How Does A Stovetop Espresso Maker Work?

How Does A Stovetop Espresso Maker WorkWhen I was first introduced to stovetop espresso made from moka pots the very first thing I was confused about was how it worked.

The process seems so opposite of other brewing methods, kind of like an Aeropress.

Turns out it is actually one of the simplest of them all because there are no moving parts, no extra steps to take, and once heat is applied to the moka pot it is entirely hands off.

How do stovetop espresso makers make coffee anyway?

The process is about is simple as can be. These pots have no moving parts and they use the basic laws of physics to make coffee. In short they are foolproof and virtually indestructible.

When you put water in the bottom of the pot and coffee grind in the middle chamber the heat source (be it a stovetop electric, gas, or an open flame) slowly turns the water into steam.

The steam fills the lower water chamber building pressure inside.

That pressure build enough to eventually start pushing the remaining water up the funnel in the center of the pot.

The water (that has not turned to steam yet) is then forced by the increased pressure through the grind which is sitting in the basket in the middle resulting in the creation of moka espresso/coffee.

Because of the pressure involved coffee brews more like espresso than drip coffee.

The pressure from the steam keeps pushing the brewed coffee up the funnel until it finally makes it through the second filter screen (a preventative screen to keep grind out of your cup) and it then enters the upper chamber through the top of the funnel.

When all the water is forced through the funnel via steam pressure the trapped steam then escapes through the funnel resulting in that distinctive hissing and gurgling sound that you hear at the very end of the brewing cycle.

In the long run these pots don’t fail however the rubber gasket in the middle may need replacing every few years as the heat can slowly damage it. These gaskets are extremely affordable and easy to find.

Here are some FAQs that we see all the time from people new to the stovetop espresso scene:

Do you have to make a whole moka pot every time?

The typical stovetop espresso maker is designed to work based on the water you put in the bottom chamber. If you don’t fill the chamber to the safety release valve then inadequate pressure will build in the pot and you won’t brew a good batch of espresso. If you use a lot less water then it may not brew at all.

How much water do you put into a moka pot?

Each moka pot is designed for a very specific amount of water. You need to use the exact amount every time otherwise things just wont brew correctly.

Luckily we don’t have to measure water out every time we want to use a stovetop espresso maker because they all come with a safety valve installed on the lower water chamber.

If you simply fill water into the chamber up to the valve without covering it then your moka pot will work just fine. This is the reason why it’s common to find households owning two or three different moka pots. Much like a sauce pan you just use the size moka pot you need for the amount of servings you want to brew.

Here are a collection of large moka pots which are harder to find in stores locally.

How Does a Moka Pot Filter the Coffee Grind

As I mentioned briefly above coffee grind is initially placed in the middle chamber of the device with water in the chamber below it. When water flows up through the grind it is reasonable to assume grind would rise with the water.

Above the grind cup however there is a filter screen that presses down ever-so-slightly on the grind kind of like you would tamp a portafilter on an espresso machine.

The screen stays pressed against the grind much like a French press does during the plunging process and it ends up holding the vast majority of the grind down, except of course for the very fine particulate that is always present in coffee grind.

Coffee from a french press is similar to that of stovetop espresso because it has body but the extraction potency of moka resembles that of the Aeropress or that of true espresso.

Why do Moka Pots Make Coffee All at Once at the Very End?

This is something else covered briefly above.

The stovetop heat source (or campfire) slowly takes cold water and brings it up to a boil.

This takes time and only when the temperature gets hot enough to start creating steam does the water start actually moving upwards through the funnel.

A stovetop espresso maker is actually a lot like a geyser that you might see at Yellowstone. As pressure builds it eventually gets to a tipping point where the liquid is forced upwards at great speed.

The entire time a moka pot is on the stove may be 3-10 minutes depending on the temperature of the heat source but the brew time is actually very quick, only 10 to 30 seconds or so at the very end.

A Few More Questions on How to Use a Moka Pot

Here are some more specific questions many people have regarding the inner workings of a moka pot and how to use one correctly. Unlick the questions fielded above we have taken more time and space to fully address the question on a dedicated page here on Stovpreso.

Click any link below to jump to the page covering that topic.

  • What kind of coffee goes into the moka pot basket?
  • Ever wonder why the vast majority of moka pots are made from aluminum? I did too when I bought my first unit. There are cool companies like Alessi making sweet stainless steel models but they do cost more. Click through to this post to read up on why aluminum moka pots are more common than stainless steel.
  • How often do you replace the gasket on a moka pot?
  • You don’t have to clean your moka pot if you use it regularly but there are very strict procedures for doing it the right way. Click through to learn how to clean a moka pot correctly.