When you clean out his tray try and leave a tiny bit of "wet" litter in as boys especially(or at least Siamese) don't like it at all when we invade their toilet and clean all of their smell completely If this isn't the case and he still insists on going in the bath-it could be that he feels his tray isn't deep enough,or try getting a water plant squirty bottle feeder-clean one-and squirt him with a little water everytime he doesn't use his tray-but do this immediately as he does a "whoopsie" i know this is a tried and harmless but effective teqnique-You could even rename this little teqnique-The AnnieCarter's cream carpet cleaner I know -i'm a born geniusKeep us updated Annie-you'll get their i promise-it's not him being Dirty-it's us silly humans-we sometimes just take a while to hear what they're sayingGood luck