Maybe you never thought of that, but bottled water has an expiration date too.

The water that we buy at the kiosk and in markets, whether mineral or non-mineral. Usually, in a bottle, has its expiration date “best used by”. This does not mean that after that period (which is usually one or two days) you should not use it. But it is not recommended. 

According to some experts, if you have not opened the bottle yet, the expiration date does not matter, therefore, the water is safe to drink.

The condition is, of course, that the bottled water is in a hygienic manner, according to the German Institute “SGS Fresenius” which deals with laboratory analyses.

When the bottle is opened, the situation is quite different. In this case, the water should be drunk at least as the next few days. In an open bottle of microbes can enter and multiply quickly, especially if the water is left out of the refrigerator, experts say.

Water does not contain sugars and proteins so that the microbes do not feed and do not destroy the water.

However, the chemical composition of water can be changed. When the water is exposed to air, the absorbed CO2 and about 0.1% water is converted to carbonic acid. Carbonic acid may form carbonate and bicarbonate to reduce pH. The result is slightly acidic water which explains why water has a slightly different flavor if you leave it in a glass overnight.

Such water is safe to drink, but a few hours after the opening, bacteria can attack.

Therefore, most bottled water contains additives of chlorine, which prevents the bacterium one to two days. Subsequently, the bacteria can begin to multiply.