Cold Brew Tastes Bad. What Went Wrong And How To Fix It

You were excited for your first sip of the last batch of cold brew that has been hanging out in your fridge for the last 24 hours. But after taking the first sip, you’re disappointed by the taste, what happened?

There are several reasons cold brew coffee can taste too sour or too bitter. Most taste problems come from using the wrong ratio of coffee to water and the extraction time. Using stale beans/grounds and keeping the cold brew for too long will also produce sub-optimal results.

So in this article, I’ll go over every common unwanted taste in cold brew, the problem that caused it, and how to solve it.

Sour Cold Brew Coffee

Probably the biggest complaint about coffee in general but also cold brew is a sour taste. What is going wrong and how can you fix it?


Your beans or brew could be old. Has it been in the fridge for a couple of days or are the beans a couple of months old? That’s likely to be your culprit.

Should cold brew be refrigerated? Find out here.

If your beans and brew are fresh, the biggest reason why cold brew is sour is because it’s ‘under-extracted’. What does that mean?

Think about tea. Tea leaves need some time to release all the aromas and flavor into the water. Coffee is pretty much the same. The taste and smell that is in the coffee grounds have to get into the water before you can drink it.

That process of compounds getting from the grounds into the water is called extraction. So ‘under extraction’ means the coffee is not extracted enough.

If the coffee is under-extracted, you can get a sour taste. Why is that?

I’ve actually written a whole post on this problem with cold brew. Click here to find it if you want to know more.

Under extraction basically means the taste isn’t balanced. The acidity isn’t balanced out by other tastes and it overwhelms the taste buds and becomes sour.

The roast of the beans is also important. A darker roast tends to have less acidity but more bitterness

Using fresh beans and grinding them just before using them will make a big difference in taste compared to pre-ground coffee. The Hario Slim (Amazon link) is a good way to get started grinding coffee at home for a friendly price.


So what can you do? The solution sounds simple, just extract the grounds more. But how can you do this?

There are a few ways you can influence the extraction of coffee;

  • Brew time
  • Grind size
  • Water temperature
  • Brewing method

For cold brew, there are a few things we can already take off the table to change. The brewing method and water temperature are pretty much decided by the words “cold brew”

What you can change is the brew time and the grind size. Up the brew time by a couple of hours and try again. You can let it steep for up to 24 hours. If that’s not enough, grind the coffee slightly finer.

If that still doesn’t work, go for beans with a darker roast. Try the Bizzy Organic cold brew beans (Amazon). They’re roasted especially to make a great cold brew.

Should you use Robusta or Arabica for cold brew?

Bitter Cold Brew Coffee

Does your cold brew taste bitter? Wasn’t cold brew supposed to be lacking any bitterness? That’s why it’s so popular in the first place. What’s going on?


We already covered sour above. That makes it easier to get to the common problem of why your cold brew is bitter.

Often the problem of bitterness is the opposite of sourness. A bitter taste often comes from over-extraction.

Basically, the bitter compounds in coffee are the last things to get into the water. So if you extract the coffee too much, it starts tasting bitter. For more information about extraction look above.

Also, some coffee beans have more bitterness in them than others so you have to be more careful with the extraction. Finally, a darker roast will have more bitter notes than a light roast.


Let the cold brew steep for a bit shorter than 24 hours. Taste it after 12 hours and see how you like it. If it’s not great, go for another 2 hours and so on. If a shorter steep time doesn’t get rid of the problem you can try a slightly coarser grind. A coarser grind means less surface area per gram of coffee and therefore less extraction.

If that all doesn’t work, it’s very possible you just have the wrong coffee beans for the job. Go to your local coffee shop and ask for a bag that’s freshly roasted. If you have a small coffee shop that does its own roasting, they will probably even be able to do it to order. If you have a very dark roasted coffee that produces bitter coffee, try to get a roast that’s one or two steps lighter. Although in general, a dark roast is better for cold brew.

Getting a simple hand grinder and grinding fresh beans will dramatically improve the taste of your cold brew. A decent hand grinder doesn’t have to be expensive. Check out the Hario Slim. It’s an entry-level hand grinder that will work well for cold brew, French press, and pour over coffee.

Watery/weak Cold Brew

Ok, cold brew doesn’t have the punch that hot brew usually has. That’s what people like about it. But too watery isn’t good either.


If your cold brew tastes watery, there can be several things going on and they all require slightly different solutions.

  1. The ratio is wrong
  2. It’s diluted too much
  3. The cold brew didn’t steep long enough
  4. Wrong coffee/grind

Cold brew ratios can differ between recipes. There is a range from 1:1 to 1:18 coffee to water in weight. The more water per coffee, the weaker the result will be. A ratio of 1:1 is very strong and has to be diluted quite a bit. 1:18 is quite weak even without any dilution.

That leads to the next possible problem; dilution. Cold brew is often diluted and/or served over ice. If you’ve added too much water or ice, it will taste weak.

If the caffeine is there but the taste isn’t, the cold brew probably hasn’t steeped long enough. Caffeine dissolves in water much more easily than other compounds in coffee beans.

Finally, you could just be using the wrong coffee and or grind for cold brew. Different coffees have different tastes and some work better for cold brew. The darkness of the roast is also important for taste and some don’t work that well for cold brew.


If there are different problems, they obviously need different solutions.

The first thing to do is look at the ratio and dilution you want to use. Simply adding less water helps a lot but maybe you want to use ice. If you don’t want to reduce the amount of ice you use, the best solution is to add more coffee to the amount of water you brew. To get consistent results it’s a good idea to weigh both your coffee grounds and water to get the right ratio and consistent results.

In the fridge, you can let cold brew steep for up to 24 hours. Up to 24 hours, the taste will change. Longer than that won’t do much for the taste. If the last batch of your brew was steeped shorter than that, try to leave it alone for a bit longer. If you’re already using the full 24 hours to steep your cold brew, try one of the other solutions

Of course, the choice of beans is going to influence the taste of the brew. If your brew is too watery at the moment and changing the ratio or brew time doesn’t fix it, the beans could be the problem. For a bolder taste try fresh beans with a dark roast. If that’s not enough a blend with more Robusta could be what you want. This is going to require some experimentation because everyone’s tastes are different.

Cold Brew Tastes Like Alcohol

My cold brew tastes like alcohol. Did I make coffee and wine by accident? I don’t really want to get drunk off my morning coffee.


Is this really a problem? I guess that depends on if you like the taste but it’s not supposed to be there. For most people, it’s not a taste they want in their coffee. Rest assured, the chances that you actually have alcohol in your cold brew are next to none. Unless you put it there of course. So in that regard, there isn’t really any problem to speak of. But why is it happening?

Different alcohol tastes can appear in coffee;

  • Generic alcohol with a nasty bleach flavor
  • Whiskey
  • Wine

Coffee washing

The biggest reason that you can have an alcoholic taste in your coffee sometimes has to do with the washing process. The coffee cherry has to be washed off the bean. Water is used to do this. If the water is reused too often and/or for too long, the mixture of coffee cherries and water can start fermenting.

This taste can get into the beans. There won’t be any actual alcohol in the beans and any that would get in there would evaporate during the roasting process.

This fermentation is not supposed to happen and can point to negligence in quality control. In the end, it’s not really dangerous or damaging but the taste can be unpleasant.


Good Arabica can have very fruity and floral notes. These are very similar notes that wines can have. So in that regard, that could lead your brain to confuse coffee with wine and therefore alcohol. That doesn’t mean it actually tastes like alcohol.  Fruity coffee is usually seen as a good thing. It’s a sought-after set of tastes that coffee aficionados tend to love.

Taste association

Another reason I already alluded to above can be taste association. For example, if you put vanilla in something, it tastes sweeter immediately because vanilla is almost always used in sweet things. That doesn’t mean it became any sweeter by putting vanilla in it though. It’s your mind tricking you.

So if you have been consuming alcohol with your coffee, like in cocktails or Irish coffee, your brain can still make the assumption there’s alcohol connected to the coffee taste, even if it isn’t.


If you put milk in your coffee, check if it’s still ok. Sometimes milk goes off and it can leave a strange taste that you can’t quite put your finger on after it’s put in coffee. It could also be the creamer or something else you add to your cup.

Just do the sniff test if the milk has been in the fridge for a while to see if it’s gone off.


There isn’t too much you can actually do except get new coffee and brew a new cup. If it’s a consistent problem, try to find a new vendor.

Of course, you can try to cover up the taste with milk and/or sugar or something else. This might work or you might end up with something that tastes like Baileys.

Floral notes are usually a good thing but if you don’t like them, you could try a blend with more Robusta beans since they are much less fruity tasting.

Cold Brew Tastes Like Soy sauce

Do you have some black liquid in your fridge? Is it cold brew or soy sauce? You decide it’s coffee and take a sip and somehow you taste soy sauce. Did you get the wrong container? Probably not. Let’s see what’s going on.


Soy sauce has a very strong Umami flavor. Umami is considered the fifth taste besides sweet, sour, bitter, and salty. If there is any similarity in taste between soy sauce and coffee, that’s the thing to look at.

Beans from different geographical locations have different tastes. Even the same plant in a different place on the globe will produce a different-tasting coffee. That’s a result of the exact climate and the nutrients in the soil.

Beans from Africa, or more specifically Kenya and Rwanda have strong umami flavors in them. So if you got coffee from those regions (and possibly others in Africa) that’s why your coffee can have hints of soy sauce.

Some soy sauce also has a slightly sour taste. So if that’s the type of soy sauce you’re used to, the acidity of coffee combined with the umami flavor can give an even stronger impression of soy sauce taste.

Besides the beans, the brewing method affects what and how get extracted from the beans. So you might get a much stronger effect with one method than another. However, that’s a downstream effect of the choice of beans.


If you don’t like it, get beans from another geographical location or blend them with different beans. If the beans have a taste you really don’t like, it’s unlikely you’re completely going to get rid of it with other brewing methods.

However, if it’s just ‘a little too much’ a different brewing method can help you get the right balance.

Other Cold Brew Problems

Above are the most common problems with cold brew. But what if you’ve got something else going on?


Cold brew is best kept in the fridge. In general, that’s a good thing but it can bring some problems.


The most likely problem is that you have an ‘exchange’ of taste or aroma going on in your fridge. Most cold brew containers are not completely airtight. That means that some aromas of other things in your fridge can get in.

Some smells will be stronger and more likely to get into your cold brew than others. If you taste something weird, see if that taste correlates with something else that was in your fridge at the same time.


The best solution is to get an airtight container for your cold brewing needs. There are several on the market. Get one that’s the right size for your needs otherwise, you might end up with way too much cold brew.

Of course, you can also go the other way and make sure that there is nothing that smells bad in your fridge at the same time as your cold brew. This is a bit more difficult though. It’s also a good idea to deep clean your fridge once in a while. Old coffee grounds are actually really useful for absorbing odors in your fridge. It’s not a permanent solution but it can absorb some of the bad smells in your fridge.

Good coffee beans

Something that should be addressed is the coffee beans. While all the bad tastes named above have their reasons.

However, good coffee starts with good beans. Good beans are not the same for every type of coffee or every person. People have different tastes and different brewing methods have different tastes as a result.

However, if you get bad coffee, there is a chance you just have bad beans. They might be old and stale or just the wrong bean for the job. Having stale beans can cause all kinds of problems.

For cold brew, you don’t have to go to really expensive, exclusive single-origin Arabica grown in the shade of a pregnant donkey. For cold brew, an average quality blend will do fine, especially if you’re new to it. More expensive coffee often needs more care in the brewing process to get the ‘right taste’.

Besides the type and freshness of the beans, the roast is also important.

For cold brew, it’s a good idea for a darker roast. Lighter roasts can be a bit finicky to get right and especially with cold brew you don’t have that much control to get it right every time. A dark roast is a bit easier and will also add some body to your cold brew.

Favorite cold brew tools

With these items, you will brew better cold brew

  • Grinder: Fresh beans have to be ground. A hand grinder like the Hario Slim (Amazon) is affordable yet effective hand grinder that will improve your cold brew.
  • Scale: The amount of grounds you use makes a big impact on what your cold brew tastes like. A simple set of scales will makes your brews more consistent. I’ve been using this one (Amazon) for over a year wit h great success. Not the most aesthetic but effective.


Welcome to CoffeeImproved! Since falling in love with coffee, I've been on a journey to improve my morning cup day by day. That means I've tried many different brew methods, beans and equipment and experimented with all of them to find what I like. This is where I share what I've learned with you.

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