I always filter. If I lost or broke my filter (or had it stolen as happened to one fella I loaned mine to one day) I would just drink. I have been out of my mind dehydrated before, not because I was afraid of the water but because I was so out of it it just did not enter my mind to stop at one of the streams and take a drink.

If giardia was the outcome, I would not suffer until at home where I could worship the porcelain in private.