[popular science] does water really go bad?
Release time：2018-10-27 Browse：1949
Put a glass of water before going to bed, can get up in the morning the first taste can not make a person feel fresh, but very light.
The situation is even worse when people quench their thirst with a bottle of water that has long been opened and may have been tanned.
Yo, gross!
Do people get sick because of this?
After all, the date of warranty can also be seen on the unopened mineral water lid.
Drinking water does not really "go bad"-it is neither protein nor sugar that will rot, mold or ferment.
But if the water is stored in an open container, the chemical composition of the water changes.
It absorbs carbon dioxide, and part of the liquid is converted to carbonic acid.
This is only a tiny fraction (about 0.13%), but enough to reduce the pH of the water and make the mouth sour.
It doesn't hurt, it just tastes bad.
But when the water is turned on, it is placed in the bacteria.
Tap water and mineral water usually contain bactericidal chlorine, which is generally safe to drink after a day in the air.
But after that, the microbes grow rapidly.
Even the cleanest indoor air is filled with tiny particles of dust.
They end up in open water cups, not to mention flies and mosquitoes that like to lay their eggs on the water.
As for the date on the mineral water bottle, the consumer can be completely indifferent to it.
Although producers must mark the expiration date on the bottle, this is definitely not the date on which the water expires.
According to the German Mineral Water Information Center, glass bottled water can be preserved almost indefinitely.
But plastic bottled water is different.
After a few months of storage, the carbonic acid may seep out and oxygen will seep in, changing the taste.
Still, it's drinkable.
In the case of plastic bottles, the concern is that the bottles themselves may contaminate the water.
Researchers found that a hormone-like chemical in the plastic gets into the water.
Although the German Federal Institute for risk Assessment believes that drinking PET (polyethylene terephthalate, a common resin that can be made into plastic bottles), bottled water is not a health hazard.
Because in any case the negative impact is far below the prescribed maximum.
But experts such as Gilbert Schoenfelder of Berlin's Sharit University Hospital disagreed, warning of unforeseeable long-term consequences.
To be on the safe side, plastic bottles containing drinks should never be put in the sun, as high temperatures and radiation can cause more suspicious substances to be released.
Because plastic is more permeable than glass bottles, PET bottles filled with beverages should not be stored next to gasoline or botanical toxins.
If the water has a plastic smell, it should be emptied immediately.
