Espresso Channeling: Causes and Fixes


Chris Clark

Chris Clark is the co-founder and chief content editor of With a passion for all things java, Chris has been a coffee blogger for the past 3 years and shares his expertise in coffee brewing with the readers. He's a hands-on expert, loves testing coffee equipment, and has written most of the in-depth reviews featured on the site. When he's not whipping up delicious drinks or experimenting with the latest coffee gadgets, Chris is exploring the local cafe. You can reach him at [email protected].

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Espresso channeling can be a frustrating issue for domestic brewers. Indeed, it is an experience I have had my fair share of over time. It has been particularly prevalent when I have used a bottomless portafilter, leading to coffee liquid spraying everywhere.

However, there are some straightforward ways to identify and resolve the issue. By understanding the reasons for the channeling and implementing some simple techniques, you can quickly and easily improve the consistency and quality of your espresso shots.

This article will detail what espresso channeling is, how it is caused, and how to fix it. In addition, I will offer practical tips and advice for identifying and preventing channeling and ways to solve the issue when it occurs.

Key Takeaways

  • What is it – Channeling results from water finding a narrow path through a coffee puck instead of spreading evenly through the bed. That is a problem because it can lead to over or under extracted espresso shot, negatively affecting the flavor.
  • How to identify channeling – Channeling can be identified visually or by tasting the drink. A bottomless portafilter is an excellent way to observe channeling in your shots. Meanwhile, if the drink tastes sour, bitter, or watery, that can be another sign of channeling.
  • Ways to fix it – You can fix espresso channeling using equipment including a bottomless portafilter, good espresso grinder, distribution tools and tamping skill. Adjusting the grind size can also help. Considering whether you are over or under-dosing the coffee can also help you identify the cause of the issue.

What is Espresso Channeling?

Espresso channeling is a common problem that occurs during the espresso brewing process. Channeling happens when water finds a narrow path through a coffee puck rather than spreading evenly through the bed. This can lead to an uneven extraction, meaning you could end up with an over or under-extracted shot. In turn, that will negatively impact the flavor and quality of the espresso.



There are several reasons for channeling, including incorrect tamping, a wrong grind size, incorrect dosing and improper distribution of the ground coffee.

When the coffee grounds are not distributed evenly in the filter basket, gaps can appear that allow the water to flow through, causing channeling. Similarly, if the coffee is unevenly tamped, you can get an uneven density in the coffee puck – another common cause of channeling.

Grind size can also be an issue. If the grounds are too fine, it can create a dense puck that water will struggle to penetrate. As pressure builds, water will find the path of least resistance, creating channels in the coffee puck. Conversely, if the grounds are too coarse, there will be a gap in the puck that allows water to flow through quickly, also causing channeling. You need to master the technique of dialing in for the perfect shot.


Signs of Espresso Channeling

In this section, I will outline the signs of espresso channeling that you can detect visually and through flavor.

Visual Signs

There are several visual signs to look for if you are trying to identify channeling. If you’re using a bottomless portafilter, you’ll have a clear indication of the extraction process, making it perfect for identifying channeling. This is what you need to look out for.

Bottomless Portafilter Spraying: If you notice coffee spraying out of the sides of the portafilter, or in many directions, rather than an even flow through the center this is a strong indication of channeling. It means the pressurized water can penetrate the areas with less resistance. Sometimes you can even see holes in the used coffee puck.

Bottomless portafilter

Uneven Flow: A beautiful espresso extraction should resemble a steady stream of honey dripping from the center of the portafilter. Check this video, and you will know what a good shot looks like.

However, if multiple streams appear or the coffee begins flowing from one side, it’s a sign that water is finding a path of least resistance and channeling through the coffee puck.


Early Blonding: As its name suggests, blonding refers to the point in the extraction where the coffee flows with a lighter color. If this happens too early (before 18-25 seconds), it is often a sign of channeling. It likely means water passes too quickly through certain parts of the coffee puck, causing under-extraction.

Taste Signs

The taste of the shot can also give some accurate clues on channeling.

If the shot tastes sour, bitter, or watery, it could be a sign of channeling.

Sourness is a common sign of channeling and suggests the water has not extracted enough of the coffee’s sweetness.

Bitterness is another sign of channeling and usually means the water has over-extracted the coffee. For example, if the water keeps flowing through a certain part of the puck, the grounds in that part will be over-extracted, leading to a bitter taste.

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If the shot tastes watery, it could be a sign that the water is finding channels in the puck and not extracting enough coffee. This can cause an unbalanced flavor profile and a bitter aftertaste.

Of course, the taste is subjective, while the coffee beans you use can also be a factor. However, a bottomless portafilter basket is the best way to troubleshoot your shot.

Why is Espresso Channeling a Problem?

The primary reason channeling is a problem is very simple: it can ruin the taste and flavor of the coffee. When water flows unevenly through the coffee bed, it under-extracts the higher-density areas while over-extracting the lower-density places. Not surprisingly, this causes uneven extraction in the cup, leading to unsatisfying bitter, sour, and muddy flavors.

Another potential issue is its effect on the espresso’s total dissolved solids (TDS). TDS means the amount of coffee solids dissolved in the water during extraction. When channeling occurs, the TDS can be inconsistent, resulting in a weaker or stronger shot.

The acidity of the espresso can also be affected by channeling. Acidity is vital to espresso, but channeling can cause it to be too high or low, offering an imbalanced flavor.

Channeling can also affect the clarity of the flavor. Ideally, the entirety of the coffee puck would have an identical volume of water throughout the shot. However, channeling means some parts of the puck interact with more water than others, leading to a lack of clarity in the finished beverage.

In short, channeling is an issue because it can lead to inconsistent and imbalanced espresso shots. However, if you can get to grips with the causes of channeling and how to prevent it, the flavor will improve significantly.

How to Fix Espresso Channeling?

As a barista, channeling is something I am familiar with. It can be frustrating as it can ruin the taste of an otherwise perfect shot. However, there are some simple steps I take to fix the issue. Let’s examine them.

Tools and Equipment

Before addressing the potential causes of channeling, ensure you have the correct tools and equipment. You’ll need a bottomless portafilter, a decent espresso grinder, distribution tools, including a WDT tool, and an espresso tamper. Before using the equipment, ensure it is clean and well-maintained.


Grind and Distribution

Grinding and distributing your grounds evenly is important in avoiding coffee channeling. Indeed, coarse grounds are often a reason for channeling. Try using a finer grind size and distribute coffee evenly across the portafilter.

Use a distribution tool. I recommend a WDT tool to prevent the bottomless portafilter from spraying coffee. The WDT tool is a simple tool with very thin needles capable of removing clumps in the ground.

Tamping and Dosing

Consistent tamping pressure is also important in avoiding channeling. Use an espresso tamper and ensure you apply even pressure. Try tamping the coffee as levelly as possible because any tilting will make some puck more resistant to the water, allowing the water to pass through the other side more easily. Always use the tamper in the right size. Smaller tamper can’t tamp the edge of the coffee puck, where the channeling often happens.

Don’t overdose or underdose the coffee. Most filter baskets show the capacity, so be prepared to adjust the measurement.

If you still have channeling after following these steps, try adjusting your grind size. Grinding too fine can cause channeling. Also, ensure you are not applying too much tamping pressure, which can lead to uneven extraction.


Pre-Infusion and Extraction Process

Pre-infusion is the process of wetting the coffee grounds before extraction. This can help avoid channeling too. Prosumer machines with an E61 brew group generally have the pre-infusion feature. So if your espresso machine has a feature, use it. Some machines even allow you to adjust the pre-infusion time, such as the HiBrew H10A.

While the espresso is extracted, observe the flow rate and adjust it if necessary. Also, follow a consistent recipe every shot.



Channeling can be one of the more frustrating elements of the espresso-making process. That’s because it can be difficult to identify without knowing what you’re looking for. Still, it is almost certain to compromise the taste of your beverage, even if every other part of the process was perfect.

Thankfully, there are some surefire ways to ensure channeling doesn’t occur, or if it does, you can fix it quickly and easily.

As with many areas of espresso brewing, a systematic approach to eradicating channeling is recommended. That way, you can soon identify the problem and act upon it. Then, before long, you’ll be enjoying beautiful espresso drinks without channeling to be found.

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Chris Clark

Chris Clark is the co-founder and chief content editor of With a passion for all things java, Chris has been a coffee blogger for the past 3 years and shares his expertise in coffee brewing with the readers. He's a hands-on expert, loves testing coffee equipment, and has written most of the in-depth reviews featured on the site. When he's not whipping up delicious drinks or experimenting with the latest coffee gadgets, Chris is exploring the local cafe.