Charlie drinks much more freely than any other cat I've owned - enough that I mentioned it to the vet. She merely checked that it was something he always did, and hadn't suddenly started doing, but seemed otherwise unconcerned, outlining the same reasons as Ian. She also speculated that if he keeps up the habit, it might ease any kidney issues later in life.
As long as you grant free access to water, she'll probably drink (or not drink) exactly as she needs. We put trays of water around the garden for all comers, and keep them topped up with fresh water. A scald with boiling every few days gets rid of algae and skeeter larvae. Charlie will hoover great laps of it once or twice a day. His diet is the usual mix of wet food and crunchies, along with whatever squeaky crunchy wildlife he's managed to butcher along the way. I'm not sure whether frogs count as food or drink, but it didn't really stay down long enough to count...
