Harris County, Texas
Shrink-swell clay limits houses without basements on 25% of Harris County's mapped land, a higher share than 76% of US counties. A shallow water table limits basements on 53%.
16.5% of the county is in drought on the September 22, 2026 Drought Monitor map. FEMA's flood data list 66,161 flood losses here since 2016, 1% of them in buildings with basements. 37% of homes were built before 1980, against 50% nationally; the median home dates from 1988.
Data as of September 22, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, September 22, 2026
of homes built before 1980
Soil under Harris County
| Expansive clay (limits slab homes) | 25.5% |
| High water table (limits basements) | 53.4% |
| Septic fields very limited | 79.2% |
| Clay swell (LEP, by area) | 5.9% |
| High-swell land (LEP 6%+) | 28.4% |
| Urban land, not rated | 20.1% |
| Mapped soil | 1,137,350 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Lake Charles | 8% | 97% |
| Bernard | 7% | 43% |
| Clodine | 6% | n/a |
| Katy | 6% | 0% |
| Wockley | 5% | n/a |
| Cyfair | 4% | n/a |
How we count · survey areas TX201 (2025-09-04)
What the numbers mean here
Clay swell averages a linear extensibility of 5.9% by land area here, and 28% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 25% of the mapped land.
Clay shrinks as it dries: 16.5% of the county is in drought on the latest map, and 25% of Harris County's mapped land has shrink-swell clay.
On 53% of Harris County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 40.46 in, 13.00 in below the 1991-2020 average year of 53.46 in.
USDA rates 79% of the land very limited for septic absorption fields.
Drought
16.5% of the county is in drought (D1 or worse) on the September 22, 2026 map. Part of the county was in drought in 33 of the last 52 weeks; the most was 100% of its area, in 10 weeks, most recently on the April 7, 2026 map.
| Category, September 22, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 16.5% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
66,161 flood losses since 2016, $6.13 billion paid. The worst year was 2017, with 49,788. Foundations of the buildings, where recorded: 1% basements, 92% slabs, 3% crawl spaces, 5% elevated. Median water depth outside the building: 15 in.
| Year | Flood losses |
|---|---|
| 2016 | 8,157 |
| 2017 | 49,788 |
| 2018 | 259 |
| 2019 | 4,773 |
| 2020 | 348 |
| 2021 | 573 |
| 2022 | 187 |
| 2023 | 187 |
| 2024 | 1,745 |
| 2025 | 63 |
| 2026 to date | 81 |
Rain
| Average year, 1991-2020 | 53.46 in |
| 12 months to August 2026 | 40.46 in (-13.00) |
| 2025 | 39.76 in (-13.70) |
| Wettest year since 1895 | 2017: 77.34 in |
| Driest year since 1895 | 1917: 21.69 in |
| Days with 1 inch or more, normal at HOUSTON NORTH HOUSTON (8 mi away) | 16.8 |
Homes
| Housing units | 1,917,790 |
| Median year built | 1988 |
| Built before 1980 | 37% |
| Built 2000 or later | 37% |
| Owner-occupied | 55% |
| Median value, owner-occupied | $276,600 |
| Single-family detached | 56% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Cities in Harris County
| City | Expansive clay | High water table | Homes |
|---|---|---|---|
| Baytown | 61% | 59% | 34,125 |
| Bellaire | 56% | 28% | 6,641 |
| Bunker Hill Village | 9% | 54% | 1,198 |
| Deer Park | 58% | 74% | 12,895 |
| El Lago | 47% | 41% | 1,268 |
| Galena Park | 67% | 59% | 3,367 |
| Hedwig Village | 0% | 55% | 1,073 |
| Hilshire Village | 27% | 56% | 388 |
| Houston | 29% | 48% | 1,040,576 |
| Humble | 9% | 68% | 6,428 |
| Hunters Creek Village | 24% | 49% | 1,642 |
| Jacinto City | 55% | 23% | 3,340 |
| Jersey Village | 0% | 56% | 3,828 |
| La Porte | 74% | 39% | 13,791 |
| Morgan's Point | 36% | 23% | 106 |
| Nassau Bay | 31% | 30% | 2,939 |
| Pasadena | 53% | 37% | 53,756 |
| Piney Point Village | 20% | 54% | 1,191 |
| Seabrook | 13% | 15% | 6,436 |
| Shoreacres | 68% | 39% | 614 |
| South Houston | 53% | 6% | 5,487 |
| Southside Place | 63% | 57% | 767 |
| Spring Valley Village | 0% | 56% | 1,381 |
| Taylor Lake Village | 41% | 41% | 1,491 |
| Tomball | 1% | 41% | 5,565 |
| Webster | 56% | 26% | 6,641 |
| West University Place | 56% | 48% | 5,362 |
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Montgomery County, TX | 31 mi | 15% | 65% |
| Fort Bend County, TX | 32 mi | 64% | 42% |
| Waller County, TX | 37 mi | 24% | 40% |
| Liberty County, TX | 39 mi | 46% | 76% |
| Chambers County, TX | 45 mi | 63% | 68% |
| Brazoria County, TX | 48 mi | 64% | 44% |
| San Jacinto County, TX | 51 mi | 16% | 42% |
| Austin County, TX | 53 mi | 38% | 20% |
Sources: USDA SSURGO (September 4, 2025) · US Drought Monitor (September 22, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status