Water needs vary on a fast vary from person to person, but a generally accurate guide by many is to drink according to thirst, and thirst only. Excess water only serves to overload the kidneys and inhibits if not prevents detox altogether. Quite a bit of our water needs on a fast are met by the breakdown of adipose tissue, where much water is stored. Any excess though is seen as harmful, whether this be food (obesity) or air (hyperventilation) or whatever.
Well done on your fast, and I hope you feel all the better for it.