The outdoor community made water filtration a must for a reason
Anecdote is not data, but ok, here is an anecdote:  When I was a boy scout growing up in the Bay Area we would camp in the mountains for a weekend or even as long as a week.  We filled our canteens in any clean looking fast running stream.  Everybody did that and they were fine.  Sure it is possible this has gotten more dangerous but I am inclined to believe the paranoia has increased faster than the danger.