If you stop by the Gothia Cup, a world youth soccer tournament in Sweden, you'll get a chance to drink some eminently potable water from a very reliable source: Your own sweat. A group of Swedish engineers has built a "Sweat Machine" that pulls the sweat out of damp clothing, and then purifies and filters it until it's fit to drink, Discovery News reports. And in case you're not sweaty enough to contribute, there's an exercise bike attached.
The project was dreamed up by a PR agency and UNICEF as a way of drawing attention to the many parts of the world that lack access to sufficient clean water. Whenever someone chips in sweat or drinks a cup of former sweat, sponsors will donate money to buy water purification tablets in these regions, according to the Gothia Cup's site. Could the sweat machine itself help in these places? Maybe, but not much; it requires a full load of sweat-drenched laundry to make a pint of water.