What happens inside a coffee machine you don't clean

Tap water contains calcium and magnesium. When heated, they form deposits that we call limescale. In a coffee machine they build up mainly in the heater (thermoblock or boiler), in the valves and in the thin hoses. The path for the water gradually narrows, the pump has to push harder and the heater heats less efficiently.

The second enemy is coffee oil. Every coffee leaves a little oil and fine powder on the brewing unit, the strainer and the spout. Over time it turns rancid, gives the coffee a bitter taste, and the deposits can even block the unit. On machines with a milk frother, dried milk adds to this and clogs the nozzles.

Typical signs of neglected maintenance:

  • coffee flows more slowly or only drips
  • coffee is lukewarm or weaker than before
  • the pump is louder and the machine whirs without dispensing
  • water appears under the machine
  • the frother sputters or the milk won't froth

How often to do what

Daily

  • Empty the drip tray and the grounds container (the used coffee “pucks”).
  • Rinse the frother after every milk drink. On bean-to-cup machines, just run the rinse programme.
  • Fill the tank with fresh water, not yesterday's.

Once a week

  • On machines where it is possible (such as De'Longhi, Philips or Saeco), take out the brewing unit, rinse it with lukewarm water and let it dry.
  • Take apart and wash the frother or the whole milk system.
  • Wipe spilled coffee from around the brewing unit.

Once a month

  • Run the cleaning programme with a tablet, if your machine has one. On machines where the brewing unit can't be removed (for example Krups or Jura), this is the main way of cleaning it.
  • Wipe the oily film off the bean hopper with a dry cloth.

As needed

  • Descaling: as soon as the machine asks for it. If it has no indicator, roughly every 1 to 3 months, depending on the water hardness and how much coffee you make.
  • Replace the water filter according to the manufacturer's instructions. An expired filter no longer softens the water.

Descaling: what to watch out for

  • Use a descaler made for coffee machines, ideally the one the manufacturer recommends. Don't use vinegar: it can damage the seals and its smell is hard to rinse out of the machine.
  • Remove the water filter from the tank before descaling, if you use one.
  • Don't interrupt the programme, and rinse the machine thoroughly at the end so that no descaler is left inside.
  • Set the water hardness in the settings using the test strip that usually comes with the machine. The machine will then know by itself when it is time to descale.

When maintenance is no longer enough

Some faults can't be solved even with careful maintenance. If any of these symptoms persist after descaling and cleaning, it is better to have the machine checked:

  • no coffee comes out at all, or only in drips
  • the machine shows an error that can't be cleared according to the manual
  • a puddle forms under the machine
  • the brewing unit can't be taken out or put back in
  • the grinder only hums, or it grinds but the coffee goes no further
  • the machine lights up but doesn't respond to the buttons

That last one is what the Tchibo Cafissimo capsule machine in the picture above came to us with recently. Over time the play between the lever and the switch had grown, so the machine “didn't know” the lever was in the brewing position and ignored the buttons. A new switch and a repaired switch holder did the trick.

Don't put off a leak or water running out. Water can reach the electronics, and a minor seal replacement suddenly becomes a control board repair. See how a coffee machine repair works and how much it costs.