I'm sure you know they get most of there fluids from what they eat, in the dry arid desert of Australia it wont rain for months on end, also little tip, they actually only really drink running water or droplets, so a fountain/waterfall is a good idea or a dripper. If he has a good balanced diet you can pretty much take the water dish out, I know some will argue with that, but if someone can say I'm wrong about how they rehydrate with fluid in the wild ill hear it, Bilbo does not have water in his Viv, he is healthy, not dehydrated, good moist poohs not sloppy wet yuck though. He has one soak for 10 mins every 3 weeks ish. Works for me and him =)
Did have a water dish to satisfy the missus cos she said its weird, but its out most if the time