All the people think that they are familiar with . Water is the source of life and is one of the necessary conditions for us to survive on the earth. In fact, we are not so familiar with water. Many truths of water are not known at all by many people. These truths are really appalling.

It is a common habit for many people to drink a cup of tap water after getting up. In fact, it is rather harmful to the health. The tap water has been stayed in the tap and water pipe for a whole night. During the night, chemical reactions can take place between the water and the metal pipe and tap. That is to say metal can pollute the tap water. In addition, a large number of microorganisms left in the tap water enable to propagate and produce a kind of contagious virus in the water which can also extremely hurt the human health. Therefore, the first several cups of tap water in the morning should not be drunk.

Many people think it is beneficial to the human health to drink salt eater in the morning. In fact, it is not absolutely right. It can not be neglected that to drink salt water is helpful to maintain healthy and supplement moisture lost by sweating. However, it is rather dangerous to drink salt water in the morning. During the sleep, people drink nothing, but physiological activities like sweating, breathing and urinating still conduct. When people get up in the morning, the blood has become concentrated. When people drink some plain boiled water at this time, the concentrated blood can be diluted and high permeability dehydration at night can be corrected. However, to drink salt water in the morning can worsen the high permeability dehydration. In addition, the human blood pressure is high in the morning, and salt water can make the blood pressure higher, which is rather harmful to the human health.

Long-placed boiled water should not be drunk any more. If the boiled water is placed aside for a long time, the organic substance containing nitrogen will be decomposed into nitrite. In addition, a large number of bacteria can be produced in long-placed boiled water. If people drink long-placed boiled water, nitrite can be integrated with hemoglobin inside the human body to affect the capacity of carrying oxygen of the blood. In addition, the boiled water should not be boiled for another time. Therefore, people should drink the just-for-once boiled water which is not placed for more than 24 hours.

In order to keep healthy, people should get rid of all the bad habits about water in everyday life, as the relationship of water and health is rather close.