I use 1L bottles with flip tops, the beer carbonates fine but after drinking half of it and putting it away for a few days (1L is too much to drink for me) it loses carbonation completely. Is this normal?

Tried leaving them outside the fridge but it ends up flat. Is there no way to retain the carbonation?

5 Answers 5


Yes, this is to be expected and perfectly normal - when you have a half filled container of beer, the carbon dioxide that's dissolved in the beer will come out of the beer to fill the space available, so you have less carbon dioxide in the beer, and less fizz.

You can try keeping the half-filled bottles cool which will retain more carbon dioxide in the beer. Also drinking them sooner will help, since it does take some time for the carbonation to come out of the beer. Finally, if you really don't drink more than 500ml at once, then consider switching to 500ml bottles.


Yes it's normal and although a lower temperature will keep more 'fizz' in the beer it will still lose most of it. The carbon dioxide that was forced to dissolve into the beer when it was sealed will be able to return to being a gas when the bottle is half empty.

Although you could try various things to avoid losing the carbonation once opened the best thing to do is to move to using smaller bottles which you will consume in one sitting.


The best solution is to drink the full liter.


mdma and n1ak are correct.

However, if you are really adamant on using 1 liter bottles then you can TRY to add table sugar or carbonation drops. It will make your beer sweeter, but there is a small chance that your beer will be LESS flat, as opposed to completely flat. I would not recommend this, but it seems like a good experiment.

To echo mdma and n1ak: Use smaller bottles.

Or drink more. :)

  • 2
    This would require there to be active yeast remaining in the beer, warming the beer up to ~70 degrees, and waiting another 2 weeks for it to recarbonate before re-chilling and drinking. Jun 17, 2014 at 17:09
  • Considering he bottle conditions where will still be some active yeast in the bottle @ChrisMarasti-Georg. You are correct on the time delay. I did not think of that! :P Jun 19, 2014 at 7:37

To repeat what others have said: It's completely normal. Have you tried the same with store bought beer bottles? I know I have, and although they possibly keep the carbonation somewhat better, the same principle apply.

The trick with adding a little bit of sugar MIGHT work, but if the beer has matured enough there should be more or less no yeast left. As I'm sure you know, carbonation happens when the yeast in the brew "eat" the sugars, producing CO2. If there's no yeast left, there is no carbonation. (This is sometimes a challenge when brewing very strong ales, with lots of sugars - when it comes to bottling, one might find that there is too little yeast left for good carbonation, hence resulting in a flatter beer than you'd probably prefer. There are tricks for dealing with this, of course.)

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