I have read an article about Dr. Wu who had rid himself of cancer after taking vegetarian diet, and one of the things he said was to drink a lot of water in the correct way. He said we need to drink water depending on specific situations. For example, if your work involves a lot of walking or doing heavy-labored tasks, you have to drink 8-10 glasses a day. If you will be soaked under the hot summer sun, you need to drink 10-12 glasses. And if your office is air-conditioned, 6 glasses of water is enough.
He also mentioned about the importance of sipping to drinking the whole glass of water all at once. He said that sipping water little by little gives your body cells time to absorb water.