Why not boil water twice

Water is one of the most unique substances in nature. It is necessary for man every day. An important factor in its use is purity and the absence of harmful impurities. Poor water quality can be extremely dangerous for the body. Therefore, before applying it is usually filtered, frozen or boiled.

What happens to water when boiling?

Each of us boils water. Some use it as drinking, cooling it further. Most brewed tea. It is often said that water cannot be boiled twice. It is believed that such a liquid becomes dangerous to humans. This is explained by the fact that even with long-term first heating, useful trace elements break up. During the second boiling in water, supposedly nothing useful remains.

Boiling is necessary in most cases. Harmful bacteria can live in tap water. They die after 2-3 minutes of heat treatment. But It is worth noting that some dangerous microorganisms are not afraid of high temperatures. In this case, boiling is powerless to cope with the problem. Also in this way it is impossible to remove heavy metal salts from water.

Why not boil water twice?

It is believed that water can not be boiled twice due to the fact that it can become "heavy." Chemistry is a myth. Heavy water is almost impossible to create at home. This is a difficult process. Such a result is affected only by long boiling for many years.

In addition, heavy water is not lethal to humans. It is relatively quickly excreted from the body.


The quality of boiled water may depend on the type of kettle. Many people do not boil water twice in plastic electric kettles. They believe that the reaction takes place with plastic. In fact, if the polymer is approved for use as a material in which water is heated, then it is safe.

Harmful to health can be caused by highly chlorinated water. She already at the first heating reacts with plastic. Various hazardous substances are released into the liquid. They may persist when boiling again. Therefore, the problem is more likely not in the secondary boiling, but in the composition of the water. Before heating in an electric kettle made of plastic, it must be kept in a glass container.

The possibility of harm from secondary boiling can also be the case if the kettle is made of low-quality material, to which plasticizers are added. These substances make plastic less brittle. They begin to stand out during heating. It turns out that we drink water or tea with a dose of plasticizers. Therefore, do not buy cheap Chinese appliances. Cost is a direct indicator of the quality of plastic. The service life of kettles from safe material is 3 years. After that, it is better to replace it with a new one.

The myth of the dangers of secondary boiling is most likely associated with the danger of boiling water immediately from the tap. It contains a lot of chlorine. It will contain carcinogens after the first heating. Therefore, the water already before the first boiling must be defended. The danger of twice-boiled water depends entirely on its composition.

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