I was given an old moka pot (this one in particular is a Junior Express pot) and noticed this buildup in the water well - it seems to be a little different from the typical scale buildup that I googled (it's grainy, thick, and hard). It has a metallic odor to it that seems to affect the flavor of my coffee. Is this just normal scaling, or something else?

I know that people feel really strongly about not cleaning these things, but I think I may have to in this case since it's affecting the flavor of the coffee. If you do think I have to clean it, what would you recommend for clearing this buildup out?

For the record, this was after I brewed a cup this morning, so it looks darker than it did before. The buildup had some white in it.

Also, how often/how do I know when I should replace the rubber gasket? I have no idea how old this thing is.

Thanks in advance for your help!

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3 Answers 3


Due to the fact that the spots are picking up the colour of the coffee, it sounds to me like they may be scales from minerals in the water being used. This is normal occurrence for almost every type of coffee maker.

When NOT to clean your Moka pot

In daily use, do not use soap and water to clean the pot. This is because oils from the coffee will build up in the pot and contribute to the flavour of the coffee for each concurrent use. Just rinse with warm water, let it dry, and put it away.

When to clean your Moka pot

If you don't use your Moka pot daily, these oils will build up but become rancid over time. If you don't use your pot daily, it's a good idea to give it a scrub with soap and water every now and again.

When to DESCALE your Moka pot

It seems that your Moka pot may have some hard mineral deposits, called scaling, inside the pot. There are multiple ways to descale a coffee machine. You can use a vinegar solution, lemon juice solution, or you can even buy coffee descaler from some supermarkets.

Recipe for lemon juice and vinegar solutions:

  1. 50 warm water, 50 percent vinegar. (Do not inhale any fumes)


  1. 25 percent lemon juice, 75 percent warm water. (Safer and more pleasant)

Notice: Don't boil these solutions as the fumes can cause damage to your eyes and respiratory tract.

When to consider throwing out your Moka pot

If your flavour is still affected after you descale it, you may be dealing with some rust. If you happen to notice any rust inside or your coffee just has a strange taste after some amount of time and many brews, you may need to consider getting a new one.

Good luck. If you have any questions, feel free to post them or comment here.


If it's in the water well then it's most likely mineral deposits from hard water OR oxidation. I think the sentiment against cleaning is in regards to detergents and the pot should be rinsed with water and let dry thoroughly to avoid any oxidation in the future. If the problem is mineral deposits it is just due to the water used in brewing and is not a major problem.

I would try to use something acidic such as vinegar to clean the pot and attempt to get out any minerals out. Cleaning it definitely can't hurt if it's affecting your flavor.

As for the gasket, if it looks worn out or the metal is damaged I would just replace it when you have a chance. They are fairly cheap and it isn't too difficult.


I can neither confirm nor deny that I do the following:

  1. After each brew cycle rinse the bottom water container but wash the top with soap and water. I know. Horrible. Rinse well.

  2. When you see the bottom water container starting to show a build up as in your picture (I do it sooner, but that is the idea) I use a descaling solution of citric acid and water. Mine doesn't take long. The vinegar or lemon juice solutions mentioned would also work. Don't leave them in the pot for very long. You only want to get the gunk mostly out. I finish this with (gasp) more soap and water along with a very good rinse ... especially if you used vinegar.

  3. I try to replace the gasket about the time it starts getting a bit brittle. They come in different sizes so get the correct one for your pot. I'm probably doing that wrong too as I use my pocket knife to start prying the old gasket out. I push the new one in with my finger. You might consider replacing the strainer at the same time since you can buy a gasket / strainer combination for $5 to $9 depending on where you get it.

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