Another anecdote: When I was in scouts, two separate groups of us went to Philmont, on different trails. Both crews had a variety of purification methods but e

Another anecdote: When I was in scouts, two separate groups of us went to Philmont, on different trails. Both crews had a variety of purification methods but ended up using a specific model of filter the most because it filtered really quickly and didn't taste off. Halfway through the trip one crew became seriously ill. That was when we realized that the 'fast' filters were fast because they were assembled incorrectly and weren't filtering at all. So yeah, backcountry streams can be totally fine. If you want to play the parasite lottery, be my guest, but know that it is a lottery.