A storage system useful for storing cryogenic liquids is disclosed. The storage system includes a storage vessel, insulation surrounding the storage vessel and a flexible vacuum jacket enclosing them both. The flexible vacuum jacket can be made from a flexible plastic film such as polyimide. Polyimide is preferred due to its ability to remain flexible at cryogenic temperatures. The inner volume of the flexible vacuum jacket is placed under vacuum such that the insulation is maintained under vacuum. The flexible vacuum jacket can collapse against and conform to the insulation when it is evacuated, saving substantially on volume. A fitting for combining multiple passageways is also disclosed, so that multiple passageways can proceed through the vacuum jacket through a single penetration.