% | n/a |
| Kincheloe | 5% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 7.8% by land area here, and 60% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 60% of the mapped land.
Clay shrinks as it dries: 95.8% of Medina County is in drought on the latest map, and 60% of Castroville's mapped land has shrink-swell clay.
USDA rates 67% of the land very limited for septic absorption fields.
Drought in Medina County
95.8% of Medina County is in drought (D1 or worse) on the October 13, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap Castroville. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78009 | 100% | 8 | $149,219 |
Homes in Castroville
| Housing units | 1,310 |
| Median year built | 1984 |
| Built before 1980 | 44% |
| Built 2000 or later | 21% |
| Owner-occupied | 73% |
| Median value, owner-occupied | $300,000 |
| Single-family detached | 82% |
Nearby cities
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status