Why Does Brewed Coffee Taste Weak? What is Bypass Water? How to Make Pour-Over Coffee?

What is Bypass Water in Coffee Brewing?

Bypass water refers to water that doesn't participate in extraction during coffee brewing and is directly added to the coffee liquid. Typically, there are only two reasons why bypass water appears in the brewing process: intentional choice or passive addition.

Intentional choice means we specifically design a coffee brewing method that includes bypass water. For example, when making an Americano: first extract espresso, then dilute the coffee concentration with additional hot water; or in pour-over coffee, first brew a small pot of high-concentration coffee with a small amount of hot water, then dilute the concentration with additional hot water. This hot water that we actively add is the intentionally chosen bypass water.

However, for most beginners, the appearance of bypass water is mostly passive. For example, during the brewing process, due to improper operation, some hot water fails to pass through the coffee powder layer and instead passes directly through the filter paper, dripping into the lower pot along the filter cup. So what impact does bypass water created in this situation have on our coffee?

When there's excessive bypass water, the coffee will taste bland and thin in texture, basically watery and insipid. Because passively generated bypass water evolves from the hot water we originally used for coffee extraction, when some of the hot water for extraction is missing, the coffee extraction rate will decrease. The flavor will be somewhat inferior due to insufficient extraction rate. At the same time, because this bypass water flows through the filter cup into the lower pot, it will also dilute the concentration of the originally extracted coffee, thereby reducing the coffee's texture performance. So, how do we avoid bypass water during the extraction process?

1. Avoid Excessive Circular Motion

This is a precaution that FrontStreet Coffee often mentions in articles: avoid excessive circular motion! Because when we brew coffee, we inject hot water through circular motion to ensure that the hot water can extract as much coffee powder as possible, while also stirring the coffee powder to increase the extraction rate. But many friends tend to be quite "extreme" when starting out, wanting to wet every place where coffee powder exists with hot water to ensure all coffee powder gets extracted, even the edge of the cup wall where only a small amount of coffee powder adheres. Or when making large circles, the amplitude is too large, splashing on the edge of the filter cup where the powder wall is very thin.

Both situations will cause large amounts of hot water to pass directly through the powder wall and filter paper, dripping directly into the lower pot along the filter cup, minimizing contact with the coffee powder. This portion of hot water is what FrontStreet Coffee mentioned earlier as "passively generated" bypass water. Therefore, when brewing coffee, we can try to reduce the range of circular motion to prevent hot water from bypassing the coffee powder and affecting extraction and coffee quality.

2. Prevent Water Level from Exceeding Powder Wall

Another situation is caused by the water level being too high, exceeding the powder wall. Many times, to make extraction more uniform, we raise the powder bed to allow hot water to extract the underlying coffee powder.

However, some lightly roasted, high-density beans are heavier and cannot rise with the water level - simply put, they can't build up a powder wall. If in this situation we still insist on raising the water level, or insist on injecting all the target water volume, then the situation shown in the picture below will occur.

As you can see, the water level exceeds the powder bed by a degree, and some areas are not covered by coffee powder. This situation is particularly unfavorable for filter cups with multiple flow ribs because the hot water will directly avoid the coffee powder and flow out from the side. Since it doesn't participate in any extraction, this portion of hot water naturally belongs to "bypass water" and will have a certain impact on the coffee. There are many solutions, such as reducing the water flow. Through slow injection with a small water flow, the coffee liquid has time to seep out promptly without accumulating in the filter cup, naturally eliminating worries about the water level exceeding the powder wall and creating "bypass" opportunities.

But this approach often tests the brewer's skill and patience, so FrontStreet Coffee would recommend increasing the number of water injection sections to reduce the amount of hot water injected in each section. For example, washed light-roasted Sidamo beans have extremely high density, so during the brewing process, we cannot raise their powder bed. If we use the conventional three-stage brewing method, then during the second water injection stage, the water volume will be too much, causing the water level to exceed the coffee powder and allowing hot water to have "bypass" opportunities. In this situation, it's best to split the total water injection into four to five sections. Because the increase in water injection sections reduces the amount of water injected in each section. For example, if the original three-stage water distribution was 30, 120, 75, then after changing to five stages, it becomes 30, 50, 50, 50, 45.

The reduction in water volume means the water level has no opportunity to rise, and all injected hot water can pass through the coffee powder, fulfilling its proper extraction duty. At the same time, we also need to appropriately reduce the frequency and intensity of stirring, because the more water injection sections there are, the longer the extraction time becomes. If you don't want to drink a cup of bitter coffee, then it's best to appropriately reduce the intensity of water injection~

Important Notice :

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