In Dune, Fremen (and anyone else wishing to travel the desert) wear a Stillsuit, an all encompassing body suit which traps and recovers all moisture leaving the body. This includes urine, fecal moisture, breathing moisture, even menstrual fluids but primarily - sweat. It is captured, condensed, runs down to the feet and is pumped through walking action into basins where it can be drunk (again) by the suit wearer. Cool idea.
But the purpose of sweat is to cool the body; how does the body cool if the sweat is never allowed to evaporate, especially on Arrakis, a notorious desert planet?