Carried the 6L tank in the Grand Canyon for 5 days. Carried between 1 an 4 liters at any given time. The size and design were what I wanted but was leery of the zip-lock type top opening. I had no spills or issues with it in the bottom of my pack under my sleeping bag. Kept it bottom down with water in it, wouldn't trust it on end without some more experimentation. It seems durable, for the price I'm happy. My buddy carried the 1 and 2 liter Platypus bags and we both liked them too.