After brewing your cup of coffee, there is a little bit of water left in the boiler of the moka pot. Is that normal, how much should be left and what is the problem if there’s too much water left? Keep reading to find out.
It’s normal for a few milliliters of water to be left in the boiler of a moka pot if it was filled with the right amount of water. The last bit of water can’t produce enough pressure to get through the grounds and thus will stay in the boiler. A compacted coffee bed can cause more water to be left.
Why is there always a little water left and how much is too much? Keep reading to find out.
Should a moka pot use all the water?
Once a moka pot is done brewing, there will be a tiny bit of water left in the boiler. That’s normal and no reason for concern about your brewing skills.
Moka pots work with steam pressure. At some point there isn’t enough water left to turn into steam and get the pressure high enough to push through the grounds. So that last bit of water and steam won’t be able to make its way through the coffee bed and will stay in the boiler of the moka pot.
This is perfectly normal and just the result of how a moka pot works. There will be a few milliliters of water left after brewing your coffee. It’ll just be a little bit though. If you have a lot of water left (let’s say more than 10% of the amount you originally put in), there might be something else going on.
It’s unlikely you’ll even use all the water in the boiler. Even if you keep it on the heat long after the coffee is done brewing, there will be a little left just because the vapor can’t go anywhere if the pressure isn’t high enough.
So what’s going on if there is too much water left?
What can you do if there’s too much left?
So a little bit of water is normal. But what about there is still 20% of water left? That’s a bit too much and can be the sign of a problem.
The simplest solution is that you just didn’t keep the pot on the heat long enough. Water takes time to turn into steam. It doesn’t all happen at the same time. And the more steam is created, the higher the pressure gets which raises the boiling point. So if you don’t get enough heat into the water, it doesn’t all get the chance to turn into water.
Next time just keep it on the heat a little longer so more water gets the chance to turn into steam and get pushed through the grounds.
Another option is that the coffee bed is packed too hard so the water can’t get through. If your safety valve doesn’t work, that means the water can’t go anywhere. This actually creates a dangerous situation where the pressure keeps building and building and could lead to a messy disassembly of your moka pot.
If you took it off the heat and the water is still in the boiler, luckily that didn’t happen. Coffee grounds (especially freshly ground) swell up quite a bit when you add water.
So if you packed too much coffee in there or you tamped it down like in an espresso machine, and then it expands, it’s going to be really packing into the filter basket. And while an espresso machine might create enough pressure to move the water through the grounds, a moka pot does not.
In this case, just pour the grounds in the filter basket next time. Don’t tamp it down. If it still happens use a little less grounds.
Put in the wrong amount of water?
Are you afraid that you put the wrong amount of water in your moka pot? You probably don’t have to be.
Filling a moka pot to capacity with water is very easy;
- Locate the safety valve on the lower part of the moka pot
- Fill the boiler with water up to 2-4 mm below the valve.
If you then fill up the filter basket with grounds until the grounds are flush with the rim of the basket, you get a pretty good ratio of water to coffee. Of course you can measure out both grounds and water if you want to be very precise.
That means there are two mistakes you can make;
- You filled the pot to over the pressure valve
- You filled up the pot more than 1 cm below the pressure valve.
Both situations mean there is a different amount of water in your moka pot than optimal.
If you fill the water level to over the safety valve it might not work properly. It’s designed to relieve steam pressure, not water. If you fill it too high and the pressure valve opens, it will shoot a jet of hot water. While steam will dissipate quickly and move up, a jet of water can easily hit you even if you’re a few feet away. Boiling water can cause nasty burns.
Even if everything goes well, you will likely throw off the coffee ratio which could lead to over extraction of the grounds which can cause bad (bitter) tasting coffee.
If you under fill the boiler, the ratio goes the other way (if you don’t adjust the amount of grounds). This can cause under-extraction and sour coffee. However, in the end, you’ll just have the same amount of water left in the boiler as when you put the correct amount because that last bit just can’t generate enough pressure. That means the amount of liquid in your cup will be even less.
Favorite Moka Pot Products
You don’t need many things to brew good coffee with a Moka pot. Here are the few things you need to make the best possible coffee.
- Moka Pot: Just buy a high quality Moka pot from the get go. The cheaper ones can be messy when brewing. Bialetti is the original and still one of the best with it’s classic looks. They cost a bit more than the cheap ones but these can last for decades and the parts that wear out are easily available for the Bialetti Moka pots. The 3 cup size is good for a single person (Amazon)
- Beans: Good coffee starts with good beans. You can’t make bad beans taste good. Espresso roast beans are good for a Moka pot and will get you closer to that typical espresso taste. Peet’s coffee does a great 100$ Arabica espresso roast. Give it a try, you can get it here on Amazon
- Grinder: Using whole beans means you need to grind them at home. This improves the taste because the grounds are much fresher. A Hario Slim (Amazon) is a great starting point for the starting home barista. If you want a good hand grinder for a good price, check out the TimeMore C2 (Amazon)
- Scales: To get consistent results, a set of accurate scales is essential. Check out this Apexstone scale (Amazon). I’ve been using it for more than a year and while it doesn’t look the sleekest, it’s cheap and just as accurate as more expensive coffee scales. It just reacts a little slower.