I use these for water and food bowls. They are very hard, basically impossible, to tip over. I use the smallest size for water, and the biggest size for food because Henry likes to sit in his food while he eats
(tried the smaller one for food, and he still tried to sit in it, but it looked very uncomfortable with his butt hanging off so we switched to the bigger one).
http://www.petco.com/product/110826/PET ... SiteSearch