Pee like you mean it

I didn't know this about space travel. Astronauts have been turning their urine into oxygen for decades now. The Russians had it on MIR and now there is a newer technology, developed by NASA that will be installed on the Intl Space Station. This technology is crucial if a planned mission to Mars is to be undertaken. Carting along enough oxygen tanks for the ride to Mars is logistically impossible.
The technology takes the astronauts urine and removes the dissolved solids and then takes the resulting purified water and splits it into oxygen and hydrogen. Neat. Sounds gross but it makes perfect sense that recycling 'everything' they can is an efficient way to remain in space. Read more HERE.