A refrigerator is described. The refrigerator includes a cabinet that defines a storage compartment. The refrigerator further includes a door. The refrigerator further includes a water tank that is located at an inside of the door and that is configured to supply water. The water tank includes a storage unit that is configured to store water. The water tank further includes a valve that is configured to supply water stored in the storage unit. The water tank further includes a cover. The cover includes a cover support part that protrudes to a side of the storage unit and that is configured to be supported by an upper side of the storage unit. The cover further includes a gasket that comprises a protrusion that protrudes toward an inside wall of the storage unit at the side toward which the cover support part protrudes.