Because the water that has been boiled for a long time has been boiled many times.

Some people call this kind of water boiled water, which refers to the water repeatedly heated in a drinking machine or kettle. Generally speaking, the content of nitrite in this water will be higher. A large amount of nitrite can directly poison people, because nitrite reacts with human blood to produce methemoglobin, which makes blood lose its oxygen-carrying function and makes people suffer from hypoxia poisoning. Although the content of nitrite in boiled water is not so high, when nitrite reaches a certain dose in human body, it has carcinogenic, teratogenic and mutagenic effects, which can seriously endanger human health. Therefore, try not to boil water repeatedly. It is also best to "burn hot water as you drink it" in the water dispenser, and don't keep it in a state of "heating-insulation" all the time.

But twice is not too much, and repeated burning is not enough. Low oxygen content, water will harden because it burns for too long, which is not good for people and is easy to cause diseases such as stones.

Can boiling water be boiled twice? 20 points

Boiled water can be boiled twice. But many things are relative. Drinking secondary heated boiled water with different water quality has different effects on people's health;

1, the second heating of boiling water is the concentration of water, which will increase the hardness of non-carbonate in water, and the content of some elements harmful to human body may increase due to concentration, so drinking this may have adverse effects on human body. Too many people say that "thousands of boiling water" can't be drunk, which is the reason.

2. In some areas, the temporary hardness of tap water is relatively high. After drinking normal boiled water, the incidence of stones is relatively high. Calcium and magnesium ions can be precipitated by heating once, which is equivalent to special treatment of water.

In the past, the water in my mining area was temporarily hard, and the way that the water treatment engineer came up with was to heat the drinking water. Most people will leave a lot of scale in the kettle when they drink this kind of secondary boiling water.

Can the water be boiled twice?

No, you must not drink these five kinds of water. What you said belongs to the fifth category. You can't drink boiled water any more.

Water is an indispensable and important substance for human survival. People can eat nothing for a day, but they can't drink water for a day. However, not all water can be drunk. The following five kinds of water will form toxic and harmful substances such as nitrite to a certain extent, which will cause certain harm to human body, so people should pay attention to it.

First, aged water: commonly known as "stagnant water", that is, water that cannot be stored for a long time. Drinking this kind of water often will obviously slow down cell metabolism for minors and affect the growth and development of the body; Middle-aged and elderly people will accelerate aging; The incidence of esophageal cancer and gastric cancer is increasing in many places. According to the research of medical scientists, this may be related to drinking aged water for a long time. Relevant data show that the toxic substances in aging water also increase with the increase of water storage time.

2. Thousands of boiling water: Thousands of boiling water refers to the water that has been boiled on the stove for a night or a long time, and the water that has been repeatedly boiled in the electric water heater. Because this kind of water takes a long time to boil, the content of heavy metals such as calcium and magnesium and non-volatile substances such as nitrite in the water is high. Drinking this water for a long time will interfere with people's gastrointestinal function and cause temporary diarrhea and bloating; Toxic nitrite can also cause hypoxia in the body, which can cause coma, convulsion and even death in severe cases.

Third, boiler water: boiler water is leftover boiler water such as buns, especially boiler water that has been reused many times, and the nitrite concentration is very high. Drinking this water often, or cooking porridge with this water, will cause nitrite poisoning; Scale often enters the human body with water, and it can also cause digestive, neurological, urinary and hematopoietic diseases, and even cause premature aging.

Fourth, the water that can't be boiled: the tap water that people drink is chlorinated and sterilized. 13 A variety of harmful substances can be separated from chlorine-treated water, among which halogenated hydrocarbons and chloroform also have carcinogenic and teratogenic effects. When the water temperature reaches 90℃, the content of halogenated hydrocarbons increases from 53 micrograms per kilogram to 177 micrograms, which is twice as high as the national sanitary standard for drinking water. Experts point out that drinking raw water increases the possibility of bladder cancer and rectal cancer by 2 1%-38%. When the water temperature reaches 100℃, these two harmful substances will be greatly reduced with the evaporation of steam. If boiling lasts for 3 minutes, it is safe to drink.

5. Boil water again: Some people are used to boiling the remaining warm water in thermos bottles before drinking, in order to save water, coal (gas) and time. But this "saving" is not enough. Because water burns and evaporates, nitrite will rise. If you drink this water regularly, nitrite will accumulate in the body and cause poisoning.

Can boiling water be boiled twice?

Try not to boil water many times when it is unnecessary.

The purpose of boiling water is to burn the water to the boiling temperature of 100 degrees Celsius, so as to kill viruses or germs harmful to human body.

However, if heated repeatedly, a large number of trace minerals beneficial to human body will be precipitated in the water, and part of the salt will be converted into nitrite harmful to human body.

Can boiling water be boiled repeatedly?

If normal water is boiled repeatedly, nitrate in the water will be converted into nitrite, which will turn hemoglobin in the human body into nitrite hemoglobin, making red blood cells lose their oxygen-carrying function.

Therefore, if you drink boiled water repeatedly, it may cause tissue hypoxia, shortness of breath, chest tightness, purple lips and nails, or easy to fall asleep. If it is more serious, "nitrite" may be transformed into carcinogen "nitrosamine" after it enters the body through the action of gastric acid.

In view of this, when you drink these repeatedly boiled water, you must remember that it will have a negative impact on your health.

Can boiled water be boiled many times?

No, if the water is boiled repeatedly, the nitrate in the water will be converted into nitrite, and nitrite will turn the hemoglobin in the human body into nitrite hemoglobin, making the red blood cells lose their oxygen-carrying function.

Therefore, if you drink boiled water repeatedly, it may cause tissue hypoxia, shortness of breath, chest tightness, purple lips and nails, or easy to fall asleep. If it is more serious, "nitrite" can be converted into carcinogen "nitrosamine" by gastric acid after entering the body.

In view of this, when you drink these repeatedly boiled water, you must remember that it will have a negative impact on your health.

Can boiled water be drunk repeatedly?

won't.

Why can't I drink water that has been boiled repeatedly? There are different opinions about the reasons. To sum up, there are about three kinds. One is that after the water is boiled for many times, all dissolved oxygen in the water runs away, and drinking oxygen-deficient water is not good for your health. We humans are not fish. We don't absorb oxygen from water, but through breathing.

There is also a saying that if boiled for too long, the scale will dissolve into the water, and the concentration of heavy metals such as calcium and magnesium in the water will increase, making the water hard, which is not good for the health.

If you drink pure water, distilled water and deionized water, it basically contains no impurities. No matter how you burn it, water is still water and will not become other substances. However, drinking water may contain trace harmful substances. Some of these harmful substances are volatile, and repeated boiling will help to remove them. However, some harmful substances are not volatile, such as heavy metals and nitrates. The third reason that the repeatedly boiled water can't be drunk is that after the water is repeatedly boiled, the water evaporates and the nonvolatile harmful substances remain, which makes the concentration of harmful substances increase and is harmful to human body.

It is impossible to boil water many times in daily life, but there is only one situation: the heating of the water dispenser is always on, and it is automatically heated every 20 minutes or so. The bottled water used in drinking fountains is purified, and the amount of nitrite produced after repeated heating is very limited. In the above experiment, after heating 18 1 time, the content of nitrite in water rose to 3.53 μ g/L, which exceeded the hygienic standard of bottled water (2 μ g/L), but it was not too much, which was serious enough to cause poisoning. According to the calculation of sodium nitrite, people have to eat about 0.2 grams to have poisoning symptoms, which is equivalent to drinking dozens of liters of this water. Moreover, the water in the water dispenser is flowing and will be taken away for drinking, and the nitrite content will not be as high as the experimental results.

In fact, nitrite is often encountered in daily diet. As a legal preservative and colorant, sodium nitrite is widely used in meat products. Even in meat products that do not exceed the standard, the content of sodium nitrite can reach 0.03 grams per kilogram, which is more worrying than nitrite in water, if nitrite is really so terrible. Can long-term intake of trace nitrite cause cancer? Nitrite is not a carcinogen, but it reacts with amino acids to form amine nitrite, and a small amount of nitrite is harmless to human body.

Don't believe even the common sense of life in middle school textbooks, which is almost impossible to meet in daily life. Boiling water several times will not do any harm to your health. If you are worried that the nitrite will exceed the standard if the water dispenser is repeatedly heated for dozens or hundreds of times, there are simple ways to avoid it: don't always turn on the heater of the water dispenser, only turn it on when you need to drink it, or simply drink cold water (bottled water can be drunk directly), which is energy-saving and environmentally friendly.

Can't boiling water be boiled twice?

No, boiling water repeatedly increases the concentration of harmful substances such as silver nitrite, nitrite ion and arsenic in water. Drinking boiled water for a long time will lead to the combination of low iron hemoglobin in the blood into methemoglobin which can not carry oxygen, thus causing blood poisoning.

Can you still drink boiled water after several times?

Yes, you can.

After repeated heating in boiling water, it was found that the nitrite content did increase with the increase of heating times. After repeated heating for 52 times, the nitrite content in the water is 2.3 μ g/L, and after heating to 18 1 time, the nitrite ion content in the water is 3.53 μ g/l, which is five times higher than that at the beginning. Don't panic when you see this "five times higher". Although this figure exceeds the hygienic standard of drinking water in China, it is still safe. The nitrite content in ham sausage that many people like to eat is much higher than this: the allowable dosage of nitrite in qualified ham sausage is 30000 micrograms (30 milligrams) per kilogram.

Ham is still safe, not to mention nitrite in the water. Generally speaking, there is not much water in the ordinary electric kettle at home, and it will be burned after heating for several times, so it is safe to burn boiled water for many times.

Can I still drink water after boiling it twice?

When water is boiled for the second time, it will decompose some chemicals harmful to health. You'd better not drink it. Of course, drinking it doesn't matter much. Many people drink it.