Caffeine consumption and drinking water

I may be the only person who didn't know this but I thought I would post it for others. I just read in Jillian Michaels book, "Making the Cut" that we should drink 8 oz of extra water for every caffeinated beverage that we consume. (I drink 4 cups of coffee every morning-it's a vice that I wasn't willing to give up, but as I'm typing I realize that I can switch to decaf.) I realize that I'm really dehydrated due to struggling to drink 8 glasses a day and not drinking extra for the coffee consumption.:drinker: