I think the article's probably right and that most contamination is self-inflicted. I solve that by hand-washing and hand sanitizer, which has worked so far.

The thing that keeps me using a filter for all water is the statement that "only 5% of water is sufficiently contaminated to pose a threat." My problem is that I can't tell WHICH 5% just by looking. Since the filters nowadays are so aftertaste-free, lightweight, and simple (for example, Sawyer), it's pretty easy to adopt a "better safe than sorry" attitude.

As for backup, I do carry some purification tablets. However, if faced with drinking untreated water or no water, I'd try to find the best source I could, drink, and hope for the best. Much of the "hullabaloo" seems to come from the no-risk/zero-tolerance crowd; thankfully, I grew up in a generation that learned to weigh risks and make decisions knowing there are probably consequences.