Short answer
A bean-to-cup machine needs descaling every four to eight weeks, a filter machine every one to three months. With soft water (below 8 °dH) the long interval is fine; with hard water (above 14 °dH) use the short one.
The intervals at a glance
| Task | Interval | Why |
|---|---|---|
| Descale, hard water (> 14 °dH) | every 4–6 weeks | Scale insulates the heating element and costs you temperature |
| Descale, medium water (8–14 °dH) | every 8 weeks | The default for most households |
| Descale, soft water (< 8 °dH) | every 3 months | Little scale, but not none |
| Rinse the brew group (bean-to-cup) | weekly | Coffee oils turn rancid and you taste it |
| Flush the milk system | after every use | Milk residue is a hygiene problem, not a flavour one |
| Replace the water filter | every 2 months | A spent filter stops softening the water |
Water hardness first, interval second
Any blanket answer to "how often should I descale" is wrong, because scale build-up depends entirely on the water. Some regions run at 5 °dH, others at over 20 °dH — a factor of four in the amount of scale passing through the machine per litre.
Your local water hardness is in your water utility's annual report, usually available online. A test strip costs pennies as an alternative. Look it up once and the number holds for years — and so does your interval.
Many bean-to-cup machines ask for water hardness during setup and derive their descaling prompt from it. That counter is useful if the configured value is correct. If it was never set, the machine assumes a default that may be far too short or far too long.
What limescale actually does
Scale settles on the flow heater first, because that is the hottest point. A layer of scale insulates: the machine takes longer to heat up and no longer delivers brew water at the 90 to 96 °C it needs. Under-extracted coffee tastes sour and thin — long before any error message appears.
Deposits also narrow the pipes, which reduces flow and loads the pump. The usual cause of death for a bean-to-cup machine is not a failed grinder but a pump that spent years working against scaled-up plumbing.
Brew group and milk system: the second job
Descaling dissolves minerals, not fat. Coffee contains oils that settle in the brew group and turn rancid over time. On machines with a removable brew group, taking it out once a week and rinsing it under warm water is enough — no washing-up liquid, it leaves residue. Every few months, add a cleaning tablet and run the machine's own cleaning programme.
The milk system is the only part with a genuine hygiene risk. Milk residue sitting in lukewarm tubing is a textbook growth medium. The automatic rinse after every use is mandatory; a thorough clean with a milk system cleaner belongs on a weekly schedule.
Filter machines and French presses
A classic filter machine has no grinder and no brew group, but it has the same flow heater — and therefore the same scale problem. Descale every one to three months according to water hardness. The carafe and filter holder should be rinsed after every use, because coffee oils settle there too.
French presses and pour-overs never need descaling, but they do need attention to oil: a French press screen is made of several layers with oil collecting between them. Unscrew it once a month and wash the parts separately.
Common questions
Can I descale with vinegar or citric acid?
Citric acid yes, at the right concentration and never above 60 °C — hotter than that it forms calcium citrate, which is harder to remove than the original scale. Vinegar is risky on machines with aluminium or rubber components. Manufacturer descalers are matched to the materials and cost little enough that the experiment is not worth it.
My machine has not asked for descaling — do I still need to?
Yes. The prompt is based on a count of brews and the configured water hardness. If that setting does not match your actual water, the count is wrong. Your own interval based on real water hardness is more reliable.
Does a water filter make descaling unnecessary?
No, it extends the interval. A filter binds some of the hardness minerals but not all of them, and it is spent after roughly two months. An old filter does not just filter worse — it can become a source of contamination itself.
What is the difference between descaling and cleaning?
Descaling dissolves mineral deposits in the water path. Cleaning dissolves coffee oils in the brew group and spout. You need both, each has its own interval, and neither substitutes for the other.