Human body water functions include aiding the digestion process, circulation of nutrients and substances across cell membranes, influencing our metabolic rate, and balance of electrolytes, which are controlled much in part through the central nervous system – all of which are under the auspices of the brain.The percentage of water in the human body ranges from 50 to 75% - depending on age and gender – with an average adult having 57 to 60 percent. Mayoclinic.org comments that men need about 1...