Drinking water – hot or cold, plain or infused with fruits – can help keep you hydrated. It is a vital part of digesting, absorbing and transporting nutrients, which is crucial for good overall health. Ignoring that fact can make you sick. About 80 percent of the human body is water. People are dehydrated when it has lost more fluid than it’s taken in, usually about 2 percent, resulting in not having enough water to allow it to perform at optimal level.