An insert for a multiple component container includes a diaphragm and a sealing element which together define a reservoir. The diaphragm includes a stationary portion and a movable portion. The movable portion is connected to the stationary portion by at least two spaced annular fold lines of opposite sense. A discharge opening is formed in the movable portion within the annular fold lines. A gas leakage path is provided in the diaphragm. A valve member is connected to the stationary portion and cooperates with the discharge opening and substantially seals it. If a great gas pressure is applied to the interior of the reservoir than to its exterior, this results in rotational movement about the fold lines and thus in movement of the movable portion away from the stationary portion and thus in the valve member moving out of sealing contact with the flow opening. Any liquid in the reservoir is then expelled through the discharge opening by the higher pressure prevailing within the reservoir.