How to make cold brew at home?

Home cold brew is made by steeping 100 g of coarsely ground coffee in 800 ml to 1 litre of filtered cold water (1:8 to 1:10 ratio), then letting it rest 12 to 18 hours in the fridge before straining. The result is a smooth, low-acid concentrate, typically diluted 50/50 with water or milk at serving.

Cold brew relies on long, low-temperature immersion — usually 4-6 °C in a fridge. The slow kinetics favour cold-soluble compounds (sugars, amino acids, chocolatey and fruity notes) while leaving behind much of the chlorogenic-acid bite and some of the bitter molecules that hot water extracts so readily. That is why cold brew tastes the way it does: pronounced sweetness, very low acidity (pH often around 5.5, compared with 4.8-5.1 for a hot filter), and a rounded body without astringency.

A working recipe starts from a concentrate ratio of 1:8 — 100 g of coffee for 800 ml of water — when you plan to dilute at service, or a ready-to-drink 1:15 to 1:17 if you want to pour straight from the bottle. Grind has to be coarse to very coarse, granulometry similar to sea salt or French press territory (around 900-1100 µm), otherwise fines will pass through filters, clog the paper, and cloud the cup. Use filtered water with moderate mineralisation (TDS target 75-150 mg/L) to avoid any metallic edge. Stir gently to wet every grain, cover, and hold in the fridge between 12 hours (lighter, fruitier profile) and 18 hours (fuller, more chocolatey profile). Beyond 24 hours, bitterness starts to dominate.

Filtering happens in two steps: first a coarse pass through cheesecloth, a French press metal screen, or a nut-milk bag, then a fine pass through a paper filter (V60, Chemex) to clarify. The concentrate keeps hermetically sealed for 7 to 10 days; flavour shifts slightly with oxidation, often gaining roundness on day two. In Brussels, Ghent or Liège, specialty coffee shops will serve it on ice in summer, sometimes with tonic or oat milk — in the same family as Japanese iced coffee, though that method pours hot water directly onto ice and should not be confused with cold brew.

Two classic mistakes: using an espresso or filter grind, which over-extracts tannins in 12 hours and gives a harsh cup; and leaving the brew at room temperature, which accelerates fermentation. Caffeine-wise, a 1:8 concentrate packs roughly twice the caffeine of a standard filter at the same volume, which is exactly why final dilution matters.

Immersion cold brew recipe — key parameters