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    "id": 1070302,
    "title": "How to make tea in a flask that still tastes good",
    "slug": "tea-in-a-flask",
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    "url": "https://teas.co.uk/wiki/tea-in-a-flask/",
    "modified": "2026-09-18T00:45:36+01:00",
    "excerpt": "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.",
    "content_text": "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 \u2014 it keeps extracting, turns bitter and drying, and arrives stewed.\r\nDo it this way instead.\r\nThe five steps\r\n\r\nPre-warm the flask. Fill it with boiling water, close it, leave it two minutes, tip it out. A cold flask steals the first 10\u00b0C from your tea, and a warm one keeps it hot for hours longer.\r\nBrew in a pot or jug, not the flask. Use your normal dose and time, or a little stronger if you like your tea strong \u2014 it will not get stronger later.\r\nStrain out every leaf or bag.\r\nFill the flask to the top. Air is the enemy: it cools the tea and dulls it. A part-full flask goes lukewarm and flat.\r\nClose it and leave it alone. Every time you open it you lose heat.\r\n\r\nMilk, sugar and lemon\r\n\r\nMilk: 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.\r\nSugar: add it before filling if you want it, since stirring on a hillside is awkward.\r\nLemon: add in the cup. Acid plus hours of standing does the tea no favours.\r\n\r\nWhich teas travel well\r\n\r\n\r\n\r\nTea\r\nIn a flask\r\n\r\n\r\n\r\n\r\nStrong black tea (breakfast, builder's)\r\nExcellent \u2014 robust and forgiving\r\n\r\n\r\nRooibos\r\nExcellent, and caffeine-free\r\n\r\n\r\nPeppermint, chamomile, fruit infusions\r\nVery good; no tannin to turn harsh\r\n\r\n\r\nGreen tea\r\nAcceptable if brewed correctly and strained; can flatten\r\n\r\n\r\nDelicate green, white, jasmine\r\nPoor. The aroma fades; brew these fresh\r\n\r\n\r\n\r\nIf 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.\r\nPacking for a walk\r\n\r\nFill the flask last, just before you leave.\r\nWrap it in a jumper in the rucksack \u2014 insulation on top of insulation.\r\nTake a proper cup. A flask lid is a poor cup and a good way to burn your hand.\r\nPlan the volume. Two people wanting a 250ml cup each at the top of the hill need 500ml, plus a little for a refill.\r\nBring the used bags home. They are not compost on a hillside, and many contain plastic.\r\n\r\nOur best tea to take travelling covers the tea choice, and making tea camping covers the version where you boil water outdoors.\r\nIced tea in a flask\r\nThe 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.\r\nKeeping the flask sweet\r\nRinse 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.\r\nCommon questions\r\nHow long does tea stay hot in a flask?\r\nIt 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.\r\nCan I brew straight in the flask if I take the bag out later?\r\nYou can, but you will have to open it to fish the bag out, which loses heat and risks a scald. Strain first.\r\nDoes a flask change the taste?\r\nA clean one should not. If it does, the lid needs stripping and cleaning.\r\nIs it safe to keep milky tea in a flask all day?\r\nNot ideal. Carry milk separately, or accept that milky tea is best drunk within a couple of hours.",
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