Most of the water at the ISS is already recycled, but they still do need periodic refills. Something like it would also work on Mars, but as far as I know the s

Most of the water at the ISS is already recycled, but they still do need periodic refills. Something like it would also work on Mars, but as far as I know the system is quite big, complex and expensive. > Submarines are probably good at doing this, but the price per square meter of floor would be prohibitive. Nuclear submarines produce clean water from sea water as an intentional byproduct.