According to a NASA Facts article, astronauts have access to toilets and showers just as they would back home, and wear diapers when they must be safely ensconced in spacesuits for longer shifts and duties. Naturally, though, those facilities are heavily adapted. Smithsonian National Air And Space Museum explains that washing is problematic due to the fact that the lack of gravity would cause the water to remain in place, and the great danger of water floating into and damaging equipment.

Early NASA missions allowed for only infrequent sponge baths, to preserve precious water. Showers were possible on SkyLab by means of specially-designed floors that held the astronaut in place, allowing them to stay anchored as they carefully washed themselves with limited water (every drop of which was sucked into a dedicated storage device afterwards).

On the International Space Station, special pouches of water and soap are used to bathe, and a sophisticated system filters all water to ensure none is wasted (none at all, down to astronauts’ urine).

Personal hygiene is certainly a struggle in space. Astronaut Mike Hopkins told The Atlantic of the perils of working out on the International Space Station: “On the ground, when you’re riding the bike, the sweat drips off you. Up there, the sweat sticks to you.” According to Hopkins, clothes are worn for two weeks (the second week to work out in) before being thrown in the garbage. All in all, space-hygiene could be worse … probably.