Water is an essential nutrient our body depends upon for optimal health and fitness. It keeps us hydrated and assists with vital processes at every level of functioning in the human body. The human body is made up of over 60 percent water. Research continues to report positive findings on why drinking plenty of water every day is essential to good health. Our bodies need water to maintain hydration, digestive, heart, and lung function, joint lubrication, protection of tissues, regulation of body temperature, and much more.