A new On-Line Analyzer providing monitoring and control capability for water fluoridation systems is now available from Analytical Technology Inc., of Oaks, Pa. Fluoride is added to many municipal water systems in an effort to improve dental health in the community. A fluoride concentration of about 1 ppm is considered optimum, while fluoride levels above 2 ppm are undesirable. Control of the chemical feed system to maintain the desired concentration is normally done by simple flow-proportioning.