Tea is ~99% water so there is no doubt that the quality of that water will make a difference to the flavours of the cup.
Tap water here is very “hard” so it leaves limescale on teapots and kettles and doesn’t taste great. Buying water is a complicated business though. Bottled Water is so heavily marketed it is difficult to disregard the branding and get a true comparison of the products. Here is a breakdown of the main types of water that are found here in Ireland:
- Public mains water – goes through a set of treatment process before it is distributed to ensure that it is filtered and sterilised and fit for drinking. The main stages in water treatment are screening, flocculation, sedimentation (clarification), filtration, chlorination, fluoridation and pH adjustment. Chlorine is added to kill bacteria and afterwards ammonia is sometimes added to the water to reduce the taste left by the chlorine. Fluoride is also added to prevent tooth decay.
- Filtered water – Filtering tap water with a simple jug filters will remove visible solids and most of the chlorine. They will improve the taste but it will not remove fluoride or change the mineral content significantly and so it will not soften the water.
- Purified/distilled water –Water that has been produced by a process such as distillation, deionization, reverse osmosis or other process. It will have no minerals.
- Spring water – Comes from underground source but naturally flows on the earth’s surface. It is naturally filtrated by passing through layers of rocks and soil. Spring water may be treated by ozonation, UV light and chlorination and unlike mineral water does not need to have a stable composition.
- Natural mineral water – Natural mineral water come from natural mineral water springs and contains at least 240 parts per million Total Dissolved Solids (TDS). Natural mineral waters are pure at source and are distinguished from other types of bottled water by its constant level of minerals. It originates from a protected underground water source. No minerals or chemical preservatives may be added to the water.
Tasting water and matching it with food is a whole other world (see Bottled Water of the World). There is a range of factors that are considered in the taste of water but the mineral composition and the acidity level (pH) are two of the main factors for still water. Acidic waters have a pH of less than 7 and alkaline water have a pH greater than 7. Alkaline water tends to taste sweeter and softer than neutral or acidic water. The Total Dissolved Solids (TDS) is the sum total of all the mineral in the water (most commonly Calcium, Magnesium, Sodium and Potassium). These minerals give water a heaviness and it correlates with the hardness of the water.
Below is an interesting graph of pH and TDS plotted for the main water brands (source).
For tea making, we are looking for water that is not too mineralised and doesn’t have any dominant mineral that stands out. Distilled water (that has no minerals) is not good either because it is too flat. Ideally tea water would be neutral pH 6-8, have no chlorine and have total dissolved solids (TDS) of ~100ppm.
Still confused about what’s what with water? Interestingly, there are some good explanations in Bret Easton Ellis’s book “American Psycho” (excerpt here)!