How to make cold brew tea: ratios and steep times

To make cold brew tea, put loose tea or tea bags in cold, fresh water, cover the jar and leave it in the fridge for several hours, then strain. A good starting point is about 10 grams of loose tea per litre of water, steeped for 6 to 12 hours depending on the tea, and adjusted to taste from there.

That is the whole method. What follows is how to tune it: how much tea, how long, which leaves suit it, and how to keep the finished jar fresh.

Why brew tea cold

Hot water pulls flavour out of a leaf in minutes. Cold water does the same work slowly, over hours. The result is usually smoother and softer, with less of the bitter, drying edge that comes from tea brewed too hot or too long and then poured over ice. Delicate teas keep their sweetness; strong teas lose some of their grip.

It also asks almost nothing of you. No kettle, no thermometer, no timer at your elbow. You measure, you wait, you strain.

What you need

• A clean glass jar or jug with a lid, 1 litre is a useful size
• Loose-leaf tea or tea bags
• Cold, fresh water; filtered if your tap water tastes of chlorine
• A fine strainer, or a jar with a built-in filter
• A clean bottle or jug for the finished tea

Starting ratios

Treat these as starting points, not rules. Leaves vary in size and density, so weigh if you can; spoons are only a rough guide.

• Loose tea: about 10 grams per litre. That works out to 2.5 grams for a 250 ml cup.
• Tea bags: start with 4 or 5 bags per litre, since bags vary in weight.
• Large, open leaves such as many oolongs and white teas take up more room per gram, so a spoonful of them weighs less than a spoonful of small, rolled leaves.

If the first jar tastes thin, add more tea next time rather than steeping much longer. More leaf gives more body; more time mostly gives more strength and, eventually, more bitterness.

Steep times by tea

Steep in the fridge, covered. Taste at the low end of each range, then decide.

• Green tea: 6 to 8 hours. Longer can turn it grassy.
• White tea: 8 to 12 hours.
• Oolong: 8 to 12 hours.
• Black tea: 8 to 12 hours. It makes a clean, brisk base for lemon.
• Herbal infusions such as mint, rooibos or hibiscus: about 12 hours, or overnight.

An overnight steep suits most people: set the jar up after dinner and strain it with breakfast.

Step by step

• Weigh the tea and put it in the jar.
• Pour in cold water and stir once so every leaf is wet.
• Put the lid on and set the jar in the fridge.
• Steep for the time above, then taste a spoonful.
• When it tastes right, strain out all the leaves or remove the bags.
• Pour the tea into a clean bottle, cover it and keep it in the fridge.

Do not leave the leaves in once the tea is where you want it. Strained tea holds its flavour; tea left sitting on its leaves keeps changing.

Keep it cold and drink it soon

Cold brew tea is brewed with cold water, so it is never heated enough to kill anything that finds its way in. Treat it as a fresh drink:

• Steep it in the fridge, not on the counter or in the sun.
• Start with a clean jar, clean hands and a clean strainer.
• Keep the finished tea covered and refrigerated.
• Drink it within a few days; 2 to 3 days is a sensible limit for best flavour and freshness.
• If it turns cloudy in an unusual way, smells sour or tastes off, pour it away.

A note on caffeine

Cold brew tea made from the tea plant, whether green, white, oolong or black, still contains caffeine. Brewing cold changes the taste, but do not count on it to remove caffeine. If you avoid caffeine, or drink tea late in the day, choose an herbal infusion such as mint, rooibos or hibiscus, which are naturally caffeine-free, and check the label of any blend, since some mix in tea leaves.

Small adjustments worth trying

• Too weak: add more leaf next time, about 2 grams more per litre.
• Too bitter or drying: shorten the steep, or move from black to green or white.
• Flat: try a different water; a cleaner-tasting water often gives a brighter cup.
• Want a little sweetness: add sliced fruit or a few mint leaves for the last hour, or stir in a spoon of syrup after straining, since sugar dissolves poorly in cold tea.

A quick checklist

• 10 grams of tea per litre to start
• Cold water, covered jar, in the fridge
• 6 to 12 hours, tasting at the short end
• Strain, bottle, refrigerate
• Drink within 2 to 3 days
• Herbal infusions if you are avoiding caffeine

Make one jar this evening and taste it tomorrow morning. Write down what you used and how long it sat. The second jar will be better than the first, and the third will be exactly yours.