I read a paper not to long about the chances of getting sick from wilderness water. I wish I could find the article. Anyway the gist of the paper was that you really had very little chance of getting sick from untreated water provided that it's flowing in some capacity. And that the issue of viruses and bacteria was largely blown out of porportion. However, given that information I think I'll continue to treat my water as long as it's practical and possible to do so. It really cannot hurt.