Brewing tea is often described as an art, and one of the most critical factors in crafting the perfect cup is water temperature. Why? Because temperature doesn’t just heat the water; it shapes the way the leaves release their complex flavors and aromas. Understanding this can make the difference between a balanced, flavorful cup and one that feels bitter or flat.

At higher temperatures, the heat draws out more catechins, polyphenolic compounds responsible for astringency and bitterness. These same temperatures also release a tea's bold, rich aromas. On the other hand, lower water temperatures encourage the extraction of L-theanine, an amino acid that contributes to tea’s umami notes and calming effect. So, depending on the tea you're brewing and the flavors you want to highlight, water temperature matters.

If you’re brewing tea without a thermometer, don’t worry—there’s an elegant, time-honored way to gauge water temperature based on bubble size and activity. Below, I’ll break it down by stages:

Bubble Stages and Ideal Teas

• Shrimp Eyes (140–165°F)
  At this "quiver stage," small bubbles gather around the edge of the pan but haven’t yet risen to the surface. This delicate temperature is perfect for high-grade Japanese green teas, such as Shizuku Gyokuro and Homare Sencha, which thrive with a gentle touch to preserve their nuanced sweetness.

• Crab Eyes (165–175°F)
  Known as the "sub-simmer stage," small wisps of steam begin to rise, and a few bubbles start to surface. This is the sweet spot for most Japanese green teas like Kukicha and Purple Sencha, emphasizing balance and subtle vegetal notes.

• Fish Eyes (175–185°F)
  Also within the sub-simmer range, bubbles now rise more consistently, and steam becomes more pronounced. Use this temperature for hardier green teas and lightly oxidized oolongs, like Watanabe Oolong, which can handle a bit more heat to unlock their complexity.

• Streaming Pearls (185–200°F)
  This full simmer sees a steady stream of bubbles rising to the surface. Ideal for roasted teas and higher-oxidation varieties, such as Hojicha and Dattan Sobacha, this temperature brings out toasty, nutty, or caramelized flavors.

• Raging Torrent (200–212°F)
  Boiling water is typically reserved for bold teas like black tea and most herbal tisanes. However, extended boiling at this stage reduces oxygen levels in the water, which can impact the tea's flavor. A brief boil is fine, but don’t let it rage for too long!

Final Thoughts

Perfecting water temperature isn’t just about science—it’s also about exploration and personal taste. Try experimenting with different temperatures for the same tea to see how the flavors shift. And while temperature is key, don’t forget that water quality is just as important. More details on that in a future post…

Sources

1. Golden Moon Tea. “The 5 Different Stages of Boiling Water and How the Chinese Use Them for Tea.” Golden Moon Tea, www.goldenmoontea.com/blogs/tea/106687623-the-5-different-stages-of-boiling-water-and-how-the-chinese-use-them-for-tea. Accessed 11/29/2024.

2. Kroll, Chas. “Five Stages of Bringing Water to a Boil.” Tea Masters Blog, www.teamasters.org/five-stages-of-bringing-water-to-a-boil-by-chas-kroll/. Accessed 11/29/2024.

3. López-Alt, J. Kenji. “Everything You Wanted to Know (Plus More!) About Boiling Water.” Serious Eats, www.seriouseats.com/how-to-boil-water-faster-simmer-temperatures. Accessed 11/29/2024.

4. Lu, Yu. The Classic of Tea: Origins and Rituals. Archive.org, www.archive.org/details/classicofteaorig0000luyu/page/106/mode/2up. Accessed 11/29/2024.

5. Okakura, Kakuzo. The Book of Tea. Project Gutenberg, www.gutenberg.org/files/769/769-h/769-h.htm. Accessed 11/29/2024.

6. Tealife. “The Best Water Temperatures for Japanese Teas.” Japanese Tea Pedia, www.japanesetea.sg/japanese-tea-pedia/water-temperature/. Accessed 11/29/2024.