Here’s Why Your Homebrew Beer Explodes When Opening

There’s probably no worse feeling than seeing your beloved homebrew go off like a time bomb. If this has happened to you, you probably want to know why. It’s also important to know about this if it still hasn’t happened to you, so you can avoid this problem. 

Homebrew beer explodes when there is too much carbonation in the bottle. Too much carbonation can be caused by infected beer, unfinished fermentation, or too much priming sugar. Refining your brewing technique and taking good care of sanitation will prevent this from happening. 

If you’re worried about another homebrew beer bottle exploding in your face, you’ve come to the right place. I’ll explain the reasons behind this and tell you how to fix those problems, so you don’t have to worry any longer. 

You May Need To Get Better Ingredients

Like in cooking or brewing other drinks, the quality of your ingredients will determine the quality of the final product. It may even determine whether or not the final product will explode.

You need to make sure that your ingredients are fresh and not dated. The freshness of the ingredients will determine how fast your beer ferments. 

Fresh malt and malt extracts will ferment faster than old ones. The same is true for yeast. For example, liquid yeast is often better than dry yeast, so you have to check for expiration dates. Expired yeast will also ferment slower than fresh yeast. 

This slower fermentation process may lead to bottling beer prematurely. You might wait out the usual time and bottle your beer, thinking it has finished fermenting. However, it’s possible that the fermentation process is not over, and that you’re bottling unfermented beer.

Then, to your surprise, your bear explodes just as you try to open it, and you’re left standing there, soaked in beer, like a cartoon character.

Or even worse, your beer might explode in the middle of the night and make a complete mess in your basement or kitchen. That might even require a new paint job, which means you have less money for brewing gear. Your spouse or roommates won’t be happy either. 

Plus, you’ll end up thirsty, and your hops and malt will go to waste. We don’t want that to happen, so let’s examine the other reasons your beer might explode. 

You Didn’t Ferment Your Beer Enough

We’ve already mentioned that beer fermentation can be incomplete because of subpar ingredients. However, it might be your mistake, too. Let’s see why. 

You might be anxious to finally taste your beer as a new brewer. I understand; we’ve all been there. This might prompt you to bottle your beer much sooner than necessary. This would be a critical mistake. 

If you bottle your beer too soon, the beer will continue to ferment in the bottle. As it ferments, gasses build up. Those gasses have to go somewhere and might go all over your cellar or living room if the beer explodes.

Plus, you’ll add some priming sugar to your beer when you bottle it. The yeast will love and eat it, and your beer will ferment, even more, causing it to explode. 

To prevent this, you first have to be patient. Even if you’re yearning to taste-test your beer, give it more time to ferment before you bottle it. 

You should also observe your beer to see if it’s still fermenting. You can do that visually and you can also use a hydrometer. 

You’ll see the yeast foaming up and churning around the fermenting vessel. You’ll also see bubbling in your airlock. These are clear signs that the fermentation is still going on. When this slows down, it’s hard to guess what’s happening.

Many assume that the fermentation is over at this point and think it’s time to start bottling. That’s how you get exploding bottles, so please, have some more patience.

You should take daily readings with your hydrometer. Compare the gravity to the recipe. It shouldn’t vary too much from it. 

If the hydrometer readings don’t change for three days, the beer has finished fermenting. Only then should you bottle it and store it. 

You can also have a small sip to see how your beer is doing. If it doesn’t taste sweet, looks clear, and the yeast cake has fallen down to the bottom, your beer has finished fermenting. 

Your beer will ferment more slowly if you use malt extract. You should keep this in mind and know exactly what ingredients you use. Not every beer ferments at the same rate. 

It’s also important to avoid using low-quality plastic fermenting vessels. These vessels have lids that fit poorly, and thus the gasses escape through them instead of the airlock. 

This can make you think the fermentation process is over and you should bottle your beer. This will lead to an explosion. Therefore, you should avoid using such low-quality fermentation vessels. 

Your Beer May Have Become Infected

This doesn’t mean that your beer has contracted some disease, but rather that there is a presence of bacteria and wild yeast. Wild yeast will always cause problems with your beer. 

Brewer’s yeast has a strict attenuation profile. This determines how much sugar it will eat before falling to the bottom of the fermentation vessel. 

Brewer’s yeast will never eat all the sugar in your beer. Some will be left behind to get the flavor profile you’re looking for. When the yeast is done, it will fall to the bottom, leaving you with tasty beer. 

On the other hand, wild yeast doesn’t have the self-control of a brewer’s yeast. Wild yeast will eat more sugar than necessary and won’t be satiated. 

If your beer’s gravity suddenly drops, it might be because of a wild yeast infection. If the infection happens before the fermentation, you might still be able to do something before the end of the process.

However, your beer can get infected during bottling. This is very tricky, as you likely won’t notice until your beer starts to explode. This doesn’t happen all the time, but it is a possibility you should watch out for. 

If your beer is infected with wild yeast, it will most likely eat all the sugar in its way. This includes the priming sugar you add to your beer. Usually, this causes explosions.

How To Prevent This?

To prevent your beer from getting infected, you must take great care of your equipment’s hygiene. All your equipment first has to be thoroughly cleaned and then sanitized

Thoroughly cleaning and sanitizing your brewing equipment will kill off bacteria and wild yeasts. Removing all dirt and residue from the previous batch is also important to ensure that no leftover yeast and beer are there to mess with your new batch.

You have to pay close attention to your beer after you boil it. There won’t be much you can do if you let it get infected after this stage. 

Using an unscented detergent and a sanitizer such as Star San is advisable. Of course, rinse thoroughly so you don’t get a detergent-flavored beer. 

Here’s a checklist of the things you should carefully sanitize.

  • Bottles
  • Bottle caps
  • Thermometers
  • The siphon
  • The tubing
  • The airlock
  • The wort chiller
  • The fermenter (goes without saying)
  • All the utensils you use
  • O-rings, spigots, and valves

If you’re forgetful, you can even print this list so you can check and recheck if you’ve cleaned everything you must clean. You can never be too sure. 

Watch Your Priming Sugar

Sometimes, the fermentation process goes smoothly, but you accidentally mess up when adding your priming sugar. This happens to everyone sometimes, and if you’re particularly unlucky, you’ll misjudge and get a batch of exploding beer. 

You usually mix priming sugar with hot water and add it to your mixing bucket before pouring the beer into it. The yeast reactivates and eats some of the sugar, which causes carbonation

In normal circumstances, everything is fine, and you get a refreshing beer. However, if you add too much priming sugar, the yeast will eat too much, release too much gas, and–you’ve guessed it–your beer will explode when you open it. 

This is unlikely to happen if you’re making beer with a kit because the sugar will be pre-measured. However, it is not difficult to make a mistake if you’re making your own recipe or following one from the Internet. 

You should measure by weight to avoid this problem, instead of by volume. It’s especially advisable to do this if you get sugar from a different manufacturer. A cup of sugar from one manufacturer may not be the same as a cup of sugar from another.

This will help you avoid mistakes, but you can make the process easier by using sugar tablets. You simply slip some of them into your beer bottles when bottling, and that’s it. They’re more expensive than regular priming sugar, but they help you avoid explosions. 

Use Higher-Quality Beer Bottles and Caps

Even if you’ve done everything right, a thin or cracked bottle will be a recipe for disaster. Even when made properly, beer can reach 30+ psi at room temperature. A low-quality bottle may not withstand this. 

You should avoid twist-off bottles. They don’t seal properly, so they won’t shield your beer well enough. You don’t have to avoid commercial beer bottles, but it’s better to get high-quality reusable bottles. Initially, they cost more, but the cost becomes negligible after a while. 

Before bottling your beer, your bottles have to be sanitized and inspected thoroughly. Examine each bottle against bright light and discard all that are damaged in some way. Even if the damage looks negligible, it’s best not to risk it. 

You should always have a stash of new caps ready. Don’t try to reuse them. They won’t seal well, so it will be like leaving your bottles half-opened. You’ll barely even feel the cost if you buy caps in bulk.

Instead of bottling your beer, you can start kegging it. While this won’t solve the underlying problems with your beer if it’s infected or improperly made, a keg won’t explode that easily, even if something is wrong. 

Plus, there is just something really cool in pouring a cold glass of beer directly from a keg. It can also be an amazing gift for a beer-loving buddy. 

Of course, after you bottle your beer, leave it in a dark and cool place. The dark glass of a beer bottle will shield it from the light somewhat, but if you leave it out in the open, it won’t help much. Ideally, store your beer in a cellar, and chill it in a fridge before consuming it. 

What To Do When a Beer Bottle Explodes

There’s no need to panic if a beer bottle explodes. It’s possible only one bottle was infected and the rest of your batch is perfectly fine. 

For a start, leave your bottles of beer alone for another day or two. If the other bottles don’t start exploding, you likely only had a problem with one bottle. However, you should still inspect the other. 

Make sure to be properly protected when inspecting your bear. You should at least wear safety goggles, but a face shield is preferable. Working gloves and a heavy jacket are good additions. This might seem too much, but you shouldn’t take any chances and get hurt. 

Take a few random bottles to test. Wrap them in a towel and take them outside. If the beer gushes out but tastes fine, it’s just over-carbonated, and storing it in the fridge may relieve the problem

If the beer gushes out but tastes yeasty or sour, the whole batch is likely infected and bad. In that case, your beer will have to go down the drain. This will hurt but is much better than chugging infected beer. 

If the other bottles also explode upon opening, it’s also a clear sign you should get rid of your beer batch. It’s okay if you cry at this point; I won’t tell anyone. 

Final Thoughts

That does it for today’s post. You should use the finest ingredients and ensure your equipment’s hygiene. This will prevent your beer from getting infected, in turn saving you a lot of grief upon throwing it away. 

About HomeBrewAdvice

Hello, my name is Simon. Together with a group of writers I write about brewing beer and making wine. We all share a passion for the great things in life, such as making stuff from scratch.

The business of HomeBrewAdvice is to bring you great information, stories and product reviews from brewing at home, and making wine


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