---
title: 'Water and extraction'
url: 'https://howtotea.me/science/water-and-extraction'
markdown: 'https://howtotea.me/science/water-and-extraction.md'
lang: en
date: '2026-11-03'
description: 'How flavor moves from leaf to water, what calcium, bicarbonate and chlorine do to the liquor, and what happens when milk, lemon or sugar goes into the cup.'
---

# Water and extraction

The same leaf brews a different cup depending on the water, its temperature and what goes in afterward. Labs have measured the physics and chemistry behind each change.

 ![A glass carafe of water and a cup of golden tea](https://howtotea.me/images/c/o/v/e/r/cover-091e661b.webp) Illustration 

Tea does not dissolve the way sugar does. Compounds leave the swollen leaf slowly, held back by the path through the leaf itself rather than by the water around it, so [extraction](https://howtotea.me/science/water-and-extraction/extraction) depends most on water temperature. Amino acids, theanine among them, come out fastest and galloylated catechins slowest, which is why several short infusions draw out more than one long steep. ISO 3103 sets 3–6 minutes at 2 g per 100 ml.

What happens next depends on what is in the water. The key factors in [water chemistry](https://howtotea.me/science/water-and-extraction/water-chemistry) are calcium and magnesium, bicarbonate and chlorine. Scum forms on the liquor when the water has both calcium and bicarbonate; boiling removes temporary hardness but leaves chloramine behind. In Chinese trials with 34 different waters, the best tea came from water low in minerals, hardness and alkalinity, and [green tea](https://howtotea.me/teas/green) reacted to the water most strongly.

[Additives](https://howtotea.me/science/water-and-extraction/additives) each work their own way. Milk caseins bind catechins and soften astringency, citric acid from lemon shifts the pH and lightens the color, and sugar makes astringency seem 30–40% weaker while the chemistry in the cup stays the same.

In this section

- [![](https://howtotea.me/images/c/o/v/e/r/cover-e0e9c551.webp) Extraction 浸出 How flavor moves from leaf to water: diffusion, swelling, how temperature and leaf size matter, and why short infusions yield more than one long steep. ](https://howtotea.me/science/water-and-extraction/extraction)
- [![](https://howtotea.me/images/c/o/v/e/r/cover-fa8c1811.webp) Water chemistry What water does to tea: calcium and magnesium, bicarbonate and pH, scum on the liquor, chlorine and chloramine, and what boiling and filters remove. ](https://howtotea.me/science/water-and-extraction/water-chemistry)
- [![](https://howtotea.me/images/c/o/v/e/r/cover-a1ab17b4.webp) Additives What happens in the cup when tea meets milk, lemon, sugar or salt: polyphenol binding, color shifts, suppressed bitterness, and what remains disputed. ](https://howtotea.me/science/water-and-extraction/additives)

---

## Navigation

- Parent: [Tea science](https://howtotea.me/science.md)
- Previous: [Tea leaf chemistry](https://howtotea.me/science/chemistry.md)
- Next: [Tea evaluation and tasting](https://howtotea.me/science/evaluation.md)
- Children:
  - [How the Leaf Gives Up Flavor: The Physics of Extraction](https://howtotea.me/science/water-and-extraction/extraction.md)
  - [The Chemistry of Water for Tea: Hardness, Alkalinity, Chlorine](https://howtotea.me/science/water-and-extraction/water-chemistry.md)
  - [Milk, Lemon, Sugar: What Additives Do to Tea](https://howtotea.me/science/water-and-extraction/additives.md)