Your cat may just have a habit of drinking from the toilet despite you giving it fresh water. Cats of any age love to play with water, but a toilet is not a safe play area, especially if you use toilet chemical cleansers. If your cat habitually drinks from the toilet, make sure the whole family keeps the lid down or the door shut. Consider buying a pet water fountain – this prolongs the fresh taste of water, is fun for the cat to use and is a much safer option.