Many of you have already noticed that water in a glass goes stale after several hours and has an odd taste. Yet, nobody can tell for sure whether the water can go bed or something else has happened. Surprisingly there is a scientific explanation about this unusual change.
Plain water is easily contaminated by microbes because unlike food it doesn’t contain sugar and proteins. The water which gets in touch with air after some time absorbs small amount of CO2 and partially it is transformed in carbonic acid and that is why its chemical properties are changed- explains Discovery News.
To be exact, when carbonic acid releases one or two protons and converts into carbonate or bicarbonate the water’s pH is decreased due to which its taste changes.
The water’s taste is also changed as a result to its exposure to bacteria and dust for several hours.