I use a small and simple espresso machine (Krups Model 963). Yesterday, I wanted to decalcify it and (being a rather unexperienced "barista") did what I usually do when decalcifying my water boiler: I poured vinegar concentrate, diluted with water, into it.

Afterwards, I wondered whether this might have been a bad idea and started some Google research. I found out that many people discourage the use of vinegar for decalcifying coffee machines because the vinegar may damage the cauldron. This seems to be of particular concern if the cauldron is made of aluminum, which seems to be the case with my machine.

After the cleaning and some iterations with pure water I tried to make some espresso. I didn't notice anything wrong so far: The machine seems to work well, espresso tastes good (or: as usual). The only thing that worries me is that when running the machine with pure water (without espresso powder in the sieve), I noticed some small white particles in the hot water coming out of the machine. These could be just chalk, but I also read that it could be part of the inner coating of the cauldron which has been dissolved by the vinegar.

Now I wonder whether it is still save to use the machine or not?

In particular, I wonder whether

  • the cauldron could be damaged so severely that it may explode?
  • the produced espresso could be toxic due to aluminum or parts of the cauldron's coating leaking into the espresso?

Any advice is appreciated!

3 Answers 3


I'll answer as a chemist and not as a coffee expert, but occasional exposure to vinegar won't substantially damage a piece of aluminum. Also ingesting traces of aluminum isn't toxic.


Diluted vinegar will not damage the boiler or hoses in your espresso machine. The reason that most commercial cleaners use citric acid is that vinegar has a penetrating taste and odor, so it will take several extra rinse cycles to get rid of any lingering traces.

The white particles you are seeing are mineral scale that was loosened but not fully dissolved by the cleaning. They're harmless.


I've always use the diluted vinegar method and never had any issues, making sure to run a few cycles of fresh water afterwards. I never emptied into the carafe, though; always into another bowl or large cup.

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