Gwinnett County, Georgia
A shallow water table limits basements on 16% of Gwinnett County's mapped land. Shrink-swell clay limits houses without basements on under 1%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 99 flood losses here since 2016, 9% of them in buildings with basements. 14% of homes were built before 1980, against 50% nationally; the median home dates from 1996.
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 Gwinnett County
| Expansive clay (limits slab homes) | 0.1% |
| High water table (limits basements) | 15.8% |
| Septic fields very limited | 44.8% |
| Clay swell (LEP, by area) | 1.9% |
| High-swell land (LEP 6%+) | 0.1% |
| Mapped soil | 279,400 acres |
How we count · survey areas GA135 (2025-09-02)
What the numbers mean here
On 16% of Gwinnett 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: 39.32 in, 13.76 in below the 1991-2020 average year of 53.08 in.
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 40 of the last 52 weeks; the most was 100% of its area, in 26 weeks, most recently on the June 16, 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
99 flood losses since 2016, $1.8 million paid. The worst year was 2020, with 30. Foundations of the buildings, where recorded: 9% basements, 36% slabs, 17% crawl spaces, 39% elevated. Median water depth outside the building: 12 in.
| Year | Flood losses |
|---|---|
| 2016 | 2 |
| 2017 | 11 |
| 2018 | 10 |
| 2019 | 6 |
| 2020 | 30 |
| 2021 | 4 |
| 2022 | 4 |
| 2023 | 17 |
| 2024 | 13 |
| 2025 | 2 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 53.08 in |
| 12 months to August 2026 | 39.32 in (-13.76) |
| 2025 | 48.28 in (-4.80) |
| Wettest year since 1895 | 1929: 76.41 in |
| Driest year since 1895 | 1904: 32.36 in |
| Days with 1 inch or more, normal at CUMMING 2N (20 mi away) | 17.5 |
Homes
| Housing units | 340,962 |
| Median year built | 1996 |
| Built before 1980 | 14% |
| Built 2000 or later | 41% |
| Owner-occupied | 66% |
| Median value, owner-occupied | $380,900 |
| Single-family detached | 71% |
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 |
|---|---|---|---|
| DeKalb County, GA | 17 mi | under 1% | 9% |
| Barrow County, GA | 18 mi | 0% | 8% |
| Forsyth County, GA | 19 mi | under 1% | 8% |
| Walton County, GA | 21 mi | 1% | 12% |
| Rockdale County, GA | 21 mi | 0% | 9% |
| Hall County, GA | 27 mi | 0% | 5% |
| Fulton County, GA | 28 mi | under 1% | 11% |
| Jackson County, GA | 29 mi | 0% | 10% |
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