Now, make that into a mask and you recycle moisture from your own breath.....................
None was mentioned in the novel, that I recall.
The human body uses water to rid itself of waste heat. It is impossible to retain the water and get rid of the heat, unless you use an outside energy source to do it. Then you have to get rid of the waste heat from the energy source...
Dune was far more fantasy than science fiction.
So cactus are smarter than mankind, after all.
P.s.....funny tagline..