A liquid dispensing apparatus for a refrigerator includes a storage tank in fluid communication with a water inlet. The storage tank is configured to retain water flowing into the water inlet. An auxiliary tank is in fluid communication with the storage tank. The auxiliary tank includes a housing with a piston disposed therein. The piston is movable in a first direction to fill a portion of an interior volume of the housing with water and in a second direction to expel water from the interior volume of the housing.