What size water bowl should you buy for your cat? Ideally, you should change your cat water every day and wash out the bowl. You should run the bowl through a thorough was once weekly. After washing, make sure you rinse it well removing all traces of soap and cleaners.
As a rule of thumb, you cats bowl should hold enough water for him to drink for at least 24 hours, preferably 36 or 48 hours.
How much does a cat drink? As a general rule, cats drink 20 to 40 ml of water per pound of body weight per day. This comes out to about 2 ½ cups for a 10 pound cat.
So the idea bowl for a 10 pound dog would be 3 cups. If you have more than one cat, that you need to ensure you have enough for all of them. You may even want to consider a large bowel in the summer when environmental conditions are hot and humid.
As an alterative to one big bowl, you can also consider placing a couple bowls around your home.
For more information on water, please read Why Water is Important