Been watching this this thread, but didn't really want to get caught up in the confrontations. Thanks, Aimless.

My experience: I made a very bad misjudgement years ago and got caught without water. I did not treat in those days but carried mil surplus halizone for emergencies. Found a beaver meadow I knew I shouldn't drink from (though I had never heard of giardia), then discovered the pills were years out of date. Decided the dehydration was more dangerous, and drank anyway. Exactly ten days later in New York City, it hit me. Doctor couldn't figure it out (and not knowing about the beaver, I failed to tell him). About three weeks later, the doc decided the situation was life threatening and sent me to the hospital. Minutes before I was to leave for the hospital, doc called with confirmed diagnosis and perscription. Hours later I was ok, just needed rest and fluids. This was 1968, before everybody knew about giardia.

I still treat relatively little water, though as civilization gets closer, that percentage has been increasing. I'm far less confident, and advise most people, in most places, to be prepared to treat (or boil) most or all of their water. I know from experience that much of it is ok, as several here have correctly noted, but the price of guessing wrong is just too high (though a mitigating factor today is that most doctors are familiar with giardia in the areas where it is common).

Just for giggles, the first time I thru-hiked the AT, some hikers noted that a traveler's check for $25 (the price then for a perscription of flagel) was lighter than filters or chemicals. Yeah, sure.

Incidentally, why, on a board devoted to lightweight backpacking, does the very minimal weight of treatment/filtration outweigh the common sense of "better safe than sorry"?

Oh, can't resist the current direction of this thread: yeah,running out of caffiene (coffee or tea) is probably one of my worst fears. And yes, Heather, after all these years in the woods, the only critter that has even threatened to attack me was a big, angry, bull moose.

best, jcp