For most people, drinking water is an unremarkable daily habit. In ancient China, however, it carried far greater meaning. Water was bound up with social rank, health beliefs, ritual practice and etiquette. As early as the pre-Qin period (Paleolithic Period – 221 BC), Chinese thinkers were already classifying natural water. The ancient encyclopedic text Master Lü’s Spring and Autumn Annals claimed that “heavy water”, rich in minerals, could cause swelling in the legs and feet, while “light...