Water temperature is perhaps the most overlooked aspect of brewing tea. The common misconception is that boiling-hot water can be used universally for all tea. This is not true! In fact, in many cases, this is why tea becomes bitter — brewing at higher temperatures can release more bitterness in your brew!
Higher-temperature water tends to extract compounds in the tea quicker — especially the more bitter, astringent compounds. This is not entirely undesirable; these compounds are part of the full profile of the tea, and are often essential for maintaining a balanced flavor. To prevent these compounds and flavors from over-extracting, it is often vital to use slightly cooler water, which will slow down the rate of extraction and allow us to control these flavors more.
In contrast to high-temperature water, cooler water will bring out lighter tastes and aromas, though the overall taste of the tea may fall flat if the water is not hot enough. As previously mentioned, the compounds extracted in higher temperatures are not necessarily undesirable, but are just different aspects of the tea’s flavor. While cooler brewing may help emphasize lighter notes, it runs the risk of feeling flat or incomplete.
Generally, lower temperatures are preferred for lighter, more delicate teas, such as green teas, fresh white teas, yellow teas, and lighter oolongs. Darker teas such as darker oolongs, black teas, and post-fermented teas, on the other hand, tend to fare better with higher temperatures. However, the best temperature for each tea will always differ, and it is best to try different temperatures to see what works best for your tea. Because of its large effect on the flavor of your tea, it is important to find the optimal temperature that will achieve the balance of flavors and express the tea’s fullest potential.