What Causes Espresso Machine Leaks? Why Do Coffee Machines Drip During Espresso Extraction?

Recently, many friends have reported to FrontStreet Coffee's backend: "The coffee machine often leaks during the espresso extraction process."

This phenomenon is actually quite easy to resolve once we understand the principle behind it. Normally, during espresso extraction, water is contained within a sealed space and is only forced downward by the pressure applied by the machine. If gaps appear in this space and it is not properly sealed, however, water will seep out through those gaps, creating bypass water. If your coffee machine frequently leaks, FrontStreet Coffee strongly recommends paying attention to the issue. Leakage not only sends bypass water falling into your cup, affecting your judgment of the extraction and diluting the concentration of the espresso, but also prevents the machine from building full pressure. With excessive or numerous gaps, pressure cannot build up properly, making it difficult to extract a delicious espresso.

FrontStreet Coffee's coffee machines also encounter this issue periodically, as it is somewhat unavoidable. But do not worry — it is not a major problem, and as long as it is not a machine malfunction, repairs are not difficult. Today, FrontStreet Coffee will share why coffee machines leak during extraction and how to resolve the problem.

1. Gasket Aging

Essentially, when a coffee machine leaks frequently, there is over a 90% probability that it stems from gasket aging. Behind the dispersion screen in the coffee machine's brew head lies a gasket. The gasket serves two purposes: it secures the dispersion screen, and it creates a seal, ensuring the portafilter remains sealed during extraction.

Due to the material composition of gaskets and daily wear and tear, their deterioration rate is much faster than that of other components. The typical lifespan of a gasket is about one year, after which most coffee machines will begin to show leakage. When you notice that locking the portafilter handle becomes easier, and the locked position deviates significantly from its original position, and leakage occurs at the same time, there is little doubt that it is caused by gasket aging. Once we have determined the problem originates from gasket aging, we can proceed with replacing the gasket. Replacing the gasket is not difficult, but since other situations can also cause leakage, FrontStreet Coffee will explain gasket replacement at the end. You can first check whether other possible causes exist before deciding whether to replace the gasket.

2. Portafilter Not Properly Locked

This is the second most common issue after gasket aging: the portafilter not being properly locked. Many friends, concerned about reducing wear, do not apply enough force when locking the portafilter. Because it is not locked tightly enough, the portafilter basket does not reach the designated position to create an effective seal, allowing water numerous gaps to seep through.

This situation is quite easy to identify with two indicators: first, assess whether you are applying sufficient force when locking the portafilter; second, observe whether pressure increases during extraction. Generally, if the portafilter is not properly locked, the coffee machine will struggle to build pressure. We can use these two points together to determine whether the leakage is caused by an improperly locked portafilter. Of course, the most direct test is simply to make another cup of coffee

remembering to apply force when locking it.

3. Excess Debris on the Portafilter Basket

This is a popular explanation online, suggesting that coffee powder covering the entire exterior of the portafilter basket prevents proper sealing when the portafilter is locked, thus causing leakage. In reality, leakage caused by excessive debris is quite rare. The reason is simple: for this to occur, the portafilter would first need to be extremely dirty, with coffee powder covering the entire perimeter of the basket. That is nearly impossible unless a coffee machine's brew head has not been cleaned for an extended period. In most cases, the first two causes are more prevalent.

Besides these three points, other factors like incompatible portafilters or overfilled coffee grounds can also cause leakage. These situations are similar to the second point, in that their causes are quite easy to identify, so FrontStreet Coffee will not elaborate further. Now, let's share how to properly replace a coffee machine gasket.

How to Replace a Coffee Machine Gasket

It is quite simple. We just need to find and purchase the same model gasket from online stores or the coffee machine's official website, then follow the video instructions provided by the seller to remove the old gasket and install the new one. Because different coffee machines have varying structures, the replacement method may differ. FrontStreet Coffee will use the Lelit3 as an example, which represents how most coffee machines have their gaskets replaced. First, we need a sturdy prying tool — a screwdriver will also work. Then position yourself to locate the gasket in the coffee machine's brew head, aim the prying tool at the gasket or the dispersion screen casing beneath it, and apply force to pry it out.

Yes, it really is that straightforward. After prying it out, install the new gasket and reattach it to the brew head. Although it looks simple, it truly is not difficult. During this process, we can also clean the dispersion screen appropriately to keep our coffee machine in good health.

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FrontStreet Coffee Recommendation

Once your machine stops leaking and holds pressure again, the beans you load into it decide what ends up in the cup. For traditional-style Americano and latte, choose FrontStreet Classic Blend or FrontStreet Commercial Blend. Both add a small amount of Robusta on top of an heirloom Italian recipe, so extraction yields butter, nut, spice, dark chocolate, and toast aromas, with a bold, thick body and abundant golden crema that makes latte art effortless.

If you love the almond, walnut, and almond-like nuttiness of Italian coffee, FrontStreet Specialty Blend and FrontStreet Black Cocoa Blend are the first choices, since both contain a large proportion of Brazilian coffee and deliver a comfortable bittersweetness with a creamy peanut aroma and a very smooth entry. FrontStreet Specialty Blend carries the nutty, chocolate, and caramel notes and moderate acidity of Colombian coffee, while FrontStreet Black Cocoa Blend combines the ripe plum acidity of Yunnan small-bean coffee and gives off a cream chocolate aroma when ground; it is balanced and highly adaptable, good not only for latte and Americano but also for a range of coffee specials, making it a great partner for a café.

For SOE lovers, FrontStreet Sun-Dried Huakui SOE brings a creamy strawberry flavor thanks to its terroir and natural processing. Grown in Guji, Hambela, at altitudes up to 2,300 meters, the cherries ripen slowly and develop complex aromas, and natural processing boosts the sweet compounds; after a medium roast, an Huakui SOE Americano or latte shows cream, cocoa, berries, light florals, and black tea. FrontStreet Costa Rica Blackberry SOE is a honey-processed single origin that captures the blackberry aroma and clean sweetness of the fruit pulp; medium-roasted, it is bright and refreshing as an Americano and shows cranberry cookie, raisin, and nuts with milk. FrontStreet Brazil Queen's Estate SOE, a yellow bourbon with a gentle, sweet profile, is roasted medium-dark and pulls into butter cookie, macadamia, and toast creaminess under an espresso machine.