I also have been using platypus for several years but always inside of my pack. I am concerned about them when they are in an outside side pocket. They can sustain a pretty good blow when completely unprotected. I am sure that I am worrying unnecessarily but I would hate to be out and break my only water container. I suppose the best thing would be to buy another platypus and keep it as a spare. They weigh almost nothing. My usual routine is to have a one liter nalgene on my hip belt and then two one liter platypus inside the pack which I fill and carry as necessary. If I will be coming across water soon I just use the nalgene. If it is noon and I will not see water for another 15 miles I fill the two platypus and carry three quarts for supper and breakfast etc.