How Does a Coffee Percolator Work: The Complicated Truth

Are you wondering how does a coffee percolator work? Yes, we know that perking can be difficult, but what is so great or bad about the percolator itself that it requires a lot of effort from the brewer? Also, while we are at it, what is percolation? Or is it called “perking”?

We have a lot of questions there but do not worry as we will answer all of those. If you think about it, this classic (and difficult) way of brewing can really take a toll on a person. Of course, we are talking about the high chances of you over-extracting the grounds, which will then result in a bitter and undrinkable coffee.

Come to think of it; it is the only brewing method wherein you can really mess up badly that you end up wasting the grounds. Why is that? Good thing, the answer lies in the parts of the coffee percolator and how they work together during the brew. With that said, we are going to take a deeper look at how percolators work.

Further, we are going to talk about the whole process of perking. We will discuss why it is so easy to mess up when you go through the perking process too.  Are you a fan of classic brewed coffee? Then you might just enjoy this read.

What Is Percolation?

First off, let us discuss what this percolation process is. Also, keep in mind that most people call it “perking” instead of “percolating” or “percolation.” Percolating or perking is a process wherein a solvent goes through a substance that is permeable. During this process, filtering is expected to happen. The end result is the final brew.

Wait, what? What did we just say? Let us make it simpler.

The solvent that we are talking about here is the water. Based on what was mentioned earlier, it goes through something that is permeable, which refers to the percolator basket. Naturally, when it goes through that, it filters the already present grounds in the basket, thus “filtering” them.

Different Parts of a Coffee Percolator

To really understand how it works without being too scientific about it, let us talk about the different parts of a coffee percolator.

  • Small chamber
  • Vertical tube
  • Perforated chamber
  • Reservoir

Small Chamber

This is a very small space at the bottom of the coffee percolator. This space is placed directly and nearest to the heat source. Further, this space is connected to the vertical tube.

Vertical Tube

This is where some of the heated water will enter by way of the small chamber. When the percolator reaches a high enough temperature, by way of gravity, water will rise up through this tube and go out at the top. Some percolator designs have upper tubes that can spray on either side.

Perforated Chamber

This is also called the percolator basket. Accordingly, this is where you place your coarse grounds. It is also connected to the vertical tube. In line with this, this is where the heated water from the vertical tube will exit.

In the process, the water heats the grounds and starts brewing them. Then, the water will pass through the grounds and seep its way out of those little perforations.


The so-called final resting place of the “now-brewed water” is the reservoir. However, this brew can mix with the non-brewed water that is yet to enter the vertical tube. When the hot water mixes with the cold water, it will then help the cold water to be pushed down and be sucked into the vertical tube.

Afterward, the process is repeated until there is no longer cold water.

How Does a Coffee Percolator Work: Just Like an Airlift Pump?

Yes, it is precisely like that. We do not know if you remember your science courses, but when heat is introduced into something, and you have something hollow near it, the heated substance will get sucked in. The same goes for perking.

So, you see, when you put the percolator in the heat, you are not actually heating up the entire reservoir. Instead, you are heating up some of the water, in order for it to go through the tube and pass through the percolator basket where the grounds are.

Come to think of it; the whole process is like giving the grounds in the basket a bath. They are not fully immersed in hot water, but instead, they go through many cycles of hot baths until all of the water inside the reservoir are heated enough.

Why Is it Hard to Perk Coffee?

It is hard to perk coffee because just like what we discussed earlier, the process is not just about heating. It is also about sucking in already heated water. With that process alone, you can conclude that you really have no control over it. You just have to trust that the coffee percolator is properly designed to suck in heated water as fast as it can.

In term of easily over-extracting the coffee grounds, the answer is also based on the actual process. Sadly, with this brewing method, the grounds will be consistently exposed to water. Some of which were already the ones that passed through the grounds the first time they went to the vertical tube.

Therefore, that batch of water will have a bitter taste. There is no exact way to pinpoint which “batches of water” will be sucked in from the reservoir. There are even cases where only the hot water will get sucked in, and it is only by the last minute that the remaining warm water will get to the basket.

But then again, you have no control over that because it is all about the process. The thing that you have control over is your view of the grounds and the color of the coffee, which, in some ways, can also tell you if the brew is already over-extracted.

Final Words

How does a coffee percolator work? It is pretty complicated. It makes use of simple laws of gravity, but at the same time, due to its inexact process, it makes it hard for the brewer always to have a consistent tasting coffee. Now that you have a deeper understanding of how it works, though, you can then find out different tips and tricks on how not to mess it up!

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