The type of water used for brewing plays an enormously important role in the final flavour, clarity and colour of the liquor. While a tea brewed in one particular water may taste dull and flat, the same tea brewed in water from a different location can be wonderfully brisk and bright. All the ingredients of an individual water play their part in the brewing process – the natural minerals, the added chemicals such as chlorine and fluoride, the amount of oxygen, etc.

To remove unwanted solubles, mains water needs to be passed through some kind of filtration system. Some filtration systems add various salts and minerals to the water and these can create different problems. The most effective types work according to a process known as “reverse osmosis”, whereby the water is passed through a membrane which forces unwanted chemicals and other deposits out of the water molecules to leave water that is approximately 99.4 per cent pure.

LuYu, China’s first tea specialist, wrote his ‘Cha Chang’ (Classic of Tea) and recommended spring water as the best for tea because of its purity, freshness and high oxygen content. The poorest water for tea is water that has stood for any length of time and has therefore become lifeless and flat.

Hard water which contains a high level of calcium is poor for most types of tea, deadening the flavour and causing a scum to form on the surface of the tea in the cup, as calcium carbonate reacts with oxygen to become calcium bicarbonate. The addition of acid to the tea helps to eliminate the bicarbonate ions, and so adding a drop or two of lemon juice prevents scum from being formed. Adding sugar to the tea also reduces the development of scum but most teas are better without sugar and so this is not recommended.

If soft water and permanently hard water (that contains calcium sulphate) are used for tea, the liquor is usually bright and clear and the flavour brisk and lively. If bottled water is used, a pH of 7 is ideal. But choose carefully since many types of bottled water contain salts and other minerals which can spoil the flavour of the tea in the same way as can some tap water.

(From The New Tea Companion by Jone Pettigrew & Bruce Richardson)