How long should black tea cold-brew?

Between eight and twelve hours in the refrigerator, with overnight being easiest. Strain the leaves once it reaches the strength you like, as leaving them longer slowly turns the brew woody.

Does cold-brew tea have less caffeine?

Usually somewhat less than a hard hot steep, because the cool, slow extraction is gentler, but it still contains caffeine. Using more leaf raises it again.

Can you cold-brew the same leaves twice?

You can, but the second batch will be markedly weaker. Cold brewing is thorough, so most of the flavour is already gone after the first long steep.

August 19, 2026

How to Cold-Brew Black Tea

Cold brew is the least demanding way to make black tea, and quietly one of the most forgiving. There is no kettle to watch, no timer that turns a good cup bitter the moment you glance away. You put leaf and cold water together, walk off for the better part of a day, and come back to something smooth, round, and almost sweet.

Why cold water changes everything

Heat is a blunt instrument. Boiling water pulls flavour from tea in minutes, but it pulls the harsh things too, the astringent tannins and the bitterness that hot brewing must always race against. Cold water works slowly and selectively. Over several hours it coaxes out aroma, sweetness, and body while leaving much of the grippy tannin behind. The result is a cup that tastes cleaner and less bitter, with none of the metallic edge that hot tea can develop as it cools. It is also, as a happy side effect, gentler on caffeine: the slow, cool extraction tends to draw less than a hard hot steep, though it is never caffeine-free. If bitterness is your usual complaint, cold brew sidesteps the whole problem that our note on why tea turns bitter describes.

The method, start to finish

You need only leaf, cold filtered water, and a jar.

Ratio. Use a little more leaf than you would for hot tea, because cold water is a lazier solvent. A good starting point is one heaped teaspoon of whole-leaf black tea per cup of water, or roughly ten grams per litre. Adjust to taste next time.
Combine. Add the leaves to cold, fresh water in a jar or bottle. Loose leaf can go straight in; you will strain it later.
Wait. Refrigerate for eight to twelve hours. Overnight is the classic move: set it going before bed and it is ready with breakfast.
Strain. Pour through a fine sieve or lift out your infuser. Do not leave the leaves in much longer than twelve hours, or the brew slowly turns woody.

Because cold water is so gentle, the timing is loose. An extra hour will not ruin it the way an extra minute ruins a hot cup. If your first batch is too light, add more leaf next time rather than more hours.

A few small choices shape the result. Fresh cold water from the tap, or filtered water if yours is hard, gives the cleanest base, since cold brewing has none of the heat that can mask off-notes. A wide jar lets the leaves settle and drift, which extracts more evenly than a narrow bottle packed tight. And a lid matters more than you would think: an open jar in the fridge will take on the smell of everything around it over twelve hours, so cover it from the start.

Choose a leaf worth the wait

Cold brew flatters good tea and exposes poor tea. Since nothing is hidden behind heat and tannin, the quality of the leaf comes through plainly. Whole-leaf black tea is ideal; dusty broken grades can turn muddy and over-extract even in cold water. A top-grade low-grown Ceylon like our Black Gold cold-brews beautifully, its cold-pressed bergamot and neroli reading as bright citrus over a smooth, honeyed base. If you are new to buying leaf this way, how to choose loose-leaf tea and whole leaf versus broken tea are useful primers.

Cold brew and iced Persian tea

Cold brew is a natural cousin of iced Persian tea, though the two are made differently. Traditional iced Persian tea usually starts from a hot, strong dam that is then poured over ice, keeping that characteristic depth and briskness. Cold brew arrives at a softer, rounder profile by another road entirely. Both belong to the same summer table, and both sit within the broader tradition set out in our Persian tea guide. If you want the concentrated-then-diluted approach for a crowd, a proper tea concentrate gives you more control over strength than cold brew alone.

Serving, sweetening, and keeping

Serve cold brew over plenty of ice, unadorned or with a twist of lemon, a sprig of mint, or a spoonful of honey. Because the base is naturally smooth, it takes to fruit and herbs without turning harsh. Store the strained brew in the fridge and drink it within two to three days; after that the aroma fades even though it remains safe. Keep it covered, since tea readily picks up the smells of a busy refrigerator, and a jar of cold brew left open beside last night's dinner will taste of both.

Cold brew also makes an elegant base for entertaining. Poured into a jug with slices of orange and a few bruised mint leaves, it becomes a summer drink that asks nothing of the host once it is made. Because it is neither bitter nor fragile, it holds its character through a long, warm afternoon on the table, which is more than can be said for hot tea left to its own devices.

Small refinements worth trying

Once the basic method is second nature, a few adjustments reward the curious. A pinch more leaf gives a bolder base for milk or for diluting down over ice. A short warm-water rinse of the leaves before the cold steep can wake up the aromatics on a very fragrant tea. And if you like structure, decant the finished brew into a clean bottle rather than leaving it on the spent leaves, exactly as you would when keeping any brewed tea. Cold brew asks little and gives much; it is the most patient member of the tea repertoire.