Cold Japanese Tea: Mizudashi vs Iced Tea
Sep 17, 2026
Cold Japanese tea can be made in more than one way, and the method matters. Mizudashi extracts tea directly in cold water. Iced or chilled Japanese tea is usually brewed with warm or hot water first and then cooled. Both end up cold in the cup, but they do not extract the leaf in the same way.
That difference changes flavour, bitterness, astringency, caffeine extraction and the role of brewing time. If you are new to Japanese tea, start with our Japanese Tea Guide. For the tools themselves, see our Tea Strainer vs Infuser vs Tea Dripper guide.
Mizudashi vs iced Japanese tea at a glance
| Method | How the tea is extracted | Typical time | General cup character |
|---|---|---|---|
| Mizudashi | Cold water from the beginning, kept refrigerated | Longer; at least about 1 hour is a useful research-backed starting point | Less extraction of some bitter and astringent compounds; umami can become easier to perceive |
| Hot-brew then chilled | Warm or hot water first, then cooled or chilled | Tea is extracted in minutes, then cooled | Retains more of the extraction character of a warm or hot brew |
The key point is simple: serving temperature and extraction temperature are not the same thing. Tea brewed hot and then cooled is not chemically identical to tea extracted cold from the start.
What is Mizudashi?
Mizudashi means extracting tea with cold water. In practice, the dry leaves are placed in cold water and allowed to infuse slowly, usually in the refrigerator.
Cold brewing is not just a hot recipe carried out more slowly. Lower temperatures change which compounds move into the water and how quickly they do so. Research on Japanese green tea shows that cold or ice-water brewing can suppress the extraction of caffeine and the catechin EGCG more strongly than it suppresses compounds such as theanine and EGC. The result is a different balance in the liquor, often perceived as softer, less bitter and more umami-forward.
That does not mean cold water magically creates more theanine. A better way to understand the effect is that lower temperature can reduce the extraction of some bitter and astringent compounds more strongly, changing the balance of what you taste.
How to make Mizudashi Japanese green tea
There is no single universal Mizudashi recipe for every Japanese tea, but the following is a useful evidence-based starting point for Sencha-style cold brewing:
| Parameter | Starting point |
|---|---|
| Tea | About 3 g per 100 mL water |
| Water | Cold, roughly refrigerator temperature |
| Time | At least about 1 hour, then taste and adjust |
| Where to brew | In the refrigerator |
- Use a clean bottle, pitcher or other food-safe brewing vessel.
- Add the tea leaves. Around 3 g per 100 mL is a strong research reference, not a rule that every tea must follow.
- Add cold water.
- Cover the vessel and place it in the refrigerator.
- After about an hour, taste the tea. Continue the extraction if you want a fuller result.
- Separate the leaves from the liquor when the balance suits you, especially if the vessel will remain in the refrigerator.
Longer cold extraction continues to change the tea. Leaf size, cultivar, processing, dose and water chemistry all influence the result, so use the numbers as a starting point rather than as a universal specification.
Is overnight cold brewing safe?
Cold-brew tea should be treated as a refrigerated food preparation. Use clean equipment and clean water, keep the tea refrigerated during a long extraction, and avoid making casual room-temperature overnight steeping your default method.
Research on cold-brewed Japanese tea has specifically considered microbiological contamination. That is one reason a refrigerator-based method is more defensible than simply leaving wet tea leaves on the kitchen counter for many hours.
We do not give one universal number of days that every home-brewed tea remains safe or at its best. Vessel hygiene, refrigerator temperature, water and handling vary. Make sensible quantities, keep the tea cold and use it fresh rather than treating homemade cold tea as a long-term preserved drink.
How is iced Japanese tea different?
Another way to make cold Japanese tea is to brew the leaves at the warm or hot temperature appropriate to that tea and then cool the liquor. Japanese tea sources also describe chilled tea made this way as distinct from cold-water extraction.
Because the leaves were extracted at a higher temperature, the tea can carry more of the bitterness, astringency and aroma profile associated with a conventional warm brew. Cooling the cup changes how you perceive it, but it does not reverse the extraction that already happened.
If you cool freshly brewed tea with ice, remember that melting ice becomes part of the final water volume. In other words, the finished strength depends on both the brewing water and the ice that melts into the drink.
Which method should you use?
| If you want... | Try... |
|---|---|
| A soft, make-ahead summer tea with restrained bitterness | Mizudashi |
| A cold drink that keeps more of the familiar hot-brew character | Brew warm/hot, then chill |
| Tea ready relatively quickly | Brew warm/hot, then cool |
| To explore how temperature changes extraction itself | Mizudashi |
Neither method is inherently superior. They are different brewing choices.
Does Mizudashi have less caffeine?
Cold brewing can extract less caffeine than hotter brewing under comparable conditions, but Mizudashi is not caffeine-free.
The final amount depends on the tea, leaf dose, water volume, temperature and contact time. A long, strong cold brew can therefore not be described with one universal caffeine number, and “cold brewed” should never be used as a synonym for “decaffeinated.”
Why can Mizudashi taste less bitter?
Temperature changes extraction selectivity. At cold temperatures, caffeine and some bitter or astringent catechins are extracted more slowly and less strongly than under hot brewing conditions. Amino-acid-driven umami can therefore become more prominent in the overall balance.
Again, this is a question of relative extraction. It is more accurate to say that cold brewing suppresses some bitter and astringent extraction than to say that it simply “extracts more sweetness” or “extracts more theanine.”
What Japanese teas can you cold brew?
Sencha is an obvious starting point and is the tea most directly supported by the cold-brewing references in our research corpus.
Fukamushi Sencha can also be explored cold, but its smaller particles and deeper steaming can make filtration and clarity behave differently from a more intact-leaf tea.
Hojicha can be cold brewed too. Because its identity comes from roasting, cold extraction produces a different balance from hot brewing rather than simply creating a chilled copy of the same cup. See our Hojicha guide.
Genmaicha can also be explored at low temperature, but remember that its roasted-rice aroma is part of the blend. Cold extraction may present that roast differently from a hot infusion. Our Genmaicha guide explains the category in more detail.
Matcha is different. Matcha is powdered tea dispersed into water rather than loose leaves being infused and filtered, so it should not be treated as the same brewing architecture as Mizudashi leaf tea.
Do you need a special cold-brew tea bottle?
No. A dedicated cold-brew bottle can be convenient, but the brewing requirement is simple: the vessel must be clean, food-safe, suitable for refrigeration and able to separate the leaves from the finished tea when needed.
A removable infuser basket can make that separation easier. A cup-top strainer can work when the tea is brewed loose in another vessel. What matters is the function of the tool, not the marketing name printed on it.
Our tea-tool comparison explains the difference between strainers, immersion infusers and drip-through tools.
Can you make Mizudashi in a kyusu?
You can use a kyusu for a small cold infusion if the pot and filter suit the leaf, but a lidded refrigerator vessel is often more practical for larger quantities and longer contact times.
The useful question is not whether the vessel is traditionally shaped. It is whether it gives the leaves enough contact with the water, can be kept clean and cold, and allows the finished liquor to be separated from the leaves.
Is cold Japanese tea traditional?
Cold Japanese tea should not be dismissed as a foreign adaptation of Japanese tea culture. Japanese institutions actively describe both cold-water extraction and tea brewed hot then chilled, and cold-water green tea is associated with summer drinking in Japan.
At the same time, that does not mean every modern bottled cold-brew method is ancient. The more accurate view is that Japanese tea culture includes both long-established hot service and legitimate modern or seasonal cold preparations.
Mizudashi FAQ
What does Mizudashi mean?
In tea preparation, it refers to extracting the tea with cold water rather than brewing it hot and cooling it afterward.
How long should Japanese green tea cold brew?
At least about one hour in the refrigerator is a useful research-backed starting point for a Sencha-style brew. Different teas and doses may need more or less time for the flavour you want.
How much tea should I use for Mizudashi?
About 3 g per 100 mL of water is a useful strong reference point from Japanese cold-brew research. Treat it as a starting condition rather than a universal household rule.
Can I leave cold-brew tea at room temperature overnight?
We recommend refrigerated extraction for long steeps, with clean equipment and clean water, rather than casual room-temperature overnight brewing.
Is Mizudashi caffeine-free?
No. Cold water can reduce caffeine extraction compared with hot brewing under similar conditions, but it does not eliminate caffeine.
Is Mizudashi the same as iced tea?
No. Mizudashi extracts the leaves in cold water. Iced or chilled tea may have been extracted with warm or hot water first and only cooled afterward.
Can I cold brew Hojicha?
Yes. Expect the balance of its roasted character to differ from a hot infusion.
Can I cold brew Matcha?
You can prepare Matcha with cold water, but technically it is not the same process: Matcha is a suspension of powdered tea, not an infusion of leaves that are later filtered out.
Cold tea begins with the extraction method
The simplest way to understand cold Japanese tea is to ask one question: was the leaf extracted cold, or was the tea extracted warm and cooled afterward?
Mizudashi is the first method. It uses time and low temperature to create a different extraction balance, often with restrained bitterness and a clearer impression of umami. Hot-brew-then-chilled tea is the second method, preserving more of the chemistry created during warm extraction.
Both belong in the Japanese-tea toolkit. Choose the method for the cup you want rather than assuming that every cold green tea is the same drink.
Continue with the Japanese Tea Guide, compare Hojicha and Genmaicha, or learn how different tea tools control extraction.
