If your cats go outdoors at all, you really shouldn’t toilet train them. Toxoplasmosis is not killed in sewage treatment plants and if you drain to the ocean, there are many other animals that can pick it up. (Otters and sea lions, particularly here in on the West Coast.)
It’s not really an issue with cats that are completely indoors as they’re unlikely to carry toxoplasmosis or other diseases/parasites.
http://theglobalfool.com/a-toxoplasmas-journey-from-cats-to-sea-otters/
Also, don’t flush your cat waste from the litter either, for the same reason.
