Cobb County, Georgia
USDA's soil survey flags shrink-swell clay on 1% of Cobb County's mapped land and a shallow water table under basements on 12%, both below the national shares of 15% and 29%. None of the county is in drought on the October 13, 2026 Drought Monitor map.
FEMA's flood data list 335 flood losses here since 2016, 11% of them in buildings with basements. 27% of homes were built before 1980, against 50% nationally; the median home dates from 1990.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Cobb County
| Expansive clay (limits slab homes) | 0.5% |
| High water table (limits basements) | 11.7% |
| Septic fields very limited | 32.5% |
| Clay swell (LEP, by area) | 1.6% |
| High-swell land (LEP 6%+) | 0.5% |
| Urban land, not rated | 3.9% |
| Mapped soil | 220,700 acres |
How we count · survey areas GA067 (2025-09-02)
What the numbers mean here
Rain over the 12 months to August 2026: 39.10 in, 13.33 in below the 1991-2020 average year of 52.43 in.
With shrink-swell clay on 1% and a shallow water table on 12% of the land, the soil survey points to neither problem across most of Cobb County; conditions still vary lot by lot.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 39 of the last 52 weeks; the most was 100% of its area, in 35 weeks, most recently on the July 14, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
335 flood losses since 2016, $9.7 million paid. The worst year was 2021, with 126. Foundations of the buildings, where recorded: 11% basements, 27% slabs, 25% crawl spaces, 38% elevated. Median water depth outside the building: 16 in.
| Year | Flood losses |
|---|---|
| 2016 | 8 |
| 2017 | 11 |
| 2018 | 14 |
| 2019 | 10 |
| 2020 | 37 |
| 2021 | 126 |
| 2022 | 4 |
| 2023 | 43 |
| 2024 | 62 |
| 2025 | 8 |
| 2026 to date | 12 |
Rain
| Average year, 1991-2020 | 52.43 in |
| 12 months to August 2026 | 39.10 in (-13.33) |
| 2025 | 43.64 in (-8.79) |
| Wettest year since 1895 | 2009: 73.05 in |
| Driest year since 1895 | 2007: 30.55 in |
| Days with 1 inch or more, normal at DALLAS 7 NE (11 mi away) | 16.1 |
Homes
| Housing units | 314,104 |
| Median year built | 1990 |
| Built before 1980 | 27% |
| Built 2000 or later | 31% |
| Owner-occupied | 67% |
| Median value, owner-occupied | $407,200 |
| Single-family detached | 65% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Fulton County, GA | 12 mi | under 1% | 11% |
| Paulding County, GA | 17 mi | under 1% | 8% |
| Douglas County, GA | 20 mi | under 1% | 10% |
| Cherokee County, GA | 22 mi | under 1% | 8% |
| DeKalb County, GA | 23 mi | under 1% | 9% |
| Bartow County, GA | 26 mi | 0% | 18% |
| Clayton County, GA | 28 mi | 0% | 12% |
| Gwinnett County, GA | 32 mi | under 1% | 16% |
Sources: USDA SSURGO (September 2, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status