Describe why water is important for life
NOVA: Life's Little Essential (Water)! - PBS
The following table lists some of the characteristics of water that explain why water is important for life and for animal biology (including human biology) in particular.
Why is water vital to life? - HowStuffWorks
The precise amount of water consumption per individual depends on the level of activity, temperature, humidity and other factors. It is advised to drink approximately 8-10 glasses of water (2 liters) a day for a normal person. An article in About Nutrition called: "Hydration: Fluids for Life" has some very interesting data on why Water is important for Life.