Even on the harsh deserts of Arrakis, the the water recycling capacity of a stillsuit prevent the wearer from would only lose a thimbleful of water a day. If you figure a thimble holds about 10 milliliters of water, and an astronaut normally consumes 2.7 liters of water per day through eating and drinking, that’s only a loss of .4% of the body’s daily water. Pretty impressive for a desert race with long life but limited resources. (In case this wasn’t clear, I’m talking about George Frank Herbert’s Dune here.)
Until recently, there was no need for us to try and engage with this sort of water recycling technology. In general, water has been plentiful in this world, and if it wasn't we just piped it in. (I just re-saw Chinatown, so I'm feeling up on all this.) But increasingly short supplies of water in the American southwest and elsewhere ...
