Moka Pots are simple brewers that make delicious coffee, but there’s a lot of debate and questions about the best way to use them. One of the most common questions is whether you should use hot or cold water in a Moka Pot coffee.
Ideally, you should pre-heat your water to 70°C (158°F) before adding it to your Moka Pot. If you start with cold or room temperature water, some desirable flavors won’t be extracted from the coffee grounds. On the other hand, water hotter than 70°C may result in bitter and over-extracted coffee.
While preheating your water does extract more of the coffee’s flavors, many people do prefer the benefits of using colder water in their Moka Pots.
Should You Use Hot Or Cold Water In A Moka Pot?
Preheating your water to 70°C (158°F) will give you the best coffee possible from your Moka Pot.
This was discovered by Warren King, a physicist who conducted research to determine the ideal water temperature for Moka Pots. (Research paper available at Laboratory MSC)
The Science Behind Water Temperature For Moka Pot Coffee
As you heat up your Moka Pot, the vapor pressure in the lower chamber will increase. It’s this increasing vapor pressure that will eventually push your water up the Moka Pot’s funnel.
However, King’s research shows that water doesn’t have to boil before the coffee gets pushed into the upper chamber. Instead, the vapor pressure is strong enough to brew your coffee at just 67°C (153°F).
But it’s even a bit more complicated than that.
As water gets forced out of the lower chamber, the remaining air expands into the empty space. This creates a suction pressure which makes it difficult for more water to leave.
To get a better idea of how this works, imagine drinking from a water bottle without stopping to take a breath. The more water you drink, the more difficult it is to keep sucking water out.
Moka Pot’s go through the same thing.
To overcome this, the water has to get even hotter for the vapor pressure to overcome this suction pressure.
But even with this increase in water temperature, experiments run by King show that the average extraction temperature is still only around 69°C (156°F)
This is way below the optimum extraction temperature of 90-96°C (195-205°F) recommended by the Specialty Coffee Association of America.
If you want your Moka Pot to extract as many desirable flavors as possible, you’ve got two options:
- Overfill your Moka Pot with room temperature water (this isn’t a good idea)
- Pre-heat your water before brewing
For Better Extraction You Can Add More Water (Not Recommended)
One way to prevent under-extraction is to overfill your Moka Pot with room temperature water.
By adding more water, you’ll minimize the air in the lower chamber. With less air, the suction pressure created will be even stronger.
So, the water temperature and vapor pressure will have to increase even more before the coffee gets pushed into the upper chamber.
And hotter water means you’re closer to the optimum extraction temperature.
While this is one way to increase the extraction temperature, we don’t recommend doing this because you’ll end up covering the pressure release valve.
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For Better Extraction Preheat Your Water (Recommended)
The best option for achieving optimum coffee extraction is to preheat your water.
If your water is preheated to 70°C before you add it to the Moka Pot, the average extraction temperature will be around 88°C (190°F).
While this isn’t the optimum extraction temperature, it is close!
However, since the Moka Pot’s temperature increases while brewing, the first bit of coffee brewed will be at a lower temperature and the last bit should be somewhere around 94°C (201°F).
So, by preheating your coffee to 70°C, your Moka Pot will get as close to optimum extraction as possible.
Keep in mind, that if your temperature is lower than 70°C you could still be under extracting. And if it’s much higher than 70°C, you’ll be over-extracting towards the end of your brew.
Other Benefits Of Using Preheated Water In Moka Pots
If optimum flavor extraction isn’t enough, there are additional benefits to brewing with preheated water as well.
First, your coffee will brew much faster if the water is already hot. A shorter brewing time makes it less likely that you’ll burn your coffee. It’ll also be able to spot brewing problems quicker.
(If you want to read more about potential problems, we’ve got a whole post on Why Moka Pots Sputter.)
Second, as you’re heating your Moka Pot, you’re also heating your coffee grounds. So, the longer you’ve got your Moka Pot on the stove, the more likely you are to cook and burn your coffee beans.
Why Do Some People Prefer Using Cold Water In Moka Pots
Despite the research, many people still prefer to use cold water in their Moka Pots.
Illy’s website recommends brewing Moka Pot coffee with cold water. Even Italy Magazine insists that you brew with cold water. (See step 2 in their article on Making the Perfect Moka Coffee.)
This is perfectly fine. Your taste buds don’t lie, and you may actually enjoy the taste of their Moka Pot coffee when it’s brewed with cold water.
But the fact is, brewing with cold water will extract your coffee at temperatures lower than the recommended 90-96°C.
If you brew with cold water, you’ll also benefit from having fewer steps when brewing and no risk of burning yourself by having to screw a hot Moka Pot closed.
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Brewing Moka Pot Coffee With Different Water Temperatures
King’s research says you’ll get the best extraction using preheated water, but we couldn’t just ignore decades of tradition that says to use cold water.
We wanted to know once and for all which was better, so we did our own experiment.
- First we brewed coffee with pre-heated water
- Second with room temperature water
- Finally we used cold water that was in the refrigerator all night.
For this, we used our Bialetti Moka Pot and Folgers Simply Smooth.
We don’t recommend using Folgers Simply Smooth to brew Moka Pot coffee since it’s mild with bigger grinds.
The point is only to test the brewing temperature and extraction rate.
Since Folgers is weaker and milder than the Cuban Coffee brands we normally go with, we figured any differences in taste and appearance would be more obvious.
We also rinsed and completely cooled off the Moka Pot after each brew, so as not to affect the brewing time of the next batch.
Brewing With Preheated Water
We used an electric kettle to preheat our water and poured it just below the safety valve. We then added 3 and a half tablespoons of coffee grounds to the Moka Pot and used a towel to help us close it up.
The coffee began to brew very quickly and at 2 minutes and 44 seconds the Moka Pot was sputtering and gurgling, so we removed it from the heat.
The coffee looked cloudy and we could clearly see that a lot of the oils had been extracted.
It wasn’t bitter, and it was dense with a heavy mouthfeel.
Preheated Results:
- Brewing time – 2 minutes 44 seconds
- Cloudy appearance
- Balanced flavor and heavy mouth feel
Brewing Moka Pot Coffee With Room Temperature Water
For the room temperature test, we added another 3 and a half tablespoons of coffee and poured water until it was just below the safety valve.
This time the brewing time was a minute and a half longer than when using preheated water.
The coffee came out clearer, which indicated a lower extraction of oils. It also tasted sharper and had an astringent quality that the first coffee didn’t have.
The coffee also didn’t taste burnt, which was thought to happen due to coffee grounds cooking during the heating process.
Room Temperature Results:
- Brewing time – 5 minutes 22 seconds
- Clear appearance
- Watery with a sharper taste
Brewing Moka Pot Coffee With Cold Water
For the last brew, we used water that was in the refrigerator all night.
Again, we added 3 and a half tablespoons of Folgers and poured water just below the safety valve.
I had expected the cold water coffee to be somewhat similar to the room temperature coffee. However, this one was more watery and had less flavor than the preheated and room-temperature coffees.
This one didn’t taste burnt either, but it took the longest to brew.
Results:
- Brewing time – 6 minutes and 9 seconds
- Clear appearance
- More watery than room temperature coffee
- Less flavorful
From left to right we have coffee brewed with preheated water, room temperature water, and cold water.
Key Takaways:
You’ll definitely get a heavier mouthfeel and fuller flavor when you preheat your water.
- Using a Moka Pot with water that’s been pre-heated to 70°C is ideal for optimum extraction.
- Cold or room temperature water will under-extract your Moka Pot coffee
- Using pre-heated water brews your coffee faster
Cheers Coffee Lovers!
KEEP READING
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- Pour Over vs Drip: Which Is The Better Brew?
- Coffee Espresso Temperature. Here’s What To Do To Brew A Unique Cup!
- Full Bodied Coffee: A Richer, Thicker, And Delicious Cup Of Coffee!
Oliver is co-owner of Coffee Break Lovers. The only thing he loves more than the process of brewing coffee is drinking it.
