Disclosed is a refrigerator. The refrigerator includes a body which includes a storage compartment, a door which opens and closes the storage compartment and includes a dispenser, a water tank case disposed in the door, a water tank separably mounted in the water tank case, a water level sensor configured to sense a water level inside the water tank when the water tank is mounted in the water tank case, and a water tank valve configured to guide water supplied from a water supply source to the dispenser or the water tank and to prevent water from being supplied to the water tank when the water level sensor senses that a certain amount of water is stored in the water tank.