Choose concentrate or ready-to-drink
A 1:5 brew ratio means one gram of dry coffee for five grams of water. A 1:1 serving dilution means one part strained concentrate plus one part water or milk. It does not mean brewing one gram of coffee with one gram of water.
Start with a clean food-safe jar, lid, coarse coffee, cold potable water and a clean strainer plus paper filter or another suitable filtration system. A clean French press can hold the steep, but its mesh alone leaves more fine sediment. These are editorial starting recipes, not laboratory-validated flavor or shelf-life claims.
Use the cold-brew planner to plan a fresh batch, dilute measured concentrate or work backward from a finished serving. It keeps the two ratios and counted ice separate.
| Plan | Dry coffee | Brew water | Starting fridge steep | After filtering |
|---|---|---|---|---|
| Small concentrate batch | 100 g | 500 g (1:5) | 16–18 hours at 4°C / 40°F or below | Measure yield; start with equal concentrate and diluent |
| Ready-to-drink experiment | 50 g | 600 g (1:12) | 16–18 hours at 4°C / 40°F or below | Taste before adding further water |
| Four 250 ml drinks, estimated | 166.7 g | 833.3 g (1:5) | Same refrigerated starting window | Estimated 500 ml concentrate + 500 ml diluent |
Wet fully, refrigerate, then filter
The steep time is a starting flavor choice. Refrigerator temperature, grind, roast and dose change extraction; do not leave a batch warm to meet an arbitrary clock.
- Wash the container, lid and filtration equipment and prepare a clean workspace. Weigh the coffee into a vessel large enough for grounds, water and stirring space.
- Add the measured cold water in stages, stirring until no dry pockets remain. Cover and mark the preparation date and time.
- Put the batch in the refrigerator at 4°C / 40°F or below. Start by comparing a small strained sample after 16 hours with the intended serving dilution.
- When the flavor suits you, strain out the coarse grounds, then pass through a suitable clean paper filter if you want less sediment. Let gravity work; squeezing adds fine material and does not produce a predictable extra yield.
- Measure the strained concentrate. Transfer it to a clean covered container, keep refrigerated and label it as concentrate with the brew date.
- Dilute the serving you need. Add milk at serving time when practical, and return the batch promptly to refrigeration.
Evidence: The Kitchn: cold-brew preparation and filtration · Wisconsin DATCP: cold-brew safety fact sheet (commercial guidance) · FDA: safe refrigerated storage
Dilute concentrate you already have
If your concentrate is store-bought, its label is the first recipe: not every product is meant for 1:1 dilution. For homemade concentrate, use a measured small tasting sample to choose a dilution, then scale it.
For a concentrate:diluent ratio of 1:d, add concentrate × d as diluent. To target a final volume, concentrate = final volume ÷ (1 + d). Water and milk can share the diluent portion.
| Task | Concentrate | Added liquid | Final before extra ice |
|---|---|---|---|
| 200 ml concentrate at 1:2 | 200 ml | 400 ml | 600 ml |
| 300 ml drink at 1:2 | 100 ml | 200 ml | 300 ml |
| 250 ml drink at 1:1 | 125 ml | 125 ml | 250 ml |
| 250 ml drink at 1:1 with counted melted ice | 125 ml | 25 ml liquid + 100 g ice | 250 ml only after the counted ice melts |
Why 833 g water can become 500 ml concentrate
The batch planner estimates liquid left with the grounds. With 1:5 brewing and an assumed 2 g retained per gram of coffee, each gram of dry coffee gives approximately 3 g concentrate. To plan 500 ml concentrate, divide 500 by 3: 166.7 g coffee needs 833.3 g brew water.
This model ignores small density differences and variable filtration losses. A measured concentrate volume is better evidence than the estimate. If your 100 g coffee / 500 g water batch gives 340 ml rather than the estimated 300 ml, use 340 ml for serving calculations rather than discarding drink to satisfy a formula.
Ice is not instant water. Counting 100 g ice as 100 ml dilution assumes it melts; a glass of cold concentrate poured over intact cubes is initially stronger. Keep serving ice separate unless you deliberately include its eventual melt in the recipe.
Correct the drink before remaking the batch
Taste concentrate at its chosen serving dilution. Neat concentrate can seem unpleasant simply because it is very concentrated.
| Observation | Next test |
|---|---|
| Balanced but too strong | Add more measured water or milk to this serving. |
| Balanced but weak | Reduce serving dilution first; next batch can use more coffee if needed. |
| Sharp or thin at the intended dilution | Extend the next refrigerated steep modestly or try a slightly finer grind, separately. |
| Dry, woody or muddy | Try a shorter steep and better paper filtration; avoid squeezing grounds. |
| Grit collects in the bottle | Filter again using a clean suitable paper and pour without disturbing settled fines. |
| Filter barely drips | First remove coarse grounds; replace a clogged paper instead of pressing through it. |
| Unexpected odor, visible spoilage or uncertain handling | Discard. Do not taste questionable coffee to decide whether it is safe. |
Refrigerate; do not assume coffee preserves itself
Keep homemade cold brew covered and refrigerated at 4°C / 40°F or below from steeping through storage. Plan small batches you will use promptly and keep the preparation date visible. There is no universal home expiry proven by this recipe; commercial date-marking rules are not a validation of your jar, temperature or handling.
The FDA advises refrigerating perishable food promptly and applying a two-hour limit at room temperature, reduced to one hour above 32°C / 90°F. Follow milk and plant-drink storage directions, and discard a batch when its refrigeration or cleanliness is doubtful. Harmful contamination need not announce itself through smell or appearance.
This guide does not provide a shelf-stable bottled or nitro-keg process. Reduced-oxygen packaging and commercial service need appropriate local food-safety controls; adding nitrogen is not a preservation step.
Evidence: FDA: safe refrigerated storage · Wisconsin DATCP: cold-brew safety fact sheet (commercial guidance)
Do not leave yesterday's concentrate in the equipment
Discard spent grounds, wash the jar, lid threads, strainer and serving container, rinse and dry. A press needs its screen assembly cleaned too. Do not continually top up an old batch with a new one; the date and handling history become unclear.
Cold brewing changes flavor and extraction conditions, but it does not establish a precise caffeine content or a guaranteed benefit for reflux. Choose decaffeinated coffee or a smaller serving when those practical changes suit your needs; use the separate caffeine guidance for health context.
Sources & limitations
This guide combines source-based explanations and practical starting points. Coffee Jacob has not performed hands-on product testing or controlled tasting trials for this guide. Source check: 13 October 2026.