I don't own cats (own hunting dogs instead) but if I did .... this would be great!
From a BYC member - The pool is large, and easy to clean out. I dug a small pit under the pool, and I put the pool over the pit. The pit is smaller than the pool in diameter. There is a hole drilled in the center of the pool, with an ordinary white bathtub plug in it. Each day, just reach in there, pull out the plug, and the pool drains quickly. Rinse, then refill. Easy as 1 2 3!!