Is It Safe to Reboil Water?

reboil-waterQuestion:

If you use an electric water kettle or other ways to boil water to drink, you may not drink the boiled water in a short time. When the hot boiled water becomes cool again and you want to drink hot water, can you reboil water again or you just pour away the boiled water and fill new cold water to boil? If you choose to reboil water again, you may have a question “is it safe to reboil water?”.

Answer:

To answer this question, we should need to understand what will happen to water chemistry when reboiling water. After that, you will know whether it is safe to drink reboiled water.

The answer is not so easy to get. And this depends on what types of water you use boil. If you use perfectly pure distilled water or deionized water to reboil, nothing will happen. However, if you use tap water that contains dissolved minerals and gases, the answer is different.

When you boil ordinary water, the chemistry of the water will change. This is because the heating will drive off dissolved gases and volatile compounds. For example, a water distiller also uses this method to evaporate and uses a filter to remove these VOCs. However, if you boil the water too long or reboil boiled water, the contaminants in the water will become more concentrated as the water evaporates. The concentration of nitrates, fluoride, arsenic as well as other chemicals will become very high, finally resulting in being harmful to our healthy if we drink the reboiled water.

Does Reboiled Water Cause Cancer?

Some people think reboiled water may cause cancer. However, there is no evidence that shows there is a strong relation between cancer and reboiled water.

However, even if the boiled seems fine, reboiled water will cause the increasing concentration of toxic chemicals that may lead to some illness, even including cancer. For example, there is a strong relationship between the excessive intake of nitrates and methemoglobinemia (as well as other certain types of cancer). And Arsenic exposure can cause symptoms of arsenic toxicity and it may also cause certain types of cancer. The increasing concentration of healthy minerals may also have problems. For example, kidney stones, gallstones, hardening of the arteries and arthritis may relate to excessive intake of calcium salt.

Our Recommendation

Don’t boil water for a long time. If you really want to reboil it, just allow it to cook and then reboil it. This can reduce the risk.For example, if your tea kettle has some cool boiled water, you can add some new fresh water and then reboil it. This will be safe. It is not recommended to reboil water more than twice. Therefore, you’d better not reboil it. For pregnant women, reboiled water is dangerous to drink.

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