How long is it safe to hold coffee in a thermal flask? Is coffee (prepared in a cezve, Turkish method, no sugar) carried in a thermal flask for 24 or 48 hours still safe?

I'm asking because black tea, for example, goes really bad in just a few hours.

  • 2
    What do you mean, "really bad"? There is a difference between unsafe (bacteria/mold growth) and bad taste. If you don't have put sugar or milk in your black tea, it is safe for a lot longer than a few hours. It may taste bad, but this is a different problem.
    – rumtscho
    Apr 2, 2012 at 8:31
  • By «really bad» I mean unacceptable for consumption, because either of: repulsive taste, unpleasant sensations in stomach, toxicity. AFAIK stale tea that went cloudy is all three. Apr 2, 2012 at 8:45

2 Answers 2


Coffee in a container is approximately as safe as boiled water in a container. While it may be unpleasant tasting, the water in coffee and tea is almost universally boiled, and the scalding liquid is placed directly on the grounds/tea leaves. There is a little nutritional value in coffee and tea extracts, providing some support for new microbes introduced after the boiling, but not much.

There is no reason to be wary of coffee kept in a clean, sealed container for a day.

  • All this provided that is plain coffee or tea. Adding sugar and/or milk changes a lot. Apr 4, 2012 at 8:14
  • This is true, but the question specified how the coffee was prepared explicitly enough that I didn't think the caveat necessary. Apr 4, 2012 at 8:22

While it is perfectly safe, I suggest you shake it up a lot before drinking. It also may not be very tasty, sorry to say, after sitting for 24 hours.

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