What you need.

— 1 cup (100g) coarse-ground coffee, medium roast works best

— 4 cups (1L) spring water, room temperature

— A glass jar or our 2.5 gallon dispenser (cold brew in a glass dispenser is its own kind of joy)

— A fine mesh strainer or cheesecloth

— Optional: a paper filter for the cleanest cup

Method.

1. Combine coffee grounds and spring water in your jar. Stir gently to make sure all the grounds are wet.

2. Cover loosely. Refrigerate for 14-18 hours. Longer steeps (up to 24 hours) produce a stronger, more concentrated brew with more caffeine.

3. Strain through a fine mesh strainer lined with cheesecloth, or through a paper coffee filter for the cleanest cup. Don't press the grounds — let gravity do the work.

4. Store in a sealed glass bottle in the fridge. Keeps for 2 weeks, though it's best in the first 3-5 days.

5. Dilute 1:1 with spring water or milk before serving, depending on how strong you took the concentrate.

Grind size matters. Coarse, like raw sugar. Too fine and the brew gets cloudy and over-extracted. Too coarse and the brew comes out weak. A burr grinder is worth the upgrade if you're serious about cold brew.

Roast level matters more than bean origin. Medium-roast single origins from Ethiopia, Colombia, or Brazil all make excellent cold brew. Dark roasts make a heavier, more bitter cold brew that some people love and others find too intense. Light roasts produce a brighter, fruitier cold brew that some people find surprising.

Glass throughout. Brew in glass, store in glass, serve in glass. Plastic containers absorb coffee oils and leach them back into subsequent batches. Our 2.5 gallon glass dispenser makes a perfect batch brewer for a household — 8-10 cups of cold brew concentrate, ready to dilute.

Dilute with the same water. If you brewed with spring water, dilute with spring water. Mixing spring water and tap water during dilution gives you inconsistent flavor — the tap water's mineral content will fight the brew's balance.