Cleaning an espresso machine, and what actually kills them

Cleaning removes coffee. Oils and grounds build up in the group head, the shower screen, the basket and the portafilter, they go rancid, and they taste of it. This is frequent, quick and obvious once you have seen the water run brown.

Descaling removes limescale from the water side — the boiler, the pipework, the heat exchanger. It is infrequent, slower, and it is the one that decides how long the machine lasts. The two use different chemicals, address different parts, and neither substitutes for the other.

Affects taste immediately

Coffee residue — cleaning

Affects the machine permanently

Scale — descaling

The variable that decides frequency

Your water, not your usage

• Every session: wipe the screen, purge the group — Knock the puck out, wipe the shower screen with a cloth, run a short flush. Thirty seconds, and it stops the next shot tasting of the last one.
• Weekly: backflush, if your machine can — A blind basket — no holes — put in the portafilter, with detergent, and the pump run in short bursts. The pressure has nowhere to go but back through the three-way valve, taking the accumulated oils with it. This only works on a machine that *has* a three-way solenoid valve, which most entry-level single-boiler machines do not.
• If yours has no three-way valve — Backflushing does nothing useful and can force detergent where you do not want it. Soak the portafilter, basket and shower screen in the same detergent instead, scrub with a group brush, and rinse thoroughly. Check your own machine’s manual before backflushing anything: this is one of the few places in the hobby where the correct action depends on a piece of internal plumbing you cannot see.
• Soak the basket, not just the portafilter — The holes in a basket block gradually and evenly, so the flow degrades without ever looking wrong. Held up to a light, a clean basket shows a full pattern of bright dots. This is the cheapest diagnostic in the hobby.

How often you need to descale is set by your water rather than by your coffee. In a hard-water area a heavily used machine can need it twice a year; in a soft-water area with filtered water, once a year or less. Nobody can give you a figure without knowing your water, and any schedule quoted without that caveat is a guess.

The far better move is upstream. Softened or appropriately filtered water slows scale formation to the point where descaling becomes a rare event, and it changes how the coffee tastes as well — brewing water chemistry affects extraction, not only the machine. Using distilled or deionised water is not the answer: water with nothing in it extracts poorly and, in some machines, will not complete the circuit a water-level probe relies on.

The symptoms that mean it is already overdue:

• Slow or reduced flow that a clean basket and fresh grind do not explain.
• The machine taking noticeably longer to come back up to temperature between shots than it used to.
• Steam pressure that builds more slowly, or a wand that spits.
• Visible white deposit in the drip tray or around the group.

Old coffee accumulates in a grinder’s chute and around the burrs, goes stale, and mixes into every dose. A grinder that has never been opened is quietly contributing a percentage of rancid grounds to each shot. Brushing out the chute weekly and stripping and brushing the burrs a few times a year is a bigger improvement in the cup than most equipment upgrades.

Burrs do wear. On a domestic machine that is a matter of years rather than months, and the sign is a grind that will no longer produce a slow enough shot at any setting.