http://www.newsweek.com/newsweek-com-how-much-water-body-actually-needs-1761727

Water makes up over half of your body weight, and insufficient water intake is a risk factor for heat stroke, kidney disease and heart failure. And yet for something so essential it is hard to quantify exactly how much of it we need every day.

Now, researchers from an international research team have developed an equation to predict how much water our bodies actually use and, by extension, how much we really need to consume.