How to Descale an Espresso Machine: Step-by-Step Guide
What "descaling" actually means
Mineral deposits, mostly calcium and magnesium from your water, build up inside the boiler and the small pipes that carry hot water. They act a bit like cholesterol in an artery. They narrow the flow, hold heat unevenly, and give your coffee a metallic or chalky edge. Descaling is the process of dissolving those deposits with a mild acid and flushing them out.
When you actually need to descale
Ignore the "every three months" rule that floats around the internet. The real signal is your water hardness and how much you use the machine. If you live somewhere with soft water (under 50 ppm) and pull two or three shots a day, once a year is plenty. If you have hard water (over 150 ppm) and pull ten or more shots a day, you are looking at every two or three months. Most manufacturers bury the actual recommendation in the manual under a line that says "based on usage."
Three telltale signs you need it now: shots pulling noticeably slower than when the machine was new, steam pressure feeling weaker or the wand sputtering instead of producing a steady hiss, and hot water from the group having a faint metallic or rusty taste.
What to use (and what to skip)
You have two real options: a commercial descaler made for espresso machines, or food-grade citric acid. Both work.
- Commercial descalers like Urnex Dezcal or Durgol are formulated to be gentle on aluminum boilers and brass fittings, with built-in corrosion inhibitors. They are the safe default.
- Citric acid is cheaper and works fine for stainless-steel boilers. Use about 30 g per litre of warm water. Do not use vinegar on an espresso machine. It leaves a smell that takes a week of brewing to clear and it is harsh on rubber seals.
Whatever you use, do not run descaler through the steam wand unless your machine's manual specifically tells you to. The wand and its valve are not designed for acid baths.
The actual descaling process
1. Empty the drip tray and the water reservoir. Remove any water filter from the tank so the descaler does not react with carbon.
2. Mix your descaler per the bottle's instructions, or use the citric acid ratio above, and pour it into the reservoir.
3. Place a container under the group head and the steam wand, in separate containers. Run about half the reservoir through the group head, in ten-second bursts with short pauses. Then run the rest through the steam wand for thirty seconds at a time.
4. Let the machine sit with the descaler inside for the time the product recommends, usually fifteen to thirty minutes. This is when the acid does the work. Flushing immediately gives it nothing to dissolve.
5. Drain the boiler if your model has a drain valve. If not, you are relying on the next rinse to push everything out.
6. Rinse thoroughly. Refill the reservoir with fresh water and run two full tanks through the group and the wand. Pull a test shot. If it tastes sour or chemical, rinse again.
After the descale
Run two or three sacrificial shots into a cup and throw them out. Wipe down the drip tray and group head. Reinstall the water filter. Make yourself a real shot. You will usually notice the temperature feels more stable and the extraction is more even. That is the scale no longer interfering with the heating element.
When to stop and call a tech
If the machine is still pulling slow shots after a proper descale, the problem is mechanical, not mineral. It could be a failing pump, a clogged valve, or a worn pump gasket. Send us a message through the contact form below with your machine model, the issue, and how old it is. We will tell you honestly whether a service call is worth it.