Boiled water is extremely dangerous to health.

As studies have shown, it is dangerous to boil water that has been purified through a filter operating on the reverse osmosis principle in kettles with an open heating element.

In tap water that has been purified through such a filter, acidity increases. Such water enters into a chemical reaction with nickel, which is part of the kettle's spiral. As a result, the amount of nickel, which is a heavy metal, increases significantly. Such water is dangerous to human health, because it leads not only to allergies, but also to various kinds of diseases.