Line pressure pre-infusion

Using municipal or reservoir water pressure (0.5–3 bar) to gently wet the puck before the main pump kicks in at 9 bar.

Category: Pumps & Pressure

A pre-infusion technique where the brew valve opens to mains water pressure (typically 3–5 bar) before the pump engages. Saturates the puck gently before full 9 bar pressure builds.

Why it matters — Line pressure pre-infusion is one of the gentlest ways to wet the puck. The lower pressure lets the bed expand and settle without channelling, which is especially helpful for light roasts and fresh coffee.

Good to know

Only available on plumbed machines (the tank gravity-feed doesn't generate enough pressure).
Common on La Marzocco GS3 paddle and many commercial 2-group machines; standard on most café espresso machines.