As a result of extensive research into the role of water in the body, the author, a medical doctor, believes that he has found chronic dehydration to be the cause of many conditions including asthma, allergies, arthritis, angina, migraine headaches, hypertension, raised cholesterol, chronic fatigue syndrome, multiple sclerosis, depression, and diabetes in the elderly.

According to Dr. Batmanghelidj, the body possesses many different thirst signals. A dry mouth is not a reliable indicator of your body''''s water needs. He describes a variety of more reliable ones, and helps you learn to understand when your body is calling for water. In this way, he claims you can prevent, treat, and cure a variety of conditions of ill health, at no cost, with what he calls nature''''s miracle medicine: Water. The author explains how much water one needs to drink a day to stay healthy, and why tea, coffee, and sodas are not good substitutes for water.