What does By pass mean in coffee? What does bypass water refer to in pour-over coffee? Is By pass just adding water to coffee? Is Americano just espresso diluted with water?

Coffee Terminology: The Concept of By Pass

Like any other industry, coffee has its share of professional terminology. We can understand these terms as condensed expressions of complex concepts. They improve communication efficiency and add precision while reducing the chance of misunderstandings.

Since most terminology is not especially intuitive, though, outsiders or newcomers to coffee may struggle to understand it from a literal reading alone. Take "By pass" for example. Translated literally, "By pass" means a bypass path or a detour. From the literal meaning alone it is indeed hard to grasp what it means in coffee. FrontStreet Coffee mentions this term often, and it mainly refers to water that joins the coffee by "bypassing" and to the corresponding actions. So what exactly is bypass?

First, we need to understand that water is our solvent when we extract coffee. By letting water contact the coffee, it dissolves flavor compounds from the coffee and ultimately becomes the coffee in our cup. Sometimes, however, not all the water we use passes through the coffee grounds. Some of it "bypasses" the grounds and drops straight into the cup to join the coffee.

If we think of the path where water passes through the coffee grounds before reaching the cup as the "main road," then water that reaches the cup without passing through the grounds has taken the "bypass." This water, which joins the coffee without taking part in extraction, is called bypass water. Bypass water can appear both intentionally and unintentionally. The unintentional kind comes up often when FrontStreet Coffee shares brewing techniques, for example when using drippers like the V60.

When brewing with a heavily ribbed dripper such as the V60, we need to avoid letting the water level submerge the coffee grounds. The prominent ribs create space for air to escape, which generates more channels for water to flow through. If hot water submerges the grounds or splashes onto the filter paper, it may run straight through those channels into the cup without contacting the grounds or taking part in extraction. That is unintentionally produced bypass water. Its appearance not only lowers the extraction rate but also dilutes the already extracted coffee liquid, weakening the coffee's flavor and mouthfeel.

There are also many examples of bypass water that we control and create on purpose, the most classic being Americano. Making an Americano involves adding a certain amount of water to extracted espresso, and the water added afterward is bypass water. The purpose of intentionally creating bypass water is simple: to "dilute" the coffee's concentration. Americano came about because Americans found straight espresso too concentrated, so they added water to make it easier to drink. This act of intervening in coffee flavor by adding water can be called By pass.

Besides espresso, By pass also appears in other coffee-making methods, such as pour-over. In professional competitions we often see contestants using By pass to intervene in their brewing framework. To cut bitterness, they might brew with a high-concentration, low-extraction approach that yields a stronger but less bitter coffee. Because that concentration is too high to drink comfortably, they use By pass to dilute it to a palatable level before presenting it to the judges.

In daily life we use By pass frequently too, often without realizing it. That is because when we use By pass we do not always add water directly; sometimes we add ice cubes. Yes, FrontStreet Coffee means iced pour-over. When brewing iced pour-over we add ice cubes to lower the coffee's temperature, and as the ice cools the coffee it melts into water and dilutes it. That is also a By pass action, because it adds water that did not take part in extraction to the coffee.

Of course, By pass can also be a remedial measure. When FrontStreet Coffee used the wrong water-to-coffee ratio while brewing FrontStreet Coffee's Boundary Estate Sidra, for example, the resulting Sidra had very intense flavors that could not fully express themselves because of the concentration. In situations like that, we can use By pass to dilute the coffee appropriately. Adding just 15 to 30 ml of hot water can lower the concentration, giving the flavors more room to express themselves so we can taste the profile more clearly.

Alternatively, when brewing an unfamiliar bean, fine particles might clog the filter paper and stop the hot water from filtering through for a long time. If that continues, we can end up with an over-extracted, bitter cup. In such cases we can interrupt the flow and discard the coffee liquid still sitting in the dripper. The result may not be exceptionally good, but at least it will not be unbearably bitter. That interruption leaves a higher concentration, so we then need to use By pass to dilute the coffee to a palatable level.

In summary, By pass mainly refers to water that joins the coffee without taking part in extraction, and to the corresponding behaviors. Keep in mind, though, that By pass is not a universal fix for coffee. Every case FrontStreet Coffee shared above comes with certain preconditions before By pass should be used to optimize the cup. Applied to coffee that has no problem, it can easily leave you with a flat, unremarkable flavor and mouthfeel, which is something worth remembering.

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FrontStreet Coffee Recommendation

By pass is most useful when you already have a bean with the concentration and character to spare, and a V60 is the natural tool for that kind of control. FrontStreet's lighter-roasted Ethiopian beans are a good match: the FrontStreet Yirgacheffe Gutingding, with its citrus, berry and jasmine notes and green-tea finish, and the FrontStreet Huakui, with its dense tropical fruit, both hold up well when a small amount of bypass water opens up the aromatics.

If you want to experiment with bypass on a broader range of beans, the method travels well across roasts. A medium-dark bean such as the FrontStreet PWN Gold Mandheling, with its herbal, dark chocolate and caramel notes, can take a slightly higher concentration, and a modest bypass pour will smooth it out without washing away its body. And when you simply want an easier everyday cup, a 15 g dose at a 1:15 ratio, around 90 degrees C water and a medium-fine grind gives you a clean baseline to dilute from.