I have always used chemical treatments to purify my drinking water. I was thinking about getting a water filter, but I understand that it will not filter out viruses. Is this something I should worry about if I'm backpacking in the U.S.?
Submitted by - Stephen
Here's the short answer: Yes, be concerned. Testing of wilderness water sources in the U.S. often shows disturbing levels of viruses. Some sources are virus-free, but how do you know? Some filters involve an iodine resin on the matrix, which kills most of the viruses–most, with some filters, being more than 99 percent.