Do not do this even if your life depends on it!
See why it is not healthy to boil water twice, even if you think it will thus be cleaner. At first glance, you can see steam and bubbles, but there is something that happens at the chemical level.
Boiling the same water several times it changes the oxygen content and potentially dangerous substances accumulate. Boiling water is a great way to kill the bacteria, but when the water boils again and again, forming dangerous toxic substances. These gases can be dangerous arsenic, nitrate and fluoride and are formed as a result of changes of the chemical structure.
Various studies have shown the connection between this and the harmful effects of fluoride because it adversely affects the nervous system and brain. After this entire process it is no longer the same healthy water that has minerals, but can cause problems and form kidney stones.
So this is why you must not boil the water twice. More dangerous is that the greater the amount of water…It is good to know that this is not as harmless as we all thought.