Chapter Three (11)Use of Water for Tea Brewing

II. Use of Water for Tea Brewing 

1. Water Quality

As an indispensable carrier of tea’s intrinsic qualities, water can extract valid substances in the tea leaves through brewing and immersion, thus resulting in the tea soup we are familiar with in its full color, aroma and taste. Standards of water used for tea brewing consist of five aspects: limpidity, freshness, softness, sweetness, and fragrance. Water used for tea brewing falls into the following six types based on source:

(1)  Spring water

Spring water often originates from rocky mountains. After being filtered through sandstone and soil, and upon dissolving dozens of chemical elements in the stone, including sodium, potassium, calcium and aluminum, the water becomes limpid, fresh and sweet and nutritious. During the brewing process, the combination of minerals and tea ingredients enriches the mouthfeel and aroma of the tea soup. 

(2)  River and lake water

As ground surface water, river and lake water from remote places overgrown with luxuriant vegetation and free from large crowds of people, is relatively less polluted because such clean, living soft water supports many living organisms and has neutral pH value. Such water is good for brewing tea and makes the tea taste better and milder.  

(3)  Well water

Well water in general is highly transparent shallow groundwater with few floating substances. As it percolates into strata of soil, well water dissolves many minerals and salts. Because well water in different regions has different substances in it, care must be taken in choosing the type of well water to use for brewing tea.

(4)  Purified water, mineral water, mineral spring water, natural spring water, etc.

Such drinking water commonly used in daily life is the predominant choice for tea brewing. There are two common kinds of drinking water on the Chinese market today: 1) Purified water not using source-based standards, potable mineral water, and other drinking water. Such water contains uniform substances and follows relevant national standards for drinking water. 2) Drinking water from natural water sources, including potable natural mineral water and potable natural spring water. Such water sources, commonly used to brew tea, are similar to mineral water and are certified by relevant quality control departments. The right type of water for brewing tea is not necessarily water containing any special substances. Instead, preferences should be given to water befitting the tea soup’s quality features that can extract the tea’s essential substances and that does no harm to the quality of the tea soup. Of course, all potable water must meet national health standards. Factors that affect the quality of tea-brewing water includes the following:

PH value

By China’s national health standard, pH value of drinking water must range between 6.5 and 8.5. Therefore, not all drinking water is suitable for brewing tea. The tea soup color is highly sensitive to variations of pH value in the water used. PH value of tea soup is normally either acidic or slightly acidic. So, pH value of water used to brew tea will generally not exceed 7. If it exceeds 7, the OH- in the water would cause polyphenols, the most important quality substance in the tea soup, to irreversibly oxidize, thus changing the ionic equilibrium among active ingredients of the tea soup and the color and mouthfeel of the soup.

Hardness

Water can be soft or hard. Soft water is water that has ions of calcium and manganese of less than 8 mg/l. Water surpassing that standard in ions of calcium and magnesium is called hard water. Tea brewed with hard water will cause the tea soup to appear dark, taste astringent, and smell abnormal, thus compromising the quality of the tea leaves. Conversely, tea brewed with soft water will cause the tea soup to appear clear and bright, taste mellow and sweet, and smell fresh and fragrant. Hard water can be further divided into temporary hard water and permanent hard water. The former can be used to brew tea, while the latter cannot. The reason is that calcium and magnesium bicarbonates in temporary hard water can decompose as soon as the water reaches boiling point, whereupon sediments of such carbonates would be developed to soften the water. But that is not the case for permanent hard water, which can easily mix with polyphenols and polysaccharides in the tea soup to affect its mouthfeel.

Minerals

China has explicit health standards for minerals and salts in drinking water. Use of water with high concentration of ions of minerals will obviously affect the quality of the tea soup. 

Iron and manganese

When the concentration of iron and manganese in waterreachesbetween 0.4 mg/L and 0.5 mg/L, the tea soup wouldappear dark brown. When such concentration goes above that, the tea soup would become dark and brownish purple.

Chlorides

Chlorides in water will react with polyphenols in tea leaves, producing a layer of oil-like substance on the surface of the tea soup that causes it to taste astringent. Therefore, we should avoid using salty water rich in chlorides and stagnant water rich in iron to brew tea.  

Concentration of floating substances in water

This refers to the concentration of indissoluble mixed solids sequestered through filtration. Concentration of floating substances is inversely proportional to the tea soup’s transparency. The higher the concentration of floating substances in the water, the more the tea soup’s color will be directly affected.

Air in water

Air contained in water mainly consists of oxygen and carbon dioxide dissolved in the water. High volume of dissolved oxygen changes the flavor of the tea soup because the oxygen in it may directly or indirectly cause oxidization and deterioration of some readily oxidizable substances in the tea soup. In contrast, high concentration of carbon dioxide enhances stimulation to the mouth and the carbon dioxide released from the tea soup gives off a fragrance that refreshes the tea drinker. The tea soup will lose its original fresh flavor once the air in it is all gone. Therefore, water used for brewing tea needs to be boiled until bubbles go out of the water. That way, the fragrance of the tea will be stronger and more leached substances will dissolve. 

Picture on P.151: 

Yiyuan Well

2. Water Temperature

The temperature of water used for brewing tea can directly affect the tea soup’s quality. The dissolution velocity and solubility of various components in the tea leaves will change as the water temperature changes and the aroma substances in the tea leaves evaporate in direct proportion to the water temperature, i.e. the higher the temperature the more volatile the aroma substances are. As the water temperature rises, the dissolution velocity and the solubility of the flavor substances in the tea go up correspondingly. The same kind of tea leaves under different water temperature conditions will have different tastes in terms of strength of flavor, freshness, and astringency.Tea polyphenols cannot be easily leached out when the water temperature is below 80°C. Only when the tea leaves are immersed in 95°C hot water for six minutes can over 90 percent of the tea polyphenols be leached out.Amino acids, which are more soluble, can be leached out in large volumes when the tea is sufficiently immersed in hot water of 40°C and can be completely leached out after the tea leaves have been immersed in hot water of 60 °C for over six minutes. At low water temperatures, flavor substances leached out in the tea soup are mainly amino acids and soluble saccharides. Aroma substances can fully diffuse and flavor substances can be fully leached out when the tea leaves are brewed in 100°C hot water.The boiling point temperature of water is directly proportional to atmospheric pressure. When the latter is up, the former goes up, and vice versa. The higher the elevation, the lower the atmospheric pressure. According to measured results, pure water’s boiling point temperature can drop by about 1°C for every 300 meters of elevation growth. In consideration of differences in product type, growth environment, processing technology, storage period, and other factors, Pu’er tea of different quality levels need to be made with different brewing techniques.However, some common points do apply. For example, all Pu’er teas involve the use of boiling water, appropriate amount of tea leaves, flexible control of water fill and soup leaching speed, and all tea soups need to be partaken at a temperature of between 45°C and 55°C.