Pretty easy to make a gravity filter. Mine is 5.5 oz. Using chemicals, I'd have to carry an extra quart of water for several hours while the pills work. With the filter (and, obviously frequent water sources!), I have to carry only a pint of water at a time. In other words, using the filter I have 2 lbs. less water to carry. Assuming the worst scenario of a soggy wet filter at about 8 oz., I'm still saving 1.5 lbs. by using the filter! With a gravity filter, I don't have to put my back out standing over the water source pumping--just scoop up the water and let it drip!

Note that aquamira liquid is not strong enough to kill protozoa cysts (giardia and crypto)--you need a higher concentration and longer treatment time than the label states (note that the label mentions only bacteria and viruses). If you haven't gotten sick when using it, either your water sources are pristine or you've developed an immunity to giardia.
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey