Descaling a coffee machine: how often, with what, and what it really costs

Look at the listing for one of the best selling descalers in Europe, durgol swiss espresso. It recommends descaling "regularly and preventively every three months", then in the same breath adds: "follow the machine's instructions first" (Amazon.fr listing, checked 09/08/2026).

That half step back is the honest part. Three months is a commercial average for a bottle sold across a continent. It is not a setting for your machine, in your kitchen, with your water.

What a bean-to-cup machine actually does is count. De'Longhi puts it this way: descaling "is necessary after a preset period of operation which depends on the water hardness setting", and "the machine leaves the factory with the water hardness configured at level 4, the maximum hardness level" (see the De'Longhi FAQ on setting water hardness, French; translation ours).

Philips does the same. The manual for the EP4349/70 bean-to-cup machine states that "the default water hardness setting is 4: hard water" (EP4349/70 manual, PDF, French edition; translation ours).

So a new machine assumes your water is very hard. If it is not, and you have never touched that setting, you have been over-descaling since day one. It is the highest return two minutes you will ever spend on the machine.

An interval with no hardness assumption and no cups per day attached to it is not advice. It is a number.

Hardness is the same physical quantity everywhere. The unit is not.

Conversion factors from Water hardness (French Wikipedia).

This matters more than it sounds, because coffee machine documentation is written wherever the machine was designed. A German manual quoting 14 °dH is quoting roughly 250 ppm, and a French one quoting 25 °f is quoting roughly the same water. Copy the number across without converting and you set your machine two notches off.

Rounding in the table is ours, from the conversion factors above.

Finding yours

Your water supplier publishes hardness for your supply zone, usually on the annual water quality report or a postcode lookup on their site. Failing that, a test strip costs a few euros and answers in a minute, which is plenty when the machine only offers four or five levels anyway. Most machines ship with exactly one strip in the box, the one everybody has lost.

The Bandelettes de test de dureté de l'eau en °fH, 10 pièces emballées individuellement is graduated in °fH, so European readers can set a French or Italian machine without an extra conversion step.

The number of cycles per year does not follow from hardness alone. The counter also counts drinks. Two households on the same hardness setting, one pulling two coffees a day and the other ten, will not see the prompt at the same time. That is exactly why no serious manufacturer publishes an interval in months.

Three practical consequences:

1. Set the hardness before you ask how often to descale. The other order makes no sense.
2. Do not postpone the prompt. It is not a comfort reminder. It is the output of a counter that has already run.
3. On a manual portafilter machine with no counter, you are the counter. A fixed rhythm is defensible there, as long as you write the assumption next to it. Say one descale per quarter for water around 250 ppm and two or three shots a day, shortened if your water is harder or your consumption higher. That is a stated rule of thumb, not a manufacturer figure.

If you are still choosing the machine rather than maintaining it, our bean-to-cup coffee machine comparison covers the other half of the question.

Vinegar comes up in nearly every forum thread. It is also the one product manufacturers name in order to forbid it.

Philips writes, in the manual for its bean-to-cup range:

Only use Philips descaler. Never use a descaler based on sulfuric acid, hydrochloric acid, sulfamic acid or acetic acid (vinegar), as this may damage your machine's water circuit and may not dissolve the limescale properly. Not using Philips descaler voids your warranty.

Philips EP4349/70 manual, "Descaling procedure", official PDF (French edition, translation ours)

De'Longhi says the same thing from the warranty side, in the Magnifica S manual:

It is recommended to use only a De'Longhi descaler. Using an unsuitable descaler, or descaling improperly, can cause faults that are not covered by the manufacturer's warranty.

De'Longhi ECAM22.110.SB manual, PDF (French edition, translation ours)

Two manufacturers, two wordings, one conclusion. Acetic acid attacks parts that the lactic or citric acid in a dedicated descaler leaves alone, and it leaves a smell that several rinse cycles do not always clear. The cheap bottle of vinegar gets very expensive on the day a service centre asks what you ran through the circuit.

On the dedicated side there is the manufacturer route and the universal route. The De'Longhi EcoDecalk Détartrant DLSC500, 5 doses de décalcification, 500 ml is De'Longhi's own, based on plant derived lactic acid, sold as a 500 ml bottle holding five 100 ml doses, which is exactly the dose the brand's manuals describe.

Philips works by whole bottle instead. The manual says to pour "the contents of a complete bottle" into the tank, so with the Philips Saeco CA6700/22 détartrant machine à café à grains, 2 x 250 ml, 2 cycles one 250 ml bottle equals one cycle.

If you have several machines of different brands at home, the durgol swiss espresso détartrant pour machines à café, 2 x 125 ml covers automatic, capsule and pod machines at one 125 ml dose per descale.

This is where in-store comparison goes wrong every time. A €7.99 bottle can cost more than an €8.56 bottle, because what matters is how many descales are inside it.

Prices seen on Amazon.fr on 09/08/2026 and likely to have moved since. The "cost per descale" column is our own arithmetic: pack price divided by the number of doses the manufacturer states, excluding delivery and promotions.

At three cycles a year that is roughly €5.13 against roughly €14.10. On a machine costing €400 to €700, neither figure justifies improvising with vinegar. Both justify reading the dose count before reading the shelf price.

Budget the time too. Philips states around 30 minutes for the full procedure in the manual cited above, descaling cycle and rinse cycle included. It is not something you start five minutes before guests arrive.

A water filter in the tank lowers the hardness of the water entering the machine and pushes the deadline out. It does not cancel it, and it has a life of its own. Philips says of its AquaClean filter that "after 95 litres of water have passed through the filter, the filter stops working", and asks for replacement "at least every three months" even without a prompt (EP4349/70 manual, cited above). The Philips Saeco AquaClean CA6903/22 filtre à eau anti-calcaire, lot de 2 is the matching cartridge.

Which water to put in the tank, and which cartridge suits which machine, is a separate subject and deserves its own article. Take only this from here: a filter changes the rhythm, never the fact that the machine will need descaling.

Prices and product details taken from Amazon.fr on 09/08/2026. Amazon pricing moves constantly, so check the displayed price before buying. Manual quotations are translated from the French PDFs linked in the text.