I've noticed a lot of people have been recently uploading videos in which they test the pH of multiple brands of bottled water and claim that the more acidic ones (5.5 < pH < 6.5) are worse for your health than the more basic ones (7.5 < pH < 8.5).

However, considering that water is made up of both H+ and OH- ions, wouldn't that mean that the concentration of both ions would be equal regardless of the pH that a sample of water has? If this is true, would it mean that two different brands of bottled water would still be neutral even though they have different pH values?

  • $\begingroup$ It surely would, if there were absolutely nothing else in the water. This, however, is not the case. $\endgroup$ – Ivan Neretin Mar 21 '18 at 14:14

pH is the measure of water basicity or acidity. If the pH is 7, the water is neutral, if it is less than 7 it is acidic, if it is greater than 7 it is basic. So to answer your question, if the pH is not 7, the water is not neutral.

Absolutely clean water has pH 7. However, absolutely clean water is extremely rare. Most waters contain various dissolved substances and some of those substances influence the pH. Even if you leave absolutely clean water in contact with air, the air gases start to dissolve in the water immediately and pH goes down due to dissolved carbon dioxide. So absolutely clean water, even common distilled water, in contact with air is acidic.

Regarding the health effect, I think it is an oversimplification. pH itself is not so important, the important thing is, what is dissolved in the water. You cannot judge that knowing only the pH.


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