Water to just below the valve, coffee untamped, low to medium heat, off the stove when the top is full. How a moka pot works and why it tastes burnt.
To use a moka pot, fill the base with water to just below the safety valve and fill the funnel with medium-fine coffee, loosely and without tamping. Screw the pot together firmly and put it on low to medium heat. Take it off the heat the moment the top chamber is full. Most of the craft is in not missing that moment.
How a moka pot works
A moka pot has three parts: a base for water, a funnel-shaped filter for coffee, and a top chamber where the brewed coffee collects. As the water in the base heats up, pressure builds — together with the air trapped above it — and pushes the water up through the bed of coffee.
A study from Trieste, published in Applied Thermal Engineering in 2009, corrects a common belief here: the water doesn't need to reach boiling point to be pushed out. The measurements showed that extraction begins at fairly low temperatures and depends on how much dry air is in the base at the start. The same study notes that the coffee bed becomes less permeable as brewing goes on.
In practice, this means the air space in the base is part of how the pot works. It is also why Bialetti's instructions insist that the water must not go above the valve: the air in that space is what heats up and drives the water through the coffee.
Water: just below the valve
Fill the base to just below the safety valve. Bialetti notes that overfilling "results in boiled coffee", and that underfilling affects the pressure and the quality of the brew. The valve is a safety part; water shouldn't cover it.
Some recipes suggest starting with hot water in the base. We haven't read a source that tests this. If you try it, hold the base with a cloth — it will be very hot.
Coffee: medium-fine, not tamped
Bialetti recommends a medium-fine grind and says to fill the funnel loosely. Don't tamp it as you would for an espresso machine. A moka pot works at lower pressure than an espresso machine, and a compacted, overly fine bed makes it harder for water to get through.
Wipe any grounds off the rim of the funnel so the parts seat properly. For how grind size affects flavour, see our grind size guide.
Heat: low to medium, flame under the base
Use low to medium heat. On gas, keep the flame from licking up the sides of the pot. Bialetti advises against letting the coffee boil or using full heat, which can give it a burnt taste.
Depending on the size of the pot and the heat, brewing takes three to six minutes.
When to take it off
As soon as the top chamber is full. You will usually hear a gurgle around this point. Bialetti's instruction is plain: remove the pot from the heat immediately once it is full. Leaving a moka pot on the flame is the quickest way to a burnt-tasting cup.
Cleaning and first use
Bialetti recommends washing all parts in hot water before the first use and throwing away the first three brews. The Moka Express isn't dishwasher-safe; wash it by hand in warm water. Coffee residue builds up inside the column of the top chamber, so clean that from time to time too. Don't use the handle as a lever when unscrewing the pot; it can break.
Quick recipe
- Fill the base with water to just below the safety valve.
- Fill the funnel with medium-fine coffee, loosely and level, without tamping.
- Screw the pot together firmly.
- Put it on low to medium heat, with the flame under the base.
- Take it off the heat as soon as the top chamber is full, and serve.
Frequently asked questions
Is moka pot coffee espresso?
No. Bialetti itself says the moka pot brews at a gentler pressure than a commercial espresso machine. The result is strong, but it isn't espresso.
Why does my moka pot coffee taste burnt?
The usual causes are too much heat and leaving the pot on the stove after the top has filled. Don't let the coffee boil.
Should you tamp coffee in a moka pot?
No. Fill the funnel loosely. Tamped coffee makes it harder for the water to pass.
Can a moka pot go in the dishwasher?
For the Bialetti Moka Express, no; hand washing in warm water is recommended.
Sources
- Bialetti New Zealand. “Moka Express”, product page and instructions. Water level, grind, heat, timing, cleaning and first use.
- Navarini, L., Nobile, E., Pinto, F., Scheri, A. and Suggi-Liverani, F. (2009). “Experimental investigation of steam pressure coffee extraction in a stove-top coffee maker”. Applied Thermal Engineering, 29, 998–1004. The thermodynamics of the moka and the temperature at which extraction begins.