Kitty probably thinks that toilet water is more "fresh" than the stuff in his water bowl. There are pet fountains on the market, not too terribly expensive, that could solve the problem.
This was taken off of www.meowhoo.com
where they have anything and everything you and your cat has ever dreamed of. This product is available at local pet supply stores, too.
Drinkwell Pet Fountain
Does your cat desire running water? This product will fill your need.
5635 Riggins Court Suite 20 Reno NV USA
Phone: 800-805-7532 / 775-322-2530 email: firstname.lastname@example.org://www.vetventures.com