# How to make tea in a flask that still tastes good

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**Source:** teas.co.uk, UK tea specialist, Tunbridge Wells, Kent

## Summary

Brew it, strain it, then fill a pre-warmed flask. The five steps that stop flask tea turning stewed, and how to handle milk, sugar and delicate teas.

## Description

The mistake is brewing in the flask. Tea left on its leaves for three hours in a sealed vacuum does not stay the drink you made — it keeps extracting, turns bitter and drying, and arrives stewed.
Do it this way instead.
The five steps

Pre-warm the flask. Fill it with boiling water, close it, leave it two minutes, tip it out. A cold flask steals the first 10°C from your tea, and a warm one keeps it hot for hours longer.
Brew in a pot or jug, not the flask. Use your normal dose and time, or a little stronger if you like your tea strong — it will not get stronger later.
Strain out every leaf or bag.
Fill the flask to the top. Air is the enemy: it cools the tea and dulls it. A part-full flask goes lukewarm and flat.
Close it and leave it alone. Every time you open it you lose heat.

Milk, sugar and lemon

Milk: better carried separately in a small bottle and added in the cup. Milky tea held hot for hours tastes cooked, and it goes off faster than black tea does.
Sugar: add it before filling if you want it, since stirring on a hillside is awkward.
Lemon: add in the cup. Acid plus hours of standing does the tea no favours.

Which teas travel well



Tea
In a flask




Strong black tea (breakfast, builder's)
Excellent — robust and forgiving


Rooibos
Excellent, and caffeine-free


Peppermint, chamomile, fruit infusions
Very good; no tannin to turn harsh


Green tea
Acceptable if brewed correctly and strained; can flatten


Delicate green, white, jasmine
Poor. The aroma fades; brew these fresh



If you want something floral on a walk, a jasmine tea is best brewed short and strong and drunk within the first hour or two, or swapped for a fruit infusion, which holds up far better.
Packing for a walk

Fill the flask last, just before you leave.
Wrap it in a jumper in the rucksack — insulation on top of insulation.
Take a proper cup. A flask lid is a poor cup and a good way to burn your hand.
Plan the volume. Two people wanting a 250ml cup each at the top of the hill need 500ml, plus a little for a refill.
Bring the used bags home. They are not compost on a hillside, and many contain plastic.

Our best tea to take travelling covers the tea choice, and making tea camping covers the version where you boil water outdoors.
Iced tea in a flask
The same flask works cold. Brew double strength, cool it, then fill a flask that has been chilled with cold water and ice. Keep the ice separate from the brewing stage or you will dilute it twice.
Keeping the flask sweet
Rinse it the day you use it, take the lid apart weekly, and dry it with the lid off. If it has started to taste metallic or musty, see why tea tastes metallic in a flask.
Common questions
How long does tea stay hot in a flask?
It depends on the flask, how full it is and how often you open it. A good vacuum flask, pre-warmed and filled to the top, should still be properly hot after four to six hours.
Can I brew straight in the flask if I take the bag out later?
You can, but you will have to open it to fish the bag out, which loses heat and risks a scald. Strain first.
Does a flask change the taste?
A clean one should not. If it does, the lid needs stripping and cleaning.
Is it safe to keep milky tea in a flask all day?
Not ideal. Carry milk separately, or accept that milky tea is best drunk within a couple of hours.

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