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Tomball, Texas
Inside Tomball's city limits, shrink-swell clay limits houses without basements on 1% of mapped land. A shallow water table limits basements on 41%.
That clay share is below Harris County's 25%. USDA doesn't rate the 28% of mapped land classed as urban land, so these shares are floors. FEMA's flood data list 564 flood losses since 2016 in the 2 ZIP codes overlapping the city. Of its 5,565 homes, 23% were built before 1980; the median dates from 1994.
Data as of October 13, 2026 · sources · in Harris County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 2 overlapping ZIPs
of homes built before 1980
Foundation repair in Tomball
Foundation repair in Tomball: shrink-swell clay limits slab homes on 1% of Tomball's mapped land.
About 3,200 of Tomball's 5,565 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 Tomball city limits
| Expansive clay (limits slab homes) | 0.7% |
| High water table (limits basements) | 41.3% |
| Septic fields very limited | 82.6% |
| Clay swell (LEP, by area) | 1.9% |
| High-swell land (LEP 6%+) | 0.9% |
| Urban land, not rated | 28.3% |
| Mapped soil | 8,456 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Wockley | 33% | n/a |
| Kenney | 9% | n/a |
| Segno | 7% | n/a |
| Hockley | 6% | n/a |
| Clodine | 3% | n/a |
| Tomball | 1% | n/a |
What the numbers mean here
On 41% of Tomball's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 83% of the land very limited for septic absorption fields.
Drought in Harris County
82.9% of Harris 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 Tomball. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 77375 | 89% | 396 | $44.3 million |
| 77377 | 12% | 168 | $10.8 million |
Homes in Tomball
| Housing units | 5,565 |
| Median year built | 1994 |
| Built before 1980 | 23% |
| Built 2000 or later | 41% |
| Owner-occupied | 52% |
| Median value, owner-occupied | $364,300 |
| Single-family detached | 58% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Stagecoach | 6 mi | 11% | 75% |
| Magnolia | 11 mi | 2% | 75% |
| Oak Ridge North | 11 mi | 0% | 42% |
| Shenandoah | 12 mi | 0% | 48% |
| Jersey Village | 14 mi | 0% | 56% |
| Woodloch | 15 mi | 7% | 38% |
| Todd Mission | 17 mi | 0% | 94% |
| Conroe | 18 mi | 10% | 64% |
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