Cleaning, descaling and machine ownership

Two deposits, two chemicals

Widely documented

• Cleaning: an alkaline detergent — Made to remove coffee oils and residue. Used on the parts coffee passes through: group heads, baskets, portafilters, carafes and brew units. It is not sold as a scale remover.
• Descaling: an acid — Made to remove the mineral scale that hard water leaves on heating elements and in boilers, kettles and water paths; the common ones are based on acids such as citric acid. It is not sold for coffee oil, and one machine maker advises against owner descaling because of the risk of corrosion.
• Milk systems: their own cleaner — Milk leaves proteins and fat that neither of the others is made for. Steam wands and automatic milk systems have a cleaner formulated for that residue.

What equipment does when a job is overdue

CoffeeHQ explanation

These are common signs, not a diagnosis. Several faults share a symptom, and a machine that leaks, trips the electrics or will not heat needs a qualified repairer, not cleaning.

A routine arranged by when, not by appliance

Typical range

1. After every drink. Wipe and purge the steam wand. Knock out and rinse the basket and portafilter. Empty spent grounds from a press, moka pot or brewer before they dry on.
2. At the end of the day's use. Flush and brush the group head. Run the rinse cycle on an automatic milk system. Wash carafes, filter baskets and anything else coffee has sat in.
3. Every week or so, under daily use. Soak baskets and the portafilter in detergent. Empty, rinse and dry the water tank. Brush out the grinder. Rinse the brew unit of a bean-to-cup machine. Backflush with detergent if the manual describes it; how often depends on how many shots you pull.
4. When your water says so. Descale kettles and machines at a rate set by water hardness: often, on hard water; seldom, on soft. Replace water filter cartridges on the maker's stated life, sooner if the water is harder than the figure it assumes.
5. When a part shows wear. Replace gaskets that leak, seals that no longer hold, mesh that has frayed and burrs that have gone blunt. These have no calendar; they are replaced on evidence.

The intervals are what is commonly done in a home, not a specification. Where a manual gives a different one, the manual is right.

What each kind of equipment needs

Widely documented

Espresso machines

Group head, shower screen, baskets, portafilter and steam wand all need regular attention. Backflushing clears oil from inside the group and is only possible on machines with a three-way valve; if the manual does not describe it, the machine cannot do it.

Bean-to-cup machines

Most have a removable brew unit to rinse, a grounds drawer and drip tray to empty, and a milk circuit that must be rinsed after use. The built-in grinder is cleaned by the maker's own method, not taken apart.

Pod and capsule machines

Empty the used-capsule container, wipe the piercing needle and brewing head, and run the machine's descaling programme. A capsule machine still heats water and still scales up.

Filter machines

Wash the carafe and basket after each use. The water path scales like any other and is descaled through the machine's own cycle, using what the maker specifies.

Press, moka pot, AeroPress, cold brew

Take apart whatever comes apart: a press's mesh stack, a moka pot's gasket and filter plate. Cold brew equipment needs particular care, because a cold steep does nothing to kill what grows in a dirty vessel.

Grinders

Brush out retained grounds dry. Do not wash steel burrs, which rust. Grinder-cleaning products exist for removing oil without dismantling; whether they suit your grinder is for its maker to say.

Reusable filters

Brush trapped fines out of metal filters. Rinse cloth filters in hot water only, never detergent, and store them wet in the fridge or completely dry, whichever the filter's maker specifies; a cloth left merely damp at room temperature is the thing to avoid.

When not to descale

Widely documented

Descaling is not an owner job on every machine. The manual for one maker's home boiler machines says the company does not recommend descaling them at all: its stated reasons are that many descaling chemicals are aggressive enough to corrode the metals inside, and that it is very difficult to rinse all of the solution out afterwards. It tells owners to control the quality of the water instead. Where a manual describes no descaling procedure, do not improvise one. Read the manual before the first descale, not after.

Where descaling is permitted, use the product and concentration the maker specifies and follow its rinse instructions exactly. Makers disagree about household acids, which is the reason to read your own manual and not somebody else's. One capsule-machine maker states plainly never to use vinegar because it can damage the machine, while the instruction book for one widely sold home espresso machine specifies a mixture of white vinegar and water. What is right for one machine can damage another.

The better strategy is to make less scale in the first place. Softer or filtered water slows it dramatically. Check what water the manufacturer recommends, because some also advise against water with almost no mineral content: one maker says it may affect how the machine is designed to function, and another that its tank sensor will not recognise distilled or very low-mineral water at all.

Handling the chemicals

Widely documented

Detergents and descalers for coffee equipment are concentrated. Use only products intended for the purpose and described as food-safe, follow the label for dilution, and keep them away from children and from food. Never mix a descaler with a detergent or with any other cleaning product.

Do not put a product somewhere the manual does not tell you to. Detergent belongs in a blind basket or a soaking jug, not in the water tank, unless the machine has a programme that says otherwise. After either job, rinse more than seems necessary and discard the first water or the first shot. A soapy or sour taste afterwards means the rinse was too short.

When the coffee is telling you to clean

CoffeeHQ explanation

Coffee has turned bitter or stale with no change of beans

Usually because: Rancid coffee oil somewhere in the coffee path.

Change first: Clean the parts coffee touches before adjusting any recipe.

Machine needs cleaning or descaling

The machine is slow, quiet or spluttering

Usually because: Scale is narrowing the water path or coating the element.

Change first: Check the manual, then descale if it is permitted.

Limescale building up

Coffee tastes of soap or acid after maintenance

Usually because: Cleaner or descaler was not rinsed out fully.

Change first: Rinse again with plenty of plain water and discard the first brew.

Coffee tastes of cleaner

Backflushing seems to do nothing

Usually because: The machine may have no three-way valve, so there is nowhere for the water to go.

Change first: Confirm in the manual that the machine can be backflushed.

Backflushing does nothing

Steam is weak or comes from one side of the tip

Usually because: Dried milk is blocking the holes.

Change first: With the machine off and cool, clear the holes with the pin tool supplied with the machine if it has one, then soak the tip. Do not force anything wider than the hole through it.

Blocked steam wand

When to stop and call someone

Widely documented

Cleaning and descaling are owner jobs. Anything involving the inside of a pressurised boiler, the electrics, a safety valve or a leak from within the casing is not. Unplug the machine and contact the manufacturer or a qualified repairer.

The same applies when a machine is still under warranty and the manual does not describe the job you have in mind. Opening a machine, or descaling one that should not be descaled, can cost more than the service it was meant to avoid.

What to do next

• Cleaning and maintenance planner — Builds a checklist for the equipment you have, with the signs that each job is due.
• Cleaning vs descaling — The difference between the two jobs, in more detail.
• Descale a machine — The procedure step by step, including what to check before starting.
• Backflush an espresso machine — How to do it, and how to tell whether your machine supports it.
• Water suitability helper — Whether your water is likely to scale, which decides how much of this you will be doing.