Last night, I was trying to carry some bottles of my home-brewed beer in the basket of my bicycle. I only made it a few blocks from my home before I noticed that most of them were leaking. The caps were firmly on but most of the beer had escaped and made a mess.

How can I prevent this from happening in the future? This has happened once before with my own beer but never with store-bought bottles.

I am thinking of using bubble wrap or something to absorb the impact but I would like to see if anyone has any better ideas. Keep in mind that I am a brewing newbie so I don't know if the caps are on tightly enough, or if the beer is under too much pressure, or if there is some other problem.

EDIT: I am using some average-looking glass bottles that I bought from Brewcraft in San Francisco. They are not twist-off bottles. I am using a wing capper.

  • 1
    Properly-capped bottles should not leak. The normal pressure your capper uses should be sufficient to seal the top of the bottle. Are you trying to cap twist-off bottles, perhaps?
    – jsled
    Nov 25, 2013 at 18:29

3 Answers 3


It sounds like you're not getting a good seal on the caps. Do you notice carb loss over time? Do they leak when you simply tip them upside down? If so, it could be any number of things: the capper, your technique or the bottle itself (e.g. twist off rather than pry-off).

  • I don't know what "carb loss" is. Do you mean carbonation loss or something else? Nov 25, 2013 at 23:43
  • I bottled the beer on November 4, but I didn't actually taste it until November 22. I tried turning a bottle upside down and shaking it and nothing came out. I am not using twist-off bottles. Nov 25, 2013 at 23:45
  • I mean loss of carbonation, yes. Are you using "standard" bottles? For example, I've had trouble re-using Anchor Steam bottles because of the neck shape. Couldn't get a good seal on them. Are you capping with a bench capper or a wing capper?
    – Tom L
    Nov 27, 2013 at 14:16
  • I am not noticing any carbonation loss. It has only been a few days since I first tasted the beer and it still seems very carbonated. Nov 27, 2013 at 19:53
  • Could be the rubber seal on the inside of the caps. If the caps are old, it might have decayed to the point where it won't hold pressure. Nov 27, 2013 at 21:15

Were you using plastic pet bottles?

If you use soda bottles some of them have a blue plastic seal under the cap which acts like a washer when you screw the cap down.

If the cap is old the plastic seal may not be effective.

Another option is that some plastic bottles do not use the blue plastic seal so you have to be careful as the what bottles go with what lids.

This is what I have found with my pet bottles compared to soda bottles I have bought from the supermarket.

ADDED since the original question added detail about glass bottle

It may be possible that the bottles are over carbonated and the transportation is the same as shaking them up, causing pressure in the bottle that is escaping through the cap. If the cap didn't leak then there may have been a bottle bomb if this is the case.

What were their reactions when you opened them when you arrived at your destination? Did they fizz over like a coke that has been shaken?

  • The beer does seem more carbonated than most beer, so that may be the issue. I am still a newbie. Nov 28, 2013 at 3:05
  • After I noticed the leak, I took the bottles back home. They still had a little bit of beer in them, which I drank by myself. I grabbed some other bottles and took the bus there. They made it there fine. Nov 28, 2013 at 3:05

You say the caps were "firmly on". No offense, but if they're leaking the caps weren't fully sealed. Possible culprits could be the bottles or caps you use, your capper, or your technique. we need to know more about what you do and how you do it to narrow that list down.

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