Why shouldn't you boil water again and again?

Drinking boiled water that has been left to cool is a habit of most Vietnamese families. In case the water has been left for a long time, many people carefully pour it into the kettle and boil it again, but experts say that this is a mistake.

So why not boil water again and again? Isn’t using heat to kill off any bacteria that may have re-contaminated the old water bottle a way to protect your family’s health?

Why shouldn't you boil water again and again?

PageLybrateAccording to Dr. Arunesh Dutt Upadhyaym - a medical expert with 37 years of experience in India - and many other experts, reboiling water many times is very dangerous. Reboiling the same amount of water can make the water more concentrated or increase the amount of dissolved salts in it.

Reboiling water many times will cause many harmful effects such as:

- Nitrate salts dissolved in water are usually not harmful, but boiling too many times or reboiling the same amount of water can turn dissolved nitrates into nitrosamines - the cause of diseases such as cancer and leukemia.

- Reboiling water can increase the amount of dissolved arsenic. Small amounts of arsenic in water are not harmful, but larger amounts can cause cancer, infertility, heart attacks, and mental disorders. Long-term use of water with high arsenic levels can harm the circulatory system and damage the skin.

- Reboiling water also increases the amount of fluoride. Fluoride dissolved in water, if consumed in large amounts, can increase the risk of bone disorders. In children under 8 years of age, excess fluoride can damage teeth and enamel.

- Reboiling water increases the amount of dissolved calcium, which can cause kidney stones and gallstones.

- Boiling water many times increases the concentration of unwanted chemicals and impurities in the water.

That is why you should not boil water again and again, and should not use boiled water to make milk for young children. Studies have also shown that using boiled water to make a cup of tea can also affect the taste.

With pure water, reboiling does not change its chemical composition at all. However, most of the water sources we drink contain many different substances. Therefore, we should only boil the amount we need each time to protect our health in the long term, save electricity and conserve water resources.

Does boiled water go bad when cooled?

Although it is difficult to feel, the truth is that boiled water that has been left to cool can go bad.

When water is boiled, the parasites die, and the remains remain in the water. According to food technology expert, Associate Professor, Dr. Nguyen Duy Thinh, if you let the water cool and drink it within 1-2 days, you will be safe, but if the water is left for a long time, it will become contaminated with bacteria and can be dangerous.

"Microorganisms left in water for a long time will be food for bacteria from the outside environment to penetrate", Mr. Thinh said. The water was "stale" at that time, so it should be thrown away. You can recognize that the water is "stale" by the slimy phenomenon at the bottom and sides of the bottle.

In addition, mixing old water with new water will accidentally increase the number of bacteria in the water, easily causing mold. At this point, the water has gone bad, even organic matter is decomposed, inorganic matter is precipitated, creating conditions for bacteria to invade.

Therefore, boiled water should only be drunk within the day, not left for longer to avoid introducing bacteria that cause intestinal diseases into the body, affecting the digestive system and general health. Before adding new water to the bottle, pour out all the old water and wash the bottle to remove bacteria from the previously spoiled water.

To safely drink boiled and cooled water, it must be covered carefully to avoid contamination from the environment.