Speaking of which, the portable 'Katadyne' filter is amazingly impressive. It has a .2 micron pore size, which means the water it produces is classified as 'steralized'. It has other very attractive features as well. Here's a link: http://tinyurl.com/mt7ywz
Also, when it comes to purifying water, two things to research are rain barrels and calcium hypochlorite. HINT: Don't count on using fire wood to boil water for purification.
Thank you. This thread has been incredibly informative.