Check Valve

A one-way valve that allows water flow in one direction only. Used throughout the espresso machine — on the pump output, the brew valve, and the boiler inlet — to prevent backflow.

Why it matters — Check valves prevent steam from contaminating the brew water, stop hot water from siphoning back into cold lines, and protect components from water hammer when the pump cycles on and off.

Good to know

• Symptoms of a failed check valve: water dripping from the wand when not in use, pressure not building correctly, unusual gurgling, or the pump cycling unexpectedly.
• Most check valves are inline components — easy to replace once you've identified which one is leaking.