Water makes up more than two thirds of human body weight, and without water, we would die in a few days. The human brain is made up of 95% water, blood is 82% and lungs 90%. A mere 2% drop in our body's water supply can trigger signs of dehydration: fuzzy short-term memory, trouble with basic math, and difficulty focusing on smaller print, such as a computer screen. Mild dehydration is also one of the most common causes of daytime fatigue. An estimated seventy-five percent of Americans have mild, chronic dehydration. Sobering statictics for a country like the United States, where water is readily available through the tap or bottle water.