Great, IdahoHiker,you're doing your research, which, IMHO, is excellent! In the US you really don't need to be too concerned about viruses, unless you're downstream of human settlements with perhaps leaky sewage or septic sytems (not an issue in the mountains). Most of us have been immunized against the serious viruses you're most apt to encounter (polio and hepatitis A). It's the protozoa (giardia, cryptosporidium) and bacteria (particularly e coli) that you need to be concerned about.
Chlorine dioxide (used in municipal water systems) will kill all three, but takes a very long exposure time for protozoa--up to 4 hours if the water is cold. Even when I take my filter, I always carry some chlorine dioxide tablets. The filter might break, or I might encounter a horrific water source (downstream of human settlement, or a stagnant cattle-trampled pond) where I want to throw everything I have at the water before even contemplating drinking it. I am considering a coarser filter (Aquamira makes a very lightweight inline filter) that will filter out the protozoa, in combination with the ClO2 tablets. This would mean only a 15-20 minute treatment time for the tablets.
If it's an emergency, go ahead and drink whatever water you find. Giardiasis takes 10 days or more to incubate (by which time you'll be back in civilization with medical care), but you can die of dehydration in a couple of days. A number of people have gotten drastically dehydrated when lost or stranded just because they've been told not to drink untreated water.
I want to advise against using iodine to disinfect drinking water. For one thing, I've read that it is not effective against cryptosporidium. For another, iodine allergies (per my doctor) are not all that uncommon. You won't know if you're allergic until you have a reaction. I used it for a little over a month (only on weekends) and then broke out in a horrible rash, with really deep lesions (lichen planus). It itched like crazy and left permanent scars. The worst of it is that since this happened (over 20 years ago), I can't eat anything with iodized salt (which causes problems when in restaurants and when invited to people's homes for dinner--I'm stuck with salads with only oil and vinegar dressings), and I can't eat any seafood or take multi-vitamin-mineral supplements. Should I ever have to have a diagnostic procedure involving radioactive iodine (such as an angiogram)--well, I'll just have to drop dead undiagnosed! So stick with ClO2 if you're going to use chemicals. Even with that, try it at home before you go out--a few people get digestive disturbances from it. (Actually, that's true for any gear--try it out at home first, in the back yard or car-camping, before heading for the back country.)
Edited by OregonMouse (01/22/09 02:28 AM)
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey