There is disclosed a water treatment appliance, particularly for on-the-counter treatment of potable water. The appliance comprises: a base unit comprising a pump, a housing and a cooling unit for chilling water in the housing; a removable water reservoir engageable with the housing; a control panel comprising a water dispensing switch; an outlet for dispensing treated water from the fluid treatment system; and a treatment cartridge removably disposed in the housing. The treatment cartridge comprises a first chamber and a second chamber in communication with one another. The first chamber is in communication with the housing and has disposed therein a filter element. The second chamber is in communication with the outlet and has disposed therein an ultraviolet radiation lamp.