REF:https://www.usgs.gov/special-topic/water-science-school/science/water-you-water-and-human-body?qt-science_center_objects=0#qt-science_center_objects The Water in You: Water and the Human Body ​​​​​​​Water serves a number of essential functions to keep us all going Think of what you need to survive, really just survive. Food? Water? Air? Facebook? Naturally, I'm going to concentrate on water here. Water is of major importance to all living things; in some organisms, up to 90% of their body weight comes from water. Up to 60% of the human adult body is water. According to H.H. Mitchell, Journal of Biological Chemistry 158, the brain and heart are composed of 73% water, and the lungs are about 83% water. The skin contains 64% water, muscles and kidneys are 79%, and even the bones are watery: 31%. Each day humans must consume a certain amount of water to survive. Of course, this varies according to age and gender, and also by where someone lives. Generally, an adult male needs about 3 liters (3.2 quarts) per day while an adult female needs about 2.2 liters (2.3 quarts) per day. All of the water a person needs does not have to come from drinking liquids, as some of this water is contained in the food we eat. Water serves a number of essential functions to keep us all going A vital nutrient to the life of every cell, acts first as a building material. It regulates our internal body temperature by sweating and respiration The carbohydrates and proteins that our bodies use as food are metabolized and transported by water in the bloodstream; It assists in flushing waste mainly through urination acts as a shock absorber for brain, spinal cord, and fetus forms saliva lubricates joints