Taste: Boiled water loses oxygen. If it cools down and sits in a plastic or stainless steel container for hours, it often tastes stale when boiled again.
-
The myth of “toxic” reboiling
You often read warnings in such articles that water boiled several times becomes “toxic” or carcinogenic because pollutants like nitrate or fluoride concentrate. Scientifically speaking, this is nonsense.
While a minimal amount of water does evaporate during boiling, theoretically increasing the concentration of minerals in the remaining water slightly, this effect is so minuscule with normal tap water that it is completely harmless. Even harmful substances from the kettle’s material (such as nickel or plasticizers) do not leach into dangerous quantities from modern, tested kettles.
In conclusion: You’re not putting yourself in danger by using the kettle “incorrectly”—but you are wasting money on electricity and causing the kettle to build up limescale faster.
