Why You Should Fill Your Moka Pot With Water That's Already Boiling

Moka pots are an affordable option for making espresso-style coffee. It's not true espresso because the device uses a fraction of the pressure of an espresso machine, but it does make a great cup of coffee. It's simple to use, but there are certain things that should be done to make the perfect cup of joe — such as not tamping the coffee grounds and using filtered water. One step that is often overlooked makes a huge difference in how your cup of coffee tastes: using boiling water to fill the Moka pot.

Using boiling instead of cold or room temperature water has many benefits in the overall flavor and smoothness of the drink. The coffee is less likely to have a bitter or metallic taste when pre-boiled water is used. An espresso machine uses this principle by injecting pressurized steam into the espresso. This results in a strong flavor and makes for a smoother cup. Of course, the type of coffee beans used determines the strength and taste of the coffee, but using boiling water ensures a velvety sip. 

At first glance, it may seem counterintuitive to use boiling water in a Moka pot, but using cooler water won't extract all of the desired flavors from the coffee grounds. Using cold water also causes the grounds to "cook" while the water is heating. In a 2008 study published in the American Journal of Physics, researchers discovered that by using cold water in a Moka pot, coffee brewed at 158 degrees Fahrenheit, far below the optimal temperature of 195 to 205 degrees Fahrenheit.

The bottom chamber of the pot develops vapor pressure which forces the coffee up the tube and into the top chamber. However, researchers noticed that the water didn't have to reach boiling temperature to pass through the coffee grounds due to the built-up pressure. Cooler water travels through the device more slowly, which leaves more time for the coffee to burn. On the flip side, starting with boiling water speeds up the process so the brew is done before the grounds burn and become bitter.

By beginning with hot water, the contents of your Moka pot will maintain the correct temperature and avoid burning. It only takes a couple of minutes to boil the necessary amount of water, and you can use this time to prep the pot with coffee grounds so no time is wasted.