I have a friend who is a doctor who read a media article on the first of the studies mentioned in Myths about Water. His response to it was, see, we don't have to drink water.
According to these articles and the reviews of the research, however, that is not what the articles said. One did say that any kind of fluid was useful for getting hydrated. The other said that if the drink is up to 2% alcohol, there is no difference in rehydration. However, if the drink is 4% or more alcohol, rehydration is delayed. (Which I guess means you have to drink more alcohol.)
I thought it was interesting that the NELH couldn't find the research from the Univ of Mex.
I found an online description of his work at What Really Works in a cached file. This article says he did research on over 800 elderly people and found that those who drank fewer than four glasses a day were not dehydrated, based on standard dehydration markers.
Healthwise at laterlife.com says that the study found no evidence that water helps boost the immune system or detoxify the body.
Neither article said how the research was conducted, which I would have liked to have known.
However, what I have found for myself is that I pee more when I drink more water. While that isn't always fun, I don't worry about holding impurities and trash in my body.
Porter Freeman, from BFL, says that in your urine you want to go for the silver, not the gold. If your urine is yellow, it's very concentrated. If it's not, there's a lot more water going through your system.
Anyway, thought you might want to know. Basically, the articles said DRINK, but you don't have to drink water.