The amount varies so much that your request in nonsensical. Hiking in S. Arizona, 5 quarts has proven inadequate for me(and others) on several occasions, while hiking in moister, higher humidity conditions (So Cal Channel Islands) I have often consumed less that one quart.

And the question arises, what if you are delayed for any reason? Just as you should have the means of starting fire, in many situations, you should always have extra water. This relates to the amount of water available in your situation.

The speed and intensity at which you are hiking, as well as the weight of what you are carrying, will also profoundly influence the required amount of H2O.