Meanwhile, my longtime hiking partner (of over 20 years now) thru-hiked a big chunk of the PCT and ended his trip with giardia, which caused him significant dig

Meanwhile, my longtime hiking partner (of over 20 years now) thru-hiked a big chunk of the PCT and ended his trip with giardia, which caused him significant digestive issues for quite a while afterward (over a year altogether). And I've occasionally taken unfiltered freshwater from streams over the years but have generally been picky about where/when/why and have accepted each time that I was foolishly rolling the dice. And and, a popular recreational "lake" in the area was recently found to have a major problem with e. coli after it hospitalized a young child with complete renal failure. Cattle are grazed all over the backcountry, people poop out there (and it lasts a -lot- longer in the wilderness than you'd guess, especially when people use TP and leave it out for the squirrels to gather for nesting material), and people do the same on snow which melts into streams at high elevation. If there's a 1 in 20 chance of picking up a parasite from drinking unfiltered water in a backcountry area (minimum 20 miles to civilization), then the average person will be lucky enough to get away with it their entire life and then tell other people, "but I did it and I'm fine!"