The Ohyo water bottle is a British designed and made collapsible drinks bottle. It comes in two sizes 500ml which is a perfect size for the lunch box and a 1ltr size for the more energetic or family outing. As the Ohyo collapses to about a third of its size when empty it fits in your pocket. But the best thing is no more carrying empty water bottles through airport security that take up valuable space in your hand luggage, just put an empty collapsed bottle in your bag and fill from a water fountain when through security. Saves on space and money (as you don't need to buy water).
It is made from toxin free plastic so is BPA free and the bottles are "carbon neutral" after just two to three uses.