I have ruined many a cup of tea, primarily green and white tea, because I had used water that was too hot to brew tea. This was during my early years of drinking tea and not knowing the chemistry behind the tea. Water temperatures can affect the taste and overall experience of tea consumption.
Each cup of tea is at the mercy of two variables (among other variables); water temperature and length of steep time. The water temperature for steeping tea and the outcome of tea is similar to the outdoor temperature, how we feel, and how our body reacts to that temperature. If it is extremely hot outside, chances are we are feeling miserable and our body is not functioning as well as if it is cooler outside. If it is extremely cold outside, there is a decrease in our body’s unencumbered movements and it takes a bit longer to have an increased exertion level. Tea is very much like our bodies; different temperatures cause different effects on the cup of tea.
Hot water extracts compounds at a faster rate than cold water. Imagine walking outside on a very hot day, fully covered from head to toe in arctic weather gear. Hat, gloves, scarf, winter parka, and snow boots are going to cause your core temperature to heat up very quickly and you most likely will start shedding the hat, parka, gloves, and scarf. Tea leaves react similarly in boiling water. The compounds and chemicals that are inside the tea leaf cell membrane walls are extracted from the cell membrane walls into the boiling water at a rapid rate.
For example, caffeine is a large molecule that is one of the first chemicals to be extracted from the leaf in boiling water. Caffeine has a bitter taste. When green tea is steeped in boiling water, the caffeine that is quickly extracted from the leaf causes the green tea to become bitter.
In addition, semi - oxidised teas (yellow, and Oolong teas) and oxidised teas (black, dark and Pu’erh teas) have a large chemical molecule called tannins in the leaf. In hot water, tannins are released rapidly into the water. Tannins, along with caffeine, have a bitter taste, and cause the tea liquor to taste bitter.
Now imagine walking outside into arctic weather wearing arctic protective clothing. You are walking around, moving and slowly getting warmer, and warmer. It would invariably take a while to increase your core heat enough so that you would be hot enough to start removing the hat, gloves, scarf, etc…. In cold water tea leaves are releasing caffeine, tannins and other compounds and chemicals at a drastically decreased rate. Green tea, even black tea, has a less bitey, bitter, and bracing flavor when steeped in cold water rather than in hot water. The reason for this is due to amino acids being released in cold water more readily than caffeine and tannin molecules. Amino acids lend to a creamier, sweeter flavor profile and a thicker mouthfeel of the tea liquor. Caffeine and tannins are still released in cold water but at a slower rate.
While it is easy to boil water, it is more difficult to stop the water before it goes to boiling. There are numerous charts for the exact temperatures for the types of teas being infused. There are water thermometers that can be used to register the exact water temperature for each tea type. Michael Harney stated “water is the mother of tea.” Plain and simple, water is everything. He also stated “different teas brew for different times and suggestions …...offered as guidelines only….”
The Chinese have used visual clues to decipher what the correct water temperature is for steeping teas. They have denoted four primary water temperatures. The lowest temperature is called a “column of steam steadily rising”. There is a pillar of steam and the water temperature is approximately 170-180F. The next stage of boiling water is called “fish eyes.” On the surface of the water, there are large bubbles that are breaking through the surface. The water temperature is approximately 180-200F. The following stage has a water temperature of approximately 200F plus. It is called the “string of pearls'' and the water is almost to a boil, with tiny bubbles looping around the perimeter of the boiling vessel. The last stage of boiling water is a full rolling boil, with temperatures over 200-212F. This type of boil the Chinese have called the “Turbulent waters.”
There is a general and approximate rule for correct water temperatures corresponding to types of tea. The rule suggests the lighter in color the tea leaves, then the farther removed from boiling the water needs to be. Green teas and white teas are best suited for water that is approximately 165-175F. Lighter Oolongs, and Darjeeling teas are best when steeped in approximately 190F water. Dark teas, Pu’erh teas and black teas can be steeped in a full boil water, approximately 212F.
It is recommended to only boil water one time and use that water for tea, and not reboil tea a second time. Using fresh boiled water for each steeping ensures the optimal level of carbon dioxide in the water. When water boils for a length of time or is boiled a second time, it loses the carbon dioxide, and is decreased in acidity. The decrease in acidity and lower levels of carbon dioxide can cause a color change and a different taste in the liquor that is not desirable.
A Tea Poem
Sitting at night in a mountain pavillion,
drawing spring water to boil tea
As the water and fire battle it out,
the scent of the pie billows through the trees as I pour a cup,
bathed in light from the clouds.
The profound pleasure of this moment
is hard to convey in words
to those of common tastes.
-Ming Dynasty Literati
Harney, Michael. The Harney & Sons Guide To Tea. Penguin Press, 2008.
Heiss, Mary Lou and Robert J. Heiss. The Story Of Tea: A Cultural History And Drinking Guide. Ten Speed Press, 2007.
Richardson, Lisa Boalt. Modern Tea. Chronicle Books, 2014.
Yun, Ling. Tao of Chinese Tea: A Cultural And Practical Guide. Shanghai Press & Publishing Development Company, A Readers Digest Association, 2009.
About the Author
Leslie Sundberg is a World Tea Academy Certified Tea Specialist, a World Tea Academy Apprentice Tea Sommelier, a Specialty Tea Institute Levl IV trained Tea Specialist, and a Tea and Business Etiquette Specialist. On any given day, Leslie can be found teaching, speaking or sharing in the joys of a cup of tea. No matter what Leslie is doing or where she is, one thing remains constant: 4:00 in the afternoon is tea time!