That is scary to me. As kids while ice fishing we boiled a pan full of snow over the fire and drank the water after it cooled. Both of us ended up with a nasty case of the poops that evening. Not sure if it was from the water but we were told it should be at a full boil for 10 minutes and we just kept adding more snow as it boiled away until we had close to a full pan. Now they make a thing called a survival straw that is supposed to work without boiling but I never tried one yet.
Just a few years ago while riding the back woods in northern Maine we came upon a pipe coming out of the mountain where people fill jugs. We filled a few jugs and bottles and my wife drank it but I didn't. That evening she spent most of it on the toilet with severe cramps and a serious case of the craps. So much for good mountain spring water! What really surprises me is my dog, she drinks from puddles, ponds, lakes and anywhere else she finds water and never seems to have a problem with any of that nasty stuff.