A trout pond in a dorm room probably takes too much space <img src="/images/graemlins/wink.gif" alt="" />. Try one of these: http://aquaflex.net

.25 or .5 gal/day is bare survival, i.e. avoid death by dehydration. If preparing, go for 1 gal/day or more. Aside from the Aquaflex tanks, 7 gallon aqua-tainers seem to be the favorite from the other forum. They are tough and stackable, so you could put a bunch of them next to a wall. Of course if you have the space for it, a trout pond or swimming pool solves the whole problem.

I'm in an urban area in a small apartment so no trout pond. But I'm a mile or so from the ocean and its infinite sea water. I sometimes take a look at ebay for marine desalinators. They do show up there but are a bit too expensive for me. If the technology gets cheaper or if I win the lotto, I'd think about getting one. $2K or so gets you a unit that can make 100's of gallons per day from 8 amps or so of 12 volt power (i.e. car with jumper cables), enough to take care of several households.