Geologic and hydrologic parameters which relate to ground water contamination are discussed. Geologic factors include nature of soils, unconsolidated materials, and consolidated sediments. Hydrologic factors are infiltration, permeability, flow in the unsaturated and saturated zones, and attenuation through mixing. Physical conditions required for liquid waste disposal are discussed; geologic considerations (nature of earth materials and structural features), hydrologic considerations (water-table depth and relation to flow systems), surface conditions (topography, cover crop, climate, and acreage), cultural considerations (distance to buildings, wells, streams, and man-induced changes in the land), and long-range effects on the soil. A case-study of feasibility of liquid waste disposal for the seven county region of southeastern Wisconsin is described. The geography, climate, geology, soils, and ground water of the area are discussed. Maps of physiographic features surficial deposits, drift thickness, bedrock geology, and soils are shown. (Author)