A water filter cartridge is provided for gravity-feed water filtration applications, and includes a granular filter media made from a mixture of titanium dioxide particles interspersed with granular activated charcoal. The granular filter media is placed in a filter housing having an upper inlet opening and a lower outlet opening. A seal may be disposed around an outer periphery of the housing at its upper region, and may include a flange region that flexes upwardly upon insertion of the sidewall into a filter cartridge opening.