5 Top Reasons For Watery Iced Coffee And How To Fix It


4 Top Reasons For Watery Iced Coffee And How To Fix It header image

Have you ever taken a sip of your iced coffee and just felt like your drinking icy water with a slight coffee taste? Here’s what possibly went wrong and what you can do to fix it. 

Watery iced coffee is often the result of the brew being diluted too much by the ice. This can be prevented by brewing stronger coffee over ice. Using less ice, bigger cubes and insulated tumblers can also as well as beans with bolder tastes. 

Iced drinks are always going to taste lighter and weaker than hot drinks but there are some things you can do to make your iced coffee much tastier. Keep reading below to find the biggest issues that contribute to watery iced coffee and how to fix them. 

Reasons Iced Coffee Is Watery

There can be a few reasons why iced coffee tastes weak and watery. Let’s go over what those reasons are and then we can figure out how to fix them. 

To be clear, we’re talking about iced coffee, not cold brew coffee here. Cold brew coffee is brewed with cold water. Iced coffee is brewed hot but then served cold over ice. This results in a different tasting drink. Iced coffee when done right has more complexity than cold brew. 

1. Dilution From Ice

The biggest reason why iced coffee can be watery is because the coffee gets diluted with water from the melting ice. Of course if you add water to coffee, it’s going to taste weaker and at some point, watery. 

There are a few things you can do to reduce this dilution, however, this is only going to work if the coffee you start with is of proper strength already. If you’re brewing your own coffee, taste the coffee before pouring it over ice. Since there is always going to be a little dilution, it should be slightly stronger than you would like to drink hot. 

two glasses of iced coffee

2. Taste Buds And Temperature

The taste buds perceive tastes differently at different temperatures. For each of the tastes, there is an ‘ideal’ temperature where you can taste a certain taste (sweet, bitter, bitter, sweet, umami), the best. Everyone knows that foods and drinks taste differently the further they warm up/cool down. 

However, in most cases colder temperatures, especially in an iced drink, is that all the tastes are subdued to some degree. You’re basically getting less taste from exactly the same drink. So while there might be the same amount of ‘taste molecules’ in the coffee, when it’s cold you just taste them less. 

Besides just tasting ‘weaker’ the taste profile will also change. Usually the sweetness is reduced quite a bit. This leaves the sour and bitter notes. Which taste is dominant depends on the specific coffee and roast level. The sweetness of coffee isn’t very noticeable when it’s there. However, once it’s gone, you’ll notice a lack of ‘fullness’ and ‘roundness’. It changes the taste and mouthfeel to be a bit empty. 

3.  Under Extraction

Iced coffee is usually pour over coffee that’s brewed over ice. This isn’t always the case but if it is, under extraction could be an issue why your coffee tastes watery.

To brew coffee you want the soluble material in the grounds to get into your water. However, you don’t want ALL of the soluble material, you want the right amount. If you dissolve too much, this is called over extraction. If you dissolve too little, it’s called under extraction. 

The best way to brew iced coffee is to replace a part of the brew water with ice. You put the ice in the pitcher under the filter and the hot coffee drips on it, melting it and diluting the coffee. However, this reduces the amount of water that flows through the grounds. In turn that results in a lower extraction or in other words; less material from the coffee beans is dissolved into your cup. 

Often under extraction will go together with a sour/acidic taste as well but other times you just have very little taste. And remember, because it’s diluted by the ice, you can make the coffee a little stronger than for drinking hot. 

To counteract this, you can do three things; Use a smaller grind size, use a longer bloom time and use hotter water. 

4. Coffee Roast Level

coffee of different roast levels
coffee beans from green to dark roasted

The roast level has an impact on both the taste and strength of the coffee. Strength doesn’t necessarily have to do with the taste in coffee. Strength is like the volume knob on your stereo where taste are the taste and treble knobs. 

Suggested: Why does homemade iced coffee taste difference?

The roast level of the coffee does two things; 1. Change the taste in the coffee bean 2. Change porous and therefore how easy to extract it is. 

In general: If a coffee bean is roasted light, you have a higher chance at a sour cup of coffee. If it’s roasted dark, it’s more likely to be bitter. That is because with a light roast there is more acidity (origin taste notes) left in the beans to begin with. The darker the beans, the ore those fruity notes disappear and the more all the compounds caramelize which create more bitterness. Acidity or bitterness in coffee is not a bad thing. It can provide a wonderful fruity, bright taste or that punchy flavor that wakes you up. It does have to be balanced though. 

So if you think your iced coffee is lacking some bitterness, go for a darker roast. If you’d like some more acidity/fruitiness, go for a lighter roast. However, if you like that fruity complexity, I highly recommend going for higher quality beans. Low quality beans usually get roasted darker because the acidity in those beans doesn’t taste good. 

Also, the darker beans are roasted, the more porous they become. That means the water can penetrate into the grounds easier and faster which means that the grounds are extracted faster. So it’s easier to extract too much from dark roasted beans which leads to more bitterness but also an overall fuller and thicker tasting coffee. 

If you buy coffee at the supermarket, there is likely no roast indication. In that case, there is probably a ‘strength’ indicator. In that case, a higher strength usually means a darker roast. 

5. Type Of Beans Used

There is an unbelievable amount of coffee beans and they all taste different. Especially if you dive into the world of specialty coffees, there is a never ending variety of things to try. Brew methods have a large impact on the taste of the final result but you can’t get different tastes out of the beans than that are in there. 

Where beans come from, where they’re grown, what height they’re grown at, where they are on a specific farm, how they’re treated after picking and more all has an impact on the taste of your cup of coffee. You especially notice this with specialty coffee but there are variation in ‘normal’ coffees as well. Looking at the tasting notes on the bag can help. 

Since iced coffee is by nature more diluted and perceived as weaker tasting than hot coffee, you can use a coffee that has a bolder, fuller taste. 

However, most supermarket coffee already is quite far on the ‘boldness’ scale meaning that it often has a pretty harsh bitter taste but also a very full body. Try adjusting one of the other factors named in this article first. 

How To Fix Watery Iced Coffee

Here are some things you can do to make your coffee less bitter by changing the beans, brewing process and a tip you can use to make your coffee less bitter after you’ve brewed it. 

1. Increase Extraction

The first thing to get right is the extraction. You want to get as much as possible from the coffee grounds without the coffee getting too bitter. 

To brew iced coffee, use about 1/3 of the amount of coffee you want to brew and replace it with ice. That will get the coffee cold (not icy cold) and leaves enough water to brew with. However, there is still less brew water so you need to do increase the extraction other ways;

  • Grind a bit smaller: Grind your beans a touch smaller than you would for a regular pour over. This increases surface area and therefore extraction. This will involve some experimentation. If the coffee is less watery, try another step finer until it gets bitter. 
  • Use slightly hotter water: Hotter water extracts faster. Use water that’s about 30 seconds off the boil. Especially with a dark roast. With lighter roasts using very hot water is usually not problem. 
  • Use a 45 second bloom time: The bloom time can help ‘loosen’ some of the solubles. Put the grounds in the filter and add enough water to soak all the grounds (about twice the weight of the grounds) and then let it sit for about 45 seconds before pouring. 30 seconds is normal for hot coffee but for iced coffee 45 seconds is usually optimal. You can try up to one minute but this could cause some bitterness.
  • Pour a little slower: Add water to the filter a little bit at a time. Less water in the filter means less pressure and a slower flow which results in more contact time and thus more time for the water to extract the grounds. 

Using fresh beans is always important. Without having high quality fresh beans, it gets pretty hard to brew really good coffee. Even if you use pre-ground coffee, make sure you don’t let it go stale. 

Buy a new bag and see if your coffee improves. Then get an airtight container to store your beans. Properly storing your beans will increase their lifespan. 

You can freeze part of the bag in an airtight container and those beans/grounds will stay fresh. Then just defrost the amount of beans you need for the week. Try to avoid opening the container too many times. So smaller containers are better than large ones. 

Leaving a big bag open for a few weeks is a guarantee you’ll have stale coffee at the end of it.

electric and hand coffee grinders
An adjustable grinder helps dial in the taste and strength of your coffee.

2. Make Sure The Coffee Is Cold

This might sound stupid. Of course you want your iced coffee to be cold, that’s the point of it. What I mean is that the coffee should be cold before pouring it over ice. That way it doesn’t melt the ice as much as hot coffee and that causes a lot less dilution. Of course over time the ice will still melt but at least the first 10-15 minutes (depending on ambient temperature) there will be very little dilution. 

You could just put some coffee in the fridge before pouring it over ice but this isn’t the best way to go for two reasons; 1. Letting coffee sit in the fridge is not great for the taste. 2. You want to drink the coffee quickly  after brewing it. 

Letting coffee sit for a while can start to oxidize it which leads to ‘off’ tastes, even in the fridge. If the container isn’t airtight, the coffee will also start absorbing tastes and smells from the fridge, which isn’t great. 

The best way to make iced coffee cold is to replace one third of the weight of the brew water with ice (Yes you’ll need a scale). Put the ice in the pitcher under the filter. This means the hot coffee drips on the ice and cools it down immediately. 

Of course this does exactly the thing we want to prevent; dilute the coffee by melting the ice. That’s why you have to increase the extraction (fix #1) and use the right beans. By using 1/3rd the weight of the brew water as ice, you’ll end up with cold coffee while all the ice cubes are molten. The goal is to use just enough ice that the last bits dissolve about 1 minute after brewing. 

If you have a lot of ice left over, reduce the amount next time and use more brew water. That way you can extract more from the grounds easier. 

That way the coffee will be cold enough immediately after brewing so it doesn’t immediately melt all the ice. At the same time you have the control to make the coffee stronger by using the tips from above. 

3. Use Less Ice And Bigger Cubes

A simple way to reduce the total dilution even after all the ice has molten is to simply use less ice. Less ice means there is less water to dilute the coffee. This is a fix if the coffee gets too watery later on but is fine after just brewing. 

Yes, the cup will look smaller if you use less ice but the actual amount of coffee will be the same. Also, if you pour the coffee over the ice cold, you don’t need as much ice to cool it down. 

Bigger ice cubes are another fix that can help a little. Bigger but fewer cubes have less total surface area so they melt slower. Slower melting means slower dilution and stronger coffee for longer. Small cubes are better at cooling things down fast but if your brew is already cold, this isn’t needed.

If you buy iced coffee at a coffeeshop, just as for less ice. 

4. Insulated Mug

Insulated mugs and tumblers don’t only keep things hot, they also keep them cold. If the coffee stays colder, the ice melts slower and there is less dilution. Of course this only helps if the coffee is strong enough to begin with. 

Using reusable stainless tumblers either by filling them at home or at a coffeeshop is more environmentally friendly anyways. 

5. Right Beans

Brewing methods and ice make a big difference but getting the right coffee beans is important as well. The same coffee you like hot tastes quite differently when iced so using different beans makes sense. 

Since watery coffee is the problem here, using coffee beans with bolder flavors will work well. If the fruity acidity is not for you, use darker roasted beans with bolder descriptors like; chocolaty, black tea, caramel, nutty. Those usually indicate a ‘darker’ more bitter taste but also a fuller body and mouthfeel. 

What is coffee strength? 

Most people think about the strength of coffee in the watery/weak – strong dichotomy. However, that doesn’t really get to the core of what strength in coffee actually means. 

Strong coffee can mean;

  • Strong taste (bitterness)
  • Strong taste (fullness) 
  • High in caffeine
  • High percentage of dissolved material in the liquid

The percentage of the dissolved material (amount of weight that gets transferred from the grounds into the water) is a pretty geeky way to measure the strength of coffee but those same people will tell you that’s the only proper way to measure it. 

The problem is that the vast majority of coffee drinkers talk about one of the other three (or multiple) and this gets confusing. For this post I’ve used strength as in the second descriptor (fullness of taste and mouthfeel). 

The caffeine content doesn’t have that much to do with the taste. Yes, caffeine tastes bitter but that harsh bitterness of some coffees is not caffeine. If the bitter edge is what you like, use a dark roasted coffee and you’ll likely find what you’re looking for. Caffeine dissolves quite easily so even a weak tasting cup can have a decent amount of caffeine.  

Recommended Iced Coffee Tools

Iced coffee is pretty easy to make but here are some things to make it taste better.

  • Scale: The key to good iced coffee is to replace 1/3rd of the brew water by ice in the carafe. To do this accurately, a coffee scale is essential. The TimeMore Coffee scale (Amazon) is high quality, looks good and is accurate.
  • Grinder: Iced coffee requires slightly finer ground coffee so having an adjustable grinder will improve your iced coffee. Freshly grounded beans brew better coffee anyways. The TimeMore C3 (Amazon) gives you perfect adjustability and high grind quality.
  • Beans: Of course with a grinder you need some beans. I like coffee with a bit more fruitiness and sweetness for iced coffee (if you drink it without milk). This Kenyan coffee (Amazon) is perfectly fruity and vibrant for iced coffee.

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