How do you make cold brew coffee? Your guide to brewing the perfect cold drink

The TL;DR of how to make cold brew coffee

Grind 36g of coffee to a coarse grind, get 200-250ml of either room temperature or iced coffee to hand and using a cheese cloth, strain the coffee over a prolonged period of time, usually between 1-3 hours depending on the outcome you desire.

We all love a steamy cup of hot coffee on a frosty morning (or any morning, come to think of it), but there are times when the thought of a hot beverage just isn’t on the radar. Perhaps it’s getting warmer out and you would love an icy drink in the garden with the added benefit of caffeination, or after a session at the gym you need a pick me up without adding more heat to the mix. Maybe it’s nothing to do with exercise or weather – you’ve just been running around after the kids all morning and need something to cool down! No need to go to your local coffee shop and battle the crowds, manage the guilt of getting another non reusable plastic cup, and navigate the extensive list of frappuccinos (not to mention the added extras of whipped cream and flavoured sauces that can often dampen the taste of your coffee beans). Get yourself a much more affordable cold brew coffee at home: a smooth, tasty, and easy to make coffee drink that will have you questioning why you ever complicated things in store. Serve it smugly in a cleaned out jam jar to ooze uncomplicated sophistication. 

What exactly is cold brew, and is it different to iced coffee?

Cold brew coffee is coarsely ground coffee, steeped in cold water over 12 hours to 24 hours in a cold environment: hence ‘cold’ and ‘brew’; and it is our preferred method over iced coffee if you’re looking for a chilled way to get your caffeine fix! The beans have to be brewed slowly due to the cold process, but this gives a smooth and sweet flavour due to the slow rate of oil extraction. This differs to iced coffee, which is a hot brew using methods such as drip coffee or filter coffee, then turned chilled with the addition of large amounts of iced water and ice cubes. Iced coffee uses a much higher water ratio to cold with the addition of ice and chilled water, meaning the original brew is made highly strong to make up for this with increased potential for bitterness and burning. The rapid extraction of the beans on heat adds to this potential of bitterness, as the bean oils haven’t had as much chance to diffuse unlike the slow process associated with a cold brew. Personally, we think cold brew gives coffee beans a better chance to develop their flavour through slow oil extraction with reduced risk of bitterness. While this method is a little more time consuming, we think it’s really worth the wait. Beyond your basic coffee ingredients and the use of some store cupboard equipment, the only essential skill is patience – it’s a cheap and straightforward method. Also, due to not requiring the use of boiling water (apart from when sterilising the jar), this is a fairly child friendly method. You might not want your kiddos to drink the final product (they have enough energy as it is!), but they can certainly have fun pouring and using measuring cups while learning about the brewing process.

I’m sold! How do I start?

Before we get started; the overall ingredient weights and water ratio are naturally dependent upon the amount of coffee concentrate you want to yield (in our recipe you put your concentrate brew in the fridge – and when ready to serve your glass is half concentrate, half iced water). In our example, we’re going to make enough cold brew concentrate for 5 mugs (or eclectic jam jars!) of coffee to see one person through the week, assuming you’re using a 32 oz (800g) mason jar to store your concentrate. Kids not sleeping and one mug of coffee per day sounds comical? Double up by doubling ingredients and using two jars, or one larger one! Typically, 1 cup of water and 28g of ground beans equals enough concentrate for 1.6 cups of coffee. While that seems like some fairly specific Maths, once you have your measurements nailed, the process is incredibly simple. We suggest starting with our assumed measurements below, and once you’re familiar with the process, you can switch quantities up to meet your needs following the ratio we’ve noted.

Ingredients, equipment and recipe:

  • 32oz/800g holding Mason Jar or sealable container. You could also use the glass from your french press here.
  • A large bowl, jug or container
  • A sieve to put under your filter paper to make getting rid of the grounds easier 
  • A tea towel to protect your hands
  • 85g of ground coffee beans (we prefer using a coffee grinder and setting this on the chunkiest grind you can get, at least to the same consistency of bread crumbs). Any finer than bread crumbs and you’re going to struggle to sieve out your ground coffee later in the process. 
  • 3 cups of water (filtered if possible)
  • 2 x large filter cloth or a few paper coffee filters together big enough to fit the mouth of your bowl or container. You can purchase ‘basket’ paper filters online that spread specifically into the shape of a bowl for ease of use, though you’ll get along just fine with a traditional filter providing it’s big enough to fit your bowl. 
  • Chilled water, ice, and milk if you fancy, to serve over ice later!
  1. Sterilise your mason jars by filling them to the top with just boiled water and sealing for 10 minutes. Once cooled, wrap the jar in a tea towel (it will be hot!) and empty the jar out. Let cool for a few more minutes to avoid the heat affecting your water or your grounds.
  2. Place your grounds in the bottom of the jar, and fill with water.
  3. Stir gently until well combined and let sit for 5 minutes. Return to the mix and give it a final stir. 
  4. Seal the jar and leave it in your fridge for 12-24 hours. The longer you leave your mix, the stronger your overall brew will be. We prefer a 24 hour brew, but we’ll leave it up to you – we know how hard the wait can be!
  5. Remove your jar from the fridge. Lay your sieve over your bowl and place your filter paper inside. Pour your cold brew over the sieve to remove the bulk of your coffee grounds. Discard the grounds into your compost or flower beds to help them grow!
  6. Placing your second filter cloth/paper over your mason jar, pour the coffee back in.
  7. Repeat steps 5 and 6 two to three times back and forth to remove as much grounds as you can. 
  8. Once you feel it’s your last time filtering into the bowl, wash out your mason jar to remove any grounds stuck to the sides, and sterilise it again with a boiled kettle full of water. Once cooled, pour your final cold brew concentrate into the mason jar.
  9. Store in the fridge. The great thing about cold brew is due to its brewing process it has very low acidity, meaning  it can be stored safely, sustaining its flavour, for up to a month. 
  10. When ready to serve, fill your cup or mug half-fill with brew mix. You can top this up by serving over ice and water. Alternatively, fill the rest of the cup with milk for a rather lovely marbling effect (if you’re serving in a glass you’ll see the effect even more). You can even add hot water to your cold brew concentrate and serve the drink warm – it retains the flavour and doesn’t increase acidity as the brewing process is already complete.
  11. Enjoy!