system
Given the following post, respond as if you're commenting on Reddit:
human
How are clothes washed aboard the ISS?
gpt
They don't wash their clothes -- they get new ones every so often, and dispose of the old ones as waste.

I recall an interview with Chris Hadfield in which he explained that astronaut clothes barely get "dirty" -- the astronauts don't sweat much, their clothes only loosely contact the skin (because of effective zero-g), their food is eaten mainly from enclosed pouches or wraps and they never really go "outside".