A container assembly for controlling rate of oxygen transfer from the atmosphere into a liquid stored in the container assembly comprising, a container (1) having a body, the walls of the body having an oxygen permeability within a predetermined range chosen for the liquid being stored, a frame (2) for supporting the container and bracing at least one of the walls of the container against bulging, a pair of access openings (3) beneath the frame for allowing entry of the tynes of a forklift, a neck (7) with an open mouth extending from an upper wall of the body, the upper wall being shaped so as to allow substantially all air to flow out of the body through the neck as the container is filled to the level of the bottom of the neck and, an outlet (4) for draining liquid from the container arranged near a bottom wall of the body.