A water filter system including a base configured for receiving water from a faucet and a filter cartridge connected to the base. The filter cartridge defines a peripheral opening and a first chamber having at least one filter element, and a second chamber in fluid communication with the first chamber. An enhancement cartridge is removably inserted through the peripheral opening and into the second chamber. The enhancement cartridge includes an enhancement material for adding minerals to the water and is removable from the system independently from the filter cartridge.