Drinking water in moderation is good for health, too much drinking water, may aggravate the burden on the kidneys and the heart and so on. Water is an important solute for various physiological and biochemical processes in the body, to ensure a certain intake of water is a prerequisite for health. Under normal circumstances, the human body needs to consume about 1500-1700 milliliters of water per day to ensure adequate urine. When the body is dehydrated or lose water too quickly in the environment, drink more water is good to have the benefit. For example, hot summer, sweltering factory workers, need to hydrate, while adding electrolytes, such as potassium, sodium, chlorine and other electrolytes as appropriate. Patients with physical disease, according to the actual conditions to choose whether to drink more water, such as heart failure, liver, kidney disease, has appeared in the limbs of the swelling, if too much water, it will lead to a large amount of water retention, may cause hypertension, heart failure, pulmonary edema and other serious consequences. In short, the principle of how much water to drink is to ensure adequate urine output without significant water retention.