HomeSoil by ZIP code
Soil and water table by ZIP code
Enter a ZIP code to see its county's soil, and its city's in Texas and Ohio: the share of land where shrink-swell clay limits slab homes, the share where a shallow water table limits basements, the most common soil series, the latest drought map and FEMA flood losses in the ZIP since 2016. It reports shares of land, not a water-table depth in feet.
Of the 33,354 US ZIP code areas, 2,549 sit in counties where shrink-swell clay limits slab homes on more than half the mapped land, and 11,769 in counties where a shallow water table limits basements on more than half.
Example result
ZIP 78209 · Bexar County, TX · San Antonio
expansive clay: shrink-swell limits slab homes (county)
high water table: limits basements (county)
of the county in drought (D1 or worse), October 13, 2026
NFIP flood losses since 2016 in ZIP 78209 (insured buildings)
Shrink-swell clay limits slab homes on 51% of Bexar County's mapped land, and a shallow water table limits basements on under 1%. These are county shares from USDA's soil survey; the soil under one lot can differ.
Inside San Antonio city limits (66% of this ZIP's land): shrink-swell clay on 61% of mapped land, a shallow water table on under 1%.
Most common soil series in Bexar County: Eckrant (15%), Houston Black (10%), Lewisville (8%).
36% of the county's homes were built before 1980. FEMA's flood data list 275 flood losses across the county since 2016.
Examples
| ZIP | County | Expansive clay (county) | High water table (county) | Flood losses in ZIP |
|---|---|---|---|---|
| 77002 | Harris County, TX | 25% | 53% | 81 |
| 78209 | Bexar County, TX | 51% | under 1% | 12 |
| 75201 | Dallas County, TX | 51% | 6% | 0 |
| 78701 | Travis County, TX | 39% | under 1% | 1 |
| 76102 | Tarrant County, TX | 41% | 4% | 0 |
| 43215 | Franklin County, OH | 12% | 71% | 1 |
| 44113 | Cuyahoga County, OH | 1% | 51% | 1 |
| 45202 | Hamilton County, OH | 7% | 9% | 24 |
| 60601 | Cook County, IL | 25% | 59% | 0 |
| 10001 | New York County, NY | 0% | 2% | 0 |
| 90012 | Los Angeles County, CA | 4% | under 1% | 0 |
| 33130 | Miami-Dade County, FL | 1% | 55% | 44 |
How the lookup works
A ZIP code here is the Census Bureau's 2020 ZIP Code Tabulation Area. Each one is matched to the county that holds most of its land, and in Texas and Ohio to the city that covers at least a quarter of it (Census 2020 relationship files). The soil shares are that county's and city's, measured by us from USDA's SSURGO soil survey (August 5, 2026) on county and city boundaries, not on the ZIP itself. Drought is the county's share in D1 or worse on the October 13, 2026 US Drought Monitor map. Flood losses are FEMA NFIP records since 2016 filed under the ZIP (September 9, 2026); they cover insured buildings only, so 0 means no NFIP records, not no flooding.
The expansive clay share is the land where USDA's "Dwellings without basements" rating lists shrink-swell as a limit; the high water table share is the land where its "Dwellings with basements" rating lists a saturated zone about 2.5 to 6 feet down. Full method and sources.
How deep is the water table in my ZIP code?
This lookup doesn't give a depth in feet. It gives the share of the surrounding county's land where USDA's soil survey records a saturated zone within about 6 feet of the surface for part of the year, which is basement depth. A depth for one lot comes from USDA's Web Soil Survey map, nearby well records or a soil boring.
What type of soil is in my ZIP code?
The result names the county's three most common soil series and the share of mapped land each covers, with a link to each one we have a page for. The series can change from one lot to the next, so a series name is a starting point, not a site report.
Not sure what the numbers mean? Read what soil is my house built on and how to tell if your house is on expansive clay. Compared with other lookups: best websites to look up the soil under a house, Foundation Soils vs Web Soil Survey, water table lookups.
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024 · Census 2020 ZCTA relationship files. Methods