[b][/b]In backcountry US, viruses are not generally considered an issue. in any case, boiling works for all pathogens....

Cooling boiled water doesn't necessarily take hours. Once, bike touring in the Black Hills, SD, I was descending a broad, rural valley with a lively stream - thinly populated with live stock. I boiled waiter, put it in a canteen, placed the canteen in the babbling brook, boiled more water; by the time the second pot had boiled, the canteen had cooled very nicely.

Doesn't one usually bring water to a boil when preparing the vitally essential tea or coffee?