No one ever expects their usual morning cup of coffee to turn into a messy disaster area… the thing is, it has happened to some Moka pot owners!
But before you think about tossing your Moka Pot out, let me share:
- the primary reasons why this can happen and most importantly,
- what you can do to prevent it.
How Does a Moka Pot Work?
A Moka pot is a stovetop coffee maker that allows you to make espresso-like coffee without buying an actual espresso machine.
First known as the Moka Express, it was invented in Italy by Alfonso Bialetti in the 1930s and revolutionized coffee brewing.
The device uses steam pressure to push water through the coffee grounds to produce a delectable cup of joe.
Unlike espresso machines, Moka pots push water upwards.
- Boiling water in the bottom chamber gains enough pressure to move upwards
- The water then pushes through the middle chamber where the coffee filter basket rests
- Brewed coffee starts filling the top chamber.
The pressurized chamber is the part that can cause problems.
So, Can A Moka Pot Explode?
Yes, a Moka pot can explode, but only under specific circumstances. It never just explodes randomly, though, which is an important thing to remember.
When you heat the water in the bottom container, the boiling water creates steam. As the steam takes up more space in the chamber, the pressure will naturally rise. This pressure needs to go somewhere. So as the water continues to boil, the expanding pressure pushes the water up through the coffee grounds into the top chamber, where the pressure finally escapes.
If that process is ever interrupted and the pressure gets too high in the bottom chamber, the spring loaded pressure safety valve opens mechanically to release that extra-pressure. This valve is essentially a safety mechanism that acts as a secondary release point for pressure to escape in case there are any obstructions in the coffee brewing funnel.
What Can Cause It To Blow?
If the pressure keeps building and the safety valve doesn’t open, you could have an explosive problem.
This can be because of:
- There is an obstruction in the valve – Hard water which is high in calcium and magnesium has mineral deposits (or limescale) that can block the release valve. Fortunately, they are very easy to clean.
- You have a bad quality valve – This is simply one of the main disadvantages of buying Moka pots that are cheap. They will be made from materials that are not of good quality compared to brands like Bialetti.
- Using the wrong coffee grind size – Finer coffee grounds could block the holes in the filter to the point that the water can’t get through anymore.
- Tamping too hard – This is more common if you used a finer grind than usual as well. You don’t want the grounds to pack too tightly together that they block the steam from going through.
So for a Moka pot to explode, there must be an obstruction in the way the device releases pressure.
How Common Is It?
Let’s just get this out of the way too: if you’ve been using a Moka pot for years, it doesn’t mean it’s going to blow up soon. And if there is one, it’s not going to be an all-out boom that shoots shrapnel everywhere.
Aside from a more serious separation between the three main parts of the Moka pot, it’s more common for coffee or water to just burst out from the weakened connection of the middle and bottom chambers.
Of course, this is not to say that it won’t be destructive. You’ll mostly likely:
- Have coffee all over your kitchen
- Smaller parts of the pot may fly off and hit fragile items like plates or glass.
Then again, there are possibly millions of Moka pots being used around the world at this moment. Most people use theirs without any problem, and an exploding coffee maker is rarely heard of.
I personally have never heard of one, but here are 3 I found that have been “documented”:
And this video:
Are There Signs To Look Out For?
Many of those who had their coffee maker explode have not observed any obvious signs, but this is probably due to the fact that they didn’t maintain their Moka pot as they should have.
- One I can point out, however, is if you notice that the coffee flows up the top chamber significantly slower than usual. It could mean that the ground coffee is blocking much of the water from flowing smoothly.
- Another possible sign is leaking between the top and bottom chambers of your pot. This could either mean that both chambers we’re not locked tightly together or the water in the top part cannot escape through the right channels.
- If the rubber gasket inside your pressure valve is old, there may be water leakage coming from the valve itself. If you notice this, get a new valve of a new pot.
What to do if my Moka Pot is about to explode?
If you see these signs while brewing with your Moka Pot and you’re afraid it might explode, you should turn off the heat from your stovetop immediately.
It’s best to assume that it will explode anytime, so you should leave the kitchen and let the pot sit for 20-30 minutes. Once it has cooled down, you can then take it apart and find out what causes the problem.
How Do I Prevent a Moka Pot Explosion?
Now that you know how your pot could explode, remember these safety tips to prevent this from happening.
Clean and descale your pot regularly
Clean your Moka pot thoroughly after every use and descale it at least once a month. This is simply the best way to prevent any unnatural build-up of gunk and minerals. Check out my complete guide here.
Keep a close eye on the pressure valve
Depending on your Moka pot’s model, you can press on the valve to see if it’s working. If it moves, that means the spring and the ball inside can freely move under pressure. Otherwise, you can remove the valve by pushing on it from the inside with a pin. DO NOT press it from the outside as this could get your valve stuck.
Don’t overfill your Moka pot with water
Only fill the bottom container just below the safety valve, the water should never reach the valve. Filling it to the brim eliminates the purpose of the valve as the water itself becomes the reason for clogging.
Get the right dosage
In the same vein, don’t overfill the filter basket with your grinds either. Stick to the recommended amount you can add based on the size of your pot.
You only want to tamp the coffee container to even out the surface. You don’t even have to make sure the grounds are all leveled. Tamping hard means some grounds could shoot through the filter and cover the holes completely.
Don’t grind too fine
When you use too finely ground coffee in a Moka pot, and God forbid, tamp it hard, the pressure may not be enough to get through the coffee grounds.
The proper grind size for the Moka pot is medium fine. Do not use espresso or extra fine coffee. Pre-ground store-bought coffee is OK as well.
You will most likely never encounter any Moka pot explosions personally, I know I haven’t.
But now you know how to keep them from happening.
But if you’ve heard of any stovetop coffee makers exploding for whatever reason, please let me know in a comment below.