Nothing refreshes like an ice-cold glass of water on a hot summer day.
Water replenishes the body's cooling system, enabling it to survive sweltering heat or elevated body temperatures due to exercise. Sweating cools the body by evaporating water on the surface of the skin and dispersing excess heat. But until the tap runs dry, most people take water for granted. Although deficiencies of other nutrients can be sustained for months or even years, a person can survive only a few days without water. Indeed, experts rank water second only to oxygen as essential for life.