Astronauts brush their teeth just like they do on Earth. There is no shower on the Shuttle, so astronauts must make do with sponge baths until they return home. Each Space Shuttle has a toilet that can be used by both men and women. Designed to be as much as possible like those on Earth, the units use flowing air instead of water to move waste through the system.
So really, what is this space toilet and how does it actually work?
A space toilet, or zero gravity toilet, is a toilet that can be used in a weightless environment. In the absence of weight the collection and retention of liquid and solid waste is directed by use of air flow. Since the air used to direct the waste is returned to the cabin, it is filtered beforehand to control odor and cleanse bacteria. In older systems, waste water is vented into space and any solids are compressed and stored for removal upon landing. More modern systems expose solid waste to vacuum to kill bacteria, which prevents odor problems and kills pathogens.
So, let's think about this for a moment...
When you go to bathroom on earth, you are relying on gravity. Imagine if you were half-way done and somebody shut off gravity.. it would be a mess, to say the least, not to mention you'd be floating off the toilet!!
Therefore, when they designed the toilets for space, the first thing was that it had to have a seat belt to hold you down.
Then they decided to seperate 'solids' from 'liquids' since it's easier to store them better this way.
Then there's a tube that you pee into which has air pulled into the tube. For the women it's like a little cup fit up against them and for the men it's like a funnel they pee into and it just goes into a sewage tank.
However, the solids that comes out of your body, well now, that's a different story! That's a harder problem to solve and it's important medically as well. At least on earth, the solids would fall to the ground and eventually well, become compose at the very least, but in space, of course, solids would float around. It would really make you sick if you re-ingest something that came out of your body (yuck!)... and they can't afford to be sick up there in space and all, so they had to design a toilet that instead of gravity pulling everything into the toilet, they would use air-flow - using air to pull everything down into the toilet.
Sure it will feel a little bit 'windy' down there.. but what the hell - at least it will be pulling everything that comes out of your body and into the storage tank which exposes it to the vacuum of space. So basically all that solid is 'freeze-dried' thereby killing any bacteria which means killing all odours as well. Then they just store it! Then when a whole bunch of it is stored up, they put it in a un-manned supply ship, undock it, and then it burns up in the atmosphere!
So, the next time you see a beautiful shooting star going across the sky... think again!
current.com, Col. Chris Hadfield, Canadian Space Agency,