Sani-System is the only NSF certified and EPA approved sanitizer for use in water softeners and reverse osmosis units. It is specially designed to kill 99.99% of harmful bacteria and maintain the quality and performance of water treatment systems without chlorine, oxidizers or acids that can harm system equipment, parts and resin. A water Softener should be sanitized every 6 to 12 months. EPA-registered (EPA Reg No: 1839-155-73529 and EPA Est. No. 88120-WI-1) and NSF 60-approved sanitizer