How water affects your tea infusion

After all, tea is a “natural drink”; it is but a mixing of water with tea leaves. Often overlooked and probably the single most important factor in bringing out the best taste from speciality teas is water.

You may have noticed changes in taste when you infuse the same tea in water from two different locations. Here we look at two important factors in choosing the right water for infusing delicate teas.

1. Mineral content

The amount of dissolved solids can have an effect on the tea's taste. In more technical terms, this is defined as total dissolved solids (TDS). TDS can create a negative taste in the water such as a bitter or salty taste, residue, films or precipitates.

Perhaps the most relevant TDS compounds for tea are calcium and magnesium salts. Water with high concentration of these compounds are known as hard water. Teas made with hard water (i.e. high concentrations of calcium and magnesium salts) have an off-taste; which precipitates around the ring of the cup, and most will impact the flavour compounds of the tea in the brew.

Note: there are two types of hard water - temporary and permanent hard water. Calcium and magnesium carbonate containing water are called temporary because these are removed on boiling. In comparison, calcium and magnesium sulphates form permanent hard water and require active filtration to remove. 

For best results, one should choose a water that does not contains too much calcium and magnesium salts - often referred to as soft water.

2. Aeration

Water contains molecules of dissolved oxygen and a high concentration of dissolved oxygen makes water taste “crisp”. On the other hand, low levels of oxygen makes water taste “dull”. Boiling water repeated will cause dissolved oxygen to evaporate off and the water will become increasingly “dull”. Therefore, take care not to repeatedly boil the water used for making an infusion.