I saw a part of that episode of Dual Survival , and as they were emptying the beer cans on the ground, I was wondering : How about mixing that beer ( diluted alcohol ) with some bad water and letting that little alcohol do some water sanitizing. The process would - in theory - consume the alcohol in the beer, as well as sanitize more water.

After mixing the water with the beer, they could boil whole thing. Boiling will get you (a) evaporating any remaining alcohol (b) making sure that nasty critetrs are dead.

Sounds like overkill, but better than throwing that precious liquid in the first moments of their situation.