Many people forget their electric kettles when boiling water due to distractions from their TV, so the water just gets cool again, leading them to re-boil it instantly. But, have you ever wondered if this is a good thing?

When water boils, its composition changes as some volatile compounds evaporate and gasses dissolve, which is why boiled water is considered safe for drinking. But, when your over-boil or re-boil water, its chemical structure changes for the worst – many dangerous substances actually accumulate in it instead of being eliminated!

These dangerous substances include arsenic, nitrates and fluoride, and even healthy minerals can become dangerous once they are accumulated. Calcium salts for example, can lead to kidney stones as well as gallstones if built up in the body.

The damaging effects of re-boiled water


The WHO (World Health Organization) claims that “Drinking-water poses the greatest threat to public health from arsenic.” Exposure to this toxic compound can develop several physical effects over time besides causing gastrointestinal symptoms, diabetes, peripheral neuropathy, cardiovascular diseases, renal system dysfunction, skin lesions and even cancer!


Nitrates are present in the soil, water and air, but when added to food and exposed to high heat they can become very dangerous. The high temperature turns nitrates into nitrosamines, highly carcinogenic compounds. Nitrates have been known to cause ovarian, bladder, colon, pancreatic, esophageal and stomach cancer besides causing leukemia and non-Hodgkin lymphoma.


The controversial fluoride has seen a lot of research lately. This dangerous substance can be found in water and can put your health at risk. Although its harmful effects are not scientifically confirmed, the government recommends avoiding fluoride.

According to data from Harvard University which examined 27 studies over 22 years, exposure to the substance has shown adverse neurological and cognitive development in children. The journal of Environment Health Sciences has also confirmed that fluoride exposure can lower the IQ of children. Fluoride has even been found to decrease fertility rates in male mice in animal studies.