Doug and CK : Please comment on the following statements from an article by Anthony Acerrano in the May 2002 issue of Sports Afield. "you don't even need to boil water for 5 to 10 minutes, as once was believed. By the time water comes to a full roll, it has long passed the temperature needed to kill the bad bugs." "....halogens will not kill Cryptosporidium cysts..." A.A. also recomends a purifier : General Ecology First Need Deluxe. Opinion ? Directing these questions to the Dynamic Duo is not to be interpreted to exclude others. It's only that I am very, very interested in their comments. Thanks.