Hello:
You drink as much as you would like, typically you would drink approximately 6 to 8 glasses of pure water per day, the same applies for the juice fast, or you can drink more if you desire it.
I also include pure water in between, and herbal teas such as peppermint tea for any stomach upset...

Hope this helps, enjoy!

I found the following from http://www.cureyourself.net/2011/03/dr-richard-shulze-juice-fasting.html
on Juice fasting
SCHULZE: The first thing an animal does when it is sick is stop eating. They fast themselves. Likewise, the first thing we need to do when we don't feel well is: stop food. There are a lot of reasons for that. Food takes a tremendous amount of energy to digest--and that's blood and energy. Our digestive system, basically the muscles and the tissues, fill with blood. When you stop eating, your digestive system rests, and all that blood and energy can be put somewhere else to heal you.

People have said to me, "What do I do for this particular disease?" Juice fasting. "What do I do for degeneration?" Juice fasting. "What do I do for heart disease?" Juice fasting.

Juice fasting is for the incurables. Juice fasting is the answer, because it allows your body to rest - and it lets your body choose what it wants to heal.

If you just keep cramming food down your mouth, you'll just get more tired. Your body has to digest large amounts of food, and it's the opposite of what you should do when you're not well.

"One of my first patients had lost a tremendous amount of blood from surgery--and doctors wanted to do a transfusion. In 24 hours on juices, I brought her blood levels back up."...... For the rest of the article and more visit the link below

http://www.cureyourself.net/2011/03/dr-richard-shulze-juice-fasting.html