OM- How do you keep a dog from drinking from streams and lakes? I thought a dog would drink wherever he pleased. Do you keep him on a leash ALL the time?

I am probably the worst example of hand washing, treating water or washing dishes and I have never had Giardia. I think suseptability is an individual thing. I have never even had mild digestive problems on the trail- in fact I never felt better!

As for cattle, a water district (client that I do work for) has grazing in their upper watershed and their water tested for Giardia. So the director of Engineering did a study- personally went out and tested tons of cow pies. He found that the cow pies created enough heat to kill the nasty microbes (southern CA). The Giardia did not show up direclty downstream of the grazing. The source of the Giardia in their water was finally tracked back to horses from several high dollar equestrian riding stables much farther downstream.

I agree with Brian Lee. There's lots of hearsay and few if any well designed studies. And I also go with that old saying, "dilution is the solution to pollution". Getting Giardia has a lot to do with the dose you get. A big burbling stream would dilute much of Giardia that may get into the water. I avoid drinking directly out of trickles or puddles. And do not drink from water down-gradient from an outhouse or campground!