Channeling

Channeling happens when the coffee puck has weak points — uneven distribution, cracks from tamping, gaps from the basket walls — that let water punch through faster than the rest of the bed. The result: water spends time over-extracting the weak path while under-extracting the rest, producing a confused shot that tastes both sour and bitter at once.

Visual signs include shots that pour fast and thin, shots with bright streaks or jets, and uneven crema with light/dark patches. Audio cues: hissing or spitting from the spout. Taste signs: muddled, harsh, both sour and bitter — never balanced.

Preventing channeling means dosing evenly (no clumps), distributing grounds across the basket (WDT or a distribution tool), tamping level (not tilted), and using a clean basket. Most channeling traces back to inconsistent preparation, not equipment failure.