Just like humans, about two-thirds of a cat’s body is made up of water. Cats need a healthy amount of water to survive and to maintain their health. When living in the wild, they obtain water from the moisture content in their food. This includes prey like insects, birds, and rodents, which also contain a high water content. Your domestic cat has a very different diet, and gets her water delivered in a bowl or through wet food.
Dehydration
Because cats can concentrate their urine, they can survive on smaller quantities of water than other animals. But they also have a low thirst drive, which means that they don’t feel the need to drink water very often. If your cat is dehydrated, you may not know it until she develops a problem. Dehydration can lead to cat bladder problems and urinary diseases, including kidney disease and feline lower urinary tract disease. Other common conditions from dehydration are bladder inflammation (cystitis), tumors, ruptured bladder, and stones. Bladder stones can lead to life-threatening urethral blockages, particularly in male cats.

There are a few ways you can tell if your cat is dehydrated. One of the best tests is to pinch your cat’s skin and gently pull upward. If her skin does not return to its normal position quickly, she is probably dehydrated. Also pay attention to signs of panting, depression, lack of appetite, sunken eyes, dry mouth, increased lethargy, and increased heart rate.