What water to use for brewing?
We’ve all had bad experiences with tea before. Often, the problem was the tea being too old or not the quality we were used to. Sometimes, the water was too hot or the steeping period too long. Maybe the use of a small tea bag made the tea unable to uncurl fully. Sometimes the water was to blame.
It is not ease to define ‘wrong water’, as the ‘ideal’ water depends on the tea you are making and your taste.
A typical answer that, while maybe correct, isn't very useful in specific situations, is given by Chinese tea scholar Lu Yu. He wrote a famous book about which water is best for tea. In the book he claims that mountain water from stony lakes, the middle of slow-flowing streams, or milky-white springs is what you’re looking for when brewing tea.
So let’s forget about finding the perfect water and just give some practical suggestions:
Mont Calm (France)
Personally we filter our tap water making it similar to the spring water above. Main advantage of this method if the cost these filters only need to be replaced each couple off years. As with Spring water this water is essential for Japanese teas while good for all other kinds as well.
There are a lot of different opinions on this matter: some say the water obtained by filtering with a osmosis system is an improved version of the spring water, others say this water loses a lot of its essence and isn't good for making tea. Just taste for yourself and find out, We would Recommend.
Some people prefer high mineral water saying it gives there tea a fuller, more robust flavour. The ones that disagree say the tea loses some of its subtlety and aroma. In my opinion this kind of water is in general not so good with subtle green or white teas but go well with stronger black or oolong teas.