Hydrologic Soil Groups

Hydrologic Soil Groups Definition




Soils are categorized according to how quickly water infiltrates or drains through the soil. The Table below defines the characteristics of the Hydrological Soil Groups A,B,C, and D and B/C.

Hydrologic Soil GroupDescription
A High infiltration rates. Soils are deep, well drained to excessively drained sand and gravels.
B Moderate infiltration rates. Deep and moderately deep, moderately well and well-drained soils with moderately coarse textures.
C Moderate to slow infiltration rates. Soils with layers impeding downward movement of water or soils with moderately fine or fine textures.
D Very slow infiltration rates. Soils are clayey, have high water table, or shallow to an impervious cover.
B/C Combination of Soil Group B and C