You can buy the best Pu'er in the world, measure it to the nearest gram, time each infusion, and still end up with a disappointing tea. Because the water was bad. Water is the invisible ingredient in tea, the one most often forgotten, and the one that makes the biggest difference. The Chinese have known this since the 8th century: Lu Yu, in his Cha Jing, dedicates an entire chapter to it.
What Lu Yu said about it
The Cha Jing (茶經), the Classic of Tea, written by Lu Yu in the 8th century, is the oldest known treatise on tea. In it, Lu Yu classifies waters by order of quality. The best, according to him, is spring water flowing slowly over granite – a naturally soft water, balanced in minerals, which does not mask the flavors of the tea but carries them. River water comes next, then well water last, often too rich in minerals to make good tea.
Thirteen centuries later, chemistry confirms his intuition. What Lu Yu called "light" and "pure" water, we call weakly mineralized water, with a moderate total dissolved solids (TDS) level. This type of water gives the best results with tea, and particularly with Pu'er, whose high-altitude terroirs produce leaves of a delicacy that deserves to be respected.
Hard water, soft water: what it changes
The "hardness" of water refers to its calcium and magnesium content. The more these minerals are present, the "harder" the water is – this hardness is what leaves a white deposit in your kettle. And it is this that, in the cup, masks the fine aromas of the tea, gives a cloudy liquor and sometimes a greasy film on the surface.
With hard water, a Pu'er loses its delicacy. The subtle notes – the floral notes of a young sheng, the crystalline sweetness of a Bingdao, the freshness of a tea from ancient trees – are muffled by the minerals. The liquor appears flat, heavy, without relief. It's not the tea that's bad – it's the water that betrays it.
Conversely, water that is too soft, completely demineralized, like some rainwater, produces a bland and unstructured tea. Tea polyphenols need a minimum of minerals to express themselves fully. The right balance is slightly mineralized water, neither too hard nor too soft: between 50 and 100 mg/L of dry residue is a good range.
Which water to choose, practically
Spring water
This is the first choice. Weakly mineralized spring water (such as Mont d'Auvergne, Montcalm, Volvic, Mont Roucous, or local equivalent) gives excellent results with Pu'er. Look for a dry residue of less than 120 mg/L on the label: the lower it is, the more the water will allow the tea to express itself.
Filtered water
If your tap water is hard (which is the case in many French regions), an activated carbon filter (such as Brita or equivalent) significantly improves the situation. It reduces chlorine, limescale, and impurities. It's not perfect, but it's a good everyday compromise. More complex filters, to be installed on the main water supply of the house, are ideal: often more complex to install and more costly, they can be cost-effective in the long run.
Tap water
It all depends on where you live. In some regions, tap water is naturally soft and makes perfectly acceptable tea. In others, it is so hard that it ruins any tea. If your kettle gets covered in limescale in a few days, your tea suffers too.
Mineral water
Avoid for tea. Mineral waters (like Hépar, Contrex, Vittel) are too rich in minerals for Pu'er to express itself. They are suitable for hydration, not for infusion.
Temperature: boiling or almost
Pu'er is a robust tea that loves heat. Unlike Japanese green tea, which can become bitter at high temperatures, Pu'er tolerates and even demands very hot water. It is the heat that opens the compressed leaves, releases the deep aromas, and reveals the density of the liquor. The different forms of Pu'er compression also require slightly different heat levels to fully open.
| Type of Pu'er | Temperature | Why |
|---|---|---|
| Fermented Pu'er (shou) | 100 °C | Full boil, without hesitation. Heat reveals roundness and woody notes. |
| Young raw Pu'er (sheng) | 90–95 °C | Slightly below boiling, to preserve subtlety without awakening bitterness. |
| Aged raw Pu'er (sheng) | 95–100 °C | Tannins have softened with age — full heat reveals depth without risk. |
Lu Yu observed the bubbles in the water to determine the temperature: bubbles like "crab's eyes" (small, numerous) indicated 70–80 °C; bubbles like "fish's eyes" (larger, fewer) announced boiling was near. A thermometer does the same job, but the imagery is more beautiful.
Do not reheat, do not reboil
A final, often overlooked point: water should only be boiled once. Each boil removes some dissolved oxygen from the water, and it is this oxygen that contributes to the liveliness and freshness of the tea in the cup. Water reboiled multiple times produces a flat, dull, lifeless tea. Lu Yu already noted this: he recommended never using water that had boiled for too long.
Ideally, fill your kettle with fresh water for each tea session. It's a small gesture that makes a real difference, and it's also one of the first reflexes taught in the practice of Gongfu Cha.
The essential
If you only remember three things: choose low-mineralized water (spring or filtered), bring it to the right temperature according to your Pu'er (boiling for fermented, just below for young raw), and boil it only once. These three simple rules will change your cup more than any accessory. And if you're looking to adapt your tea to the seasons, our article on Pu'er through the seasons complements this reading.
Frequently asked questions
Can Pu'er be steeped with tap water?
Yes, but the result will be different. Tap water often contains chlorine, limescale, and minerals that flatten the nuances of the tea. An activated carbon filter significantly improves things. To discover what your Pu'er truly has to offer, weakly mineralized spring water remains the safest choice. And if you live in the mountains or near a spring, you might be lucky enough to already have very good tap water.
What is the ideal temperature for Pu'er?
For fermented Pu'er or aged raw Pu'er, boiling water (100 °C) gives the best results: these teas need heat to release their depth. For young raw Pu'er, dropping slightly to 90-95 °C avoids exacerbating bitterness and preserves the freshness of the aromas.
Should bottled mineral water be used?
Not just any kind. Highly mineralized water (beyond 300 mg/L of dry residue) makes the liquor heavy. Choose weakly mineralized spring water, with a dry residue of around 50 to 150 mg/L: this is the best compromise between neutrality and mineral presence.
