Water makes up at least two-thirds of the human body. It plays a large part in your normal functions, such as lubricating your joints and eyes, keeping your skin healthy by eliminating toxins, and facilitating proper digestion. Once the water in your body is reduced, it needs to be replaced because an imbalance between the salts and sugar in your body can affect the way you will perform.
Chronic dehydration may affect your organs and lead to kidney stones, cholesterol problems, constipation, and liver, joint, and muscle damage.
Chronic internal dehydration means that your body does not have enough fluids to function properly. Basically the symptoms of dehydration can be pretty mild if it is caught early on but when the internal organs become chronically dehydrated, the symptoms can lead to all sorts of health problems. (Source:mercola.com)