County soil summary
Soil types in Cobb County, Georgia
The most widespread soils are Madison, Gwinnett and Appling; the most common drainage class is well drained (80% of the land), and typical topsoil pH is 5.5.
- Well or moderately well drained
- 89% of land · state 69%
- Typical topsoil pH
- 5.5 strongly acidic · state 5.3
- Septic fields very limited
- 33% of land · state 68%
- Subject to flooding
- 11% of land, any frequency · state 19%
Most common soils in Cobb County
Share of mapped land
A county is a patchwork of many soils. These 8 cover 82% of the mapped land; 18 named soil series are mapped here in all.
| Soil | Share of land | Drainage | Topsoil pH |
|---|---|---|---|
| Madison | 26.0% | Well drained | 5.5 |
| Gwinnett | 18.2% | Well drained | 5.8 |
| Appling | 10.6% | Well drained | 5.5 |
| Pacolet | 8.0% | Well drained | 5.5 |
| Cecil | 6.4% | Well drained | 5.5 |
| Cartecay | 4.3% | Somewhat poorly drained | 5.8 |
| Toccoa | 4.1% | Moderately well drained | 5.8 |
| Urban landLand type, not a soil series | 4.0% | — | — |
What this means
What the soils in Cobb County mean for gardens, lawns and septic systems
For your garden
Typical topsoil in Cobb County is strongly acidic: pH 5.5 (most land between 5.5 and 5.8). Most vegetables and lawn grasses do best around 6.0 to 7.0, so lime is often needed; blueberries, azaleas and rhododendrons like it as it is.
Loamy topsoil (loam, silt loam and similar) covers 95% of the land: generally the easiest soil to garden, holding moisture without staying waterlogged. The most common surface texture is sandy loam (41% of the land).
89% of the land is moderately well to excessively drained, which suits most garden plants.
For your lawn and yard
Most land is in hydrologic groups B and C, where rain soaks in at a moderate pace.
For a septic system
For conventional septic absorption fields, NRCS rates 33% of the land in Cobb County very limited, 62% somewhat limited and 0% not limited (5% not rated, such as urban land, pits or water).
Statewide, 68% of the land is very limited, so Cobb County is less restrictive than typical.
Flooding is mapped on 11% of the land (6% occasional, 5% frequent).
Only a licensed site evaluation or perc test at the actual lot decides whether a system is allowed and which design.
Drainage
How long the soil stays wet
The most common drainage class is well drained (80%). 89% of the land is moderately well drained or better, compared with 69% across Georgia.
Show as a table
| Category | Cobb County | Georgia |
|---|---|---|
| Excessively drained | 0.0% | 2.1% |
| Somewhat excessively drained | 3.4% | 3.0% |
| Well drained | 79.7% | 58.8% |
| Moderately well drained | 5.8% | 4.7% |
| Somewhat poorly drained | 5.3% | 7.4% |
| Poorly drained | 0.8% | 16.5% |
| Very poorly drained | 0.0% | 5.9% |
| Not rated | 5.0% | 1.5% |
Septic absorption fields
NRCS rating for conventional drain fields
The rating looks at the soil from 24 to 60 inches deep: permeability, depth to a seasonal water table or bedrock, flooding and slope. “Very limited” means at least one feature is unfavorable enough that a conventional field is hard to make work.
Show as a table
| Category | Cobb County | Georgia |
|---|---|---|
| Not limited | 0.0% | 0.3% |
| Somewhat limited | 62.1% | 30.3% |
| Very limited | 33.0% | 68.0% |
| Not rated | 4.8% | 1.5% |
Rain, runoff and water table
Hydrologic soil group, flooding, seasonal water table
Hydrologic soil group
How fast rain soaks in when the soil is already wet. Group A soaks in fastest, D slowest.
Show as a table
| Category | Cobb County | Georgia |
|---|---|---|
| A: fast infiltration (mostly sandy or gravelly) | 4.3% | 10.5% |
| B: moderate infiltration | 74.5% | 44.5% |
| C: slow infiltration | 1.5% | 10.9% |
| D: very slow infiltration (clayey, shallow or wet) | 8.5% | 6.8% |
| A/D: D as is, A if drained | 5.0% | 7.4% |
| B/D: D as is, B if drained | 0.3% | 12.4% |
| C/D: D as is, C if drained | 0.8% | 5.9% |
| Not rated | 5.0% | 1.5% |
Flooding
Show as a table
| Category | Cobb County | Georgia |
|---|---|---|
| No flooding | 88.1% | 80.5% |
| Rare or very rare | 0.0% | 1.2% |
| Occasional | 5.6% | 4.7% |
| Frequent or very frequent | 5.4% | 12.7% |
| Not reported | 0.9% | 0.9% |
Seasonal high water table
Show as a table
| Category | Cobb County | Georgia |
|---|---|---|
| Within 18 inches at some time of year | 6.1% | 25.4% |
| 18 inches to 3.3 feet | 1.7% | 8.6% |
| Deeper than 3.3 feet or none reported | 92.2% | 65.6% |
| Not reported | 0.0% | 0.4% |
Topsoil pH and texture
First mineral layer of each soil
Typical topsoil pH is 5.5 (strongly acidic); 80% of rated land falls between 5.5 and 5.8. Median topsoil organic matter is 1.2%.
Show as a table
| Category | Cobb County | Georgia |
|---|---|---|
| Strongly acidic (below 5.5) | 7.5% | 56.5% |
| Moderately to slightly acidic (5.5–6.4) | 87.5% | 40.7% |
| Near neutral (6.5–7.3) | 0.0% | 1.2% |
| Alkaline (7.4 and up) | 0.0% | 0.0% |
| Not reported | 5.0% | 1.6% |
Texture
Show as a table
| Category | Cobb County | Georgia |
|---|---|---|
| Sandy | 0.0% | 42.8% |
| Loamy (loam, silt loam and similar) | 95.0% | 53.7% |
| Clayey (40%+ clay) | 0.0% | 1.0% |
| Organic (muck or peat) | 0.0% | 1.0% |
| Not reported (rock, urban land, etc.) | 5.0% | 1.5% |
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- Cobb County, Georgia (FIPS 13067): 216,449 acres of mapped land, 3,300 acres of open water excluded. State comparisons pool all mapped land in Georgia.
- Method
- Shares are by mapped land area: each map unit’s acres in the county times each soil component’s percentage. Open water is excluded. Topsoil values use the first mineral horizon of each component. Full methodology.