A method for preparing a pressure regulating system for a beverage container system, comprising a pressure regulator, a first compartment for containing a pressurized gas, in fluid communication with a surrounding space through at least a gas valve for opening and closing a passage between the first compartment and surrounding space, wherein a gas valve control system is provided, comprising a deformable and/or movable wall or wall part, wherein said deformable and/or movable wall part is operably in contact with said gas valve for opening and/or closing said gas valve, wherein a second compartment is provided at a side of said deformable and/or movable wall part, said movable and/or deformable wall part forming a wall of said second compartment, wherein the second compartment forms a pressure regulating space and comprises a wall part formed by or comprising at least a gas permeable, liquid tight permeable wall part, wherein at least the second compartment is purged with a gas or gas mixture which is present in a beverage to be pressurized with said pressure regulator.