For some reason that I have not figured out yet, many PHRASECENSOREDPOSTERSHOULDKNOWBETTER.-types don't consider boiling a viable means of water purification. I have talked to more than one person while strolling through the isles at REI or some place similar and I get the striking impression that if their pump action water filter clogged they would die of dehydration. These are people that for whatever reason, don't carry chamical purifiers as a backup and don't even consider boiling, nor do they carry any equipment with which to boil water even if they wanted to.