Storage and water

Tea has five enemies: light, air, moisture, heat and other smells. Green tea is unoxidized, so it turns and loses aroma faster than black tea. Assume the clock starts the moment you open the packet.

Seal it, keep it dark

Move it into a tin or an opaque airtight container. Left in a clear bag it fades in the light. Under the sink and next to the stove are both bad — heat and humidity together.

The fridge, with one rule

Good for long storage, but opening a cold container straight from the fridge condenses moisture onto the leaf. Let it come back to room temperature before opening. If that is hard to keep up in practice, room-temperature storage is the safer choice.

Keep smells away

Tea absorbs odors readily. If it goes in the fridge, double-seal it so nothing else transfers. Don't store it beside strong seasonings.

Buy less at a time

The single most effective change. Buy what you will drink in a month. Fifty grams bought monthly keeps its flavor far better than a hundred grams stretched over three months.

Matcha fades fastest

As a powder it has enormous surface area, so it oxidizes and takes up moisture quickly. Keep it sealed and refrigerated after opening and finish it within weeks. Once the color dulls, the flavor has gone with it.

Japanese tea suits soft water, and Japanese tap water is mostly soft, so it works as it comes. Hard water holds back both catechins and theanine and dulls the color of the liquor.

Use soft water

Under about 100 mg/L is the guide. In hard-water regions the tea can taste thin and look cloudy — switching to a bottled soft mineral water usually fixes it.

Boil the chlorine off

Chlorine in tap water masks the tea's aroma; a few minutes at a rolling boil reduces it. How well that works depends on how the water is treated, and a suitable filter is sometimes the surer route.

Draw it fresh

Freshly drawn water is generally recommended. Water held hot for a long time, or repeatedly re-boiled, can taste different.

Or brew it cold

Steeping in cold water for a few hours holds back the more astringent catechins, so the amino acid character comes forward. The result tastes sweet — but caffeine still extracts, so it is not caffeine-free. Works well with sencha and gyokuro in summer.