Many people may take drinking water for granted, but keeping hydrated can have a huge impact on overall health. Despite how crucial it is that people drink enough water, a significant amount of people may be failing to drink recommended levels of fluids each day. Around of 70% of the body is comprised of water, and around of 71% of the planet's surface is covered by water. Perhaps it is the ubiquitous nature of water that means that drinking enough of it each day is not at the top of many people's lists of healthy priorities? How much water should you drink? According to the Institute of Medicine (IOM), an adequate intake for men is approximately 13 cups (3 liters) a day. For women, an adequate intake is around 9 cups (2.2 liters).