Can you boil water multiple times?

We often reheat water for our morning tea or coffee, bring soups, borscht, and marinades for canning to a boil. But can you boil water multiple times? Is it harmful?

Even on scientific resources, you can find a lot of evidence that with repeated boiling, the amount of harmful substances in the water increases: for example, nitrites or fluorine. And it all depends on the composition of the water itself – because it is a solution with organic and inorganic impurities. When H2O evaporates, the solution becomes more saturated, since the impurities themselves remain in it. But is this so important for the volumes of water that we boil again?

In order for the amount of harmful substances to reach significant concentrations, it is necessary to evaporate a very large amount of water. That is, to boil it not twice, but, say, a hundred times. You are unlikely to be able to do this with a regular kettle. Therefore, theory is theory, but the repeated boiling of water in the home itself does not pose a danger.

Possible Threats

The only significant argument for why you should boil water only once is the container in which the boiling takes place. When testing electric kettles of various brands according to different parameters, it turned out that in some kettles, after repeated boiling, the water increased the content of formaldehyde – a compound dangerous to health. After each subsequent boiling, the concentration of the toxic substance increased. This may be due to the fact that some devices use low-quality plastic, which releases formaldehyde.

If your equipment is from a trusted manufacturer with quality materials, you should not be afraid of repeated boiling. But still there are ways to do without repeated boiling:

  • If you are brewing not black, but any other tea, it does not need boiling water. For example, herbal tea is brewed at 65°C, fruit tea at 50°C, and green tea at 80°C. For the preparation of baby food, water should be heated only to 40°C. Therefore, the cooled boiling water can simply be heated to the desired values. Modern models of electric kettles have the ability to set the desired temperature.

Another option is to use a thermopot as a replacement for a kettle. This is a thermos with a boiling function and several temperature modes.

Therefore, in the question of whether it is possible to boil water several times, there are several possible harmful factors and you yourself must decide what to correct in order to avoid possible harm to health.