Background: In 8 hours range, I have bought cold mineral water (brand A), then refill the plastic bottle with cold mineral water (brand B) from my office. As far i know, brand B has high pH while brand A is almost neutral. After that, I refill again with another mineral water (brand C). After few minutes, I'm surprised the inner-wall of my plastic bottle is filled with micro bubbles. These bubbles seems have sticky property because they are hard to clean even on hard tap. Even they do not burst easily when in the surface almost like bubble soap.

Other property:

  1. Has normal taste, slightly base
  2. Has no smell
  3. Has no color

Question: Is it possible for mineral water from different sources to not mixed well then generates (yes, they generate!) hard-to-burst bubble? Or something has contaminated my relatively new plastic bottle?

Supporting Image:


  1. Fogs
  2. Floating bubbles. Haven't burst in 5 minutes
  3. Bubbles
  4. Bottle condition after hard-tap

Bubbles in Mineral Water

  • $\begingroup$ Generally, it is not a good idea to mix different kinds of mineral water. $\endgroup$
    – Poutnik
    Jul 15, 2023 at 13:06
  • $\begingroup$ @Poutnik Why that? :D $\endgroup$
    – Karl
    Jul 16, 2023 at 9:40
  • $\begingroup$ "... brand B has high pH ... " Extremely unlikely if you say that "brand A is almost neutral" $\endgroup$
    – Karl
    Jul 16, 2023 at 9:46
  • $\begingroup$ @Karl For similar reasons as it is generally not good idea to mix 2 solutions unless you really know what you are doing. :-) $\endgroup$
    – Poutnik
    Jul 16, 2023 at 10:05
  • $\begingroup$ @Poutnik Good general precaution for chemisty, but a bit out of proportion for drinking water. $\endgroup$
    – Karl
    Jul 16, 2023 at 10:15

1 Answer 1


The bubbles, floating or not floating, are made of $\ce{CO2}$ which was initially dissolved in one of the mineral waters (physically dissolved or combined as $\ce{HCO3^-}$ ion). By mixing it with a slightly more acidic water, this $\ce{CO2}$ is liberated and forms tiny bubbles.

  • $\begingroup$ Thank you! Glad to know $\endgroup$ Jul 15, 2023 at 14:40
  • $\begingroup$ Is the analytical result spectral or putative? Could the bubbles be insoluble, therefore not much affected by tapping? That is, unaffected by water as a solvent. CO2 is assumed because Brand C is assumed to be acidic and the (assumed?) high pH of Brand B is assumed to be from bicarbonates - but it could be due to Mg(OH)2. Temperature is reported vaguely. Could the temperature of Brand C be somewhat colder, therefore likely to warm up and produce micro bubbles of air because it had dissolved more air to begin with? Air bubbles would have the same visual spectra as CO2 bubbles. $\endgroup$ Jul 15, 2023 at 15:33
  • $\begingroup$ James Gaidis asks whether the bubbles are insoluble. This question has no meaning. All bubbles contains an insoluble gas. If the gas were soluble, the bubbles would get dissolved and thus disappear. Furthermore, $\ce{Mg(OH)2}$ is a solid. It is nearly insoluble. But it is not a gas. $\endgroup$
    – Maurice
    Jul 25, 2023 at 20:21

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