Channeling

Channeling refers to the formation of small water jets during espressoA small coffee beverage, about 20 ml, prepared on an espresso machine where pressurized hot water extracted through compressed coffee.: In its most stripped-down, basic form, this is... brewing due to poorly distributed grounds. When high-pressure water is forced toward the espresso puck, the water attempts to find the path of least resistance out, so if the coffee is not distributed evenly the water may form a small “channel” through the puck, rather than being forced through the coffee. This will result in a watery, under-extracted cup.