Can Water Go Bad? How to Recognize It

Water can also go bad, especially when it comes into contact with oxygen. Therefore, open water should be drunk quickly. Drinking foul water risks gastrointestinal problems.

Water can go bad – especially when combined with oxygen

Water contains neither fats nor sugar nor proteins. So the liquid should be good forever, right? The answer is yes. In principle, bottled and hermetically sealed water cannot go bad. Nevertheless, mineral water bottles also have a best-before date on them.

• When water is kept in an open container, it comes into contact with oxygen. This changes the chemical composition of the liquid. The pH of the water drops, giving the taste a sour note. But that just makes the water undrinkable. It becomes harmful to health when microbes settle in drinking water, for example through saliva, dust, dirt and mold spores.
• Water in a water glass – whether tap water or mineral water – should be drunk within a few hours. So it’s not a good idea to leave a glass of water by your bed at night to drink from the next morning. Then the water is not only stale, but can also be contaminated with germs.
• Once a water bottle has been opened, the shelf life depends on whether the water is carbonated or still. The following applies: the more carbonic acid the water contains, the longer it can be kept open.
• Still water in an opened bottle should be used up within a few days. With carbonated water you have a little more time. Opened bottles or canisters of water should be stored in a dark, cool place or in the refrigerator. If the container is exposed to direct sunlight, the water will go bad faster because germs can settle and multiply in a shorter time.

Unopened water generally does not go bad

If a water bottle or canister is opened, microorganisms can get into the bottle. This is especially true if you drink straight from the bottle. To extend the shelf life, it is advisable to always drink water from a clean glass.

• Theoretically, sealed water lasts forever. Nevertheless, there are expiration dates on water bottles and water canisters. The reason for this is that the water becomes stale over time and therefore less drinkable. It’s usually not bad though.
• Nevertheless, it is advisable to empty water in plastic bottles within a year and water in glass bottles within two years.
• With water in plastic bottles, hormone-like chemicals that are released by the plastic can build up in the water over time. In addition, closed water should also be stored in a dark and dry place.
• If you drink bad water, for example a glass that has been open for a long time, the bacteria, fungi and other microbes it contains can lead to gastrointestinal problems. The consequences can be diarrhea, abdominal pain, nausea and vomiting.
• Important: If tap water smells like rotten eggs, this indicates hydrogen sulfide gas. This is usually not dangerous, but tastes less delicious. Nevertheless, you should draw the attention of the responsible waterworks to the foul smell, as contamination may be present.