There are many variables that contribute to the flavor of tea in your cup, but one of the most commonly overlooked is the quality of water. As brewed tea is made up of nearly 99% water, this primary ingredient definitely deserves some consideration.

In the oldest known book on the topic of tea, famed writer Lu Yu was already commenting on the quality of different water sources, noting that the best came from mountain springs, but the center of a flowing river was also an adequate source. Well water, he said, was of the lowest quality. Today, while tea aficionados rarely gather their own water from these natural sources, the debate still rages. Is tap water sufficient, or should it be filtered? Which brand of bottled water has the best flavor? How does “pure” distilled water stack up?

How Does Water Affect Flavor?

To get to the heart of these impassioned debates, it is important to define what variables make up the flavor of the water itself. Specific metrics like pH and TDS (Total Dissolved Solids) that measure minute mineral content are usually generalized into two tastable categories: hard water and soft water.

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Hard water typically has a high pH level and high levels of dissolved solids, or minerals. To be more specific, “hardness” refers to levels of calcium and magnesium in the water, which can cause notable changes in flavor and white, crusty residue on the inside of your kettle. If your tea tastes sharp or metallic, hard water may be to blame.

Soft water, on the other hand, is low in minerals and in pH levels. Particularly hard water is sometimes processed with a water softener, which removes calcium and magnesium and replaces them with sodium ions to avoid residue buildup in pipes. These processed (or "softened") waters often brew some of the worst tea, with flavors that are either flat or notably tainted with chemicals. Distillation and reverse osmosis are more natural processes used to remove excess mineral content, but the resulting purity still usually results in flat-tasting tea.

How to Improve Your Water

In San Francisco, we are fortunate to be supplied with high quality tap water that we have found perfectly adequate for all our years of brewing tea - but we know that not everyone is so lucky. If your water quality is not ideal, you have a few options.

1. Filter your water

Use a countertop filter to filter out chlorine, calcium, and magnesium from hard water, if you find your tea is tasting metallic or sharp. Many of our neighbors across the bay use simple Brita filters, or invest in more robust charcoal filtration systems. For a rustic version, simply boil your water with chunks of bamboo charcoal.

2. Add minerals

If your water is so pure that your tea is tasting flat, you might try adding a small amount of salt to the kettle. Boiling your water with bamboo charcoal or other  sources of selected minerals can also improve a flat flavor.

3. Find another source

Sometimes the water available to you is beyond help - tainted with chemicals, or so mineral-rich that it tastes hard even after filtration. Though we hesitate to recommend bottled waters due to the environmental impact of the required plastic and packaging, the variety between different brands does offer plenty of opportunity for experimentation and testing. Some tea drinkers swear by the flavor results from their favorite bottled waters, so it may be just what you need to take your tea to the next level.

The Perfect Pairing

In the end, though, there’s not one single water that will produce the best flavor from all teas. Just like every other aspect of brewing, quality comes down to a balanced pairing. One anecdote from Japan tells about the popularity of Fukushima Sencha, a tea of relatively low quality that became well known due to the way it improved the flavor of poor water in Tokyo. Though neither the tea nor the water was prized for flavor, the combination of the two achieved a balance that became famous worldwide.

In addition to his hierarchy of water sources, Lu Yu also commented: "The water that is from the same region as the tea will be its best fit." While we don’t suggest sourcing your water from China, we do recommend experimenting to find the best water for your favorite tea, and for your palate! In general, we find darker or roasted teas are often complimented by mineral-rich water, while lighter teas shine most when brewed with neutral-tasting water.

Do you take your water straight from the tap, filter it yourself, or buy bottled waters to brew your tea? Have you experimented with different sources? Tell us about your experience in the comments below!

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