A closer look at water for tea

The quality of the water you use is as important as the quality of your tea.

In eighth-century Tang Dynasty China, Lu Yu wrote in the “Cha Jing”, or “Classic of Tea”, that the best water for brewing tea came from the center of a swiftly moving mountain stream.

While Yu likely knew that good-quality water needed no purification or enhancement, he understood that many reading his book would not have access to the best water, and also wrote the following – “During the first boil, add a measure of salt appropriate to the amount of water to harmonize the flavor.” He believed that salt would neutralize any flavors or aromas present in the water and allow the flavor of the tea to shine through.

One could say this was the first known attempt at controlling tea water to elicit the desired outcome in flavor. Given that few of us have access to clean, fresh mountain water for tea today, we most likely have to modify our water to make it more suitable for brewing tea. Before that, let’s take a look at what the best tea water is.


Tea is 98.5% water

Much alike brewing coffee, it’s fairly well known that when preparing tea, the most important consideration outside of tea leaf quality is the choice of water. Good-quality water can elevate bad tea into something palatable, whereas poor-quality water can make good tea undrinkable.

Many tea shops boasting custom water systems hear from customers how much better the tea tastes when prepared at the shop, as opposed to when customers brew the same tea at home. Sometimes this can be attributed to incorrectly followed brewing instructions regarding tea-to-water ratios, water temperature, or steeping time. However, the most common reason for inferior tea at home is a result of the water quality.

While advice varies for tea from person to tea person, the general argument all comes down to what’s in your water besides water. That includes minerals endemic to a water supply, additives like chlorine, and also contaminants. For instance, too many minerals and your water is “hard”, which can add funky metallic flavors to tea. Absolutely pure water like distilled water is no good either; it’s so bland it can make tea taste flat and dull.

Here’s a general rule of thumb: If you wouldn’t drink your tap water as water, you probably wouldn’t want to drink it as tea.


The chemical compositions of water for tea – pH, TDS, hardness

According to the Tea Association of the USA, this is the ideal tea water analysis:

  • 6 – 8 pH
  • 50 – 150 ppm TDS (Total Dissolved Solids)
  • 80 ppm total hardness
  • No chlorine, iron, and magnesium

Three major factors must be considered when looking at what makes good water for preparing tea: the pH level, TDS, and water hardness.

The pH scale ranges from 1 to 14 and defines acidity or alkalinity of the water. Ideally, the more neutral the water, the better. A pH of 7 is neutral, although anywhere between a slightly acidic pH of 6 to a slightly alkaline pH of 8 is considered acceptable.

Water for tea should have a neutral pH so it doesn’t turn the tea sour or bitter. And it should be freshly boiled, as water that’s been boiled again and again can absorb off flavors from the air around it.

TDS measures not only the total quantity of minerals present in water, but also the amounts of metals, salts, or any other impurities that may have been dissolved.

Within the range, 150 ppm is the ideal amount of TDS in water for tea, containing a mixture of calcium, potassium, and sodium to meet the suggested measurement. Unlike coffee, no magnesium is added, as it makes tea taste over-extracted and metallic in flavor.

Water hardness makes up part of TDS, but should not to be confused as being the same measurement. Water hardness describes the amount of calcium and magnesium in water. Tea tastes best when the water hardness is between 17 – 68 ppm. Too high (over 120 ppm), and the tea tastes flat and lacks flavor. At this level of hardness, the brew clouds over and an oily film forms on the water’s surface. When water hardness is too low (below 10 ppm), tea becomes bitter and astringent.

Besides these requirements, another aspect paramount to brewing good tea comes down to the temperature of the water. While the pH, TDS, and also hardness ranges stated above applies to water required for brewing all types of tea, the temperature varies greatly from one variety of tea to another.


Different tea varieties and brewing temperatures

All tea comes from the same plant – Camellia sinensis. It is how it’s grown, harvested, and crafted that produces the different tea types.

For instance, some types of teas are fermented and oxidized, while others are not. To ferment tea, leaves need to wither or be bruised by hand. This process allows enzymes on the leaves to interact with the air, oxidize, and change the chemical compound and color of the leaves. The tea flavor can change greatly depending on temperature, humidity, and other air conditions. Heat treatments, like pan-firing or steaming, will stop the oxidation process.

These following teas are the most common types consumed globally. There are many varieties of each kind, and it’s common for other flavors to be blended with these varieties.

This chart will guide you through the water temperature, amount of tea to use, and the length of the brewing time – all of which depends on the type of tea. It’s important to stick to steeping times to prevent tea from becoming bitter. If you want a stronger tea, use more leaves instead of longer steeping time.

Type of teaTeaspoon/ cupWater temperatureSteeping time
White tea1 - 2 tsp175 F (70 - 80ºC)4 - 5 mins
Green tea1 - 1.5 tsp160 - 180 F (70 - 80ºC)1 - 3 mins
Oolong tea1 - 2 tsp195 F (90ºC)3 mins
Black tea1 - 1.5 tsp195 - 212 F (90 - 100ºC)2 - 4 mins
Herbal tea1 - 2 tsp212 F (100ºC)4 - 6 mins

White tea

White tea varieties are the least processed of all teas. The leaves are simply left to wither and dry on their own, which gives them a very delicate, naturally sweet, and well-rounded flavor. It has very little caffeine while retains the highest levels of antioxidants.

Flavor profile: naturally sweet, delicate taste with a balance of floral and fruity undertones.

Most people agree that white tea should be brewed with water that is well below boiling and that higher temperatures will scald the tea.


Green tea

Green tea is unoxidized as the Camellia sinensis leaves are picked, dried, and heat-treated at high temperatures to prevent oxidation. Chinese people often pan-fire leaves, which creates a duller green color, while Japanese people will typically steam them and achieve a brighter green shade.

Flavor profile: milder flavor than black tea; can have a citrus-like, vegetal, sweet, or smoky flavor depending on variety.

It’s better to err on the side of lower temperatures with green teas. Most green teas are best when brewed well below boiling temp, at somewhere between 160 F and 180 F. Steamed Japanese green teas tend to require lower temperatures than other green teas.


Oolong tea

Oolong, or wulong, lies artfully between green and black tea, being partially oxidized. The leaves are bruised by being tossed or shaken in baskets, which changes the oxidation process. They’re heat-treated to stop the oxidation, which can vary based on region and create different flavors. The lighter are green and fruity whereas the darker are roasted and nutty.

Flavor profile: can taste flowery, naturally sweet, fruity, or smoky.

The best temperature for brewing oolong tea depends on how you’re preparing it. Gong fu brewing usually requires higher brew temperatures (as well as more leaves and very short brew times) compared to Western-style brewing, between 190 F to 200 F.


Black tea

Black tea is one of the most common tea types and is fully oxidized to bring out the deepest flavors. The leaves of the Camellia sinensis plant are withered, rolled, oxidized, and dried or fired to produce a strong, full-bodied flavor. Assam, Darjeeling, Nilgiri, and Sri Lanka are a few well-known black tea producing regions, and the flavor will vary based on the region and type of black tea.

Flavor profile: strong, bold, full-bodied flavor that can be bitter, sweet, vegetal, fruity, or spicy depending on the variety.

Some delicate black teas (like First Flush Darjeelings) require lower brewing temperatures of around 180 F to 190 F. However, most black teas can be brewed between 195 F and 212 F.


Herbal teas

Herbal tea doesn’t come from tea leaves like other varieties; it is made from dried herbs, fruits, and flowers, which can create a wide range of delicate flavors. These tea types are caffeine-free, making them ideal for customers with dietary restrictions. Common ingredients for herbal infusions include chamomile, ginger, lemongrass, peppermint, rosehips, hibiscus, and dried fruits.

Flavor Profile: often has a delicate flavor that can be vegetal, naturally sweet, citrus-like, floral, minty, or spicy depending on the variety and blend of ingredients.

As herbal teas come from many different plants, their brewing instructions can vary widely. A few (like catnip and yerba mate) should not be steeped in water that is fully boiling. Others (like fennel seed) should be boiled to release their full flavor. However, generally speaking, water at a full boil (212 F) will work.

In general, there is much debate over how to brew tea and what the best water temperature or even chemical breakdown is for each specific type of tea. Ultimately, it also boils down to personal taste and the specifics of how each individual brews – including factors like whether you pre-warm your teapot and what ratio of water to leaves you use.

At the moment, we are just starting to explore how each water characteristic affects tea. Hopefully in the coming years, this knowledge can be broadened and further disseminated, raising water quality for every cup of tea.

By Mitte Team — Feb 27, 2019
The information contained in this article is provided for educational and informational purposes only, and should not be construed as health or nutritional advice.

Recent articles

WaterMay 28, 2020
How to Pair Mineral Water With Wine

In wine pairing, mineral water can play an underestimated role in enriching the sensory experience. Just like wine, each mineral water has its own flavour profile and taste, thanks to its own particular source, unique origin and circumstances that developed its flavour. And while the taste might be more understated compared to wine, pairing the

Mitte NewsMay 22, 2020
11 Quickfire Qs With Our C-Level

[From left to right] Jan (CTO), Karan (CMO), Johannes (COO), Moritz (CEO). C-suite, senior execs, leaders – otherwise known as Mitte’s Moritz, Johannes, Karan and Jan.  Whatever you’d call a company’s C-level, there’s often an air of curiosity that surrounds those who lead a company. In Mitte’s case, our C-level are those who have developed