You can effectively treat up to 500 gallons of water with the Culligan Replacement Cartridge for IC and US-Series. Culligan Replacement Cartridge for IC and US-Series, Level 3-Advanced Filtration: * Easy-Change replacement filter for US-EZ-3 * Level 3: Advanced Filtration * Reduces bad taste and odor, aesthetic chlorine taste and odor * Reduces sediment, lead, cysts such as giardia and cryptosporidium and turbidity * Particulate Class I * Twist-on, twist-off mechanism * Quick-connect fittings * Cartridge life: 500 gallons * Includes manufacturer"s 2-year limited warranty * Model# RC-EZ-3