Cats typically can survive without water for about three to four days, but they begin to become dehydrated within 24 hours. Dehydration in cats can quickly lead to stress on the organs, potentially causing severe complications like organ failure. The exact duration depends on factors like the cat's age, health, body weight, and environmental conditions such as temperature. Kittens and senior cats are more vulnerable and can deteriorate faster without water. If a cat is not drinking water for more than 24 hours, it is crucial to seek veterinary care as soon as possible to prevent serious health issues.