WATER TANK OF A BEVERAGE MACHINE

A water tank (2) of an automatic beverage machine, in particular an automatic coffee machine (1), with a container (3) and a cover (4) closing off the top of the said container (3), and a container bottom (5) closing off the bottom of the container (3), and the bottom (5) with a lower surface (9) comprises an opening (23) and an annular valve holding boss (10) with a substantially cylindrical inner surface (11) that extends down from the lower surface (9) in surrounding relation to the opening (23) with a shoulder (20) and inside the annular valve holding boss (10) a tank valve (13) is provided, which slidably fits within the inner surface (11) of the annular valve holding boss (10), wherein the tank valve (13) has an elongated vertical body (16), that on an upper end comprises a gasket (18) that tightly closes the opening (23) when the tank (2) is removed from the beverage machine, and a base ring (14) arranged on a lower end of the body (16) which guides the sliding movement of the tank valve (13) inside the annular valve holding boss (10), and the inner cylindrical surface (11) of the annular valve holding boss (10) comprises at least one groove shaped recess (12) in relation to the annular valve holding boss (10), wherein the recess (12) is provided such that water or air can flow through the recess (12) between the base ring (14) of the tank valve (13) and the annular valve holding boss (10).