The best hot drink flask will keep your brew hot and your lunch cool all day – with zero bag spills. While Thermos may be a well known and generic term for a flask, it’s just one of many brands. In fact, the best flasks come in all shapes and sizes and under many names. Our recommendations below have managed to master the art and science of the vacuum flask – that ingenious, insulated container that does the job of a portable kettle or fridge without the need of a plug socket.
Whether it’s a chunky “food flask”, sleek “vacuum bottle” or something in between, the job of a flask is to keep food and drink hot or cold without leaking, all day long. Some of the winners on our list can insulate for more than 24 hours, which is long enough to survive the toughest hike or most gruelling commute.
For this article, we’ve picked out several flasks that excel at insulation, leak-proofness, durability and, of course, value for money. Before you scroll on, take a look at our buying guide below for some helpful tips on buying the best flask.
Top 10 Best Hot Drink Flask in UK 2021
1. Thermos stainless steel 1.2-litre flask – Best flasks and thermal cups to buy
This stainless steel flask is large and proudly bears the Thermos name. Most importantly, it works.
Despite plenty of competition, Thermos is still the most recognisable name in the market, offering an extensive range of products to keep food and drink hot or cold.
We tested the 1.2-litre capacity flask in bold red, but there are plenty of colour options available. All aspects of its design have been carefully considered. For instance, the cup is insulated with plastic, so our tea retained its heat without being too hot to hold.
The flask features a simple screw-top cap that can be loosened for pouring, and ensures not too much heat escapes.
Although the flask is on the hefty side, a sturdy, loose-hinged metal handle makes it easy to use and carry. Its handsome metal cup easily screws on over the cap.
The flask is just over 30cm tall (including the cup) and weighs in at 1.8kg when full, despite being quite light when empty. We didn’t find any signs of leaks around the cap, and pouring was easy with no excessive dripping.
Best of all was its performance. Its label promises to keep drinks hot for 24 hours, and when we finally opened it a day after making our tea, it was as hot as when we’d brewed it the morning before.
This flask is reliable and immensely practical, and with a confident 50-year guarantee, it could remain a staple of family days out for years.
2. Stanley Master Vacuum Bottle 750ml: Best flask for keeping drinks hot and cold – for days
New from the creators of the 106-year-old Stanley Classic, this sleek, rugged flask keeps hot drinks hot for longer than the promised 27 hours and iced drinks cold for a staggering 100+ hours (good luck if you’re caught out in a heatwave for that long, frankly). So if you’re packing the car for a camping trip, this is the flask to take.
The Master achieves its insulating magic with a ‘QuadVac’ quadruple-walled insulation system, made entirely from BPA-free 18/8-grade rust-proof steel. The insulated cup is made from the same stuff, and does a brilliant job of retaining a drink’s temperature while you take your time over lunch. The stopper is plastic but lined with steel, so your drink never comes into contact with plastic, and we found it to be reliably leak-proof.
Our only grumble is that the flask weighs nearly a kilo even before there’s anything in it, and isn’t available in a smaller size.
3. Hydro Flask Travel Coffee Flask
With a choice of colours from the dark and moody to the bright and vivid, as well as a pick of different sizes depending on when and where you are going, this bottle is the perfect companion for any eventuality.
The double-walled vacuum insulation will keep your hot drinks safe for up to six hours, which is likely plenty of time for any coffee addict to finish the lot off. It is made from 18/8 high-grade steel so is fabulous quality, and its also completely BPA free for anyone wanting to avoid plastic.
This also means that it won’t impart any funny tastes onto you drink no matter what you have in there. There is no absorption of odours either, and if you’re opting for a cold drink for the day, it will taste clean even 24 hours later.
With a powder matte finish, it will never look covered in condensation and will be hard to tarnish too. This also means you won’t have moisture dripping down your work shirt or leaving a puddle on your desk.
4. T2 Tea Insulated Flask
You don’t want tea, you want coffee. We hear you. But it doesn’t mean we can’t use some of their products, because after all, we all do come together in the search for a hot drink.
The idea is that you pop loose tea leaves into the diffuser and the taste stays strong over time. This could be good for anyone who wants their coffee granules to develop in order to make a flask of cold brew, or you can leave it out altogether if your drink is already perfect.
Screw the top on and then place it into your bag for coffee on-the-go. It won’t leak everywhere, so running for the train is no longer a difficult process. It can keep drinks warm at 60°C for up to six hours which will get you (almost) through a working day.
It would make a great flask for anyone who sometimes loves tea, sometimes needs a coffee, occasionally tries a green tea when on a health kick and sometimes adapts their hot drinks for the summer months.
5. Klean Kanteen Unisex
The Klean Kanteen Insulated TKWide is a colourful thermos designed with portability in mind. It’s available in a range of colours and sizes (our pick is the 32oz thermos in lime green). The powder coating adds a grippy finish and ensures the bottle’s exterior remains as vibrant as the day you bought it. The wide mouth – one of the widest we’ve seen on a thermos – makes it easy to drink from and fill up, and the unusual internal thread design on the bottle’s neck results in an ultra-tight seal.
Although it’s slightly on the heavy side, the pay-off is fantastic insulation – the flask will keep hot drinks hot for 22 hours, and chilled drinks cold for 75 hours – over three days. The flask is also incredibly versatile, with various extras for anyone keen to enhance its performance when it comes to specific drinks. The extra lids which can be purchased include a chug cap ideal for cold drinks, a cap designed to be used with a straw and a coffee cup-style lid for hot drinks.
6. SIGG Switzerland Unisex’s Hot and Cold Insulated Water Bottle
When you are travelling, how long a bottle will keep your drink warm for is really important. But as is how you drink the coffee and how the bottle can be carried. All of that makes this one the best flask for travelling.
This one is slim and convenient, with a practical screw cap which also doubles up as a carry handle. It can be hooked onto a bag, a waist belt, around your neck or simply carried by hand (although it is on the heavier side so maybe best in a bag for long periods). The integrated mug is handy as it takes up no more space, yet is always there when you need it.
Able to keep hot drinks for 18 hours and cold for 24, it will see you through the day no matter the contents. It is made from stainless steel and avoids BPA, pollutants and phthalates.
7. Contigo Autoseal Chill water bottle – Best flask for cold drinks
If you’re not a big hot drink fan but still want an exceptional flask to keep drinks cool on camping trips, long days and overnight stays, this slick offering from travel favourite Contigo is ideal. It claims to keep drinks cold for 28 hours and during our testing, it lived up to this. While the temperature will drop a tad when ice begins to melt, we found that iceless liquids were the same temperature 28 hours later as they were when first added. In some instances, they stayed chilly for far longer than the time stated too.
It’s 100% leak proof – no matter how hard we tried, we couldn’t get any liquid to escape and the automatic opening trigger means you can drink from it one-handed with ease. Finally, there’s an additional loop handle on top so it can easily be attached to bags or simply carried this way. All in all, this is brilliantly stylish and robust
8. Lifeventure 1000 widemouth flask with handle
The Lifeventure has brought back the retractable handle with style. It’s an excellent feature on the 1000ml flask, which although feels a bit top heavy, is lightweight overall and also comes with the option of an adjustable shoulder strap.
Its matte black screw lid acts as a bowl-shaped cup and there’s another which sits beneath it, this time in white plastic.
Both are broad and work well filled with cereal and soup alike. Unscrew the stopper part way and you can control the pour of the flask’s liquid contents. Or for filling, the whole lid unscrews, leaving a broad opening.
The specifications state that hot drinks will stay steamy up to eight hours, whilst cold ones will be cool for 12. When tested, this insulated flask over-performed, keeping contents chilled for up to three days.
Within its stainless steel construction is a copper lining, although there’s no metallic smell on opening.
Considering its performance, this litre flask is of remarkable value and would be a great investment for anyone wanting an easily portable insulated thermal flask for sharing.
9. SIGG Hot and Cold ONE – Best cheap durable flask for hikers
Drop it, dent it, dishwash it, drink straight from it, even brew tea in it. This fab lightweight flask is designed to survive anything, without messing with the temperature of its contents, keeping your brew comfortably hot for 12 hours.
The two-part locking lid doubles as a rotatable spout, so it’s ideal for taking a sip when you’re walking, although the plastic part of the lid does feel somewhat less durable than the metal. We also love the classic Sigg handle, which doubles as a lever so you can open it using a stick if your hands are cold or dirty. There’s even a built-in tea filter, so you can make tea using loose tea leaves or whatever you find on your adventures.
10. Black + Blum Food Flask – Most stylish food flask
This vacuum-insulated flask from Black+Blum is a highly distinctive and eco-friendly option for keeping your food nice and warm. It has a capacity of 400ml and its leak-proof twist lid ensures that food and drink stay put, wherever you go. Once sealed, it can keep food hot for up to six hours, while boiling water will stay piping for ten or more. Meanwhile, cold food and drink will keep their cool for roughly eight hours. Finally, that colourful, ergonomic spoon stays fixed to the flask by slotting into the artificial leather strap, so you’ll never end up drinking your soup like tea.
How to choose the best Hot Drink Flask in UK 2021
As much as we love a new type of insulation of a hi-tech finish, it’s important to remember that the best thermos flasks aren’t necessarily the ones packed with features. Start by taking a second to consider the flask’s primary purpose. Are you using it for hot or cold drinks? While most thermos flasks will keep drinks hot or cold for a minimum of 12 hours, certain models offer hi-tech insulation (such as Hydro Flask’s brilliant TempShield insulation), which keep cold drinks cold for much longer (up to 24 hours).
Consider which features you’re most likely to benefit from. Handles on the lid are surprisingly useful, making it easy to attach flasks to rucksacks, while a powder coating is essential for style-conscious hikers who’d like to colour coordinate their thermos with their thermals. Wide mouths are a godsend if you’re gulping on the go – although the best of both worlds is a double-layered cap which screws off in sections, to give you the choice of a wider mouth or a narrower one.
Finally, don’t be seduced by unnecessary lingo, such as ‘double-walled’. Most thermos flasks are double-walled – that’s simply how they work. However, a growing number feature triple-walled construction, which is certainly worth considering if you’re a hardcore hiker heading out into the wilderness for longer periods of time.
Whether you are looking for a flask to keep your drinks hot, cold or even carbonated, once you find the right Thermos flask it will surely last you for years. We hope the best hot drink flask in UK 2021 has helped you find the best one for your own individual needs!