Ramifications of contamination are increasingly involved in the majority of ground‐water problems. The volume of usable ground water is shrinking in many places because of dispersion of contaminated water. Consideration of ground‐water contamination as a multitude of independent problems, separately solvable as each problem arises, is outmoded; wise policies, relating water supply to contamination potential, are needed to alleviate and to forestall problems. Methodology of managing contamination problems calls for appropriate classification of the hydrogeologic environment; these classifications include aspects of interdependent factors such as permeability, sorption, hydraulic gradient, position of water table relative to some base, and distance from source of contamination. Effective evaluations relate the dynamics of the hydrogeologic environment to contingencies involving contamination, as man changes his water‐development and waste‐disposal practices. Ways of contamination and pertinent parts of the physical environment include: waste‐disposal practices (at or near land surface and in deep formations), artificial recharge (at land surface and in aquifers), accidents, and salt‐water contamination of aquifers (shallow depth from salty surface water and at variable depths from subjacent salty aquifers). Evaluation of waste‐disposal problems calls for appreciation of two opposing tendencies–the tendency of wastes to move with ground water and the tendency to be attenuated near disposal sites by decay or inherent decrease in potency, by chemical and physical sorption, and by dilution through dispersion of ground water. Mixed wastes of differing attenuation habits represent special complex problems.