(Get it? The title is a play on the movie title, Water for Elephants.)
Cats are known to drink very little water compared to many other animals. The sand cat, for example, an adorable wild cat that typically lives among sand dunes in desert areas, does not need water to survive. They reportedly get enough hydration from their diet of birds, hares, reptiles, etc. But our domestic cats are accustomed to having water and it should be available to them at all times.
Some cats don’t drink enough water; they need encouragement to drink. Several bowls of 
fresh water placed in strategic places throughout your house can help. Some cats are fascinated by water fountains and will be enticed to drink more from a fountain. Other will drink more water if you turn on the spigot for them at least occasionally.
Then there are cats who adore water. Olivia likes to jump into the bathtub just after the water has drained and it’s still damp. Winfield, our white odd-eye cat, had a fascination for water. He’d dip a paw in the water and 
lick the droplets off. That’s how he drank. Lily and I had a ritual where every morning I’d turn the bath water on ever so slightly and she’d take a long drink before breakfast.
Cats will drink out of the toilet, so if you 
aren’t trained to perfection when it comes to keeping the lid down, never ever use any of those automatic toilet bowl cleaners.
By the way change your cat’s water often. No need to waste it, just pour it out into a potted plant or the bird bath, wash the bowl and refill. If you have hard water like we do, soak the bowls in vinegar occasionally to remove the deposits.
To the question as to whether to give cats water from the tap or filtered drinking water—according to the sites I visited, most agree that filtered tap water is best. No soft water for sure.
