Gongfu BrewingGuide
The Best Water for Tea: What Actually Changes the Cup
The best water for tea is soft, fresh and clean-tasting, with a low but not zero mineral content. For most people that means filtered tap water or a low-mineral bottled spring water. Very hard water dulls aroma, darkens the liquor and leaves a film on the surface; distilled and reverse-osmosis water have almost no minerals and make tea taste flat. Use freshly drawn water, don't reboil it, and match the temperature to the tea.
I didn't take water seriously until I moved to a flat where the tap water was noticeably harder than I was used to. My favourite Wuyi oolong suddenly tasted muddy. I blamed the tea, then the kettle, then my technique. It took a friend to suggest the obvious: brew the same tea with a bottle of soft spring water and compare. The difference was so large it was almost funny. The aroma came back, the liquor was brighter, and the mineral "rock" character I love in Wuyi tea was suddenly clear again.
Since then I've tested a lot of waters side by side, at home and at friends' places around Slovenia, where tap water varies quite a bit from town to town. This guide is what I've learned. The good news: you don't need anything exotic. You need to know what to avoid and how to test. More in the gongfu tea guide.
Why water matters so much#
A cup of tea is about 99% water. Everything you taste has been dissolved out of the leaf by that water, and what's already in the water changes how that happens.
The main factors:
- Minerals (hardness). Calcium and magnesium are what make water "hard". A small amount gives tea body and helps flavour come out. Too much binds with aroma compounds and polyphenols, and the tea turns dull.
- Bicarbonate (alkalinity). This usually travels with hardness. High alkalinity darkens the liquor, flattens brightness and encourages the scum you sometimes see on tea.
- Chlorine and off-flavours. Treated tap water can carry a chlorine smell, and old pipes can add a metallic note. Both cover delicate aromas.
- Freshness. Water that has been boiled repeatedly or has sat in the kettle all day tastes flat.
Water types compared#
| Water | How it works for tea | My verdict |
|---|---|---|
| Soft tap water (low minerals) | Clean and bright, if there's no chlorine smell | Great, often after a simple filter |
| Hard tap water | Muted aroma, darker liquor, film on the surface, scale in the kettle | Filter it or switch |
| Filtered tap water (jug or under-sink filter) | Removes chlorine and reduces hardness; big improvement from hard tap water | My everyday choice |
| Low-mineral spring water (bottled) | Usually excellent: soft, fresh, lets aroma through | The easiest fix, and my go-to for tastings |
| High-mineral mineral water | Heavy, flat or salty; aroma disappears | Avoid |
| Distilled water | No minerals at all; tea tastes flat and thin | Avoid |
| Reverse-osmosis water | Almost no minerals; same problem as distilled | Avoid unless remineralised |
| Sparkling water | Carbon dioxide and minerals, not for brewing | Avoid |
Traditional Chinese tea writing praised mountain spring water above everything else, and meltwater and rainwater were also prized. The idea behind it still holds: fresh, soft water with a little life in it.
How to read a bottled water label#
Most bottled waters in Europe list the dissolved minerals on the label, often as "dry residue" or "total dissolved solids" in mg/L. For tea, look for a low figure. As a rough guide, waters with a dry residue under about 100 mg/L usually work well, and very low-mineral spring waters are often the best of all. Waters in the several-hundreds range are the ones that dull tea. Also glance at calcium, magnesium and bicarbonate: lower is generally better for tea.
This isn't an exact science, and different teas like slightly different water. A touch more mineral content can suit dark teas and roasted oolongs; the softest waters suit green, white and delicate teas. But "low and fresh" is the right starting point.
How to tell if your water is the problem#
Signs that your water is holding your tea back:
- The tea tastes dull or muddy no matter what you change.
- There's a film or oily-looking scum on the surface of the tea as it cools.
- The liquor is darker and cloudier than it should be.
- Your kettle builds up white scale quickly.
- You can smell chlorine when you run the tap.
The definitive test is simple. Brew the same tea twice, side by side, same leaf, same temperature, same steep times, once with your tap water and once with a soft bottled spring water. If the difference surprises you, your water is the problem. I describe how to run a fair side-by-side tasting in how to taste tea.
How to fix your water#
- Try a filter jug. An activated carbon filter removes chlorine and off-flavours, and many jugs also reduce hardness. For many people this fixes most of the problem.
- Switch to low-mineral bottled water for tasting. If you only want the best result for special teas, keep a few bottles for tasting sessions.
- Consider an under-sink filter if your water is very hard and you drink a lot of tea.
- Avoid over-correcting. Don't go all the way to distilled or reverse-osmosis water. If you do use RO water, add minerals back or mix it with some tap or spring water.
- Descale your kettle regularly. Scale adds its own taste and makes the kettle less efficient.
Boiling, reboiling and temperature#
- Use fresh water. Fill the kettle with fresh water for each session rather than reboiling what's been sitting there all day.
- Don't reboil it. Repeated boiling concentrates minerals and makes water taste flat. Topping up the kettle with fresh water during a session is fine.
- Heat to the right temperature. Shou wants water just off the boil; roasted oolongs 90–95 °C and aged sheng 90–98 °C. Green and white teas want it cooler. My gongfu brewing chart lists the temperature for every tea.
- No temperature-control kettle? Let boiled water sit with the lid open: about 2–3 minutes gets you to roughly 85 °C. For 75–80 °C, wait closer to 10 minutes, or pour the water into a pitcher first to drop it faster. A kettle with temperature settings makes this much easier; I compare a few in best kettle for tea.
Which water for which tea#
| Tea | Water that suits it |
|---|---|
| Green, yellow and bud white tea | The softest water you have; hard water flattens them fastest |
| Light oolongs and Dan Cong | Soft water; aroma is everything here |
| Wuyi rock oolongs | Soft to medium; too hard and the "rock" character turns muddy |
| Red tea | Forgiving; filtered tap water is usually fine |
| Pu-erh (sheng and shou) and dark teas | Forgiving, and can take slightly more minerals; still avoid very hard water |
If your tap water is hard and you only change one thing, filter it for green, white and aromatic oolongs first. Those are the teas that suffer most. See also my guides to Wuyi rock tea, white tea and brewing pu-erh.
Read next: gongfu vs Western brewing and the best gaiwan for beginners.
Questions people ask
What is the best water for tea?
Soft, fresh water with low mineral content: filtered tap water or a low-mineral spring water. Avoid very hard water, distilled water and reverse-osmosis water.
Is filtered water better for tea?
Usually, yes. A filter removes chlorine and off-flavours, and many filters also reduce hardness. If your tap water is hard, filtering it is the simplest improvement you can make.
Can I use distilled water for tea?
It's not a good idea. Distilled water has no minerals, and tea brewed with it tastes flat and thin. A small amount of minerals helps bring out flavour and body.
Why does my tea have a film on top?
That film usually comes from hard water: calcium and bicarbonate react with compounds in the tea. Filtered or softer water reduces or removes it.
Is it bad to reboil water for tea?
It's best avoided: reboiled water, especially water boiled many times or left standing all day, tastes flat. Use freshly drawn water for each session.
Does bottled spring water make better tea?
A low-mineral spring water often does, especially for green tea and aromatic oolongs. High-mineral waters make tea worse, so check the label before you buy.
What water temperature should I use for tea?
It depends on the tea: just off the boil for shou; 90–95 °C for roasted oolongs and up to 98 °C for aged sheng; around 90–95 °C for red tea; cooler for green and delicate teas. See the gongfu brewing chart for every tea.