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Here in USA supermarkets often sell water in plastic 1 gallon jugs. These jugs seem to all be stamped with the text "HDPE" (meaning that the material is High-density polyethylene) and a resin number of "2" on the bottom.

I had one of these jugs, containing distilled water, on a counter in the kitchen, and another one in the refrigerator. For some reason the water on the counter had a light plastic taste, whilst the water in the fridge did not.

Could this taste be because of plastic leaking into the water? Or what else could cause the plastic taste?

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  • $\begingroup$ Polymer itself is insoluble, but additives not completely. $\endgroup$
    – Mithoron
    Commented Feb 1, 2015 at 17:12
  • $\begingroup$ Nice question but do we really have an answer yet? $\endgroup$
    – user95145
    Commented Jun 23, 2023 at 19:22

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HDPE has a molecular weight more than several hundreds of thousands, "leaking" is plainly impossible. This taste is the tase of stale water, nobody knows what that taste is actually. Maybe its just the taste of not cold enough water, lacking some dissolved air, or some bacteriae develop after contact with air and light. (google for pseudomonas) The only substance which ever got into the jug prior to the water is the air (or some other gas?) used to
inflate the jug in production. But that cause would impair the taste of the water in the fridge as well.

BTW why do You drink such botteled water? What about the tap water in your town/city/village?

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  • $\begingroup$ Thank you for the explanation, Georg. I use tap water for coffee and such, the distilled water was just for other purpose. $\endgroup$
    – user13112
    Commented Feb 1, 2015 at 22:31
  • $\begingroup$ Nah, I can tell the difference between plastic and stale. And the water in the HDPE tasted like plastic. It's not bacteria; it's not air; it's not temperature; it's plasticizers. @burak-ulgut's answer is a better answer. $\endgroup$
    – zylstra
    Commented May 3, 2019 at 20:42
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This should've been a comment as it only backs up Georg's answer, but it just got too long for that.

Plastic doesn't "leak", scientifically. However, it can go through the degradation process.

You don't provide enough info for anyone to decide, but if you're certain that was the "plastic" taste (I don't have much idea how you do) it's possible it may have gone through degradation, though I can tell you 95 percent of the time it isn't. And that's simply because if the plastics were too unstable to resist minor chemical or energetic "attacks" (read the wikipedia article for degradation to see what I mean), they wouldn't have produced it like that.

There is the urban hoax that doing stuff like pressurizing a mineral-water bottle by freezing the water inside releases dioxins that are carcinogenic and which cause the change of the taste of water, but this, is not true. (See here.)

Georg's answer pretty much sums it up, but I think it's better to add: It may also be possible that you (or anyone else, or mistakenly the company itself) put the "tasty" water in contact with soluble mineral salts. Thus, you drink hard water and swear for its taste!

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  • $\begingroup$ Thank you for your comments, MARamezani. To explore your last paragraph further, could the soluble mineral salts lead to a plastic taste? Otherwise could it be that the water is not as distilled as it is marketed to be(?). $\endgroup$
    – user13112
    Commented Feb 1, 2015 at 22:29
  • $\begingroup$ I wouldn't say it's to be blamed on the company too much. It's not only HDPE that's in contact with water. To "optimize" plastics there are many things done. (As an easy example the polymer is PE but you "HD" it) One of these things is adding material like phthalates (No phthalates, not in this case) to plastics. As mithoron points out, the minute solubility of these in the water could've caused what we know as plastic taste. $\endgroup$
    – M.A.R.
    Commented Feb 2, 2015 at 17:39
  • $\begingroup$ degrade? The article that is linked says 58 - 1200 years. Should we scratch that off? $\endgroup$
    – user95145
    Commented Jun 23, 2023 at 19:35
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I agree with the other answers, it is definitely not HDPE, however, it could be one of the chemicals known as plasticizers that are used in the process. There is always leftover plasticizer in the bottle and these are known to leach into water.

The NIH sponsored multiple studies on the levels of this, one of them published here:

http://www.ncbi.nlm.nih.gov/pubmed/21400322

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  • $\begingroup$ Ha, why do you say you agree? Your answer is in direct contradiction to those of the others. It's not bacteria; it's not air; it's not temperature; it's plasticizers, like you state! Or possibly degradation, like M.A.R. states. $\endgroup$
    – zylstra
    Commented May 3, 2019 at 20:44
  • $\begingroup$ @zylstra .....I will post. How do we know HDPE is degraded. The I will post again. $\endgroup$
    – user95145
    Commented Jun 23, 2023 at 19:26