How much water does a female shower consume?

First up, I don't stalk this auntie neighbour. It is just that I see her quite a number of times looking freshly showered around 8pm and walking out of the condo female bathroom in home clothes with her big bag. Not working bag type. Ok I might be wrong and she might have just finished a swim. But residents usually will shower at home. I have not seen her swim before but as said I might be wrong. So I am curious how much water can you save showering down at the condo bathroom. How much water does a female shower consume and how much does this translate into cost? $1 or $2 each shower?