then these units are used by people in swamps, military types on missions, etc. --

however, if you saw how much volume you get out of these units, you're not going to have worry about it getting "stale" in a life raft OR having nothing to keep you occupied. YOu'll be working your hands and wrists to keep hydrated ;^)))).

The PUR 35 is a much more robust unit. It would, in a pinch, work to keep the crew going if you had to use it because you ran out of water in the deep blue.