Bless Ruth, she found the coke part on Snopes (I missed it because the title was about Coke being like acid...I was looking for "Coke and Water"...):
Another friend sent me the link for the water...though I have to say that I think they addressed more the question "Should I drink 8 glasses of water a day?" than checking out the specific claims in the e-mail. I've heard the "drink when you're thirsty" thing before...but what if it's true about our inability to notice thirst? We've talked in here before about thinking that we're hungry but finding, after drinking some water, that the feeling goes away. We were actually thirsty! Personally, I feel thirsty all the time, so I'm sticking with my water.
I do believe I've heard that, over time, drinking any kind of soda often will result in calcium loss. They didn't address that part in the Snopes article.
Either way, we know that it's better to drink water than soda...not that I don't enjoy a diet coke now and then!