Introduction to primarily aqueous-phase equilibria governing water-quality characteristics of interest in potable water supply, wastewater treatment and natural waters. Topics include acid-base and metal-ligand equilibria, oxidation-reduction reactions, and chemical reaction thermodynamics. Some emphasis on equilibria governing interphase (gas-liquid, solid-liquid) chemical distribution. Mathematical approaches to prediction of equilibrium chemical speciation are stressed. Graduate-level requirements include application of canned computer algorithms to solve equilibrium chemistry problems.