In article ,
Fred J. McCall wrote:
:You can accept some small water losses, because human metabolism converts
:food to CO2 and water...

In addition to this, if you're using fuel cells for some of your
power, you're producing water there as well. You do have to refuel
those cells, but then the mass you're lifting is doing 'double duty'.

A spacecraft that's up there long enough to be doing water recycling is
*probably* going to be solar-powered; fuel-cell reactants simply weigh too
much. Gemini and Apollo used fuel cells mostly because their basic design
was fixed at a time when solar arrays were still in their infancy. (Note
that Soyuz, designed only a few years later, uses solar power.)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |