Generally, unopened bottled water will not go bad. But don't drink bottled water for about 3 months, even if it is unopened. It is best to drink unopened bottled mineral water within 10 days, and try not to drink pure water for more than 10 days. It is easy to breed bacteria after a long time. If the cup is not cleaned regularly, bacteria will remain; Drinking fountains are the easiest places to breed bacteria, because impurities and minerals in bottled water will be deposited in the inner container of drinking fountains, which will seriously affect the quality of drinking water over time. The drinking fountain can be used, but please put it in a cool and ventilated environment to avoid direct sunlight, which can prevent the growth of green algae and thus prevent the threat of green algae spores to the body.
If you open it, you can drink 15 days at most. If it is left for more than half a month (15 days), although the taste has not changed, the bacteria have exceeded the standard. If the time interval is longer, it can't be drunk in the producing area, because the bacteria in country Z greatly exceed the standard, and even the water has deteriorated. Bottled water can't be drunk after one month of opening. The shelf life of bottled water is 1 to 3 months. If the bottled water after opening the bottle exceeds 15 days, you can't drink it. It should not be more than a week after the bottled water is opened, because bacteria in the air often enter the water with bubbles when the bottled water is discharged. Generally, there are about 5000 bacteria (not pathogenic bacteria) in one cubic meter of air, which will multiply and grow in large numbers over time, affecting the hygiene of drinking water.