A refrigerator comprising: a cabinet having a storage compartment defined therein; a door for opening and closing the storage compartment; a dispenser provided in the door and comprising a water dispensing port for providing water when a user pushes a water dispensing lever; and a water tank provided at an inside of the door for supplying water to the dispenser, wherein the water tank comprises: a storage unit for storing water; a valve for supplying the water stored in the storage unit to the user; and a cover for opening and closing the storage unit, the cover comprising: a cover support part protruding to one side such that the cover support part is supported at an upper side of the storage unit, characterized by a gasket comprising a protrusion protruding toward an inside wall of the storage unit; wherein the water tank supplies water to the dispenser through a drainage port provided at the rear of the door so as to communicate with the water dispensing port, wherein the protrusion comprises: a recess configured to be concave: and contact parts configured to be brought into contact with the inside wall of the storage compartment in a state in which the recess is interposed between the contact parts, and wherein an air layer is defined in the recess in the state in which contact parts are to be brought into contact with the inside wall of the storage compartment. a cabinet having a storage compartment defined therein; a door for opening and closing the storage compartment; a dispenser provided in the door and comprising a water dispensing port for providing water when a user pushes a water dispensing lever; and a water tank provided at an inside of the door for supplying water to the dispenser, wherein the water tank comprises: a storage unit for storing water; a valve for supplying the water stored in the storage unit to the user; and a cover for opening and closing the storage unit, the cover comprising: a cover support part protruding to one side such that the cover support part is supported at an upper side of the storage unit, characterized by a gasket comprising a protrusion protruding toward an inside wall of the storage unit; wherein the water tank supplies water to the dispenser through a drainage port provided at the rear of the door so as to communicate with the water dispensing port, wherein the protrusion comprises: a recess configured to be concave: and contact parts configured to be brought into contact with the inside wall of the storage compartment in a state in which the recess is interposed between the contact parts, and wherein an air layer is defined in the recess in the state in which contact parts are to be brought into contact with the inside wall of the storage compartment. a storage unit for storing water; a valve for supplying the water stored in the storage unit to the user; and a cover for opening and closing the storage unit, the cover comprising: a cover support part protruding to one side such that the cover support part is supported at an upper side of the storage unit, characterized by a gasket comprising a protrusion protruding toward an inside wall of the storage unit; wherein the water tank supplies water to the dispenser through a drainage port provided at the rear of the door so as to communicate with the water dispensing port, wherein the protrusion comprises: a recess configured to be concave: and contact parts configured to be brought into contact with the inside wall of the storage compartment in a state in which the recess is interposed between the contact parts, and wherein an air layer is defined in the recess in the state in which contact parts are to be brought into contact with the inside wall of the storage compartment. a cover support part protruding to one side such that the cover support part is supported at an upper side of the storage unit, characterized by a gasket comprising a protrusion protruding toward an inside wall of the storage unit; wherein the water tank supplies water to the dispenser through a drainage port provided at the rear of the door so as to communicate with the water dispensing port, wherein the protrusion comprises: a recess configured to be concave: and contact parts configured to be brought into contact with the inside wall of the storage compartment in a state in which the recess is interposed between the contact parts, and wherein an air layer is defined in the recess in the state in which contact parts are to be brought into contact with the inside wall of the storage compartment. a recess configured to be concave: and contact parts configured to be brought into contact with the inside wall of the storage compartment in a state in which the recess is interposed between the contact parts, and wherein an air layer is defined in the recess in the state in which contact parts are to be brought into contact with the inside wall of the storage compartment.