no, and yes.
I don't se a water system in the high mountains, above 8000' in Idaho. I have gotten sick from low valley water but never in the high country. Mostly drink from spring fed only, or lakes. the larger creeks can be a little warm and can have over bearing nutrients on the water from the higher temps.
But if you are not wanting to get sick, do use one. I use water from lakes or springs in camp. Coffee water gets boiled anyway.