The most common mistakes when making espresso (and how to avoid them)
Most espressos don’t fail because of bad beans, but due to small mistakes during brewing. A grind that’s too coarse, too little coffee or a cold brew group can completely change the flavour. Luckily, these mistakes are easy to spot and prevent. With the right attention and technique, you’ll pull an espresso every time with a full body, a beautiful crema layer and exactly the flavour you’re after.
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Using the wrong grind size
The wrong grind size is the most common mistake when making espresso. The grind size determines how fast water flows through the coffee and thus greatly affects the flavour.
If the grind is too coarse, the espresso flows too quickly and tastes sour and watery. If the grind is too fine, it flows too slowly and the flavour becomes bitter and heavy. The ideal espresso has a brew time of about 25 to 30 seconds and a nice, even crema.
Adjust the grind size in small steps, change one setting at a time and taste the difference. This way you learn exactly how your grinder reacts and find the perfect balance step by step.
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Using too much or too little coffee
The amount of coffee determines how strong and full your espresso tastes. If you use too little coffee, the espresso becomes weak and watery. If you use too many espresso beans, it tastes bitter and heavy and the water may struggle to flow through the puck.
For a double espresso, use on average 18 to 20 grams of ground coffee. Always weigh the coffee with a barista scale instead of dosing by feel. Even a one gram difference can noticeably change the flavour.
Keep tasting and noting with every adjustment. Working with fixed amounts helps you get to know your machine better and quickly correct mistakes.
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Incorrect tamp pressure or distribution
Wrong tamp pressure or an unevenly distributed puck is one of the biggest causes of a poor espresso. If the coffee is tamped unevenly, the water finds the easiest path. This is called channeling. The result is an espresso that is partly over- and partly under-extracted: bitter and sour at the same time.
Always tamp the coffee evenly and firmly, with about 15 to 20 kilos of pressure. More important than the force is that the tamp pressure is consistent every time. Use a flat tamper and make sure the coffee is well distributed in the portafilter before tamping.
A small investment in a distribution tool or a tamper with a spring mechanism can help you work more consistently. This way you get an even extraction and an espresso with a nice, creamy crema.
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Wrong water temperature or pressure
The temperature and pressure of the water determine how well the flavours are extracted from the coffee. Water that’s too hot scorches the coffee, making the espresso bitter and harsh. Water that’s too cold extracts too few aromas and oils, resulting in a flat and sour taste.
The ideal water temperature for espresso is between 90 and 96 degrees Celsius. Most modern espresso machines regulate this automatically, but with manual machines you can set it yourself. Also make sure the pressure stays around 9 bar. Too little pressure makes the espresso flow too fast, too much pressure makes it flow too slowly.
Let your machine fully heat up before you start, so the water stays stable. A constant temperature and pressure ensure a balanced espresso with full flavour.
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Poor machine cleaning
A poorly cleaned espresso machine is a silent flavour spoiler. Old coffee residues, fats and oils build up in the brew group, portafilter and spout. These residues burn with every new brew and give a bitter, stale taste to your espresso.
Clean your machine daily. Rinse the brew group with water after each use and wipe the portafilter clean with a dry cloth. A thorough cleaning once a week is recommended. Use a special cleaning agent to loosen coffee residues and oils. Don’t forget to clean the steam wand and water spout as well.
A clean machine not only makes tastier coffee but also lasts longer. Good cleaning is therefore not only a matter of flavour but also of maintenance.
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Forgetting to properly warm up the machine
A cold espresso machine is one of the simplest but most underestimated causes of a poor espresso. If the brew group, portafilter or cups are too cold, the water temperature drops during brewing. This results in a flat, sour taste and a thin crema.
Always let your machine warm up properly before you start. Give it at least 15 minutes to fully heat. Also warm the portafilter by leaving it in the machine. Then run some hot water through the system to stabilise everything.
Finally, use warm cups. A cold cup cools your espresso down quickly, causing the flavour to be lost. With a well-warmed machine you’ll immediately taste more body, aroma and sweetness in your espresso.
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Old or improperly stored coffee materials
Old or improperly stored coffee beans are one of the biggest flavour killers. Once coffee is exposed to air, light or heat, it quickly loses its aromas and freshness. You’ll notice this immediately in the cup: the espresso tastes flat, bitter or stale and lacks its lively aroma.
Always store coffee beans airtight, in the dark and at room temperature. Preferably use packaging with a freshness valve or a storage container that keeps oxygen out. Buy smaller amounts that you use up within two to three weeks so the beans retain their flavour.
Also avoid using old, ground coffee. It loses most of its aromas within a few hours. So always grind your beans just before brewing for the best flavour.
Conclusion: A good espresso lies in the details. Small mistakes in grind, dosing or temperature can make the difference between a bitter failure and a perfectly balanced cup. Take the time to get to know your machine, work neatly and taste consciously. With some attention and practice, you’ll be pulling espressos you can be proud of from now on.
