Abstract: A water management system for heat exchange devices is disclosed which includes an aqueous based heat exchange liquid containing dissolved corrosion inhibitors and a fluorescent dye, conduit means adapted to circulate the heat exchange liquid between a source of heat, such as an engine, and a cooling device, such as a radiator, a liquid or solid concentrate containing measured amounts of the corrosion inhibitors and the fluorescent dye packaged in defined unit quantities, and a comparator calibrated to provide a visual indication of the concentration of the corrosion inhibitors in the liquid and, if the concentration falls below an established level, the number of units that must be added to restore the established level.