Why descale a coffee machine, and can you use vinegar

What limescale does to a coffee machine

Limescale is mostly calcium carbonate. It coats the inside of the boiler, thermoblock or thermocoil, narrows pipes and sticks to valves and seals. A coated heater transfers heat less well, so water may not reach the right temperature, which affects taste. Narrowed pipes slow the flow. Flakes break off and block small parts such as solenoid valves, steam wand tips and shower screens.

Common signs that a machine needs descaling are slower flow, weaker or spitting steam, coffee that tastes less hot or flatter, louder pump noise and white flakes in the drip tray or cup. Many machines also count usage and show a descale reminder.

• Slower flow from the group head or spout
• Weak, spluttering steam
• Coffee less hot than usual
• White flakes in the drip tray
• A descale light or message

Can you descale with vinegar?

Vinegar is a dilute acetic acid, and it does dissolve scale. But many coffee machine makers advise against it in their manuals and recommend their own descaler instead. The reasons usually given are that vinegar's smell and taste are hard to rinse out of the system, that it may affect rubber seals, O-rings and some metal parts over time, and that it works less efficiently than a descaler designed for the job.

Using a product the manual does not approve can also matter if you need a warranty repair. The safest course is to read the manual for your model and follow what it says. If it names a specific descaler, use that one.

Note:Never mix descalers with other cleaning products, and follow the label. Descalers are acids, so keep them away from children and rinse the machine thoroughly afterwards.

What to use instead

Coffee machine descalers are usually based on lactic acid or citric acid, formulated to remove scale without leaving a strong taste and to suit the materials inside. Makers such as De'Longhi, Sage and Philips sell their own, and some approve others. Citric acid powder is sometimes suggested as a home alternative, but some manuals say not to use it in certain machines, so check before trying it.

Follow the machine's descale programme if it has one. These run descaler through the heater and valves in stages, then prompt you to rinse with fresh water. Machines without a programme have a manual routine in the instructions.

How often to descale

It depends on your water hardness and how much you use the machine. Set the hardness level in the menu from the test strip supplied, so reminders come at the right time, and descale whenever prompted. Machines without a reminder need a regular routine based on the manual, more often in hard water.

A water filter in the tank slows scale build up but does not remove the need to descale. Our hard water and coffee machines guide explains how to find your hardness, and the water hardness converter translates your supplier's figure into the units your machine uses.

Step by step guides for popular machines

Routines vary by model. For specific steps, see how to descale the Sage Barista Express, how to descale a De'Longhi Magnifica and how to descale the Gaggia Classic. If your machine has already stopped pumping because of scale, see Gaggia Classic not pumping water. If you are choosing a new machine for a hard water area, our best bean-to-cup coffee machines guide notes which have built-in filters and descale reminders.

Frequently asked questions

Can you descale an espresso machine with vinegar? It can remove scale, but many makers advise against it because of lingering taste, possible effects on seals and parts, and warranty terms. Use the descaler your manual recommends.

Why do you need to descale a coffee machine? To remove limescale that slows water flow, weakens steam, affects temperature and can block valves. Regular descaling helps the machine work properly for longer.

How do I get the vinegar taste out of my coffee machine? Run several full tanks of fresh water through the brew and steam paths, as you would after a normal descale, until no smell remains.

Is coffee machine descaler better than vinegar? For most machines, yes. It is designed for the materials inside and rinses out more easily.