One of my cats insisted on drinking from anywhere except his water bowl. I caught him many times head first in the loo drinking. (clean water I might add) I was so afraid he would slip, get his head stuck and drown, that I had to instill in hubby to not only to put the seat down, but also the lid. I certainly would not want my cats to use my toilet. They had a perfectly good litter tray.
Coralie