How to Clean Coffee Equipment: Machines, Grinders and Brewers

Rinse your equipment after every use, wash the removable parts with unscented detergent regularly, and give machines a periodic deep clean with a product made for coffee equipment. The reason is not tidiness: coffee oils left behind go rancid and make fresh beans taste stale, and a damp water reservoir is an excellent place for mould.

Why it matters more than you think

Oil. Roasted coffee is oily, and every brew leaves a thin film of that oil on whatever it touches — the brew basket, the carafe, a French press mesh, an espresso machine's group head, the burrs of a grinder. Exposed to air, the oil oxidises and turns rancid. It does not wash away with a quick rinse, it builds up over weeks, and it adds a stale, bitter, slightly cardboard note to every cup. Many people who think their coffee has gone off are really tasting their equipment.

Microbes. Water that sits in a warm machine grows things. In 2011, NSF International's microbiologists had 22 households swab everyday items in their homes. About half of the coffee maker reservoirs had yeast and mould, around one in ten had coliform bacteria, and on average the reservoirs had higher germ counts than bathroom door handles.

Minerals are a separate problem. Scale from hard water builds up inside machines and is removed by descaling, not cleaning — the descaling guide covers it.

Drip coffee makers

• Every use: rinse the carafe and brew basket, and throw away the filter and grounds promptly.
• Weekly: wash the carafe, basket and lid with warm water and unscented detergent. Empty the water reservoir, wash it and leave it to dry.
• Monthly or so: run a cleaning cycle with a cleaner made for coffee makers, then run plain water through two or three times.
• Never leave water standing in the reservoir for days. Empty it and let the machine air out.

A thermal carafe collects a stubborn brown film. Wash it with detergent and a bottle brush, rather than abrasive scourers that scratch the surface and give residue somewhere to cling.

Espresso machines

Espresso machines deal with oil under heat and pressure, and they need the most attention.

After every session

• Flush the group head with a few seconds of water to clear loose grounds.
• Wipe the gasket and shower screen with a damp cloth or brush. Grounds trapped under the gasket stop the portafilter sealing.
• Rinse and wipe the portafilter and basket.
• Wipe the steam wand immediately and purge it. Milk protein bakes onto a hot wand within seconds and becomes very hard to remove, and dried milk harbours bacteria. The milk steaming guide has more on wand care.

Backflushing

Many machines can be backflushed: you lock in a portafilter with a blind basket — one with no holes — and run the pump, so water is forced back up through the group head and out through the machine's pressure-release valve, carrying old coffee with it.

Only do this if your manual says your machine supports it. Backflushing relies on a three-way valve to relieve the pressure, and machines without one should not be backflushed. Where it is supported, a common routine is a plain-water backflush regularly and a backflush with an espresso machine cleaner periodically, followed by thorough flushing with clean water and a throwaway shot.

Periodically

Soak the portafilter and baskets — not the plastic handle — in hot water with espresso machine cleaner to lift built-up oil, then rinse well. Remove and clean the shower screen if your machine allows it.

Grinders

Grinders get forgotten, and they hold more old coffee than people expect.

• Brush out the chute and burr area regularly. Old grounds trapped inside go stale and end up in your fresh dose.
• Clean the burrs every few weeks if you grind daily. Follow the manual to remove them, brush them clean, and wipe away oily residue.
• Keep water away from the burr chamber unless your manual says otherwise, and make sure everything is completely dry before you reassemble it.

The grinder guide covers retention — the grounds a grinder holds back between uses — and why low-retention grinders stay fresher.

Manual brewers

• French press: a rinse is not enough. Unscrew the plunger every week or two and separate the mesh and plates, because oil and grounds hide between the layers. The French press guide explains why this matters so much.
• Pour-over cones and Chemex: wash after use. A Chemex's narrow waist needs a bottle brush, and it should be cleaned before stains set.
• AeroPress: rinse the chamber and the plunger seal after every use, and let them dry.
• Moka pot: rinse after every use, wash with a little mild detergent now and then, and dry the parts separately — see the moka pot guide.

What to use

• Unscented dish detergent for removable parts, rinsed thoroughly. Scented soaps leave flavours behind.
• Dedicated coffee machine cleaners for anything with an internal water path or a group head. They are designed to dissolve coffee oil and rinse away cleanly.
• A soft brush and bottle brush for corners and narrow vessels.
• Nothing abrasive on glass, stainless steel interiors or thermal carafes.

A simple routine

Ten minutes a week keeps equipment from undoing the work that went into growing, roasting and brewing your coffee.