a closure is provided for a water bottle of the type used in conjunction with a water fountain . the closure comprises a body having an open feed cylinder and a sealing cap which is movable between a sealing position and an open position and is adapted to seal the feed cylinder when in a sealing position . the sealing cap is biased towards a sealing position by biasing means which preferably comprise a plastics spring that anchors the sealing cap to the body . the form of the spring and the arrangement of the sealing cap and the feed cylinder are such as to minimize and compensate for creep in the plastics material of the spring in use of the closure to ensure resealing of the feed cylinder if and when the water bottle is removed from the water fountain .