How do astronauts drink water? As space missions grow longer, keeping crews supplied with drinking water matters more and more. Reverse osmosis plays an important part in space exploration, above all in recycling and managing water. This article traces reverse osmosis technology through its history in space, and its everyday uses back on Earth.
Reverse osmosis in space: the history
RO's use in space began in the 1960s, when NASA and other agencies started exploring how to manage water on long missions. Early missions relied mainly on stored water, but as missions lengthened and crews grew, that approach stopped being viable. Developing systems that could recycle and purify wastewater became essential.
In 2000, researchers began exploring the potential of RO membranes for treating mission wastewater. Studies showed RO membranes could effectively remove ions and organic contaminants, providing safe drinking water for missions. They indicated that low-pressure RO membranes (LPRO) offered high flux and good contaminant removal when treating synthetic mission wastewater.
RO applications in space
- International Space Station (ISS): on the ISS, all water — including water recovered from astronauts' sweat, breath and urine — is treated through an RO system, turning wastewater into drinkable water and minimising reliance on water from Earth.
- New spacesuits: scientists have recently designed a spacesuit with built-in reverse osmosis and forward osmosis systems that can turn an astronaut's urine into safe drinking water. It raises water recovery rates and provides an extra source on long missions — critical for the coming Artemis III and Mars missions.
- Water recovery and management systems: to support long-term exploration, NASA is developing more efficient recovery and management systems that will use RO to treat wastewater from daily crew activity, keeping water safe and sustainable.
- Future missions: as deep-space exploration expands, RO will matter still more. NASA plans to use it on future Mars missions to treat and recycle water to support crews.
How astronauts actually drink
Aboard China's Tiangong space station, a crew of three needs 11 to 12 litres of water a day for drinking, oxygen production and hygiene. The urine processing system is the most important water source. An astronaut passes about 1.6kg of urine a day; apart from roughly 5% organic matter and inorganic salts, 95% of it is water. After purification and sterilisation in the water treatment system, this water — from urine and from condensate in the cabin air — becomes recycled water that meets drinking standards, supplying the crew's drinking, oxygen production and hygiene needs. Tiangong's water loop recycles about 80% of its water, stretching supplies as far as they will go.
The development of reverse osmosis has made water treatment more efficient and offers a workable answer to global water scarcity. In space, RO keeps astronauts' drinking water safe and gives future exploration a sustainable water supply. As the technology innovates further, it will play an ever larger role in space missions, helping humanity explore for longer.
Want to know more about RO water and how reverse osmosis filtration works? Hong Kong's drinking water management is comparatively stable, and many homes and offices still choose to add filtration equipment to lift the quality and experience of daily drinking water.
Interested in a home-friendly Water Purifier or RO water dispenser, pick an option that fits your household's water habits, installation space and maintenance needs. Bio-Link's current home recommendations include:
- RO838: for households that want an under-sink RO filter in the kitchen, covering daily cooking and drinking needs.
- DT400: for households or small spaces that need a countertop hot-and-cold machine, with optional filtration as required.
For offices, schools, clinics or commercial premises needing a Office Water Dispenser, choose a model by daily headcount, installation position and maintenance arrangements. Bio-Link's current commercial recommendations include:
- ST1523: suited to medium and large offices, with higher capacity and RO filtration for shared pantries.
- ST9102: for schools, educational institutions or commercial premises with steady foot traffic.
- STC15: suited to small offices, clinics or studios with limited space — the body is just 36cm wide, for compact commercial installations.
Why choose Bio-Link?
Bio-Link was established in Hong Kong in 1997, providing consultation, installation and maintenance for filtration systems and hot-and-cold water dispensers, serving residential homes, offices, F&B businesses, hotels, educational institutions, community centres, medical institutions and laboratories across Hong Kong and Macau. The team helps customers choose the right filter and dispenser solution around site needs, water-quality goals and maintenance arrangements.
Further reading on RO water
To first understand what RO water is, how reverse osmosis filtration works, and how to choose an RO filter for home, office, school or commercial use, read What is RO water.