We could not function without water. 
It helps to detoxify the body effectively and is essential for all your body's vital organs to work well. 

Water is one of the secrets of having healthy skin. However the body does not always store water in the right place. If you suffer from unexplained puffiness or bloating especially on your arms, around your eyes on your abdomen or if your fingers or ankles swell you may be suffering from water retention. Other common signs are dry skin, dandruff, sudden fluctuations in weight. How can you have dry skin and yet have water retention? The answer lies in your bodys fats. Your body is made up of 2/3 water and your body cells have a membrane made of special essential fats that keeps the right amount of water in and outside of your cells. These essential fats help eliminate water in the wrong places as well as rehydrating your skin.

The main reasons for water retention are
Lack of essential fats
Too much sugar in the body
Too much salt in the body
Allergic reactions to food