"I rarely treat water when hiking in the mountains. I only treat if it's a major river or if there is stock use in the area. My father and his father backpacked and never ever treated their water. They never got sick and they never knew anyone who got sick. I don't see why backcountry water is any different now from when they hiked."
Au contraire! It is a different planet than your father and grandfather hiked on. I do think that the incidence of giardia is overblown, but it is spread by wild mammals and you're playing roulette. An area that was safe a couple years prior may be infected now.
I didn't see tablets mentioned. I use Micropur tablets as a backup for my filter system and for day hike CYA if not carrying a filter. They cost a little more, but represent a tiny fraction of the total cost of a hike. They are convenient and guess-free: rip the pack open and drop in one per liter. No drop-counting, wondering if the chemicals are in working condition, etc, etc.
