Why Is Homebrew Flat?

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Having flat homebrew can be incredibly frustrating. You followed the recipe to the latter, used the right ingredients, and even let it ferment for the right amount of time. However, when you bottle your beer, you realize that it’s completely flat. So, why is homebrew flat?

Why Is Homebrew Flat?

The main reason why homebrew is flat is that the yeast did not eat all the sugar in the bottle to create carbon dioxide. When yeast ferments, it eats the sugars and produces carbon dioxide and alcohol. However, if there is not enough yeast or if the yeast is not active enough, it will not eat all the sugar, and your beer will be flat.

There are a few reasons why this could happen. First, the yeast might not have been properly hydrated before pitching it into the wort. Secondly, you might have used old or dead yeast. Therefore, it’s essential to ensure that your yeast is healthy and active before pitching it into the wort. This would ensure that fermentation will occur properly.

An image of flat homebrew

Another reason your homebrew could be flat is slow or incomplete fermentation. This happens when the yeast doesn’t have enough time to eat all the sugars in the wort. Ensure that the fermentation process is not interrupted and that the yeast has enough time to eat all the sugars.

Other Reasons for Flat Homebrew Beer

Many reasons could be hindering you from having fizzy homebrew. You don’t want to have a flat beer next time you brew, so it’s important to find out the reason for your alcohol being flat. The following are some of the other reasons why homebrew beer could be flat:

Not Enough Priming Sugar

Priming sugar is essential for carbonation. When you add this type of sugar to the bottles, it provides food for the yeast, and the yeast will produce CO2. However, if you don’t add enough priming sugar, the yeast will not produce enough CO2, and your homebrew will be flat.

The best way to avoid this is by using a priming sugar calculator. This way, you can calculate the amount of priming sugar needed to achieve the desired level of carbonation.

Improper Cleaning and Sanitation

If your brewing system is not properly cleaned and sanitized, it could lead to flat beer. The bacteria present in the equipment can eat the sugars meant for yeast and produce carbon dioxide. As a result, there will be less sugar for the yeast to eat, and your beer will be flat.

Always clean and sanitize all your brewing equipment before use. This way, you can be sure that your beer will not be flat and will have the desired level of carbonation.

Overcarbonated Beer

It is also possible to have an over-carbonated beer. This happens when the yeast produces too much carbon dioxide. As a result, the beer becomes too fizzy and might even explode.

It is important to monitor the fermentation process completely to prevent this from happening. If the beer is over-carbonated, simply open the bottle and release some of the gas.

Leaky Bottles

Leaky bottles can also make your homebrew flat. This is because the CO2 can escape from the bottles. When the CO2 escape, it takes the carbonation with it. You can avoid this by making sure that you store your bottles in a cool, dark place.

Also, ensure you use tight caps that create an airtight seal. If you are unsure if your bottles are airtight, you can test them by submerging them in a bucket of water. If any bubbles escape, then you know the bottle is not airtight and needs to be replaced.

An image of why homebrew is flat

Temperature Fluctuations

Temperature changes can also cause your homebrew beer to be flat. This is because temperature changes can cause the yeast to become active or dormant. As a result, carbonation will be affected. The ideal temperature for storing homebrew beer is between 55 and 60 degrees Fahrenheit. Avoid placing them in your fridge to keep the temperature stable.

Characteristics of Flat Beer

A flat beer has characteristics that you should be able to identify and troubleshoot. The following are some of the signs that you have a flat beer:

  • There is no carbonation present in the beer.
  • The beer has a dull appearance and might even look watered down.
  • The beer has no head, and the foam disappears quickly.
  • The beer tastes sweet since there is no carbonation to balance the sweetness.
  • The beer has no aroma since the CO2 is not present to carry the aromatics.

Frequently Asked Questions

Can You Recarbonate Flat Beer?

Yes, you can re-carbonate flat beer. The best way to do this is by adding sugar to the bottles. This will provide food for the yeast to help them produce carbon dioxide. You can also use a Sodastream to fix your carbonation problems.

What Happens if You Bottle Beer Too Early?

Bottling beer too early can cause it to be flat. You need to give your homebrew some time to sit, for the yeast to have enough time to eat all the sugars and produce carbonation. As a result, your beer will be flat and will not have the desired level of carbonation.


Flat beer is undeniably unappetizing. The good news is, there are a few things you can do to avoid it. The quickest way to fix flat beer is by adding priming sugar. This will provide food for the yeast and help them produce carbonation.