I know I'm a little late here, but my fish tank evaporates about a 1/2-to 1 gallon of water per day and that only has an exposed area of about 3 square feet, maybe even less. According to my admittedly non-scientific anecdotal evidence, it could be quite a small still needed to produce enough drinking water for a day. Plus, how would all those castaways survive if they needed acres to make a still?


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