The best time to drink water, including the morning, about 30 minutes before three meals and before going to bed, and other time periods can drink water according to demand. Water is an important substance to maintain the function of the body, can promote the metabolism and absorption of food, maintain the stability of the internal environment, is a necessary substance for cellular metabolic activities. A glass of water in the morning can play a laxative, improve the role of blood viscosity. Drinking a small amount of water about 30 minutes before a meal can increase the secretion of gastric acid, which helps the digestion and absorption of food. But it should be noted that immediately after eating should not drink a lot of water, so as not to dilute the stomach acid affect food digestion. Drinking water at night must pay attention to a small amount, so as not to cause increased night urination affect sleep. Patients with underlying heart and kidney disease are not recommended to drink excessive amounts of water to avoid water and sodium retention, swelling, induced electrolyte disorders, heart failure, etc.