Abstract: A hot water tank is provided for use in beverage dispensing machines which comprises a cover, a discharge valve for hot water, an inlet valve for fresh water, a heating system, controlling means for observing water temperature and water level, an overflow opening communicating with the atmosphere, and an overflow edge extending between the cover and the water level along an external wall of the tank. The overflow opening is covered by means of an automatically closing valve element in the form of a plate. One side of the valve element is swingably fastened to the cover. There is also a ventilating hole provided in the cover, the hole being substantially smaller than the overflow opening.