Cold Brew Tea with Hario: Steeping Time, Dosage, Effect
Cold-brewed tea tastes different from a cooled hot infusion: softer, sweeter, less astringent. There's a clear explanation for why – and the process is easier than the effort involved might suggest.
What happens during cold brewing?
Not all compounds dissolve equally well in cold water. Caffeine and EGCG, the most abundant catechin by quantity, need heat. Amino acids like theanine, on the other hand, dissolve readily even cold. The result is a shift in ratio: less of what tastes bitter and astringent, proportionally more of what feels sweet and round.
Monobe (2018) provides concrete figures for Sencha: with ice water at 0.5 °C, caffeine content was under 20 percent of a hot infusion, and around 50 percent at 10 °C. EGCG reached about 20 percent at 10 °C, while EGC reached around 70 percent. Lantano and colleagues (2015) describe the same pattern as slower extraction with less degradation – though they found only minor caffeine differences.
What follows from this, and what doesn't: less caffeine, yes. Caffeine-free, no. And how much less depends on temperature and time – anyone citing a fixed percentage is going beyond the data.
Which Hario vessel do you need?
Retailers often list a «Hario Cold Brew Tea Bottle». Hario has no product by that name. Officially, the vessels are called:
| Official name | Sizes | Design |
|---|---|---|
| Filter-in Bottle | FIB-75 with 750 ml, FIB-30 with 300 ml | Bottle with a hanging strainer |
| Mizudashi Cold Brew Tea Pot | HCC-12 with 1200 ml, HCC-7 with 700 ml | Pot with strainer insert |
| Filter-in Carafe, Ka-Ku Bottle | depending on model | Carafe or bottle, respectively |
For everyday use, the Filter-in Bottle is enough: it fits in the fridge door, the strainer hangs from the lid, and you can pour straight out of it. Our Hario selection and the tea brewers and teapots are in our shop.
How does it work, step by step?
- Add the tea. Guideline from Hario Asia: around 15 g of leaves per 750 ml, so roughly 20 g per liter. Hario's global sites don't give a gram figure – take this as a starting point.
- Pour in cold water. All the leaves should be wetted. Hario explicitly specifies the refrigerator, not room temperature.
- Let it steep. 3 to 6 hours in the refrigerator. Finely cut leaves are ready faster than large whole leaves.
- Remove the strainer. Otherwise the tea keeps steeping and eventually turns bitter after all.
- Drink. We recommend two to three days chilled – that's our own experience, not a manufacturer specification.
Which tea works best?
Green tea is the classic case, because the effect shows up most clearly there: a Sencha that turns grassy and harsh quickly when brewed hot stays mild and lightly sweet when cold-brewed. It works well for black tea too. For white tea, oolong, and herbal and fruit teas, the same body of research doesn't exist – there, only trying it out helps. And that's not a shortcoming, it's the fun part.
And coffee?
The same principle works with coffee, just with different times and different equipment – here's how it's done, in our article on Cold Brew Coffee with Hario, and the difference between immersion and drip methods in Cold Brew vs Cold Drip. Our home-roasted coffee beans work for both approaches.
Sources
- Product names, the 3 to 6 hour steeping time, and the refrigerator recommendation: global.hario.com (Cold Brew tea overview, FIB and HCC product pages) and hario.co.uk.
- Dosage of around 15 g per 750 ml: Hario Asia Official – a regional manufacturer site, not a global standard.
- Shelf life: not found on any accessible Hario page; the figure in this text is our own recommendation.
- Monobe, M. (2018): Health Functions of Compounds Extracted in Cold-water Brewed Green Tea from Camellia sinensis L., JARQ 52(1), 1–6.
- Lantano, C., Rinaldi, M., Cavazza, A., Barbanti, D., Corradini, C. (2015): J Food Sci Technol 52(12), 8276–8283.
Frequently Asked Questions about Cold Brew Tea
How long does Cold Brew Tea need to steep?
Hario recommends 3 to 6 hours in the refrigerator. The often-cited range of 2 to 8 hours doesn't appear anywhere on Hario's own pages. The Filter-in Bottle feature page additionally says «overnight», and Hario Asia mentions around 6 hours for a stronger flavor.
Cold water or room temperature?
Hario is clear about the refrigerator: fill with cold water and let it steep cold. We didn't find a recommendation for room temperature on any official Hario page.
What's the correct name for the Hario vessel for Cold Brew Tea?
«Cold Brew Tea Bottle» is a retailer name. Officially, the products are called Filter-in Bottle (FIB-75 with 750 ml, FIB-30 with 300 ml), Filter-in Carafe, Ka-Ku Bottle, and Mizudashi Cold Brew Tea Pot (HCC-12 with 1200 ml, HCC-7 with 700 ml).
How much tea do I need per liter?
The only official gram figure we found comes from Hario Asia: around 15 g of tea leaves per 750 ml, so roughly 20 g per liter. Hario's global and Japanese pages don't give a number. Treat this as a guideline, not a standard.
Does Cold Brew Tea have less caffeine and fewer bitter compounds?
The direction is scientifically documented; the extent depends strongly on temperature and time. Monobe (2018) found that for green tea with ice water at 0.5 °C, caffeine content was under 20 percent of a hot infusion, and around 50 percent at 10 °C; EGCG reached about 20 percent at 10 °C, while EGC reached around 70 percent. So Cold Brew Tea is not «caffeine-free».
How long does finished Cold Brew Tea keep?
We didn't find a manufacturer specification for this from Hario. Our own recommendation: drink within two to three days, chilled and sealed. This is our own practice, not a Hario guideline.
Which types of tea work well?
The documented studies concern green and black tea. For white tea, oolong, and herbal and fruit teas, the same body of research doesn't exist – here, trying it out beats citing studies.
