Water and Oxygen and Tea

Water and oxygen and tea are like this super triumvirate. Combined, they do much more than when separate. Combined the right way and they guarantee a wonderful tea experience. Let’s look at each in turn.


A lot has been written about the quality of water as related to your tea. A big issue is the amount of calcium (contained in such minerals as dolomite, calcite and gypsum) and magnesium (most often found in dolomite) in that water, and those amounts vary based on the source of water such as an aquifer. The calcium and magnesium ions are usually charged (fairly active). Hard water full of these minerals can make your tea taste one way, and soft water with low levels of these minerals produces another tea taste. This can be so important that some tea companies actually blend their teas for different parts of the world.


Where would the human race be without oxygen? Indeed, where would most animals be without it? We go around sucking up oxygen and expelling carbon dioxide. The plant life sucks up that carbon dioxide and expels oxygen. It’s a well-developed symbiotic system.

Oxygen is one of those things needed in the right quantity. Too much causes metals to rust and humans to show signs of premature aging, for example. Too little can lead to expiration on a permanent basis. Fire and water are the same way.

In water, oxygen levels, especially when making tea, are a subject of much concern. For centuries, tea sages have advised about this. They caution against using water that has sat awhile or that has been boiled and then has cooled and so has to be re-boiled. My knowledge of the chemistry of the world around us is fairly basic, but this old adage doesn’t quite make sense to me. So, I did a bit of research about it. It seems to be one of those old sayings without any merit. The main concern is that the re-boiling process will reduce the amount of oxygen in the water. However, since boiling water does not change the amount of oxygen in it, this concern has no basis in scientific fact.

What you should be concerned about are those aforementioned minerals since boiling does produce steam which is water molecules so there are fewer of these molecules in the kettle. The minerals do not go up and out with the steam, so the water gets a higher concentration of them each time the water is boiled and more steam (that is, water molecules) go up and out of the kettle.


This higher concentration of minerals due either to using hard water or to re-boiling can make your tea taste more metallic due to an increased concentration of those minerals. A strong Assam or smoky Lapsang Souchong will not be affected, but a delicately flavored Dragon Well or Sencha or Darjeeling will be.

Also, go for one of those blends designed for your type of water, hard or soft. Your tastebuds will thank you!

© 2017-2021 World Is a Tea Party photos and text


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3 thoughts on “Water and Oxygen and Tea”

  1. Excellent article. I’m glad to see someone else agree with me that I’m not ruining everything by reboiling water. I’m not using water that’s been sitting out all night, but I reboil a few times when I’m gongfu-ing oolong or pu-erh. I’ve never tasted a difference between reboiled and fresh water. It’s so nice to see common sense prevail!


    1. You’re welcome! Common sense is my byword. When writing about tea I’ve always taken that approach. 🙂


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