One of the experiments heading into space when Atlantis launches at the end of the week is a magical bag that can turn any kind of liquid (any kind of liquid) into a tasty electrolyte-filled sports drink without needing any energy input at all.
The secret inside the The Forward Osmosis Bag (FOB) system is, well, I guess the name gives it away: it's forward osmosis. Here's how NASA explains the process:
"Forward osmosis is the natural diffusion of water through a semi-permeable membrane from a solution of a lower concentration to a solution with a higher concentration. The semi-permeable membrane acts as a barrier that allows small molecules such as water to pass through while blocking larger molecules like salts, sugars, starches, proteins, viruses, bacteria and parasites."
So basically, you fill this bag with any kind of liquid that contains water (including, you know, pee), and then osmotic pressure causes the water molecules to scoot through a filter into a concentrated sugar solution. You don't need to plug it in, heat it, or even shake it: it just does its thing for four to six hours, and then you've got a liter of absolutely clean water with a bunch of sugary electrolytes in it for flavor. Yum!
NASA already recycles astronaut pee on the ISS, but the advantage of the FOB system is that it requires no energy and is very space efficient: by weight and volume you get about 14 times as much fresh water out of FOBs as you do by just shipping water itself, and weight and volume are both at a premium when it comes to sending things into space.
If you like this whole self-sufficient fresh water idea, you can try it out for yourself, since the company that makes the FOB also sells them here on Earth, for camping, emergency kits, and disaster relief. A six pack of bags that can each produce 12 ounces of drinking water from any liquid that you immerse them in will run you about $23.