"Stephen M. Henning" wrote in message
...
snip
If one must drink water of uncertain sources, boiling kills the parasite
instantly. You do not have to boil the water for 5-10 minutes. As soon
as the water comes to boil, the parasite is killed.

Boiling time is something I have seen discussed before, and the best
argument for a 5 minute boil is that at different altitudes boiling
temperatures vary. A good 5-10 minute boil is a general rule of thumb for
safety. I prefer a proper water filter system, and keep one in my pack for
all trip longer then a few hours.

BV.