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Link between Water Hardness and the Taste of Tea

Link between Water Hardness and the Taste of Tea

Sachiko Murata |

Have you ever had the experience that the Japanese tea you made at home tastes different from the product description or people's reviews although you steeped it properly? 

This article might give you an answer to you. Although you haven't had such an experience, I'd like to share my interesting experience I had this summer.


What Shocked Me During My Holiday in Europe 

I took some of my favorite Japanese green tea with me on my holiday in the UK this summer. One day I made a cup of tea with the tea leaves, then, I was shocked at the taste, which was very different from the taste in Japan. It tasted less astringent and some funny aftertaste."Why did it happen although I steeped it in the same way as I did at home?"

I suddenly remembered the first day drinking the tap water there.The taste of water was very different from my place in Japan.The taste was like water with Nigari, I sometimes make and drink at home in Japan. Nigari is the liquid that is left after salt has been precipitated from seawater, and contains lots of minerals such as magnesium, potassium and calcium. 

Read more about Nigari here

The water there must've contained lots of minerals. In other words, the water hardness must be quite high. That's why I thought the water hardness affected the taste of the tea.


What’s Water Hardness   



The simple definition of water hardness is the amount of dissolved calcium and magnesium in the water. General guidelines for classification of waters by WHO (World Health Organization)  are: 0 to 60 mg/L (milligrams per liter) as calcium and magnesium is classified as soft; 61 to 120 mg/L as moderately hard; 121 to 180 mg/L as hard; and more than 180 mg/L as very hard.

Water hardness in Japan is lower than other countries, as the tap water is mainly derived from river water ,while most European nation’s tap water comes from groundwater, and river water tends to flow rapidly down because the rivers in Japan are steeper and shorter than other countries. 

Let's see the tap water hardness of the area, Odawara, Kanagawa, Kanto district where I live. The hardness is 51mg/L, which is classified as soft water.  Most of the places of water hardness in Japan are between 20mg/L and 80mg/L,  and the average hardness is 48.9mg/L. Kanto district tends to be higher, comparing to Hokkaido and Tohoku district. 

How about the water hardness of the area I stayed in the UK? It's over 201mg, obvious hard water. The UK tends to be a hard water area although north part of the UK is mainly a soft water area. Europe is considered to be a hard water area although there are pockets of soft water areas.  


How Water Hardness Affects Japanese Green Tea



Generally, soft water is said to be good for making tea.

As well as other types of tea, Japanese green tea is also good to make with water hardness between 30mg/L to 80mg/L. Japanese green tea is the balance of sweetness, umami savoriness, bitterness and astringency. Soft water allows the delicate flavors.

On the other hand, hard water flattens the taste, and make the color of the tea pale.  


How to Get Soft Water in Your Place

So, what can you do if you live in a hard water area?

First, try boiling your tap water before using it although most of Japanese green tea doesn't need such a high temperature for steeping. Temporary hardness can be removed by boiling, but you can’t be eliminated if your water has permanent hardness contains irons. Then, it might be time to think about buying a water softener. Buying a bottle of water is an easy option. Check the water hardness on the label before buying it. Bottle of water for babies is normally soft water. 


Is Hard Water Really No Good For Making Green Tea? 

Though, I’ve told you how to get soft water, I’m still wondering if hard water is really bad for making Japanese green tea. Some people say they like having Japanese green tea with hard water as it tastes mild and less astringent. There is also a report that people tasted umami savoriness more with the green tea steeped with the water (water hardness 304mg/L), than the green tea steeped with the water (water hardness 38mg/L).

It doesn't seem to be so simple we can say hard water is no good for making tea.


Let’s Enjoy Steeping Experiences !



Although it can't be said unconditionally that soft water is good for making Japanese green tea, we see water hardness effects the taste of tea. It would be a good try to make your favorite tea with different water. 

Let's experiment with different water to find a taste we enjoy!





    1. Mayumi Hori, Katsumi Shozugawa, Kenji Sugimori, Yuichiro Watanabe 2021 “A survey of monitoring tap water hardness in Japan and its distribution patterns” Retrieved from:http://www.nature.com/articles/s41598-021-92949-8

    2. Aqua Cure Ltd. How hard is my water. Retrieved from https://www.aquacure.co.uk/knowledge-base/uk-hard-water-map/

    3. 内山裕美子, 築舘香澄, 加藤みゆき,山口優一, 陳栄剛, 大森正司, 2014.『茶の呈味におよぼす水質(特にCa)の影響と味認識装置による評価』日本調理科学会誌Retrived  from:https://www.jstage.jst.go.jp/article/cookeryscience/47/6/47_320/_article/-char/ja/




    Other Articles: 

    Do you know how to steep Japanese green tea properly?

    Japanese Tea Steeping Techniques


    How many types of Japanese tea do you know? 

    More than 15 types of teas are here.

    List of Japanese Teas & Terminology 




    Thank you for the interesting information.I hope you could have a cup of green tea with soft water in Japan.

    Yunomi Staff,

    In my place, green tea tastes like black tea. I experience only two flavors bitter and sour. That’s probably why concentrated fruit juices and strong teas are popular in Europe.


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