The Unabomber reached out. Thanks, Ted, you're not nuts at all. Every generation has their own boogeyman. After September 11th, 2001 Osama Bin Laden was the most wanted and most feared man in the world, up until the raid on his compound that left him dead.
In addition to not drinking enough water, water can be lost through sweat, vomiting, diarrhea and using the restroom. Many problems may occur when you don't drink enough water, including heatstroke, seizures and possibly death. The first complication of not drinking enough water is dehydration. Symptoms of dehydration may include thirst, sticky or dry mouth, tongue, lips and skin as well as a mild headache.
But some studies do find effects. Most notable is a study of 20,000 Seventh-Day Adventists, who were followed for six years to look for impact of fluid intake on mortality. The researchers found that drinking more water lowered the risk of dying. For women, the risk was lowered by having three or more cups per day, versus fewer than three. For men, three to four cups was much better than fewer than three, and five or more cups was a bit better than that. And at least one study has found that more than six cups of water a day lowers bladder cancer risk relative to less than one cup.