It takes 3 minutes for water to boil, because drinking boiled water is easy to get cancer. People in cities drink chlorinated tap water to remove microorganisms and other impurities. However, at the same time, chlorine interacts with the residual organic matter in water, which will form toxic carcinogenic compounds such as halogenated hydrocarbons and chloroform. It is proved that the contents of halogenated hydrocarbons and chloroform are closely related to the change of water temperature and the duration of boiling. When the water temperature reached 90℃, the content of halogenated hydrocarbons increased from 53 μ g per liter to 19 1 μ g, and chloroform increased from 43.8 μ g per liter to 177 μ g, both exceeding the national standard by two times. When the water temperature rose to 100℃, the contents of halogenated hydrocarbons and chloroform decreased to 1 10 μ g and 99 μ g respectively, which still exceeded the national standards. If boiling continues for 3 minutes, the contents of halogenated hydrocarbons and chloroform will be reduced to 9.2 micrograms and 8.3 micrograms respectively, and then they will become safe drinking water. Of course, the longer the boiling water is boiled, the better, because the longer the boiling time is, the nonvolatile harmful substances and nitrite in the water will be concentrated because of the evaporation of water, and the content will be higher. Drinking such water is also harmful to your health. If you are thirsty in summer and need to drink more water, you must add salt, and you must not drink water before and after eating.
You can't drink five kinds of boiled water.
1. It has been burned on the stove for a night or a long time, and it is already warm water when drinking;
2. Boiled water was boiled in the automatic water heater all night;
3. Boiling water remaining after repeated boiling;
4. The water boiled in the thermos is not the water of the day;
5. Boiled water left over from steamed rice and other foods.