Cold brew is coffee steeped in room-temperature or cooler water rather than brewed with hot water. A clean jar or pitcher, coarsely ground coffee, water, and a filter are enough for a manual batch. The National Coffee Association's cold-brew method uses a coarse grind, a 1:4–1:5 coffee-to-water ratio by weight for concentrate, and about 12 hours of contact time. Treat those figures as a starting point, not a fixed rule.
A simple starting method
What you need
- A clean jar, pitcher, or other food-safe container with a cover
- Coarsely ground coffee
- Water
- A strainer and paper coffee filter
- A clean, covered container for the strained coffee
Start with a concentrate-style ratio
Weigh 1 part coarsely ground coffee and 4–5 parts water. For example, use 100 grams of coffee with 400–500 grams of water. This makes a strong brew that can be diluted to taste after filtering. A scale helps make later adjustments easier to repeat, but the important point is to keep a note of the ratio you used.
Combine and steep
Put the grounds in the clean container, add the water, and stir gently until the grounds are wet. Cover the container. The National Coffee Association describes about 12 hours of steeping at room temperature or in the refrigerator as one manual approach. Start there, then change the contact time in a future batch if the result is not to your liking. Coffee, grind size, roast, water, and filtration all affect the finished cup.
Filter without rushing
Pour the brew through a paper coffee filter set in a strainer into a clean container. Let it drain on its own. If you want less sediment, pass it through a fresh paper filter a second time. Filtering changes the texture of the cup, so use the result to guide the next batch rather than treating one filter method as universally best.
Chill, dilute, and keep the batch covered
Refrigerate the strained coffee in a covered container. The U.S. Food and Drug Administration advises keeping refrigerators at or below 40°F (4°C) and keeping refrigerated foods covered; clean hands and equipment are part of the same basic food-handling guidance. Follow those storage practices, but do not treat homemade cold brew as shelf-stable or rely on a guaranteed storage period. Discard a batch that looks or smells suspicious, and remember that an ordinary appearance or smell is not a safety guarantee.
Because this is a concentrate-style starting recipe, add cold water, milk, or another mixer in the glass until the strength suits you. Record both the brew ratio and how much you dilute it; that is more useful than assuming a single serving formula will suit every coffee.
Adjust one variable at a time
If the coffee seems too strong after dilution, use more water in the glass or begin the next batch with more brew water. If it seems too weak, reduce the dilution or use a slightly higher proportion of coffee next time. If filtering is slow or the cup carries more sediment than you want, begin with a coarser grind or add a second paper filtration. These are adjustments for your equipment and coffee, not diagnoses of a flawed batch.
What cold brewing can and cannot tell you about acidity and flavor
"Low acid" is too broad a description of cold brew. In a 2018 study of selected coffees, cold and hot brews had comparable pH values, while the hot brews had higher total titratable acidity. The measures are not interchangeable, so the finding does not establish that every cold brew is less acidic in every sense or that it has a health advantage. Read the study, Acidity and Antioxidant Activity of Cold Brew Coffee, for its specific tested conditions.
Flavor is also conditional. In a controlled 2022 full-immersion study, cold-brewed samples were less bitter and sour and more floral than hot-brewed samples under the study conditions, but the effects also interacted with roast and origin. That is useful context for tasting your own batch, not a promise of a particular flavor. The study details its methods and limits.
A brief caffeine note
Caffeine in a homemade concentrate varies with the coffee, dose, brew, serving size, and dilution. An undiluted pour can deliver more caffeine than a diluted serving of the same batch. The FDA cites 400 milligrams per day as an amount not generally associated with negative effects for most adults, while noting that sensitivity, medications, health conditions, pregnancy, and breastfeeding can change what is appropriate. See the FDA's caffeine guidance for context.
A compact batch log
For the next batch, write down the coffee weight, water weight, steep time, where it steeped, filter method, and dilution. Change one item at a time. A short record makes it easier to find a result you prefer without presenting one ratio or steep time as the answer for every coffee.
Sources
- National Coffee Association: Cold Brew Coffee
- Rao and Fuller, Acidity and Antioxidant Activity of Cold Brew Coffee
- Batali et al., Sensory Analysis of Full Immersion Coffee
- U.S. Food and Drug Administration: Are You Storing Food Safely?
- U.S. Food and Drug Administration: Spilling the Beans: How Much Caffeine is Too Much?