Second post in this series and I thought that I’d talk about a part of tea that is vital to the beverage but not really considered [1]: water.
To me, water is water, but there are apparently three things to consider.
1. Hardness of the water
The book that I’m using (Black Tea Bible) divides water into three types of categories:
Hard water: Hard water refers to water with high amounts of calcium and magnesium (hardness level – 硬度 in Japanese – of over 300 [2]). When you use this water to brew tea, the tea tends to be dark, not as fragrant, but also less astringent and very deeply flavoured. It’s good for brewing milk teas.
Medium-hard water: This is water with a hardness level of 100 to 300. Because the fragrance will be softer with teas brewed using this water, it’s suitable for flavoured teas. It’s also suitable for making milk teas because it brews teas with stronger flavours.
Soft water: This refers to water with a hardness level of less than 100. It results in teas with a lighter-colour and more fragrance. However, there is also more astringency in teas brewed using this water so be careful not to steep it for too long.
In general, water in England tends to be hard, while water in Japan and Singapore is considered soft.
2. Oxygen levels in the water
This is another thing that I’ve never really considered, but the level of oxygen in the water also affects the flavour of the tea. If there is too little oxygen, it’s hard for jumping to occur and the best flavour of the tea cannot be brought out. ‘Jumping’ refers to the action of the tea leaves as they move between the top and bottom of the pot.
Because you don’t want there to be too little oxygen, it’s best to use water fresh from the tap or freshly boiled. Water that has been standing for too long, the oxygen will tend to seep out [3].
And that leads us to the third thing to consider:
3. The temperature of the water
Tea is apparently a lot like Goldilocks, and it likes a temperature that is neither too hot nor cold. For reference, here’s a picture from page 19 of The Black Tea Bible:
The picture on the top refers to water that has not been sufficiently boiled. The tea leaves end up floating at the top and do not absorb enough water, leading to weak tea.
The picture in the middle shows perfectly boiled tea. Jumping has occurred and the tea leaves are unfurling (you can really see the difference when you compare the two pictures). The tea here has good colour, taste, and scent.
The picture on the bottom refers to water that has been boiled too many times/overboiled. There isn’t enough water and jumping does not really occur, leading to tea that with a weak fragrance and taste.
And this is only for tea that requires freshly boiled water. Different teas do have different optimal brewing temperatures. For example, the green tea I bought from お茶の山口園 recommends using water between 60 to 70 degrees [4] while the green tea from Lupicia recommends a water temperature of 75 to 80 degrees [5]. So in general, Japanese green teas require a lower brewing temperature while black teas require a higher temperature/freshly boiled water, while I’m not too sure about the other types of tea.
Of course, you could also cold-brew the tea. Cold-brewing tea basically involves steeping the tea for a long, long time in cold or room temperature water. It’s definitely not as efficient as using hot water but it does lead to less astringent tea. Plus in Singapore, it’s nice to drink non-hot drinks occasionally. Even Oishinbo has a chapter where gyokuro green tea is cold-brewed, leading to a tea that is naturally sweet and a beautiful colour [6]
And there you have it. I’ve never thought about water much but it does make sense that it’s makes a huge difference to the quality of the tea. I’m afraid I’m not so fanatical that I’ll measure my water with a thermometer to make sure I’m using the optimal brewing temperature, but I’ll definitely not be double-boiling my water and trying to agar-agar a suitable brewing temperature.
Notes and References
Yamada, Sakae. The Black Tea Bible (紅茶バイブル). Natasume, 2017 – Most of this post was based on information in this book. It’s entirely in Japanese, but if you know the language, it’s worth reading. You can read my review of the book here.
Post on Water Temperature from A Tea Addict’s Journal
Very detailed post on how to make cold-brewed tea from Serious Eats (highly recommended if you intend to make some tea and want more information)
[1] At least by me.
[2] That said, the WHO defines hard water as 120-180 mg/l hard and water with over 180mg/l very hard. Source
[3] This is because moving water will pick up more oxygen, not because there’s a chemical process where oxygen unbinds itself from the H2O molecules.
[5] Link to other relevant blogpost.
[6] The English translation of Oishinbo is translated according to topic rather than the way it was published, but it’s basically the chapter where the newspaper’s president’s old friend comes to visit Japan. You can read a summary of the chapter here (link is in Japanese)