As far as water consumption goes I feel the difference between drinking one liter or four liter per day. I just feel much better with four liter.
There were times two years ago when unless I had drunk 4 liter by the time I entered my Salsa dancing location in the evening, my muscle coordination was worse and the dancing didn't flow well.
Does that mean that everyone has to drink 4 liters to be at his optimum? No, it doesn't. Get a feel how different amounts of water consumption effect you. For me the effect was clear to see without even needing to do QS. Even it's not as clear for you do QS.