Is it dangerous to boil the same water twice?

Preparing tea is an art. Although it is appropriate to respect certain rules to ensure the quality of your infusion, such as the temperature of the water or the choice of tea, boiling your water again would have no impact… and even less on your health. As long as the water is clean and drinkable, this practice does not present any risk. Explanations.

No change in composition after boiling

To the question “does twice-boiled water become harmful?” » asked on the RTS* website (Radio Télévision Suisse francophone) by an Internet user, Didier Perret, doctor in chemistry and biochemistry at the University of Geneva, is categorical: no, water boiled twice does not become harmful and would not be more concentrated in nitrate, fluoride or even arsenic. Certainly, certain substances such as nitrates or fluorides are present in small quantities in tap water but as for arsenic, if “the initial water contains arsenic, it is potentially toxic (so not potable) before even having undergone a first or second boiling” explains the scientist. “This is typically the kind of information that abounds on many websites and which generates totally fallacious rumors,” he laments. Allegations that he characterizes as “fake news or fake news against which it is difficult to protect yourself if you do not have some basic notions of science, a somewhat critical mind, and a little common sense” . This is clear, you have absolutely nothing to fear from reboiling water, except perhaps a small additional energy expenditure.

Beware of tartar

However, water naturally contains minerals such as calcium and magnesium. Although these minerals are not harmful at normal concentrations, they create mineral deposits in the water, especially if the water is very “hard”, that is to say loaded with calcium and magnesium ions. As you boil water, these deposits build up in your kettle and it becomes scaled. A scaled kettle can completely alter the taste of delicate drinks such as tea, herbal tea or coffee, giving it an unpleasant or even bitter taste. So remember to descale your device regularly to maintain pure water, without unwanted taste, using for example white vinegar or baking soda.

* RTS Discovery

Similar Posts