Cold Brew Coffee

Thu, 19/07/2018 - 14:50 -- James Oakley
Iced Coffee

The UK is enjoying a rare thing - a summer with week after week of hot weather.

That means it's time for cold coffee. Here's a simple recipe, that's very easy to do and needs (nearly) no special equipment, along with some commentary on what I'm doing.

Normally, people brew coffee in the usual way, and chill it. By all means do that. But there's another option - cold brewed coffee.

Do it right

Some people have been put off this because they've experienced it done badly. If a cafe chucks some mediocre grounds into a bucket with some cold water, leaves overnight, then crudely strains it, you're not trying cold brew at its best. Done well, the colder brewing temperature means that some of the harsher, bitter tastes are not extracted from the bean. The result is a mellow drink.

What kit do you need

One way to do this is to buy a kit, such as the one made by Toddy. Do that if you want, but it's yet more money to shell out, and yet one more bit of coffee-making kit to store. And those of us who are coffee fanatics lovers already have about 30% more of our kitchen given over to coffee kit than can be justified.

Toddy Brewer

There's no need for special kit; you can use equipment you likely already own. If you don't own any of the below items, you are allowed to go and buy them, because this is stuff any coffee lover should already have

  • Scales
  • A (burr) grinder
  • Cafetiere
  • Spoon

There's one other thing you'll need.

  • Muslin bag

You need this to strain your brew. Some people have used a standard paper coffee filter, but it chokes and clogs far too quickly, so needs several filter papers and takes forever. A muslin bag is much easier.

You could use an actual muslin bag, made of finely woven cotton. Personally, I quite like these nylon bags which do much the same thing. They're stronger than cotton, when you wash them out between uses they don't stain (and so possibly retain stale flavour that could find its way into the next batch) and the mesh is finer than most cotton muslins.


There are many variables to this, and (as is the way) endless articles on the internet with people giving you their take.

  • Grind: Like cafetiere, finer, coarser?
  • Time: 12 hours, 18 hours, 24 hours, 36 hours?
  • Temperature: Room temperature? Refrigerated?
  • Water: Tap? Filtered? Bottled?
  • Filtering: What system do you use?
  • Ratio: How much coffee grounds for how much water? Is that weight / weight, or volume?
  • Stirring: Not at all? Just to begin with? Every few hours? At the start, then after two hours, then leave alone?

Some of those variables play off each other. You need longer if you're using a coarser grind or if the water's warmer.

Here's what I went for, having read around a little, then given up reading and decided to experiment:

  • Grind: The same as for cafetiere. That's purely pragmatic — it saves me re-dialling my grinder
  • Time: Go for 18 hours. The people who advise 12 seem to do it at room temperature.
  • Temperature: Let's refrigerate and do this slowly. All the "I've tried this and it's fowl" comments came after room-temperature brewing.
  • Water: Filtered. Bottled seems obsessive. On the other hand, there's probably something in the observation that filtered water has fewer dissolved minerals and therefore will be able to absorb more of the soluble contents of the coffee.
  • Filter: I'll go for cafetiere then muslin
  • Ratio: Tricky. Read around, and you'll find a range of recommendations from 1:4 to 1:8. 1:7 is a number that comes up regularly, so I'll try that. Interestingly, I tried it as 1:7 on weight. The dry grounds looked to take up about a quarter of the volume of the water, so maybe the 1:4 advice is based on volume and 1:7 is based on weight.
  • Stirring: I'll stir once, well, then leave alone. I want this to be easy. Once is necessary, so that the grounds are all fully wet from the beginning, otherwise extraction will be uneven. More seems unnecessary, given the length of time this will brew, so that chaos theory can be your stirrer.


It's very simple

  • Start with fresh coffee. (Coffee is a fresh food. Always brew with freshly roasted and ground coffee. Cold brew may be more forgiving than many brewing methods, but "garbage-in, garbage-out" still applies.)
  • Grind 150g at cafetiere grind. (You want the same as coarse sand, so you can see the grains as you rub between your fingers.) Yes, that's a lot of coffee.
  • Place into a large, 12-cup cafetiere. If the largest you have is 8-cup, you'll need to scale the recipe down to 100g of coffee.
  • Add 1 litre (or 1050ml if you want to stick to 1:7 obsessively, which of course I didn't) of filtered water. (If you're using the 8-cup cafetiere, reduce that to 700ml).
  • Stir well. I mean a good 30 seconds of stirring, scraping right to the bottom of the cafetiere. That's a thick pile of grounds at the bottom, and you want them all saturated with water, with no dry pockets that will take some time for the water to penetrate. Metal is best kept away from coffee, so a wooden spoon (that doesn't get used for strong-tasting savoury cooking) is best, but anything will do.
  • Place the plunger on top, but do not plunge. In fact, keep the metal filter clear of the surface of the coffee - again, you don't want the metal touching the liquid. But you need the lid on to stop other flavours from the fridge from getting into your coffee.
  • Place in the fridge, and leave alone for 18 hours.
  • Plunge and pour into a jug. Keep tipping, to get every last drop out.
  • Pour the coffee through the muslin bag for a second round of filtering.
  • Pour it into a bottle or some other container that has a tight fitting lid. Toddy say that concentrated cold-brew coffee keeps for up to 3 weeks, but again it needs covering (to keep excess oxygen away, and also other flavours).


What you've just made is a concentrated drink, so it needs diluting (unless you want to drink a brew from 75g of coffee in one go!)

You can mix with iced water, sparkling water, lemonade, milk or cream. I'd suggest one part of coffee to three parts of water / milk etc. My personal favourite is chilled sparkling water — it makes an extremely refreshing drink. Lemonade works well, too; you can't taste the natural sugars so clearly in coffee that's cold, and the lemon adds a little something.

Let's think about what you're drinking. We started with 150g of coffee and a litre of water. I got about 750ml of coffee out of my cafetiere. A 300ml glass will need 75ml of coffee (and 225ml of water / milk), so you'll get 10 glasses of coffee out of this batch. That means each glass contains the soluble content of 15g of coffee beans. Other brewing methods may vary, but I tend to use 12g per mug when brewing with cafetiere, and 18g with espresso or pour-over filter. In other words, one half-pint glass of diluted cold brew contains a similar amount of flavours (and caffeine) to a typical hot coffee drink

Drink and enjoy!

If you've got any other tips, please leave them below.

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