Apparatus for introducing a liquid into a sealed external container or a sealed external system, the apparatus having a bellows which is sealed a first end, which is sealed at a second end solely by a valve, and which contains the liquid; wherein the valve is one which is positioned remote from the first end of the bellows, which retains the liquid in the bellows, and which permits liquid flow only in a direction from the apparatus to the sealed external container or the sealed external system; and wherein the apparatus further has a connector which in use forms a sealed connection between the apparatus and a sealing valve on the sealed external container or the sealed external system.