Most people do not get enough water. Water is vital for the function of the kidneys that purify the blood. When the body does not get enough water some of the load is shifted to the liver. The liver's main function is to metabolize the body's fat for energy. If it is busy doing the kidney's job, you are not burning off fat! (Not to mention all the other benefits of a well hydrated body!)
Some recommend drinking 8 glasses of water each day, but that is the amount of water it takes for a sedentary 128 pounds person to stay hydrated. If you are bigger or more active, you will need more water to take care of your body's needs. (Makes sense to me!)
An easy way to figure out the minimum amount of water you need is to divided your weight (in pounds) by 2 and drink that many ounces of water daily.
Example: A 180 pound person would need a minimum of 90 ounces of water to stay hydrated daily.