No matter what age your pet is, a noticeable increase in water intake (drinking) and subsequent increased urination often means there is an underlying medical problem, if your animal is not on a medication such as prednisone. Also, a change in urinary habits, such as urinating in the house or where the pet sleeps, increased urge to urinate, or very dilute urine needs to be evaluated as soon as possible.
Diet and environment will cause small differences in water requirements, but an average daily intake for dogs and cats should be about 30ml per pound per 24 hours.* For reference, 30ml is approximately 1 fluid ounce. Some of this daily intake of fluid will be found in food, too, especially with a moist diet.
Puppies and kittens have a higher fluid requirement. If you notice a change in your pet's fluid intake (and subsequent increased urine output or increased urinary accidents) call your veterinarian for an examination.
One exception for urinary accidents would be a senior pet with dementia (disoriented, forgetting housetraining), but other more common medical conditions must be ruled out first.
* Textbook of Veterinary Internal Medicine, Vol 1, Ettinger
