What are the qualities of coffee and how does water choice affect Dancong oolong?
For highly aromatic oolongs such as Songzhong Huangzhixiang Dancong, the mineral content of the water strongly affects how aroma and flavor come through. A US study by Franks et al. (2019) found soft water dissolves more catechins, especially in green tea, but ordinary participants preferred tea brewed with hard water, calling soft-water green tea too bitter and astringent.
The researchers noted that expert Chinese tasters differ from large numbers of ordinary American drinkers. Baristas typically brew tea with the same reverse-osmosis or cartridge-filtered water used for coffee. Traditional tea practice adjusts water differently: Yu Xiuhua suggested a pinch of salt to remove off-flavors, while others add maifan stone or bamboo charcoal when boiling water, which can quietly change mineral composition.
Whether to use soft or hard water for brewing tea has always been a hotly debated topic among tea enthusiasts. A U.S. study targeting ordinary consumers showed that although soft water extracts more catechins, participants actually preferred tea brewed with hard water. For highly aromatic oolongs like Songzhong Huangzhixiang Dancong, the mineral content in water significantly affects the presentation of aroma and flavor. This article reviews the effects of different water qualities on tea, introduces water treatment methods commonly used in cafés and water adjustment techniques in traditional tea art, and combines brewing suggestions from Front Street Coffee to help you find suitable water quality and brewing methods for Dancong under everyday conditions.
American researchers once conducted an experiment that did not invite expert judges, but instead recruited a group of ordinary tea drinkers to evaluate the effects of minerals in water on tea (Franks et al., 2019). The conclusions were broadly consistent with earlier similar studies: soft water can dissolve more catechins, and this effect is more pronounced in green tea than in black tea.
However, this study had a distinctive finding—participants actually preferred tea brewed with hard water. The researchers explained this by saying that "the tastes of a few Chinese experts differ from those of a large number of ordinary American tea drinkers." For the American participants, green tea brewed with soft water tasted too bitter and astringent, and was not smooth enough to drink. They therefore suggested: if drinking tea for health reasons, deionized water is a better choice; if simply pursuing flavor, then for most consumers, ordinary tap water may be more appealing.
In coffee shops, baristas usually use the same water they use for making coffee to brew tea, and this water is either treated by reverse osmosis or filtered through filter cartridges. Traditional tea brewing, on the other hand, has passed down several methods for adjusting water quality. Yu Xiuhua once suggested adding a pinch of salt to eliminate off-flavors in water; some other tea masters add a mineral stone called "maifan stone" or bamboo charcoal when boiling water. These practices are often promoted as "purifying" water, but in reality they may quietly alter the mineral composition of the water, thereby shifting the taste of the tea.
Although no peer-reviewed paper on this issue has yet been found, tea author Rie Tulali (2020) offered a conjecture: the common element in these treatments may be silica. Tulali pointed out that drinking water rich in silicon, such as Fiji water, can enhance the flavor and sweetness of tea, and bamboo happens to be a well-known source of silicon. But until more in-depth research emerges, we cannot determine whether silica is the mineral missing from a perfect cup of tea.
That said, multiple studies do clearly show that minerals in water affect different types of tea in different ways. Precisely for this reason, many tea experts suggest that when brewing white tea and green tea, the water should be softer than when brewing oolong and black tea, so as to bring out the flavor these teas should have. If you want a cup of tea with a strong, rich flavor, you can even refer to Mrs. Beeton's method—she once wrote: "Before the boiling water is poured over the tea leaves, adding a few grains of bicarbonate of soda helps release the essence of the tea." But for the more refined teas commonly found in specialty cafés, you may find that brewing tea with coffee water can bring some unexpected new flavors.
The above content is compiled by CoffeeHunters, a coffee news website.
