Cold brew's appeal is simple: smooth, low-acid coffee with zero technique anxiety. Time does the work — 12 to 18 hours of steeping instead of precision pouring. Get the ratio right and it's nearly impossible to ruin.
The only ratio you need
1:5 for concentrate — one part coarse-ground coffee to five parts cold water by weight (100g coffee to 500g water). Dilute the result 1:1 with water or milk over ice. Prefer ready-to-drink strength? Brew at 1:8 and skip the dilution. Coarse grind matters: fine grounds over-extract into bitterness and clog filters.
Gear, from free to fancy
Level 1 — any large jar: stir grounds and water, steep on the counter, strain through a fine-mesh sieve. Works, but straining is messy. Level 2 — a dedicated cold brew maker: built-in filter basket lifts out clean, spigot pitchers dispense from the fridge. The sweet spot for most homes. Level 3 — slow-drip towers: theatrical, delicious, and a countertop commitment.
The method
Coarse-grind, combine, stir until no dry pockets, cover, and steep 12–18 hours (room temperature is faster; fridge is cleaner-tasting). Strain or lift the filter, then store concentrate in the fridge up to two weeks — it actually rounds out after a day.
Serving it well
Concentrate over a big clear cube (small ice melts fast and waters it down — see ice molds), topped with cold water, oat milk or a vanilla syrup. An insulated tumbler keeps it cold through a commute. And if mornings are rushed, brew a double batch on Sunday — future-you will be grateful.
Troubleshooting
Bitter → grind coarser or steep shorter. Weak → check your ratio by weight, not scoops. Muddy → double-strain through a paper filter. Sour → steep longer; it's under-extracted. That's the whole science.