I've read that most people do not get giardia (they tested this unethically on a prison population in the 1950s) - 1 in 8 people carry giardia naturally. Hard to test for because maybe you carry giadia but it isn't what got you sick in the first place. Most people get giardia from day care or their fellow hunters rather than the water. In my opinion water filters are just an overblown 'scare'. I have always just drunk the available water- avoid the stuff with green scum and obvious contamination. And I've never gotten sick either. But then again maybe I'm a carrier!
Patrick
