Overcarbonated Keg (How To Fix It & Avoid It Next Time!)

As homebrewers, we sometimes have to deal with a few minor setbacks to achieve the desired results, and having an over-carbonated keg is one such setback. It is understandable to be quite frustrated when all you are pouring is foam, but how do you fix it?

Although an inconvenience, all is not lost when dealing with an over-carbonated keg. From venting and purging methods to possibly adjusting your keg lines and adding a spunding valve, there are methods available to help eliminate any excess carbonation that may be plaguing your kegged beer and prevent it from happening again.

Read on to learn what different homebrewers are doing to combat an over-carbonated keg. You will learn how to deal with the issue at hand, plus learn ways to reduce the likelihood of having to deal with an over carbed keg in the future.

How do you know if your keg is overcarbed?

When poured, a glass that is mostly foam rather than beer is a good sign that your keg is over-carbonated, resulting in wasted beer.

Here are some signs your beer may be overcarbonated:

  • Unexpected bitter taste – A beer that is bitter and is off-tasting is a sign your beer is over carbonated. In this case, the CO2 is affecting the final flavor of the brew.
  • Bubbles in the line – Before pouring, small bubbles visible in the keg lines are another way to tell if your keg is carbonated. A properly carbonated beer will flow smoothly through the line.
  • Extra foamy pour – When pouring from a keg, if all you are getting is foam, that is a good sign that your keg may be over carbonated. An over-carbonated keg will pour mostly foam instead of beer in your glass, which can be rather disappointing since it results in wasted beer. 

If you happen to catch the signs of over carbonation before serving, you may be able to address the issue in time to save your brew.

How do you fix an over carbed keg?

There are a few methods you may use to fix an over-carbonated keg.

You may be able to fix your beer by venting and shaking your keg a few times to remove excess CO2. However, you may be facing a keg design issue that means you will need to refabricate your lines set up to feed the keg. 

Before discarding your beer, there are methods available to a homebrewer to help eliminate the excess carbonation in your keg that has given you only foam. If you have time to wait, it may be as simple as purging your beer and letting it sit for some time.

If looking for a more speedy approach, you may want to vent your beer allowing the carbonation to escape. Venting in combination with shaking your keg multiple times a day for a few days could help hasten the process.

The lengths of the lines used are essential to carbonate a keg properly. The specific lengths needed will depend on the PSI you are using, with the standard length being 1ft per 1psi used. You can use this keg line calculator to help determine what line length works best with your setup. 

How to decarbonate an over carbed keg?

Most effective methods for reducing the excess carbonation in your keg revolve around releasing the top pressure from the keg leading to an increase in the headspace and a drop in carbonation levels by disconnecting the gas or purging the keg.

If your issue is a little more complex, checking on your keg lines could be another reason why your keg is over carbonated. 

Here are some methods you can use to help de-carbonate an over-carbed keg:

  • Purge, shake, or roll the keg
  • Disconnect lines
  • Check keg lines

Before decarbonating, it is best to allow your keg to get to room temperature, making it much easier to release the carbonation. 

Purge, shake, or roll 

The simplest and quickest way to help eliminate any extra carbonation is to agitate the beer, causing it to release the carbonation.

This method works great if there are no issues regarding line length and if looking for a quick pour:

  1. Disconnect lines running from your gas and beer.
  2. Remove your keg from the fridge.
  3. Release all the pressure from inside your keg using the pressure relief valve.
  4. While upright, in a back and forth motion, rock your keg for 30 seconds.
  5. Let your keg settle for a few minutes (1-2 minutes should be fine).
  6. Release all the pressure inside the keg using the pressure relief valve.
  7. Repeat steps 4-6.
  8. Set up your regulator and connect to your keg. Reconnect all beer lines as well.
  9. Pour.

If your beer is still over-carbonated after completion, continue to repeat steps 4-6 until you reach ideal carbonation levels.

Purge the headspace

This process is similar to the previous suggestion, but it takes a little longer as it requires the keg to be disconnected from the gas for a more extended period to allow more gas to escape naturally.

To allow the carbonation to be released naturally:

  1. Disconnect lines from keg.
  2. Purge the headspace by pulling the pressure relief valve (PRV) and leaving it open until all the gas is purged.
  3. Leave the keg disconnected from the gas for 3 hours allowing all gasses to be released naturally. Raising the temperature of the keg can speed up this process.
  4. Pull the pressure release valve to purge the headspace.
  5. Reconnect lines and set to adequate pressure.
  6. Pour.

If your beer is still over-carbonated after completion, continue to repeat steps 2-5 until you reach ideal carbonation levels.

Keg lines

Kegs require a specific length to reduce foaming. The beer line calculator is a great resource to ensure the lengths of your keg lines are correct.

To check your keg lines:

  1. Disconnect lines.
  2. Check length and add a longer/shorter line if necessary.
  3. Make adjustments as needed.
  4. Pour.

How to avoid over carbing your homebrew keg?

Using and maintaining the proper PSI is one of the main reasons behind over carbing your homebrew keg.

Consider adding a spunding valve to your setup if you are having trouble staying at your set psi. Temperature can also affect carbonation, with kegs stored at colder temperatures ( >36°F) will maintain a higher level of carbonation.  

PSI is incredibly important to home brewing, and a slight change can significantly impact the quality of the beer. 

One advantage of kegging is the ability to force carbonate and control the amount of CO2 gas used, with most homebrewers recommending using 10-12 PSI when carbonating.

If you find it difficult to maintain the PSI, consider adding a spunding valve to help maintain a set pressure. This valve works by allowing any excess pressure to vent out to maintain the set psi pressure.

The temperature of your beer can have an impact as well. When stored at temperatures below 36°F, your beer is more likely to be over carbonated. This is due to carbonation being more soluble in colder temperatures, resulting in higher carbonation levels in the beer. As the beer’s temperature rises, carbonation escapes from the beer.