The Water Recovery System racks use a series of chemical processes and filters to treat the astronauts’ urine, perspiration and hygiene water, recycling about 93% of the liquid it receives to provide water clean enough to drink.
Water is recovered from urine in the Urine Processor Assembly by spinning up a keg-sized distiller to create artificial gravity. Contaminants press against the side of the distiller while steam in the middle is pumped out. Water from the urine processor is combined with all other wastewaters and delivered to the Water Processor Assembly for treatment. The water processor removes free gas and solid materials such as hair and lint, before the water goes through a series of multifiltration beds for further purification. Any remaining organic contaminants and micro-organisms are removed by a high-temperature catalytic reactor assembly.
This rigorous treatment creates water that meets stringent purity standards for human consumption. The purity is checked by sensors, with unacceptable water being reprocessed, and clean water being sent to a storage tank ready for use by the crew. The Water Recovery System reduces the amount of water that needs to be delivered to the station by about 65% – about 2850 litres over the course of a year.