WaterChef U9000 Premium Under-Sink Water Filtration System, Brushed Nickel Faucet Superior Performance & Taste Powerful Big Block Filtration Technology 1,000 GALLON Rated Capacity. (For most households, that's just ONE cartridge per year.) Intelligent Monitor(No more cartridge replacement guesswork.) Tested & Certified by NSF International - NSF/ANSI Standards 42 and 53