Water is an essential and indispensable substance for human survival. A person can go without food for a day, but not without water for a day. However, not all water is drinkable. The following five types of water, to some extent, can form nitrites and other toxic and harmful substances, which can pose certain hazards to the human body and therefore require people's attention.
One, Stagnant Water: Also known as "dead water," it is water that has been stored for a long time without moving. Drinking this water often can significantly slow down the metabolism of cells in minors, affecting physical development; for middle-aged and elderly people, it can accelerate aging. In many places, the incidence of esophageal and stomach cancer is increasing daily. According to research by medical scientists, this may be related to long-term consumption of stagnant water. Relevant data shows that the toxic substances in stagnant water also increase with the storage time.
Two, Re-boiled Water: Re-boiled water is water that has been boiling on a stove all night or for a long time, as well as water in an electric water heater that has been boiled repeatedly. Because it has been boiled for too long, this water has high levels of non-volatile substances, such as heavy metal components like calcium and magnesium, and high nitrite content. Drinking this water for a long time can interfere with human gastrointestinal function, causing temporary diarrhea and bloating; toxic nitrites can also cause hypoxia in the body, and in severe cases, can lead to coma, convulsions, and even death.
Three, Steamer Water: Steamer water is the leftover water from cooking steamed buns, especially steamer water that has been used repeatedly. The nitrite concentration in this water is very high. Drinking this water often or using it to cook porridge can cause nitrite poisoning; scale often enters the human body with the water, which can also cause digestive, nervous, urinary, and hematopoietic system diseases, and even cause premature aging.
Four, Unboiled Water: The tap water people drink is sterilized by chlorination. Chlorinated water can separate 13 harmful substances, of which halogenated hydrocarbons and chloroform also have carcinogenic and teratogenic effects. When the water temperature reaches 90°C, the content of halogenated hydrocarbons increases from 53 micrograms per kilogram to 177 micrograms, which is twice the national drinking water hygiene standard. Experts point out that drinking unboiled water increases the possibility of developing bladder cancer and rectal cancer by 21% to 38%. When the water temperature reaches 100°C, these two harmful substances will greatly reduce with the evaporation of steam. If boiled for another 3 minutes, it is safe to drink.
Five, Re-boiled Water: Some people are in the habit of re-boiling the remaining warm water from a thermos to drink, with the purpose of saving water, coal (gas), and time. However, this kind of "saving" is not advisable. Because the water is boiled again, the water evaporates again, and the nitrite level rises. Drinking this water often can cause nitrites to accumulate in the body, leading to poisoning.