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I know flavor is subjective and not exactly quantifiable, but I think there's merit to this question.

We've all experienced that tap water often tastes a lot worse than bottled water or filtered water. I've always felt, however, that cold water actually tastes much purer than warmer water.

For instance, I was recently in a house where I knew the water was so called "hard water" and I could taste that it had the typical mineral flavor straight from the tap.

So, I took a glass of this tap water and refrigerated it for about a half hour and then drank it and I couldn't taste the typical tap water flavor at all.

I'd encourage people to try this just to make sure I'm not crazy.

Additionally, I have family that lives in Ohio and if anyone has ever tasted Ohio's tap water after living in a place like Washington (where I live) which has extremely fresh water, you know that Ohio's water is disgusting. I have found, however, that it tastes much better after being refrigerated for a while.

So, there are a couple of questions here.

Is it even true that refrigerating water (and thus cooling it) would cause a significant amount of oxygen to be dissolved in the water?

If so, would the amount of time the water is being refrigerated (even at a constant temperature) continue to dissolve more oxygen into the water? In other words, how long might it take for oxygen to reach it's equilibrium level of dissolution?

Those last two are definitely answerable chemistry questions. This next one is a little hairier.

Is there any reason, related to chemistry, that oxygen rich water would taste better than water not saturated with oxygen? Meaning, does the oxygen actually have a well-defined effect on the flavor of water, or is this simply answered by the fact that most people like the feeling of cold water more than luke-warm water and hence I identify cold water as "tasting better"?

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  • $\begingroup$ To my recollection, any bunch of water which is allowed to stand for a while will lose its "chlorine taste", with or without refrigeration. It has nothing to do with oxygenation, but it should be more pleasant to drink. And given the number of questions about water tonight, I assume that it was all planned, so I (and others) should give a global answer: 1. Boiling the water once or twice will not create any new contaminant, nor will it remove chemical contaminants. It will only kill bacteria. 2. The difference between mineral/spring/tap water depends on your country's laws. Please refer $\endgroup$ – SteffX Jul 25 '16 at 19:24
  • $\begingroup$ ... (con't from above) to them especially for toddlers. There is no such thing as a "miracle" water that everybody should drink, but it is clear that too much of highly mineralized water is unhealthy (once again especially for toddlers). It is known that levels of nitrates and fluorides (not an exhaustive list) should be of particular concern, depending on the age. $\endgroup$ – jonsca Jul 26 '16 at 0:29
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Many public water systems spray water into the air or trickle over rocks (aeration) to let some dissolved gases bubble out (e.g. odorous $\ce{H2S}$). This also may make the water less acid and thereby precipitate dissolved manganese and iron.

When tap water treated with chlorine, bromine, ozone or other disinfectant is allowed to stand, open, then those chemicals also can escape.

However, I doubt anyone actually tastes dissolved oxygen (the human body can sense $\ce{CO2}$, but not oxygen, which is why miners kept canaries. In addition, one can taste the acid of $\ce{CO2}$ in soda water, and feel the bubbles bursting.)

So the practice of letting water stand and refrigerating is useful in improving flavor, but $\ce{O2}$ has little to do with it. Chilling water does increase the solubility of gases, though.

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