Cold water extracts slowly and selectively. Its flavour and acidity depend on beans, extraction and dilution; a smooth taste does not establish a particular pH or a health benefit. The trade-off is time: what a V60 does in three minutes, cold water needs twelve to eighteen hours to do.
Concentrate or ready-to-drink?
- Concentrate: 1:4 to 1:5 coffee to water by weight. Dilute 1:1 or 1:2 when serving.
- Ready-to-drink: 1:12 to 1:15. Pour straight over ice, no dilution.
Concentrate is the better default for home. It occupies less fridge space, keeps longer, and lets you make black cold brew, an iced latte or a coffee tonic from one batch.
Steeping time
Use a recipe written for the actual brewer and steeping temperature; changing from room temperature to a refrigerator changes extraction. Use clean equipment and follow the manufacturer’s preparation and refrigeration instructions. Do not treat a longer steep as a guaranteed improvement.
Grind very coarse. Fines suspended for 16 hours are the main cause of muddy, silty cold brew.
Filtering properly
Strain first through a mesh basket or French press screen to remove the bulk of the grounds, then a second pass through a paper filter for clarity. Skip the second pass if you like a heavier body — just expect sediment at the bottom of the bottle.
Dilution maths when serving
Using brew ratio as a rough strength proxy, 1:4 to 1:12 suggests two parts added liquid per part concentrate; retained liquid and actual extraction limit that estimate. For an iced latte, treat melting ice as part of the water: 60 g concentrate, 120 g milk and a full glass of ice lands close to a café-strength drink.
Storage
Storage duration is recipe- and equipment-specific; follow the manufacturer’s instructions rather than inferring shelf life from concentration. Use a clean, food-safe covered container suitable for the product, and keep it away from anything aromatic — coffee absorbs fridge smells enthusiastically.
Check the serving arithmetic
For 250 ml of concentrate and a 1:2 concentrate-to-added-liquid serving ratio, add 500 ml and obtain 750 ml total. Do not confuse that serving ratio with the coffee-to-water ratio used during steeping. Weigh the beverage collected after filtering if repeatability matters; input brew water is not equal to recovered concentrate. Our tool’s 1:5-to-1:16 example estimates 550 ml addition and explicitly identifies the strength assumption.
References and scope
Reviewed November 5, 2026. References support the named background topics; the comparison plans and arithmetic above are illustrative, not claimed equipment tests. Follow the instructions for your own equipment.