Is it possible to boil water several times

Why is it believed that it is impossible to boil water several times

There is an opinion that repeated boiling Maybe make the water harmful as some of it evaporates and the remaining liquid becomes more concentrated.

Thus, if there were nitrates or heavy metals in the water, there will be more of them after the first boil. And if you repeat this procedure many times, their concentration can reach dangerous values ​​and eventually lead to illness. For example, nitrates can turn into nitrites, which can be toxic, while heavy metals can lead to poisoning.

Another concern concerns hardness water. This indicator reflects the content of metal ions, mainly calcium and magnesium. It is believed that increased stiffness can adversely affect health, for example, increase the risk of kidney and gallbladder stones.

However, none of the assumptions are supported by scientific data. Moreover, there are studies that refute these popular opinions.

Will water become harmful if you boil it several times?

In one Chinese research decided to check whether repeated and long boiling increases the concentration of mineral salts, nitrates and heavy metals.

Two modes were used for the experiment. In the first, 15 liters of water were brought to a boil in an open container, the temperature was maintained for 3 minutes, and then allowed to cool to 25 °C. After that, a sample was taken and the procedure was repeated again until the water completely boiled away.

In the second mode, boiling continued without stopping for about 6 hours, and every 20–25 minutes, scientists collected 500 ml to analyze the composition of the liquid. This continued until the container dried up.

Even before the experiment, scientists took water samples and evaluated it according to 44 criteria, including pH, the amount of various minerals, nitrates, heavy metals and microorganisms.

It turned out that despite prolonged or repeated boiling, all indicators of the quality of the liquid remained within the normal range, with the exception of pH. The balance shifted to the alkaline side a little more than necessary - to 8.95 against the allowed 8.5.

At the same time, in the Russian SanPiN requirements for the quality of drinking water from the central water supply system specified pH range from 6 to 9.

Also, in the process of boiling, the total number of solid dissolved substances, the amount of potassium, magnesium, chlorine and nitrates. However, all these indicators remained within the permitted limits, even when the 15-liter container was almost empty, which is rarely found in domestic conditions.

Can hard water hurt?

World Health Organization (WHO) claimsthat the side effects of hard water are unknown. Moreover, she even Maybe provide additional calcium and magnesium.

Thus, even if you have very hard water and repeated boiling will increase the amount of mineral salts, this is unlikely harm your health.

With regard to nitrates, there is evidence that, having consumed from 2 to 9 g of this nitrogenous compound, Can earn methemoglobinemia - a condition in which "useless" hemoglobin that does not carry oxygen increases in the blood.

However, according to norms the level of nitrates in tap water should not exceed 45 mg/l. So if you boil the liquid for 6-18 hours and their amount doubles, as was the case in the Chinese experiment, you will have to drink 22 liters to get poisoned.

If you are still very worried, just buy bottled water or a filter, and then boil the purified water as many times as you like.