Common Mistakes When Brewing Coffee

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It’s a Saturday morning, you don’t need to rush off to work and so you can finally take the time to immerse yourself in that morning coffee routine. You get out your coffee maker with the eager anticipation of a memorable cup, brew your coffee, and sit back to enjoy the reward of your labours. But as soon as you have the first sip your heart sinks as you realise something is off. Maybe you got the grind size wrong, maybe you over or under-extracted the coffee. It doesn’t really matter what. Something is off, and it doesn’t taste quite right. The only thing that is memorable about this cup is how disappointed it makes you feel. 

Unfortunately, as coffee lovers this experience can happen more often that we would like to admit. In fact if you take your coffee seriously then it is a given that the road to mastering any brewing method will be through a string of imperfect and disappointing cups of brew. The truth is that brewing good coffee is an art that requires careful precision and easily malfunctions. 

But while there is no silver bullet to a perfect cup every time, there are plenty of pitfalls which will guarantee a less than perfect coffee. We have compiled this list to highlight what we have found to be the most common enemies to that memorable cup. 

Bean Issues

Using Bad quality Beans

The taste of your brew can never go beyond the quality of the coffee beans you are using. What this means practically is that if you are using beans that you found down the aisle of a supermarket of grocery store, then you are going to be severely restricted in the flavours you are able to extract. This is a common error particularly to those who are new to the hobby of brewing coffee and are allured by the cheap price tag of supermarket beans.

photo of freshly roasted artisian coffee beans

The first step to high quality and delicious coffee is high quality, freshly roasted beans. Here at The Coffee Folk we recommend that a local artisan roaster is the single best option for sourcing your beans. Speciality roasters choose and roast their beans carefully for maximum flavour. Thus buying a bag of quality beans is often a quick and relatively easy step that can really lift the quality of your coffee. 

Using Stale Beans

One of the most common misconceptions about coffee is that it is a long-life product like nuts or flour or dried fruit. Instead it is more like fresh produce that is best enjoyed quickly and deteriorates over time.  

A quick way to derail your morning coffee is to use beans (even high quality ones) that are stale. While coffee doesn’t become (strictly speaking) undrinkable, it does go stale and loses much of its distinct flavour. Using stale beans is a little like pairing a delicious roast chicken with old potatoes that have gone all rubbery and wrinkly. Don’t do it! After coffee beans are roasted they retain their peak flavour for around two weeks and then still taste fairly good for about another two weeks. Anything beyond a month past its roast date is less than ideal and will only decline in taste. An interesting experiment to prove this is to pull an espresso shot first from beans a week old and then some others that are a 5+ weeks old and compare taste and crema. The difference is significant! 

Incorrectly Storing Beans 

A closely linked mistake to the one above is incorrectly storing your  beans which speeds up the process of going stale or detracts from the flavour of the beans. The world of coffee, just like most other areas of life, is often plagued by well-meaning but incorrect myths. One of these ‘myths’ is that storing coffee in your freezer is a good idea and will effectively keep your beans from going stale. This is expressly NOT how coffee is to be stored! While it is true that it does slow the aging process, it is no substitute for fresh beans and should only be used where getting regular fresh beans is not an option.

Coffee beans in storage container

Instead, coffee is best stored in airtight containers somewhere that is cool (but not the fridge or freezer!) and dry and away from direct sunlight. This is the best way to retain the flavor and freshness of the beans for that month or so before they begin going stale. Our recommendation is to always buy beans that have a roast date on them (as opposed to a best-before date) and only buy as much as you will consume in 2-4 weeks. So for my wife and I, we have signed up with a local roaster who sends us two 250g bags of beans every fortnight which is about right for us. While this is more expensive than buying bulk it is a significant factor in brewing good coffee. 

Grind Issues

Using Pre-Ground Coffee

Another common mistake that detracts from the flavour of the cup is using pre-ground coffee beans. As soon as coffee is ground it begins to release aromatics and begin the process of oxidation which decreases the flavour and enjoyableness of the final coffee. This is the reason that your favourite cafe has a hefty looking Mazzer or Compak Grinder on the bench rather than bags of pre-ground beans. Because the best way to get the maximum flavour in the cup is to grind the beans yourself immediately before brewing. So we highly recommend investing in a hand grinder which tend to be relatively cheap, come with burrs rather than blades (a good thing!), and work great especially for manual brewing methods (such as Aeropress, Pour-over, and French Press). Provided you are grinding with a quality burr grinder this can again really lift the final taste of your coffee.

Using the Wrong Sized Grind

Another common brewing mistake is to be using the wrong size grind for the given brewing method. This small oversight can dramatically impact the flavour of the coffee and turn what should have been a delicious cup into a bitter mess which is only good to be poured down the sink. This mistake is particularly common when using pre-ground coffee which is often either a generic grind size meant for a drip coffee maker or fine for espresso. 

What many beginning coffee lovers may not realise is that almost every different brewing style requires a different grind size. For example, while a Moka Pot or Stovetop coffee maker makes an espresso-ish cup of coffee and is often made with an espresso size grind, it should actually be a little bit coarser than espresso. Similarly, a pour over method such the V60 will use a far finer grind than French Press or Cold Brew. This is a remarkably easy way to ruin a perfectly good coffee routine and recipe (as we found our the hard way!). 

Different sized coffee for brewing methods

So if you are using pre-ground we recommend buying quality whole beans and then asking your local cafe to grind it to your specific brewing method (ie Aeropress). Alternatively if you are grinding from home you are going to have to learn the often tricky skill of ‘dialing in’ for a given brewing method. This will depend on what type of maker you are using and is often a matter of trial and error that is governed by taste and time. 

Inconsistent Grind Size

One of the easiest ways to ensure a bad cup of coffee is inconsistent grind size. You can have great fresh beans, the correct grind size, a killer routine, yet if your grind size isn’t uniform you will have an average if not downright unpleasant cup of brew! Inconsistent grind size is often visible to the naked eye and consists of a mix of what coffee gurus call boulders and fines or dust  (basically different sized grinds). The reason this is a problem is that when brewed the fines will over-extract leading to a bitter taste while the larger particles add an acidity which is often unpleasant. While some brewing methods are more forgiving than others (espresso is the most unforgiving), this will negatively impact any way of brewing coffee.

coffee beans, ground to make espresso

The most common cause of this is a cheap and inadequate grinder. Grinding your own beans is only really worth it if you have a quality burr grinder whether hand or automatic. When it comes to coffee an equation that you will come across again and again is blade grinder = rubbish coffee! So if your coffee is tasting off one potential culprit is a less than adequate grinder. If so either ditch the grinder altogether or even better upgrade to a quality burr grinder. A decent entry level hand grinder can be bought for $50 or over while an automatic worth getting will tend to be upwards of $150. 

Gear Issues

Bad Quality Gear

Another easy way to ruin good intentions is to attempt to brew coffee on too old or sub-par gear. We have already had enough of a rant about cheap grinders so basically just stay away from them! Depending on your chosen brewing method you will likely have a range of different gear from the coffee machine itself to filters, specific kettles, and parts. It is important to realise than no matter how well you maintain these they will age with time and need replacing. However if you brought your espresso machine or French Press from the supermarket it won’t need time to decline but is most likely already there! Coffee gear is pretty typical of consumer goods in general: you get what you pay for. So if you want high quality coffee then you will need a high quality coffee machine and grinder. 

Poorly Cleaned Gear

Another common mistake when brewing coffee is to fail to adequately clean your coffee maker between uses. The coffee commentator James Hoffman contends in his World Atlas of Coffee that up to an astounding 95% of commercial espresso machines are not cleaned properly. And if that is true of the world of professional baristas how much more of the home brewer. Whether you are using an espresso machine, a french press, a moka pot, or an Aeropress proper cleaning and maintenance will add to the taste of your coffee and the longevity of your coffee maker. Especially in manual methods such as French Press and AeroPress, leftover coffee grinds will add a bitter taste that can easily ruin a cup of coffee. Proper cleaning is also especially important for espresso machines. The cleaning of these are often very specific and should be according to the manufacturer’s instructions. 

Brewing Issues

Bad Water

This mistake is almost embarrassingly obvious and yet is overlooked by the vast majority of coffee lovers. And that is that bad quality water = bad quality coffee. If you think about it coffee is basically made up of two things; coffee beans from which flavour is extracted, and hot water which extracts the flavour and makes up 90 (espresso) – 98% (drip or pour over) of the final black drink. And yet while we are happy to spend both time and money investigating and finding the best beans we often completely overlook the quality of the water we are using!

This is basically important for two reasons; flavour and the longevity of our coffee gear. Bad (or hard) water has a major impact on the extraction process and can dull the nuance and complexity of an otherwise great cup of brew. Tap water, depending on your location, will have a certain level of mineral content that is designated somewhere on the spectrum from soft (low mineral content) to hard (high mineral content). This can be found out from your local water supplier but basically hard water = bad water for coffee brewing. For this reason if you are living in a hard water area (or even if you aren’t), a simple way to up your coffee game is to use either bottled or filtered water. This is especially important for espresso machines as constant use of hard water can lead to limestone buildup and malfunction!  

Wrong Water Temperature

Another common mistake across various brewing methods is either over or under-heating the water. Too hot and you burn the beans, too cold and you under-extract – either way a less than desirable cup to disgusting cup of brew! According to the National Coffee Association the perfect temperature for brewing coffee is between 195F (90.6C) and 205F (96.1C). For this reason it is important in manual brewing styles (such as French Press, AeroPress, and Pour Over) to make sure that when you boil your water you are able to get it to the golden range. This can be done through a temperature control kettle, a thermometer, or by boiling the kettle and then either transferring it to another vessel or waiting 30 seconds before using. 

coffee thermometer

This is also a huge issue with the vast majority of drip coffee machines which often never reach the golden temperature leading to a sub-par coffee. The easiest way around this is to only use Specialty Coffee Association Approved (SCAA) Drip Machines which have been tested on a range of fronts including whether they reach and retain optimal water temperature. 

Over-Brewing Coffee 

I am sure that sadly we have all had that experience one time or another of sipping a delicious looking coffee only to discover that it is sour and bitter and deeply disappointing! A common reason for this is that coffee is left in the coffee maker after the brewing process has finished and keeps extracting past the optimal brew time. This is particularly common with French Press where it is not unusual to make a batch for the day and pour out the coffee as desired. This leads to over-extraction and significantly degrades the quality and flavour of the coffee. Instead, for any brewing method that involves immersing the beans in water (such as French Press or AeroPress), the brewed coffee should be poured into a decanter or thermos from which it can be transferred into cups as needed. 

Coffee being poured out of a server

Another common way that coffee is over-brewed is in Moka/stove top coffee makers. When the coffee maker is removed from the stove top the brewing process although formally finishes actually continues and can over-extract due to the hot water in the water compartment. To counteract this, various coffee gurus recommend that as soon as the Moka Pot is removed from the heat the water compartment should be placed under cold running water to stop the extraction process. As I am sure you are starting to see, the amount of different ways a coffee can be ruined are simply staggering. No wonder that we get a few duds!

Lack Of Precision In Measurement 

This mistake is somewhat close to home for us as we certainly fell into this one for far too long. The mistake basically goes ‘a measuring spoon or a quick look is all that you need to measure the amount of coffee used.’ It sounds innocent enough, but this seemingly innocuous little mistake has ruined far more cups of coffee than you might expect.

The reason that this is a mistake is because well-brewed coffee is about careful and precise ratios of water to coffee. And while ‘eyeing it’ or using a measuring spoon might seem to get you by it is almost definitely at least slightly altering the ratio every time making it hard to repeat a great coffee. Even two equal volumes of coffee beans may have different weights due to different densities. Long story short, if you don’t already have one, then investing in a set of quality coffee scales is a quick trick that is surprisingly helpful in mastering almost any brewing style.

Wrong Coffee Ratio

This is really beginning to get into coffee geek territory (which is not necessarily a bad thing). If you hang around with invested coffee lovers you will inevitably start hearing them talk about ratios and recipes and they are not talking about tomorrow night’s dinner! Coffee ratios show the ratio of water to coffee beans for a given brewing method, like the French press, while a recipe is generally more specific and includes the amount of water, the amount of coffee, and the extraction time. So, for example, a typical espresso recipe would be an 18g dose (amount of coffee used), with a 36g yield (how much extracted coffee comes out), in 26-30 seconds (the time of extraction). 

The point of this long preamble is that the ratio/recipe you use is absolutely vital for the final taste of your coffee and getting it wrong is an easy way to ruin any morning. That is the great thing about fixing both the previous mistakes. If you learn to measure precisely then it means that when you find the right ratio for you, you can more easily replicate it. The general rule of thumb here is more coffee or less water equals stronger coffee, while less coffee or more water equals weaker coffee. While some coffee gurus cite the golden ratio of 1:16 coffee to water it really depends on the brewing method and your palate. So is your coffee overpowering or simply watery? The culprit may well be the recipe you are using and the remedy is as simple as tweaking that ratio. 

Drinking Issues

Pouring Coffee Into A Cold Cup

The final common mistake that people make when brewing coffee is pouring freshly brewed coffee into a cold cup. While this may not be a capital offense it can cause the temperature of the coffee to drop significantly and affect the enjoyment of the drinking experience. And the reason that this matters is that ultimately we brew coffee for both the process which is enjoyable and therapeutic, and for that experience of sitting back and drinking the coffee that our own hands have brewed. And so the little things matter. And thankfully this little mistake is easily remedied. It really is as simple as filling your cup with hot water when you begin the brewing process and pouring it out immediately before pouring in the coffee. A small thing that can add another little dimension to the enjoyment of your brew!

Drinking Coffee from the wrong cup

This mistake is a lot like the previous one. It is not a huge deal but making this mistake can rob your coffee drinking experience of another level of pleasure. Basically find the right cups for your brewing method and even more importantly find cups that you simply enjoy drinking out of! As a general rule you should try and go for either ceramic or glass and stay away from any form of plastic. And finding the right cup for you can not only up your coffee experience but be a really fun process 🙂

Brewed coffee in a server

So for example, my wife and I have different cups that we drink out of for espresso and for pour over. Do we need them? Probably not. But does it make our coffee drinking more enjoyable? Absolutely. We even got a special wooden board and carafe for pour over because the coffee drinking experience matters!


So hopefully you have been able to see that while we believe home brewing is the way to go, it is also a real art and science that does take time and experience to progress. And really the point of this article is not to discourage you with the pitfalls but to warn and inform you so that you can really up your coffee game through changes that are often surprisingly easy! As always we would love to hear from you. Have you experienced (as we have) any of these brewing mistakes? Are there other mistakes you would add to the list?

Happy Brewing!

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