
It would be worth getting a measure of how much she's drinking in a day, if at all possible - chances are the vet will ask, if it looks like a significant increase.
I say if possible - I tried once with Remy as he's seemed to drink a LOT for a few years (I know now he drinks normal amounts, but not often so has a lot in one go) - but in a house with 8 dogs it was flippin hard work :-P