A common question that is often asked is, how long does a keg last? This question while being a simple question isn’t, however, a question that has a clear-cut answer. It is a topic that has a variety of different opinions, conditions, and facts on how long beer in a keg may last.

Depending on where you read, you might get an answer that ranges from 20 days to 120 days, but quite simply it’s almost impossible to know exactly how long it may last.

The Three Major influences on Beer Stored in a Keg

The first thing to note is that beer in a keg never actually goes bad (unsafe to drink it). It alters in taste. However, that altered taste can be quite rancid. Three major factors contribute to the speed in which the beer in the keg will spoil.

These three main factors are the number of bacteria living in the beer, the amount of oxygen in the beer and lastly the temperature that the keg is stored at.
how long does a keg last
While these three factors are a big influence when it comes to the freshness of the kegged beer, there is a general rule you need to keep in mind. As soon as that keg is filled at the brewery, the supposed “freshness clock” starts. The beers taste will immediately begin to alter, so the sooner you drink the beer in the keg the better it should taste.

Now the three different factors to the lifetime of a beer all complement each other in how they affect the freshness of the beer in the keg if one is neglected it can cause other problems to happen.

Bacteria

For instance, with bacteria. There are two types of bacteria, good bacteria, and bad bacteria. Luckily after a beer has been brewed, there is very little chance of bad bacteria living and growing in it as the nature of beer does not support them.

Good bacteria can still grow in beer and is not affected as much by the alcohol that prevents the bad bacteria from growing. The good bacteria that grow in the beer won’t make you sick like bad bacteria, as it grows, it imparts a flavor into the beer. This flavor tends to be very undesirable and not something you want occurring in your keg.

Oxygen

Oxygen is also another factor to how long your beer will last. Oxygen, in fact, has two negative effects on the beer, the first of these is that it provides fuel for the bacteria to grow in the beer. The second of these is that it oxidizes the beer, causing a change in the beer. As soon as oxygen has been introduced into the keg, it only becomes a matter of days before the flavor of the beer will be altered substantially.

With the introduction of oxygen it’s likely there will be a reduction in the Co2 in the beer, meaning it will also go flat. Using a hand pump or a picnic pump will cause the beer to change in flavor quite rapidly, this is due to these sorts of pumps introducing oxygen into the keg. If you’re lucky your beer will last for a day before its taste is completely altered, but it should be consumed within 8 hours of use.

However, a kegerator that has a Co2 bottle attached to it will allow you to keep your beer fresh much longer. This freshness is because it allows the keg to remain pressurized and prevent introducing oxygen into the keg. To avoid over pressurizing your keg, you may need a Co2 regulator. So if you want your keg, to last over a month instead of a matter of hours, it will pay to invest into a kegerator with a Co2 bottle.

Temperature

Lastly, out of the three main components, there is temperature. Temperature is probably the easiest to control out of these factors but is also one of the most important ones.

The warmer you store a beer, the faster the growth of the bacteria becomes, damaging the taste of the beer.

The cooler you keep the beer the slower the growth is, though it is worth noting that if you keep the beer too cold it will begin to freeze, so it pays to keep the keg cooled at the ideal temperature for the type of beer in your keg. One of the easiest ways to do this is to make use of something like a kegerator.
Beer Kegerator Setup

So, How Long Does a Keg Last?

The lifespan of a keg can be affected by a variety of different things, these mainly being the temperature of the beer, the amount of oxygen that has been introduced into the keg and the growth of the bacteria inside the keg.

Meaning that if you keep your beer cold, make the use of Co2 and not drive any air into the beer, keep the dispensing system clean, your beer should be able to last up to 4 months with a minimal amount of change in the flavor of the beer. One of the easiest ways to keep all of these in check would be to purchase something like a beer kegerator that can hook up Co2 as well.

I hope this guide has helped clear up any confusion how long does a keg last. If you have your own opinions, experiences or anything else that you would love to share, then please leave a comment below! I would love to hear your thoughts on this topic.