Taste aside, is it safe for drinking? Whiskey that was left inside a stainless steel flask?

Stainless steel flask

  • 16
    If whiskey held in cheap flasks for months or even years was a serious health threat, it would have been obvious a hundred years ago. Commented May 25, 2013 at 0:55
  • 6
    Life expectancy 100 years ago was 55 years. Today it's in the high 70's. No one then would have the technology to know if you died from lead poisoning from ceramic, steel, paint or iron. Also, remember, this is the China that made toothpaste with anti-freeze as an ingredient not very long ago. ...And OP uses MS-DOS, no way!
    – Paulb
    Commented Jan 29, 2016 at 20:20
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    @paulb - old thread that popped up somehow. The life expectancy at birth for whites in the US 100 year ago was about 55 years. However, if the person survived childhood, the average life expectancy was closer to 70 years - not too far away from current statistics. I would think that the impact of drinking whisky by children on life expectancy would be minimal.
    – doneal24
    Commented Sep 29, 2019 at 15:56

5 Answers 5


Whiskey is quite high in alcohol, on the order of 40% by volume, and is not hospitable to pathogens growing.

The flask is intended to hold liqueur, and so is made from or lined with a food safe material, such as food grade stainless steel (assuming you have one from a reputable manufacturer).

So yes, it should be fine.

Remember: when it was distilled, the whiskey was probably held at different stages for long periods in a stainless steel vat.

  • 3
    "assuming you have one from a reputable manufacturer" - well, that's the problem, it's a chinese brand, named "Honest". It's REALLY well built, but I'm not sure... Commented May 24, 2013 at 23:04
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    Well... would you use anything for food or drink that isn't from a reputable manufacturer? Perhaps that is your real question.
    – SAJ14SAJ
    Commented May 24, 2013 at 23:16
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    @SomebodystillusesyouMS-DOS: Alcohol is a preservative. It's as safe now as it was a month ago. If you don't trust the manufacturer then maybe it wasn't safe a month ago, but as long as it's actually stainless steel then it hasn't gotten any worse since then.
    – Aaronut
    Commented May 25, 2013 at 0:36
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    @TimB The reason 40% is so common is that it's not legal to sell anything lower-strength and still call it whisk(e)y, and because it's the common opinion that it's the optimal balance of flavour and least burn. It comes from the still around 95% and then is diluted to aging strength, about 65–70%, before barrelling, and comes out of the barrel around 60% due to evaporation. You can get "cask-strength" whisk(e)y from a number of distilleries, but often they're best with water added anyway; I have a 59.0% Aberlour A'Bunadh that's good neat and diluted down to 40%. Commented May 27, 2013 at 0:06
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    Are the flask parts welded or soldered together? People used to keep whiskey in leaded glass decanters until it was found that lead leaches from the glass into the whiskey. A soldered stainless steel flask might well have lead solder exposed to the liquid. Commented Jan 29, 2016 at 23:24

My stainless flasks, USA made, purchased from distilleries indicate that spirit alcohol (of any proof) should not be stored for more than 3 days. I've never pursued an explanation for the statement. The flasks generally don't have any contents left by the beginning of the third day. While this may not constitute an answer, it's worth considering all the same.

  • Answers that provide a reason are more appreciated here.
    – Robert
    Commented Feb 13, 2017 at 22:09
  • @Robert, this is a valid answer. It's given within the literature for nearly all flasks sold. So while one study may say it's healthy to consume liquor after being stored in a flask for months, I will defer to the manufacturer's suggestion, and wash it out the next night. Commented Jul 26, 2018 at 13:24

Do keep in mind, though, that some cheap flasks will have plastic liners on the inside - you may want to see if this is the case with your flask. (A month is not particularly long, though.)

  • Welcome to the site! I was wondering about your answer, since it does not really answer the question, imho. If there is a plastic liner, is the whiskey not safe to consume?
    – Mien
    Commented Jun 14, 2013 at 11:50
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    Thanks. Safety issues regarding chemicals leaching out of plastic into liquids have recently drawn some attention from regulatory agencies. For example, the FDA (as well as equivalent agencies in the EU and Canada) have recently declared bisphenol A (a common component in the production of many plastics, as well as liners for beverage cans) to be toxic, due to increased cancer risk and weird hormonal effects. I realize that doesn't really answer your question, sorry. Potentially informative link below: scientificamerican.com/…
    – user18740
    Commented Jun 14, 2013 at 12:09
  • @Mien: Also, IIRC, high-strength alcohols have a solvent effect on many plastics (i.e., they dissolve them).
    – Vikki
    Commented Dec 18, 2021 at 20:25

Problem is with the joining process & material used in the SS flask. I think some may be lead soldering which is poison


I have a dozen stainless flasks, that i place 80 proof whiskey in and age an additional 4 years before drinking.......some of the best stuff I've ever drank.

  • 9
    Tasty or not, this has nothing to do with its safety. For a food to be declared officially safe, it must meet very stringent criteria. Matters of public health are settled with large studies, not with taste or "I did it and didn't suffer any problems".
    – rumtscho
    Commented May 5, 2014 at 19:55

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