Originally Posted by BlairsDen
But water is needed for the cooking/smoking process, isn't it?
The mass of water in the bowl helps keep temps low and stable. Water does this best. Some very inexpensive smokers with no controllable vents require water to keep temps under control.
If your smoker is well sealed with good adjustable vents none of this is really needed but sand or a clay saucer can help keep stable temps, and no mess.
Also, a well sealed smoker creates its own moist environment, if that matters...