States / Texas
209 counties · median score 18
Crawl space moisture in Texas
Most of Texas drains well: only 22 of 209 counties score high or elevated, and the median is 18. Chambers County is the exception at 72; crawl-space moisture problems here usually come from grading, gutters and plumbing rather than the soil itself.
- 1Wettest county Chambers County
- 2High or elevated 22 of 209
- 3Median score 18
- 4Driest county Terry County
Texas's soil, taken as a whole
Across the 148,512,011 acres mapped in these 209 counties, 6% of soil with a drainage class is somewhat poorly, poorly or very poorly drained, and 12% of acres report a seasonal water table within about two metres. That is a dry figure; wet soils here are confined to river bottoms and wetlands. 204 of the 209 counties have mapped soils subject to occasional or frequent flooding.
| Drainage class | Share of mapped acres |
|---|---|
| Excessively drained | 0.7% |
| Somewhat excessively drained | 1.4% |
| Well drained | 75.9% |
| Moderately well drained | 16.3% |
| Somewhat poorly drained | 3.6% |
| Poorly drained | 1.7% |
| Very poorly drained | 0.3% |
| Subaqueous | 0.1% |
Radon. By EPA zone, 0 Texas counties here are zone 1 (highest potential), 39 zone 2 and 169 zone 3; 1 are not in the EPA table. EPA says to test regardless of zone; a sealed crawl space is the cheapest moment to add radon venting if a test calls for it.
Every Texas county
Sorted wettest first. High and elevated counties link to their own page with the full soil breakdown.
What drives the Texas numbers
The wettest county, Chambers County, is 56% somewhat poorly drained by dominant condition, with a seasonal water table averaging 2 ft below grade across the 92% of acres that report one, and sits in EPA radon zone 3. The driest, Terry County, is 98% well drained. 4 Texas counties reach the high tier, where poorly drained soils, group D clays and a shallow water table occur together.
The score is a guide to the soil, not to a house: a well-graded lot with working gutters in a high county can have a dry crawl space, and a bad downspout can flood one in a low county. The R408 calculator sizes venting or encapsulation for any footprint.
Sources: USDA NRCS SSURGO via Soil Data Access (muaggatt: drclassdcd, hydgrpdcd, flodfreqdcd, pondfreqprs, wtdepannmin), acreage-weighted; EPA Map of Radon Zones, county table (June 2024 JSON). Checked 2026-10-23.