We always say that water is the mother of tea. In the Qing Dynasty, Zhang Dafu (張大複) stated in the Brush talks from the plum flower cottage (梅花草堂筆錄), “The nature of tea must be revealed by water. If you have eight points of tea and match it with ten points of water, the tea will be fully revealed. But if you have eight points of water and ten points of tea, the tea will only reveal eight points of its nature.” The quality of the water used to brew tea is directly related to the tea soup, so high-quality tea requires high-quality water for brewing to fully showcase the aroma of the tea.
In the Tang Dynasty, Lu Yu described the water used for brewing tea in his The Classic of Tea (茶經): the mineral water from the mountains is the best type for brewing tea, followed by the river, then the wells (山水上，江水中，井水下 ). Water from the mountains has been filtered through layers of ores, and impurities in the water have thus been removed. As a bonus, the water also contains a small amount of minerals, which can help in the dissolving of the active ingredients of the tea, making the tea exceptionally fragrant. However, there is one thing to take note of. Water with an overly high concentration of minerals, known as “hard” water, should never be used. If the contents of the calcium and magnesium of the water are too high, it will prevent the dissolving of the active ingredients in the tea, and after heating will clump together and affect the texture of the tea.
Ancient people had even more requirements for the water used to brew tea. For instance, there is a character called Miao Yu (妙玉) in the Dream of the Red Chamber (紅樓夢), she collected the snow gathered on plum flowers to place into a jar - 鬼臉青, literally “Ghost Face Green” (a special, blue-glazed piece of porcelain). Then, it was buried under a plum tree, and the water would be taken out in the summer of the next year to brew tea. Similarly, ancient people had special pursuits in making incense and medicine too, such as using only the rain collected on the Rain Water (雨水), the dew from the day of White Dew (白露), frost from the day of Frost's Descent (霜降), and snow from the day of Lesser Snow (小雪).
Going back to the topic, what water should we use for day-to-day brewing of tea? As most of us live in cities, and it is very difficult to obtain fresh water from natural sources like the ancient people, so we need to rely on the market supply chain to find suitable water. We often assume that more expensive and well-known brands, like the very famous Evian, are better. Some of my friends initially used it for brewing tea and later they asked me why for the same type of tea, what I brewed tasted completely different.
The biggest difference is the water we used, if we carefully check the mineral content of Evian, we will realise that it contains 80 mg/l of calcium and 26 mg/l of magnesium. This kind of water is considered very “hard”. Such water is only suitable for drinking directly, but not good for boiling to 100 degrees. Similarly, there are also waters from other places with very high mineral content, so water is rarely boiled in these areas, and the kettles used are often left with thick scales.
Personally, I prefer using the soft mineral water, such as the one from the Mount Daisetsuzan in Hokkaido, Japan. Its calcium and magnesium are only 2.2 mg/l and 0.9 mg/l respectively. Compared to other waters, this is very suitable for brewing tea.
Additionally, another water from Hokkaido, Suisai no Mori 水彩の森, is another suitable alternative for brewing tea. Its Calcium is only 2.72 mg/l and Magnesium is 0.94 mg/l. “Soft” water like these with relatively low mineral concentrations are the true “mineral water from the mountains 山水上” (see second paragraph). If we can't find such water where we live, it's better to use the distilled water, which contains no minerals at all, rather than using water with high mineral content.
Lastly, when brewing Cliff Tea, it is best to use water freshly boiled to 100 °C for each brew. For example, in the Chaoshan (潮汕) region, people prefer to brew tea with 蟹目水 (crab-eye water), which is water that had just reaching 100°C, and the bubble looks like the crab’s eye. Water in this state is the most active, which making the tea soup the most vibrant. However, a thing to note is not to boil the same kettle of water repeatedly. This kind of water is called “thousand boiled water 千滚水 ”, also known as “dead water”. Repeated boiling significantly increases the “hardness” of water, adversely affecting the taste of the tea.
