A cap for use with bottled water dispensing systems. The cap includes a main cap and a liner. The main cap has an opening which receives and seals against a probe. The liner is gripped between the main cap and the bottle neck and has a outside part and an inner movable part. The inner movable part is linked to the outer part by a large connecting section that serves as a hinge, and breakable or frangible connecting section. When the bottle is lowered onto the dispensing system, the probe enters into the opening in the main cap, breaks the frangible connection, and pushes the inner movable part open like a flap. The liner, at the location of the large connecting section, is resilient such that the inner movable part tends to close when the bottle is removed from the dispensing system. When the breakable connecting section is a cut in the liner that does not extend through the liner, the liner itself acts as an additional barrier to the egress of the contents from the container and acts as a barrier to the ingress of dirt or organisms into the container.