Is it harmful to boil water repeatedly?

Some people live very frugally and are reluctant to throw away even some water, and would choose to reuse it. In fact, some scientific evidence has shown that boiled water cannot be reused, because boiling warm water again may produce some chemical substances that have a certain impact on your health. If you drink such water for a long time, you will experience reactions such as panic, so we must be careful not to boil the water repeatedly.

What are the dangers of boiling water repeatedly?

One situation is that the water is boiled, then heated again after it cools down, and then boiled again. If it is boiled once or twice, there will be no safety issues. But sometimes with an automatic heating kettle (water dispenser), as long as the temperature drops to a certain level, it will automatically reheat. If the water in the water heater is heated repeatedly for more than ten hours or several days (some people call it "thousand-boiled water") without being replaced, the water may contain higher levels of health hazards, such as harmful substances dissolved from the heating elements and containers, and some trace harmful substances contained in the raw water will also accumulate and increase.

Points to note when boiling water

1. When the water is about to boil (80℃-90℃), the lid of the kettle should be opened. Because there are more and more organic pollutants in the water now, some substances are volatile and will evaporate with the water vapor when heated. Therefore, when boiling water at home, you should open the lid of the kettle when the water is about to boil. This will allow the unhealthy substances in the water to evaporate to the maximum extent, so that people will be healthier when drinking it.

2. After the water boils, wait for about 3 minutes before turning off the heat. This is because ordinary river water must be chlorinated after being sent to the water plant to remove impurities such as microorganisms. But at the same time, chlorine interacts with residual organic matter in the water to form toxic and carcinogenic compounds such as halogenated hydrocarbons and chloroform. The content of halogenated hydrocarbons and chloroform is closely related to the change of water temperature and the duration of boiling. When the water temperature reached 90°C, the content of halogenated hydrocarbons increased from 53 micrograms per liter to 191 micrograms, and the content of chloroform increased from 43.8 micrograms per liter to 177 micrograms, both exceeding the national standard by twice. when. When the water temperature rose to 100°C, the contents of halogenated hydrocarbons and chloroform dropped to 110 micrograms and 99 micrograms respectively, which still exceeded the national standard. If boiling continues for 3 minutes, the halogenated hydrocarbons and chloroform contents drop to 9.2 micrograms and 8.3 micrograms respectively, at which point the water becomes safe drinking water.

Therefore, boiling water for a longer time is not good, because if you boil it for a long time, the harmful substances and nitrites in the water will begin to concentrate due to the evaporation of water, and the longer the water is boiled, the higher the content of harmful substances and nitrites will be. Drinking such water will cause certain harm to the body.