A lot of water is probably not a good thing while fasting.
The easiest fasts I ever done were dry fasts. The hardest was with a lot of water.
However since I got a kidney stone after dry fasting (I have no 100% proof it's correlated but it was close to a fast and it never happened before or after) I now drink a little bit of water while fasting (something like 300 ml per day, I do several days fasts, not intermittent).