Cleaning an Espresso Machine: Water Alone Is Not Cleaning

Espresso, Explained · Part 11

Coffee oil does not dissolve in water. Flushing water through will not remove what has built up, and cleaning means a detergent made for the job and a basket with no holes.

01 Flushing water through is rinsing, not cleaning

Every shot leaves oil behind.

It coats the water path and the screen the water comes through, and over time it builds into a layer. Water passing over that layer carries the taste of it into the cup.

Oil does not dissolve in water.

It is the same reason you use detergent on a greasy pan. A few flushes take off the loose grounds you can see and leave the oil exactly where it was.

You taste it before you see it.

If the first shot of the day smells stale or the finish is muddy, look at the machine before you blame the coffee.

02 You need a blind basket and a proper detergent

A basket with no holes gives the water nowhere to go.

It is pushed back into the machine instead, washing the path on the way. A normal perforated basket cannot do this.

Use a detergent formulated for coffee oil.

Washing-up liquid does not rinse out cleanly and leaves its taste in the cup. Do not substitute something with a different composition.

Not every machine can do this.

On a machine with no pressure-release valve, forcing water against a blind basket puts strain on the system. Check the manual before you make it part of your routine.

03 Take the screen off once a month

A blocked shower screen sends water to one side.

The face you cannot see holds most of the oil. Scrub it in place and that side never gets touched.

Remove it and soak it in hot water.

Twenty minutes in hot water with the proper detergent lifts the oil out. A brush on its own will not reach inside the holes.

The gasket is checked at the same time.

Once the rubber hardens it cannot grip the portafilter and water escapes around the rim. A portafilter that now turns further than it used to is telling you to replace it, and since it often comes out with the screen, both are worth doing together.

04 Put the schedule on the wall

Cleaning that happens when someone remembers gets skipped.

Write down what happens when, stick it beside the machine, and the routine survives a change of staff.

How often	What to do	What happens if you skip it
Every close	Backflush with detergent, clean the wand and the tray	Oil hardens overnight and lands in the first shot
Weekly	Soak baskets and portafilters in detergent	Holes narrow and the flow turns unpredictable
Monthly	Remove and soak the shower screen, inspect the gasket	Water concentrates on one side and channelling starts
Quarterly	Replace the gasket and the shower screen	A hardened gasket crumbles and is hard to get out

Removing oil and removing scale are different jobs.

Backflushing deals with oil. Mineral scale inside the boiler needs its own chemistry and its own procedure. On a machine that has been neglected, loosened fragments can block the water path, so have a technician assess it first.

The line between your job and theirs is water, pressure and electricity.

Leave the boiler interior, the pressure valves and the electrical parts to a technician. Tell them when the symptom started and when the parts were last replaced, and the repair goes faster.

First Penguin Coffee Company We roast to order and ship afterwards. For wholesale customers we visit on the first order and go through settings and machine condition with you. Our coffees are listed under Beans in the top menu. Enquiries: 010-3444-1721

Also in Korean This article is also published in Korean. The original series it draws on, 50 parts on café practice, runs on our Naver blog. Read the Korean series

Next: grinder burrs, and how to measure when they need replacing.