I know the ones Barkingdog means. It's a water bowl that has a bigger upside down bottle attached to its base. In proper words like BD said it's a reservoir.
It doesn't have a motor, doesn't make any noise and they're affordable. Ive seen them in Wal Mart even.
I think it's a great idea. Your cat will still pkay with the water but it's unlikely he'll knock it over and there will be plenty for kitty brother.
+1 To that idea