How to Prepare Your CoffeeJapanese Mizudashi Cold Brew
Mizudashi — 'water-extracted' — is Japan's cold-water method: grounds steep in cold water for half a day, then the concentrate is strained and poured over ice. It sits beside Japan's other iced coffee, which brews hot and drips straight onto ice, as the slow, patient half of the same cold-coffee culture: where flash-brewing keeps a hot cup's brightness by chilling it in an instant, mizudashi trades heat for time and comes out rounder, sweeter, and almost acid-free. The equipment is little more than a bottle and a filter, which is why it became the home kitchen's answer to summer, and why the same 1:12 ratio scales from one glass to a whole jug.
Ratio breakdown
Ingredients run from the top of the cup to the bottom; the last item is the bottom layer. Values are normalized to a true 100% stack.
What you need
- 600 ml cold or room-temperatureWater
- 50 g coarse groundsCoffee
Method notes
- Grind
- Medium-coarse — like coarse sea salt, a touch coarser than filter
- Water temperature
- Cold — 12–15 hours in the fridge
- Total time
- 900 min
Steps
Combine the grounds and the cold water
A 1:12 coffee-to-water ratio is the immersion norm — strong enough to drink over ice without turning thin. Cold water extracts slowly and gently, pulling the sweet, rounded compounds out of the grounds while leaving the harsh, sharp acids behind, which is why the brew never meets heat.
Steep in the fridge for 12–15 hours
Time does the work that temperature cannot. The fridge is the modern default because a cold, stable steep is clean and repeatable; a room-temperature steep extracts a little faster and bolder but is less forgiving if left too long.
Strain through a cloth, paper, or mesh filter
A long steep leaves fine sediment suspended in the liquid; filtering it out is what gives mizudashi its clear, tea-like body rather than a cloudy, gritty cup.
Serve over ice, straight or lightly diluted
The concentrate is built to be poured over a full glass of ice, where the melt brings it to drinking strength. Taste before you dilute — a good mizudashi is sweet enough that many drinkers take it black and unsweetened.
Tips
- Keep the ratio at 1:12 and scale it freely — 25 g to 300 ml, 50 g to 600 ml, or 75 g to 900 ml; only the grind and the steeping time stay the same.
- Grind a touch coarser than you would for a hot pour-over — over 12 hours, a fine grind over-extracts into bitterness and clogs the filter.
- A dark roast gives more body and a little more bitterness; a light roast stays bright and tea-like, so pick the roast to match how you want the glass to read.
Common mistakes
- Grinding fine — the long steep then drags out harsh, woody compounds and turns the brew cloudy instead of clear.
- Steeping for a day or more — past about 18 hours the extraction tips from sweet and rounded into bitter and flat; mizudashi is a window, not a marinade.
- Serving it warm — mizudashi is a cold drink by design; if you want it hot you have brewed a different coffee entirely.
FAQ
How is mizudashi different from Japanese iced coffee?
They are two routes to the same cold glass. Japanese iced coffee brews hot and drips the coffee straight onto ice, so it keeps the brightness and acidity of a hot cup. Mizudashi never uses heat at all — the grounds steep in cold water for 12–15 hours and come out smoother, sweeter, and lower in acid.
Is mizudashi the same as Dutch or Kyoto-style cold drip?
No. Dutch coffee and Kyoto-style iced coffee are slow-drip methods — cold water trickles, drop by drop, through a tower of grounds. Mizudashi is immersion: the grounds sit fully in the water and are strained afterwards. Both are cold, but one percolates over hours and the other soaks.
What ratio and grind should I use?
The common professional anchor is 1:12 — 50 g of medium-coarse coffee to 600 ml of cold water — steeped 12–15 hours and strained. Sources range from 1:10 to 1:15 and from 8 to 18 hours; go stronger and longer for a concentrate, or lean toward 1:15 for a lighter, more tea-like glass.
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