Our daily lives are inseparable from water. Plain boiled water may seem simple and transparent, but the questions surrounding it seem to be endless.
Take the question "Does boiled water have a 16-hour shelf life?" for example. It successfully caught my attention. However, after checking some sources, I found the issue is not that simple.
The shelf life of boiled water is not necessarily 16 hours!
Even if the result that "the shelf life of boiled water is 16 hours" has been experimentally proven, it may not be very convincing. Why 16 hours and not 15, or 17?
Does that mean after we boil water, we have to remind our family, "At XX o'clock tomorrow (16 hours later), this water can't be drunk anymore"?
In reality, the experimental environment is not entirely consistent with the specific environment of each household. Moreover, the experimental equipment, the environment where the boiled water is stored, etc., also vary greatly.
How long it takes for boiled water to spoil and for bacteria to grow is closely related to the container in which it was boiled, the surrounding hygiene, and the climate and temperature at the time. Especially in hot summer, the shelf life of boiled water is even shorter.
Therefore, it makes sense that boiled water has a shelf life, but that shelf life is not necessarily 16 hours! In cases of good water quality and good hygiene conditions, it might be safe for 20 hours, whereas in poor hygiene conditions, it might only last 10 hours.
Since we don't have a standard to judge our own water quality and hygiene levels, the most reliable principle is to "boil and drink water on the same day, and don't boil too much at once."
Additionally, many mothers around me also believe in the saying that "re-boiled water can cause cancer." How can this be explained?
Is re-boiled water really that scary?
Re-boiled water is water that has been boiled repeatedly. A friend once warned me not to let my family drink water that has been boiled over and over again.
The rumor claims: "Re-boiled water contains a lot of nitrites, which can cause poisoning, and in severe cases, even loss of consciousness or death. Moreover, nitrites are carcinogenic."
In reality, nitrite is a legal food additive, and it's often added to snacks like ham, biscuits, and preserved fruits. The nitrite content in repeatedly boiled water does increase, but the amount is very small. If the water has been kept sealed, the increase is even smaller, typically between 0.002-0.02 mg/L. This amount is even lower than that in many mineral waters on the market.
Instead of worrying about the nitrites in "re-boiled water" harming your family's health, it's more practical to let them eat fewer sausages.
"Re-boiled water" is not that scary, but there's no need to let your family drink too much of it. In any case, freshly boiled water is always the best. At the same time, be sure to remind your children that unhygienic water, unboiled water, or water that has been left out for a long time should absolutely not be drunk, as these are the real "potential killers" that threaten health.