Everything You Need to Know About No-Bypass Brewers

Several years back, Jonathan Gagné introduced the concept of no-bypass brewing. This term describes brewers who channel all brewing water through a bed of coffee. 

The “Other” Type of Bypass

The term “bypass” typically refers to water seeping through the wall of a pour-over filter above the grounds’ level. It’s important to note that this differs from the bypass feature found in a batch brewer. Batch brewer machines are equipped with a secondary water-dispensing spigot strategically placed near the inner edge of the basket. When the user opts to use some bypass, the bypass water pours into the basket but outside of the filter. Batch-brew bypass dilutes the final brew, similar  to how adding water to an espresso creates an Americano - they are both undergoing dilution. 

First Generation No-Bypass Brewer

The first and most surprising lesson from the first-gen no-bypass brewers was the noticeable reduction in pour over bypass, leading to a decreased potential extraction levels compared to what could be accomplished with a no-bypass brewer. Achieving extraction levels as high as 29% with coffees from kenya and Ethiopia in a no-bypass brewer is not a difficult task. That is no to say that those extraction levels are optimal; it simply highlights that the extraction ceiling is much higher in a no-bypass brewer. 

Second Generation No-Bypass Brewer

The second generation of the no-bypass brewers features a key design modification. This important design change was the addition of a valve capable of stopping and modulating the flow of liquid out of the brewer. Other improvements included lowering the shower screen, decelerating the water flow through the shower screen, and narrowing the brewer to elevate bed depth within the commonly used ground dose range of 20g-25g. 

Closing the valve during the bloom enables one to maintain a slurry above the grounds, which helps keep the slurry temperature higher. This “wet bloom” presumably makes it more likely the grounds will fully saturate with water. Many have observed consistently better results on average using a wet bloom, compared to letting the bloom dry out. 

A surprising lesson from the second generation no-bypass brewers was the significant impact of bloom time on cup quality. Comparing bloom times in a pour over in an apple-to-apples comparison is nearly impossible due to the complicating factor of whether (and for how long) the slurry dries out. The second gen allows for direct comparison of results across various bloom times while ensuring a slurry remains above the grounds in all cases. Many have notes that shorter bloom times tend to produce more aromatic and delicate brews, while longer blooms result in less aroma and heavier cups. 

Choosing a brewing method is a personal decision, and no-bypass brewers offer a great method for crafting your coffee. The preference is now in your hands - decide which brewing method suits you best!