Better coffee. One cup at a time.

Troubleshooting and Fixing a Bad Cup of Coffee (Your Manual Coffee Brewing Toolbox)

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Chances are that all of you have been disappointed in a cup of coffee you have brewed. You may have even been in a coffee brewing “slump” where countless cups of coffee in a row don’t have that “darn good” factor.

Brewing a bad cup of coffee can be frustrating, especially if things were going well previously.  Don’t worry; there is hope. Whether you are suffering from a coffee slump or simply looking to improve the overall quality of the coffee you are brewing at home, here are some basic things you can explore in am attempt to troubleshoot your brewing woes.

Before I Begin a Few Points of Emphasis (Author’s Note)

At some levels fixing a bad cup of coffee is easy. Below are the basic issues most people run into when trying to improve their coffee. Be forewarned. Pursuing brewing better coffee at home is a winding path the goes deeper and deeper into the abyss of coffee science. Somewhere early on in the journey, you will be passing me up and will need to find a new sherpa to guide you in your pursuit for manual brewing greatness.

I also want to emphasize that this article is meant to be helpful, not to scare you off. If you are brand new to manual brewing, don’t let this barrage of information overwhelm you. At it’s core brewing coffee manually is easy.

“Help me, I’m making bad coffee!”

Your first stop on the road of improving your coffee brewing skills is one of introspection. Take a minute to think about your current coffee brewing situation. Why do you think there is a problem with your coffee? Why do you dislike the coffee and what would you change about it?

It is helpful to answer these questions so you have a direction to head.

It is also important to mention that for the home coffee brewer, your reasons for improving coffee quality should be mostly intrinsically motivated. If you love the coffee you are making at home right now, don’t change because someone else said you make bad coffee. Make coffee that you enjoy.

So how about it, what don’t you like about your coffee that makes you want to make a change?

If you don’t know anything about your coffee except you are unimpressed with it, it is okay to go to the next step. You can still improve your coffee even in you aren’t exactly sure what you don’t like about it. Sometimes you don’t know what was wrong until you taste something better.

The Big Three

Way before you go out and buy a three hundred dollar coffee refractometer (even though they do look pretty sweet),  there are some basic things you need to look at with your home brewing set up. There is nothing groundbreaking here, just coffee brewing fundamentals that deserve a review.

Even if you feel you are way past basics, these are worth a gander; you never know when there is something you may have overlooked.

One: You can’t get blood out of a turnip

First and foremost, you need to be brewing with coffee that you enjoy. There is no use tweaking your grind setting or changing your brewing techniques if you don’t enjoy the particular coffee you are using to begin with.

Start with a coffee that you like. This may mean trying some coffee at coffee shops or getting a recommendation from a service like Mistobox. If you don’t know what kind of coffee you enjoy, head on over the Angels’ Cup and sign up for a tasting flight subscription. It is a great way to try a lot of high quality coffees.

Sometimes bad coffee has an easy explanation, it is possible that you simply do not like the current coffee you are brewing.

Two: Water is everything (well 98.75% of everything)

The solubles that make up a cup of coffee are really just a tiny percent of what you are consuming. Most cups of coffee are 98-99 percent water. What this means is that water is actually a really big deal when it comes to brewing coffee.

If you don’t like how the water you are using to brew with tastes, it should not be surprising that you don’t like how your coffee tastes. There are also some kinds of water (like distilled) that are definitely not a good choice for making coffee (you can read a little more about water for coffee here).

If you suspect your water is a problem, try getting a some spring water (people like Volvic) and brew your coffee with it. It is amazing how water can change a cup of coffee. Another option is to  pick up a pack of Third Wave Water, a mineral additive that makes coffee friendly water out of distilled or reverse osmosis water.

Three: Do you have the proper equipment?

Depending on your brew method and brewer of choice, you may need extra equipment to tighten up the variables and make a better cup of coffee. Although not mandatory, it helps to have a scale, a gooseneck kettle (for applicable pour-overs) and a quality burr grinder (what burr grinder should I buy? is something I also hope to retackle soon, short and sweet is: check out the Encore or read this “older” post about grinders and handmills).

For the scale, there really is no substitute. You will be way more accurate if you use one. Accuracy leads to consistency and consistency leads to the ability to change only one variable (relatively speaking) and improve your cup of coffee. I have had good success with this scale by American Weigh Scales.

There are plenty of brewing methods (french press, clever coffee dripper) where a gooseneck does not give you a huge advantage but for most pour-over devices I recommend getting one if at all possible. It will help with consistency.

If you are not able to get a scale or a gooseneck kettle, that is okay. You will just need to be careful to be as consistent as you can with your measurements and how you pour.

At Home Study and Experimentation

If, after you have found coffee that you enjoy and have your water and gear situated, you still want to tweak your brewing process, it is time to go a little science-y on the situation.

Everyone’s brewing situation and coffee palette is different. The only way to truly narrow down which techniques and methods will be most successful for you is to do some experimentation, taste your coffee and practice.

Record Everything

If you are not in the habit of taking brewing notes (I myself have an on again off again relationship with brewing notes), start for the purpose of improving your cup quality. You don’t have to record every time you brew but the more you record the more data you will have to examine. It also helps you see how consistent you are from session to session.

Here are some things that are helpful to record: what coffee you are using, grind setting, water temperature, total brew times and if you liked the results or not.

You can also record: coffee roast date, no stir or stir, amount of stirs, current mood, moon phase, wind direction and mean sea level altitude…

Are you doing anything extreme?

How does your brewing recipe stack up to what everyone else is doing? Once you have some notes, you need to look at your process and standardize the outliers.

Find one or two recipes for your brewing method and take note of the dosage, water temperature, and brewing time. If there is a specified range for particle size, try to match up with that as well. Were there any of your recorded parameters that were way outside of the recipes you selected?

If you have really short or long brew times, high or low ratios or a really low water temperature. Try making a cup using a more normalized set of parameters. Was it better or worse? Could you tell a difference?

In your brewing journal make a note of what you changed and if it made a better or worse cup.

The scientific method says don’t change more than one variable at a time. If you have more than one parameter on the extremes list, start by changing one. Make a note if it was better or worse. If it is better keep that parameter as your new baseline and then change another extreme parameter to be more normalized.

Make a study of extremes (Make some bad coffee)

Sometimes it can help to intentionally make some bad coffee. This might sound like a waste but sacrificing a good bag of coffee to further your knowledge is almost always a worthy cause.

It can be hard to pick out the problems in a cup of coffee if you don’t know what you are looking for. Start with making some extremely over and under extracted coffee. It can help you pin point some of your problems.

  1. Extremely under extracted- To make a extremely under extracted cup of coffee, use a large particle size for the grind and water in the mid to low 190s. If you are using an immersion method like French press, cut the steep time in half (or more). If you are using a pour-over method, only drink the first half of the coffee that filters out (put the other half in a separate cup, you can always taste it later).
  2. Extremely over extracted– To make extremely over extracted coffee, grind your coffee fine and use near boiling water. If you are using an immersion brewing method like French press, let the coffee steep twice as long as you normally would. If you are doing a pour-over, only drink the second half of the coffee that comes through the dripper. Whether you are doing a pour-over or French press, make sure you introduce a good amount of agitation (stirring) to the process as well.

You can (of course) run many other experiments to experience how the different variables of coffee interact. Try a variety of waters, high doses, low doses, different water temperatures and changing your grind setting. There is a lot you can do. If you are going through the effort of experimenting with something, make it a big enough change so you can understand the difference it will make. You can adjust with smaller changes next time.

Use your knowledge

Go back to your coffee introspective time and remember what you did not like about the coffee you were brewing. Use what you have learned by playing with your coffee and make some minor (or major) tweaks until you have a brewing recipe that you enjoy.

Remember that each new bag of beans will present new challenges. The way the coffee is grown, processed and roasted has a big impact on how soluble the coffee is.

Don’t let this freak you out. Simply start with your go-to baseline recipe and make small tweaks. This is called dialing it in.

Words of Encouragement 

If you are stuck, talk to other home brewers, roasters and baristas. Watch YouTube videos. Don’t give up, ask people for help. Don’t lose sight of the trees in the forest.  Brew coffee because you enjoy it. Don’t let the elusive pursuit of the perfect cup of coffee steal your joy (although some people really enjoy the tweaking and experimenting).

In my experience, good coffee tastes good even if the extraction is a little off or you are not using that golden ratio. It is a balancing act, don’t get so screwed up and twisted that you run away from the fundamentals but don’t be afraid to try something out of the normal boundaries either. Slow down, sit for awhile and enjoy your coffee.



  1. Kat

    This is very helpful info, John! Thanks a lot :) It’s amazing how many details are involved in a brewing process. Most of the people don’t even realize that they drink bad coffee till they try something extraordinary. I’ve recently discovered Chemex and I’m slowly trying out the ratios and temperatures. It’s all very precise process, isn’t it? Thanks again I’ll definitely implement some of your tips(or maybe all ;))

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  3. Tomás Franco

    Very good info, you should make a video of this post, you have YouTube channel?

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