I used them for about a few years and got diarrhea multiple times and full-blown food-poisoning once, all of which I now attribute directly to badly filtered water (I hoped it was something else). I used these things in "not too bad" areas while hiking, too, not sewage, the Ganges or industrial waste facilities. Here you go: https://www.bbc.com/news/articles/c98rpgqyqygo Just another story of these things failing spectacularly. I'm not gonna advertise something else, but try and find another way. submitted by /u/Remarkable-Gate922 [link] [comments]