I'm very excited and happy to read this:

“Also, keep in mind you don't have to limit yourself to water. You can drink highly diluted fruit juice, herbal tea, or a well-watered-down sports drink. Sparkling water with a little fruit juice or lemon is also nice. All of these count toward your 64 ounces a day. Drinks like cola, though, work against the count, because caffeine is a diuretic and removes fluid from the body. Three cups of coffee or tea are comparable to just two cups of water."
(source: Dr. Andrew Weil, Mar. 05, 1997 issue of “Wired News,” http://www.wired.com)

I've been wondering if I could drink 4 16-oz cups of decaffeinated herbal tea and 4 glasses of water and get the same nutritional benefits as 8 glasses of water!

Although, the guy does seem to have some sort of hidden agenda:

"While you're doing all this drinking, make sure you're not adding new toxins to your body. Drink high-quality bottled water or, better, get a water-purification system for your home.”

Oh come on.