ZeroWaters five stage process:Stage 1: Coarse filter to remove fine particles/sediment.Stage 2: Distributor that maximizes contact time.Stage 3: Multi-layer system using activated carbon and oxidation reduction alloy. Stage 4: Comprehensive ION EXCHANGE array. Stage 5: Non-woven membrane to remove fine particles. EIGHT ZeroWater Replacement Filters Most conventional carbon filters only filter certain substances from your water. ZeroWater’s patented Ion Exchange System, with FIVE combined technologies, provides the only filtered water that meets the FDA definition for purified bottled water. Stage 1: Activated carbon infused micron cloth. Stage 2: Multi-layer system using activated carbon and oxidation reduction alloy. Stage 3: Distributor that maximizes contact time. Stage 4: Comprehensive ION EXCHANGE array. Stage 5: Non-woven membrane to remove fine particles. Filter cartridge life is based on household water consumption and inlet water quality. How often the cartridge needs to be replaced is determined by how much water you put through the system and how hard the cartridge has to work to clean the water you put through it. Filtering your water through ZeroWater filters not only improves the taste of your tap water, it also prevents you from throwing plastic water bottles into the trash and clogging up landfills. Zero Technologies, LLC is proud to be the only major company that recycles gravity filter cartridges from U.S. customers. Contains 8 Cartridges.