Staying hydrated is an important part of life. It's also important to building muscle. As mentioned, I've read about the 1 gallon water challenge. As much as I like drinking water, 1 gallon of the same liquid is too much for me. I drink a lot of Green Tea, I drink it hot and cold, as use it as a way to stay hydrated during the day.
Green Tea has been called the "Healthiest Drink in the World". It has a lot of amazing health benefits. Here's a great list: