Dissolved inorganic contaminants in water can be cationic, anionic, or neutral forms of ions, atoms, or molecules of any element in the periodic table. The article describes the physicochemical treatment processes typically used to remove the more common inorganic contaminants from water and wastewater. These are precipitation, coprecipitation, adsorption, ion exchange, membrane separations by reverse osmosis and electrodialysis, and combinations of these processes. The general criteria for process selection are discussed, and the processes and their typical applications are described. (Copyright (c) 1986 American Chemical Society.)