it's supposed to be one 12 oz glass of water per drink. If I find that to be hard to do. Any more than 4 beers I'll have at least 1 glass of water. I'll even sometimes drink some water while I'm drinking, I've never had a problem doing that. If your stomach is upset, there's nothing you can do about it anyway. Drink as much water as you can stand before you go to sleep. It helps. Drink water the next morning, then go have a breakfast/lunch that has a liberal amount of grease. Hashbrowns, eggs, pancakes and bacon or sausage is a great recovery aid along with a big glass of OJ. If you wake up late enough, anything with french fries, or pizza is wonderful. This to me, is almost as important as the water the night before. The food soaks up any alcohol that is left in your stomach, and I always feel alot better after I eat.