Tea and Water

We have been learning about what is in tea. There is in fact one more element, and it is the most important of all: water.

Almost all of the liquid in a cup of tea is water, and it is water’s job to draw out the savour and aroma of the leaf. It is no exaggeration to say that the quality of the water decides the fate of the taste.

The most important measure of water is hardness, determined by the amount of calcium and magnesium it contains — the more of these, the harder the water.

• Calcium binds with catechins, the astringent compounds. Brewing with hard water therefore alters the catechins, damping astringency and giving a rounder taste.
• With soft water, by contrast, the catechins change little, and you get the sharp, delicate flavour the leaf has of itself.
• Magnesium bears closely on umami and body; it is also the main constituent of nigari. Plenty of it gives a firm, rich taste; little of it gives something lighter and cleaner.

pH indicates acidity or alkalinity. pH 7 is neutral; above that is alkaline, below is acidic.

• Alkaline water makes the constituents of the leaf, catechins especially, dissolve more readily, so extraction is promoted and the taste tends to feel stronger. Most hard waters are weakly alkaline.
• Acidic water extracts poorly, and the taste can come out blurred and unsatisfying. Some bottled waters are weakly acidic, but boiling brings them closer to neutral, so there is no need to worry.

Tap water contains chlorine, which can dull the palate and spoil the aroma of tea. If you use it, always boil it off — five minutes at a boil with the lid off is effective.

Bottled mineral water is convenient and consistent. Check the hardness and pH on the label and choose to suit your preference and the type of tea.

Spring water and other natural sources: water you have collected yourself carries health risks from parasites, bacteria and chemicals, however clear it looks. Avoid it unless the local authority has declared it safe to drink, and always boil it to sterilise if you do use it.

Here is how to prepare water for good tea.

Step 1: Filtering

• The first step in removing chlorine and impurities from tap water.
• A household filter or a filter jug is convenient.
• Filters are consumables. Replace them as specified to keep the performance up.

Step 2: Boiling

Boiling serves three purposes.

• Sterilisation — safety first.
• Removing chlorine — the enemy of both taste and aroma.
• Driving off dissolved air — this lets the water penetrate into the fine structure of the leaf, and extraction efficiency rises markedly.

Incidentally, water that has been boiled and then cooled to the right temperature is said to extract better than water at the same temperature that has not been boiled. This is why: the air has been driven out.

Step 3: Temperature

Water temperature is the single most important element in designing the taste.

• Hot (90°C and above): the gap between leaf and water is large and the constituents extract all at once. Suited to drawing out the roasted character and body of black tea or hōjicha.
• Cool (70°C and below): the gap is small and extraction is slow and gentle. This brings up the umami and sweetness of sencha and gyokuro while holding astringency back.

The world of water goes deep, but the basics are these four: hardness, pH, boiling, temperature.

With that in hand, try various waters with a leaf you like. The search for your own best cup will make tea more interesting still.

When the water, the leaf and your own taste come into accord, tea stops being merely a drink and becomes an experience of its own.