The ISS toilet costs $23 million and separates urine into a centrifuge that recycles 98% of it back into drinking water — a closed-loop system that took NASA 40 years to perfect - Space Daily

The $23 million toilet on the International Space Station feeds a centrifuge-driven water recycler that reclaims 98 percent of urine, sweat, and cabin humidity — a closed-loop system NASA spent four decades getting right.