Originally Posted by corporate-wage-slave

When you are next in the United States, go to a REI store. They have plastic bottles that flatten to the thickness of a pancake when empty. I think they're Australian. So no problem with Security anywhere when devoid of liquid - they weigh approx 20 grams, depending on the various sizes available. I then fill these up in BA lounges the world over, no problem at all, frequently to the envy of my fellow passengers when stuck at the end of the tarmac waiting in the queue to get airborne on a hot day.