How to descale a coffee machine?
Descaling a coffee machine means dissolving the calcium carbonate scale that builds up on heating elements and hydraulic circuits, by running an acidic solution — diluted citric, lactic or sulfamic acid, or a dedicated product like Durgol, Saeco or Jura — through the machine and then rinsing thoroughly. It takes 20 to 45 minutes and should be repeated every 2 to 6 months.
Scale is a mineral deposit formed when calcium and magnesium carbonates precipitate out of water heated above 60 °C. In Belgium, most major cities — Brussels, Antwerp, Liège, Ghent — deliver water with total hardness between 20 and 40 °f on the French scale (200-400 ppm CaCO₃), putting the country among the hard-water zones of Europe. A coffee machine — espresso, electric drip, or Jura/Delonghi super-automatic — heats 1-2 litres a day in an active household. At that hardness, an untreated boiler builds up 1-2 mm of scale within six months, cutting thermal efficiency by 20-40 % and eventually clogging valves and solenoids.
The generic procedure: empty the tank, remove the portafilter and any internal water softener (Claris for Jura, BWT for Delonghi), fill with the descaling solution per the manual — typically 30-50 g of citric acid per litre of warm water, or one sachet of commercial product. Run the built-in descale cycle if the machine has one (most super-automatics do, through the menu), or manually purge 300-500 ml through the group in 50 ml bursts every 2-3 minutes to let the acid act. Then rinse with two full tanks of fresh water, drawing 300 ml at each stage. On an E61 espresso machine, you must detach the portafilter during the cycle, purge the 3-way valve and flush the steam wand separately.
Product choice matters. Citric acid is cheap and food-grade but attacks rubber seals and brass parts at high concentration; some makers (Jura, Delonghi) void warranty if pure citric is used. Commercial descalers (Durgol Swiss Espresso, Saeco CA6700, Jura Claris, Delonghi EcoDecalk) typically use buffered lactic or sulfamic acid — gentler on seals and warranty-safe. On a machine still under warranty, the original product is strongly recommended. On an out-of-warranty machine, 30-50 g/L of citric works well provided you rinse generously.
Sequence discipline matters: drain water → descale → rinse → reinstall water filter → stabilising purge → return to service. A common mistake is to reinstall the Claris or BWT filter right after descaling: residual acid clogs it. Always purge one litre of fresh water before remounting a fresh or just-rinsed filter.
Standard descaling steps
| Step | Action | Volume / duration |
|---|---|---|
| 1. Prep | Remove water filter, empty tank | 5 min |
| 2. Solution | 30-50 g citric acid / L or dedicated product | 1-1.5 L |
| 3. Active cycle | Run auto-cycle or purge 50 ml bursts | 15-30 min |
| 4. Soak pause | Let acid dwell if doing it manually | 10-15 min |
| 5. First rinse | Fresh water, full purge | 1 L |
| 6. Second rinse | Fresh water, group + steam wand | 1 L |
| 7. Restart | Reinstall filter, purge 300 ml | 5 min |
What Descaling Actually Does Inside Your Machine
Limescale is calcium carbonate - the same compound that forms stalactites in caves. Inside an espresso machine, it deposits on heating elements, boiler walls, solenoid valves, and flow restrictors wherever hot water contacts metal surfaces. The chemistry is simple: calcium bicarbonate dissolved in water decomposes when heated, releasing CO2 and leaving solid calcium carbonate behind. In hard water areas (above 150 ppm total dissolved solids), a machine used daily can accumulate several grams of scale per month. As the layer thickens, the heating element must work harder to reach temperature, electricity consumption rises, temperature stability decreases, and eventually the element burns out entirely.
Descaling agents work by dissolving calcium carbonate back into solution. Citric acid (the most common), acetic acid (vinegar), and proprietary solutions like Cafiza or Dezcal all achieve the same chemistry - they lower pH enough to protonate the carbonate and release it as CO2 bubbles. The differences matter for machine longevity: citric acid is effective but can corrode certain rubber seals over time with repeated use; commercial descalers are formulated to be effective without attacking gaskets or O-rings. Never use vinegar in an espresso machine - its acetic acid odour can linger in rubber components and taint your coffee for weeks after descaling.
Practical Recommendations
Run a descaling cycle every 2-3 months if you use hard tap water, or every 4-6 months if you use filtered or softened water. Check your machine's water hardness indicator (most modern machines have one) or buy a simple TDS meter - water above 150 ppm TDS is hard enough to require more frequent descaling. After the descaling cycle, always run at least two full tanks of fresh water through the machine to flush all traces of descaling agent. Then pull a test shot and discard it before brewing coffee you intend to drink. Keep a logbook of descaling dates - it helps diagnose temperature problems later.