I drank straight from a high altitude creek........once. You absolutely do not want to do this. I was sick as a dog for a week, and in day three passed out from convulsions while puking. I was so sore after a week I could hardly sit down if you know what I mean. I never, ever, want to feel that way again. I get a mild cold maybe once every 5 years, but that stream wiped me out. The hell of it was after I finished my drink, my evil buddy replied: "oh look, I did bring 2 extra bottles of water." To top it off, the next morning my evil buddys brother drove back in a state truck and dropped of 2 five gallon containers of fresh water, all planned and known about in advance and without my knowledge.[:@]