Cold water pulls less acidity and less bitterness out of coffee than hot water does, and it takes far longer about it. What you get is round, sweet and low in edge — a different drink from iced filter coffee, and worth making on its own terms. It also suits the weather here.
What you need
- 100g of coffee per litre of water, ground coarse
- Cold filtered water
- A jar or jug with a lid
- A paper filter for straining
The method
- Combine the coffee and water, and stir once so no grounds sit dry.
- Cover, and leave sixteen hours at room temperature or twenty in the fridge.
- Strain through a sieve to take the bulk of the grounds out.
- Pass it a second time through a rinsed paper filter. This is slow. Leave it to it.
- Bottle the concentrate and keep it in the fridge.
Serving
What you have made is a concentrate. Dilute it one to one with cold water or milk over ice, then adjust to taste. Pour it over the ice rather than mixing first, so the drink chills as it goes.
Keeping it
Sealed and refrigerated, the concentrate holds for about a week. It is at its best in the first three days; after that the aromatics fade and what is left is flatter, though still pleasant.
Which coffee
Cold brew flatters fruit-forward coffees. A natural process lot with dark fruit in it comes through clearly, where a delicate washed coffee can get lost. Grind coarser than you think — anything fine turns the straining into an afternoon.