Current Water Recovery System at ISS, recycles urine and other non-drinkable liquids into drinkable water and compressed waste fluids. Urine, sweat, etc.
This system recovers around 93% of the liquids it receives.
On Earth, distilling is a simple process of boiling water and cooling the steam back into pure water.
Without gravity, the contaminants in water never separate from the steam.
So, the keg-sized distiller spins to produce an artificial gravity field while boiling the water. The contaminants in the urine or greywater press against the sides of the drum while the steam gathers in the middle and is pumped to a filter.