Considering every Sci-Fi movie and televsion show we have ever watched has either talked about it or connoted this in some way shape or form it shouldn't bother anyone - we probably already thought it was happening up there with out actually giving it any thought.
The human body is mostly water - we could go so far as to go completely "Dune" and recycle all water expended from the human body. But most people wouldnt agree to that as it might come across as a little less than connected to our own people emotionally.