I sorta agree with you Jerrwhy as to the possibility of a lot of hype(lots of money in water treatment) but I was once very sick. Doctor figures it was either Ecoli or Giardeha(sp?). Either way I was puking and crapping violently literally at the same time. This was not a case of the runs that would be merely uncomfortable or a bother. This was I can't move from dehydration and pain. If I was in the woods without help I am certain that it would have taken luck or will to survive it. Doctor had asked me why I didn't come to the hospital at the time and I really could not move and as long as my wife was getting me water, I liked my home better than a hospital. I always treat water just in case <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> I have been told that once a person has giardea and gets through it with out meds, the body is immune to it but I am not taking chances.