Theory of Bubbles in a Glass of Water

Has anyone noticed that if you drink half of a glass of water, then set it aside for a while, the remaining water is gradually filled with bubbles?

Similarly, if you drink from a bottle of mineral water, then cover the empty bottle up and leave it for a couple of days, the inner surface of the bottle is eventually entirely covered with miniscule bubbles.

Someone told me once that these bubbles are caused by the microbes in the saliva of the person who drank from the water.

I have in fact noticed that the rate of accumulation of the bubbles varies - for example, at a dinner party where everyone has drunk partially from their glasses of water, some people have many more bubbles in their remaining water than others.

I never share drinks with other people, so I welcomed this explanation of the bubbles with disgusted triumph, but recently my theory has been challenged a couple of times and can no longer remember who originally told it to me. Can anyone verify/disprove this theory?

I think the amount of biological activity necessary to produce the bubbles you are describing would cause other changes in the water. Like making it cloudy and causing it to stink mightily.

The more likely explanation for the bubbles is dissolved gas. Mineral water, or water from the tap has a certain amount of air disovled in it. Under pressure the air remains in solution, but when allowed to sit the air comes out and forms bubbles. Also, warming the water will produce more bubbles because warm water cannot hold as much air as cold water.

Thanks Dr Lao, I guess that answers my question.

I suspect that the rate of accumulation is the same, given that the water came from the same source, at the same temperature, and the glasses are equally clean (providing the same level of nucleation sites for bubbles).

The difference among the glasses at your party is probably due to how often and how vigorously each person drinks. Once some bubbles form, if you drink from the glass gently, you can do so without displacing many of the bubbles. If you swirl your drink, you can clear the bubbles completely.