This one is sort of hard to understand. On the one hand, you get super dehydrated on planes. Keeping folks from bringing water on seems sort of cruel.
But from a practical standpoint, couldn't someone carry liquid explosives on a plane inside their body? Couldn't you insert it into a body cavity?
Logically, it would seem to me that if you have a liquid explosive that is undetectable by the xray machines, you are going to be able to get it on the plane.
Banning water bottles seems to be doing something for the sake of doing it. Practically speaking, I can't believe we are even one iota safer because of this ban.