Cats drink alot of water because their tongues are always dry and once they get wet, in a few seconds their tongue is dry all over but their stomach is still digesting the water.
There are a few reasons why it might.
A change in food may have more salt and therefore increase the cats need for water.
Cat can develop diabetes which shows as excessive urination and water intake ravenous appetite and weight loss. Seek veterinary care if these signs are noticed.
Hyperthyroidism : The most common signs of hyperthyroidism are weight loss, increased appetite, increased thirst and urination. Hyperthyroidism can also cause vomiting, diarrhea, and hyperactivity. The cat fur or coat may appear matted or greasy. Again, testing can confirm this so seek veterinarian assistance.