How Does a Keurig Work? Understanding Pod Coffee Makers

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As pod-based coffee machines like the Keurig rise in popularity, more and more people are becoming accustomed to this new technology. However, several people still don’t understand how they work or what makes these machines unique.

Are they more like drip coffee makers or espresso machines? How do they make coffee so quickly? In general: How does a Keurig Work?

You could go and read the technical manuals, but who has time for that? Instead, lets go over these machines, their history, and how they work at a high level. That way, next time you and you friends are gathered around the coffee machine, you’ll be ready when someone asks “How do Keurigs Work?”

What Is a Keurig?

There are several types of coffee makers available. From cold brew makers and french presses to percolators and drip coffee makers, consumers have several options to choose from.

Over the decades, companies have taken great strides toward offering more versatility and ease-of-use in their coffee makers. What used to be a complicated task that required skill to execute properly can now be done by anyone at the touch of a button.

Okay, that is oversimplified. It only took the touch of a button after you measured the water and the grounds. It still seemed like there was more convenience that could be brought to the coffee world.

Simultaneously, there was a developing need for coffee makers that could brew a single cup of coffee. I would argue that there was always a need for this, but the advent of the Starbucks age had made it clear that the ultimate in coffee convenience could only exist when coffee was available one cup at a time.

Along came Keurig. 

By using pre-portioned coffee pods in place of loose grounds, Keurig replaced the messiest part of the coffee-making process with insert pod. This started the pod coffee maker revolution, a movement that would spawn machines from Nespresso and Ninja, among several other competitors.

Add in a partnership with Green Mountain Coffee Roasters for the early pods (and a deal to become McDonald’s coffee distributor), and Keurig had guaranteed their name would forever be associated with this new era in coffee brewing methods.

How Do K-Cups Work?

A detailed breakdown of a k-cup and how k-cups work

The unique advantages of Keurig coffee machines would not be possible without the K-cup, Keurig’s proprietary coffee pods.

As with most other coffee pods, k-cups are basically just a pre-measured amount of ground coffee sealed in filter paper and covered tightly with a layer of aluminum foil. These Keurig cartridges are, in many ways, just like the coffee filters that you are used to using in drip coffee makers. The genius of them just comes in pre-measuring the grounds and packaging it all together for complete simplicity.

One crucial aspect of K-cups is their airtight design. The main concern about buying pre-ground coffee — instead of grinding your own coffee beans — is that ground coffee goes bad much faster than coffee beans. If you want to slow the degradation of coffee grounds, you need to remove oxygen and light, the two factors that cause much of the decay.

I certainly won’t say that K-cups don’t go bad. However, they last much longer than regular ground coffee because each container remains airtight until you are ready to use it. This is much better than buying a bag of ground coffee which — even if it was initially airtight, will not remain so after you open it. Unless you are in a position to use the entire bag of coffee at once, that bag of coffee will be less fresh than if each portion had been individually sealed the way that coffee pods are.

Are k-cups instant coffee?

No, they aren’t, but this is a common misconception. Instant coffee isn’t the same as ground coffee. It’s actually made by brewing coffee then dehydrating it. Since k-cups are filled with ground coffee, they are not the same as instant coffee.

How much coffee is in a k-cup?

The exact amount depends on the brand and blend of the coffee. In most cases, though, a k-cup has about 2 tablespoons of coffee grounds. That’s about 8-12 grams of ground coffee or about 1 standard coffee scoop.

Breakfast blends and light roasts are typically at the low end. Dark roasts and extra bold blends are at the high end, with a few containing as much as 14 grams of coffee grounds. Medium roasts are somewhere in the middle.

How Do Keurig Brewers Work?

Keurigs are drip coffee makers…. mostly. They also introduce some aspects of espresso makers into their unique design.

There are multiple Keurig models on the market, including the successor to the original model — the K-classic — and the upgraded K-Select and K-Elite models. Advanced features aside, all of these models work in basically the same way. 

A Keurig has three basic compartments, which are connected by a series of hoses.

  • A water reservoir
  • A heating chamber
  • A K-cup holder

When prepping your Keurig, you need to make sure that there is water in the reservoir and a K-cup in the K-cup holder. When you close the lid, the machine punctures both the top and bottom of the K-cup, creating a pathway through which water can flow. But I’m getting ahead of myself.

When you press one of the start buttons, water is pulled from the reservoir into the heating chamber by the first hose. During this step, the water is pressurized, which is where the design borrows from espresso machines. Keurigs don’t achieve the level of pressure that good espresso machines do, which will be important later on.

Once the water is heated to the appropriate temperature, another hose pulls it above the k-cup holder and forces it — still under pressure — through the K-cup and into your mug below. Since the hot water is pressurized, it can extract the coffee grounds much faster than a standard drip coffee maker. This is why you get a cup of coffee in less than a minute.

How Do You Care for Your Keurig?

There are two parts to the care of a Keurig: the daily steps you take and the less frequent descaling process.

Daily care of your Keurig

If you’ve ever used a Keurig, you know that the daily care process is amazingly simple. Essentially all you have to do is keep the water reservoir filled and throw out (or preferably recycle!) old K-cups as they are used.

Descaling your Keurig

Every few months you’ll need to go through a more involved process — called descaling — to keep your Keurig running properly. Depending on how frequently you use the machine, whether you use filtered water, and the quality of your water, you may need to descale your Keurig as frequently as once a month.

You can use either a descaling solution or a mixture of vinegar and water to descale your Keurig, the latter option being cheaper.

The process for descaling a Keurig is fairly simple:

  1. Turn off the machine and empty the water reservoir.
  2. Pour the descaling solution or vinegar and the appropriate amount of water into the reservoir.
  3. Turn on the machine, place a mug in the chamber, and select a 10 oz cleansing run.
  4. Pour out the mug and continue the process until the add water light turns on.
  5. Rinse the reservoir thoroughly.
  6. Fill the reservoir with water and run 12 cleansing brews. (Don’t skimp on this step!)

Can You Put Milk in a Keurig?

Absolutely not. Every once in a while you see a video that claims that you can make a latte in your Keurig by adding milk or some bogus idea like that. It won’t work, and it will break your machine. Neither the reservoir nor the pipes are intended to have any liquids other than water and descaling solutions go through them.

If you want to have milk in your Keurig beverages, you should do one of three things:

  1. Add it after the coffee is complete. You can use cold milk, heat it in the microwave or on the stovetop, or even froth it in your favorite milk frother before adding it to the mug.
  2. Purchase a K-cafe, which includes everything you need to make lattes and cappuccinos with your Keurig.
  3. Buy k-cups that come with milk, like the Gevalia Cappuccino K-Cup Coffee Pods With Froth Packets.

The Downside of Keurigs

Keurigs are impressive pieces of machinery, but new technologies rarely come without a downside. You may already be familiar with some of these problems, but they are worth reiterating just in case.

K-cups are expensive

The typical low-end K-cups cost about $0.35 to $0.50 each, even for non-branded pods. If you buy only the K-cup branded pods, you’ll be paying about double that.

You can save quite a bit of money by using refillable pods, but you lose a lot of the convenience of the Keurig machine at that point. You will have to deal with coffee grounds and all the extra steps and mess that come with them. You still have a fast single-serve coffee machine, so it’s not all bad.

K-cups aren’t environmentally friendly

There’s a lot of extra plastic involved with K-cups, and that plastic has to wind up somewhere. Keurig claimed that they were on track to make 100% of their K-cups recyclable by the end of 2020, but we are waiting for an indication of whether they met that goal.

Of course, even 100% recyclable K-cups are still worse for the environment than simply not producing the plastic in the first place. Refillable pods help, but I talked about the downsides of them in the last section. 

Keurigs produce weak coffee

I mentioned earlier that I was going to return to the pressurized water, and here it is. The use of pressurized water is an important part of what makes espresso a stronger drink than drip coffee. You might expect the same to be true of Keurig coffee since it is also made using pressurized water and a shorter brew time, much like espresso.

However, a good espresso machine uses at least 9 bars of pressure, and the great ones use closer to 15 bars. Keurig machines simply can’t produce that much pressure.

The other important factor for making espresso-strength coffee is the coffee grind size. Espresso uses a fine grind, whereas K-cups use a medium to medium-fine grind. The finer the grind, the less time it takes to extract all that coffee goodness from the beans.

Put all of that together and you get the weak coffee that Keurig machines produce. The strong brew button on newer Keurigs helps to overcome this issue by slowing the brewing process. I personally wouldn’t buy a Keurig machine that didn’t have the strong brew feature, because I can’t survive on the weak default setting.

Final Thoughts

That’s pretty much all there is to these machines. The single-serve pods and the machine itself are both uniquely designed, based on an idea that is not quite a drip coffee maker but not quite an espresso machine. They are incredibly convenient, but they do have their downsides.

Other single-serve coffee machines have tried to improve on this idea, and many have done a fantastic job of creating the next generation of pod-based coffee machines and non-pod-based single-serve coffee makers. But the Keurig is still one of the best, most popular, and most iconic brands available.

Now you know what makes Keurigs unique. Next time you are sitting around the coffee machine, be sure to let your friends know you learned it at

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