The Pentek WS-20 water softener filter cartridge contains FDA Grade Softener Resin. The Pentek WS-20 cartridges provide softened water in a convenient cartridge-style design. The Pentek WS-20 softening water filters utilize a bed of sodium form cation resin beads to reduce hardness and scale deposits. The Pentek WS-20 convenient and space-saving design means that softened water can be provided easily and cost-effectively at the exact point of need. NOTE: For drinking water applications, do not use where the water is microbiologically unsafe or with water of unknown quality without adequate disinfection before or after the system.