Bean to cup: what breaks, and when

Four failures, in the order they usually arrive

Brew unit seals, two to four years

The unit’s piston rides on O rings. They harden, they leak, and the first symptom is coffee in places coffee should not be: under the drip tray, around the unit, in the waste bin as liquid rather than a puck.

Preventable, largely. Rinse a removable unit weekly under warm water without detergent, let it dry, and grease the rails and seals with food-safe silicone grease twice a year. Machines that get this treatment run far past four years.

Scale in the thermoblock, three to six years

Most bean to cup machines heat water on demand in a thermoblock, a narrow metal path with a heating element wrapped round it. Narrow paths scale quickly, and a scaled thermoblock first makes the coffee cooler, then triggers flow errors, then stops.

Preventable. Descale when the machine asks, use its own product or an equivalent that names thermoblocks, and do not skip a cycle because the coffee still tastes fine. By the time it does not, the deposit is hard.

Grinder burrs and the chute, four to eight years

Burrs dull slowly, which shows up as weaker, faster brewing rather than as a fault. The chute is the more common problem: oily beans build up a paste in the throat, the dose drifts down, and eventually a slug of it drops into the unit at once.

Preventable. Avoid oily dark roasts, brush the chute when you clean, and never put anything but coffee in the hopper.

Electronics and motors, five years and up

The board, the brew unit motor, the flowmeter. These are age and duty rather than neglect, and this is where a machine becomes uneconomic to fix if the manufacturer has moved on.

Not preventable. Only survivable, by buying a brand that still sells parts for its ten-year-old models.

The weekly ten minutes that decides all of it

Empty and wash the drip tray and waste bin. Rinse the removable brew unit. Wipe the milk circuit or run its clean cycle the same day you use it, never the next morning. Brush out the grounds chute.

Machines that die at four years are almost always machines that got the annual descale and nothing else.