All's I can say is that my C.O. (commanding officer, for those militarily disinclined) wanted me to buy these for our brigade (4000+ ffolkes)...I heartily reccomended against them. Cost was a factor (dollars per liter...and it's ****** gatorade, not water), but I felt our ROWPU's (motorized filters) did a darned sight better. And cheaper.

Do such "gadgets" have their place? Yes. Can you filter urine? Yep.

Don't count on your kidneys keeping up with the urea, tho. The filters won't handle that...in simple terms, in an extended situation, your kidneys would shut down and kill you <img src="/images/graemlins/smile.gif" alt="" />

Still, a cheap, positive-pressure membrane that filters giardia/viruses would be handy. Just add water, and blow.
_________________________
Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein