How many times does a cat urinate each day?

Our four cats would probably pee twice a day if they just slept a lot while we are away on weekend trips.

However, when we are home, they are so happy and playful, chasing each other for exercise and fun, that they will drink much more and pee more often. I set up a large sandbox and use shredded paper from the office mixed in with sand and earth, to take care of any odour until the box can be cleaned up.