This happens to me at least once a week: I fill my electric kettle up with water to let it boil for my evening tea and then… well, anything can happen. I was in the middle of working on something, or the TV show I’m watching just got really good and now what?
The perfectly hot water is now regrettably cold. The solution may seem simple; just turn the kettle back on and reboil it to be enjoyed in a couple more minutes.
But what happens to water when we reboil it?
It’s something they never taught us in chemistry class, but really should have. When we boil water, the chemistry of it changes, which is usually a good thing as it boils out volatile compounds and dissolves gases. This is why boiling water mostly ensures that it’s safe to drink.
If water is left boiled too long or is reboiled, the chemical compounds change for the worst. By leaving your water to boil down, you’re actually concentrating many harmful chemicals instead of getting rid of them.
The same thing happens when you reboil water, as the compounds concentrate and increase the risk of ingesting certain chemicals.
These chemicals could include arsenic, nitrates, and fluoride. Even the minerals that are healthy for us can become dangerous when concentrated, such as calcium salt which can lead to kidney stones and gallstones when taken excessively.