Stanley Classic 25oz Bottle
This heavy-duty flask has an effective easy-pour stopper that reduces the chance of spillages. The integrated cup is a good size and has an insulated rim to prevent burnt lips. You can actually get more in the flask than the manufacturer’s stated capacity too – we filled it up to 800ml.
Pros: A well-made and durable flask with very good heat retention. This was the second-best performer in its class in our temperature test. It features a simple but effective twist and pour stopper, and has a useful integrated cup.
Cons: The chunky design adds weight and bulk to your pack.
Temperature test: 0 hrs 90°c, 90 mins 85.2°c, 4 hrs 79.5°c, 6 hrs 75.3°c, 8 hrs 71.4°c, 24 hrs 48.4°c
Sho Original 2.0 Bottle
Another good-looking flask with a hard-wearing, textured, non-slip finish. The design prevents condensation from forming on the outside of the flask and ensures it stays cool to the touch. We particularly liked the useful carabiner accessory (sold separately, £3.99), for attaching the flask to a pack.
Pros: Performed impressively in our temperature test, being beaten only by the larger capacity flasks from Sigg and Klean Kanteen. A versatile option for a multitude of everyday and outdoor uses.
Cons: The only design drawback is the flask’s narrow neck and mouth, which minimises heat loss but makes cleaning a little tricky.
Temperature test: 0 hrs 90°c, 90 mins 87.2°c, 4 hrs 81.8°c, 6 hrs 78°c, 8 hrs 74.1°c, 24 hrs 50.6°c
Outwell Wilbur Vacuum Flask M
This flask has a familiar design with a classic ‘pop’ stopper that makes for easy pouring. With cheap, inferior flasks these are often prone to leaking but with this Outwell version the component seems well-made and reliable. It certainly didn’t leak on test.
Pros: A simple, inexpensive flask that makes use of a classic tried and tested design. The wide mouth makes the flask easy to fill and clean, while the cup’s plastic liner ensures you won’t burn your mouth.
Cons: Fairly bulky for a 750ml flask, with a small cup compared to some other designs. The external finish is a bit slippery and prone to scratching.
Temperature test: 0 hrs 90°c, 90 mins 83.6°c, 4 hrs 74.4°c, 6 hrs 68.2°c, 8 hrs 62.5°c, 24 hrs 33.6°c
GSI Glacier Stainless Microlight 720
Designed for gram-counting backpackers, this is an extremely lightweight flask with double walls that are 60% thinner than standard vacuum flasks. The design is neat and compact, but also incorporates a locking, flip-top cap for one-handed drinking. A non-slip silicone pad helps to prevent accidental damage to the base of the flask.
Pros: An impressively light and versatile design. The wide mouth makes for easy filling and cleaning, while the ergonomic spout is easy to drink from.
Cons: Treat the flask with care, as the stainless steel outer wall is very thin and will dent more easily than others. The smooth finish is also easily marked and scratched – though perhaps that just adds character?
Temperature test: 0 hrs 90°c, 90 mins 83.7°c, 4 hrs 75°c, 6 hrs 69.1°c, 8 hrs 63.4°c, 24 hrs 35.4°c
Lifeventure TiV 700 Vacuum Flask
This vacuum flask incorporates an internal copper coating in its construction for greater heat retention. We liked the solid screw-in stopper and integrated cup, as well as the external powder finish that stays condensation-free and cool to the touch, while being resistant to scratches.
Pros: A good value flask with solid all-round performance, finishing a respectable fifth overall in our temperature test. It’s relatively lightweight and the slim design slips easily into a pack.
Cons: Despite the ‘pouring spout’, pouring can be a bit slow and splashy if you don’t completely remove the stopper. The mouth of the flask is quite narrow, while the integrated cup is quite small.
Temperature test: 0 hrs 90°c, 90 mins 85.7°c, 4 hrs 79.5°c, 6 hrs 74.8°c, 8 hrs 70.5°c, 24 hrs 44.6°c
MontiiCo Original Bottle
This attractive flask looks great and incorporates a number of practical design features, including a grippy, scratch-resistant powder-coated finish and a plastic-free stopper with an eco-friendly bamboo insert. We also liked the integrated carry handle.
Pros: A lightweight and versatile flask that makes a good general-purpose drinks bottle, while also keeping a brew warm in a pinch. The slim design slides easily into a pack.
Cons: Tests showed that heat retention was not as good as other flasks, and the stainless steel outer wall of the flask is very thin and thus likely to dent more easily than others.
Temperature test: 0 hrs 90°c, 90 mins 79.6°c, 4 hrs 66.5°c, 6 hrs 58.3°c, 8 hrs 51.6°c, 24 hrs 22.2°c
Camelbak Hot Cap 20oz
This innovative flask has a leak-proof cap with an unusual twist stopper that allows 360° drinking from any angle. It’s ideal for swigging coffee on the go. The wide mouth also makes for easy filling.
Pros: A lightweight and portable design with a nice powder-coated finish, which makes the flask easy to hold in one hand.
Cons: We found the cap design a bit awkward to clean. The flask’s heat-holding power reaches its limits after about 4 hours.
Temperature test: 0 hrs 90°c, 90 mins 79.8°c, 4 hrs 67.2°c, 6 hrs 59.3°c, 8 hrs 53°c, 24 hrs 25.9°c
S’well Traveler 16oz
When single-use plastics started getting a bad rap, S’well became the drinks bottle of choice for a host of celebrities and ‘influencers’. But they’re not all style over substance – the design consists of a triple-walled construction incorporating a copper layer for improved insulation.
Pros: Lightweight and practical – the ergonomic shape makes it easy to hold, the really wide mouth makes for easy drinking, filling and cleaning, and the grooved lid makes it easy to open, even if screwed on tightly.
Cons: Small capacity and relatively expensive for a little flask.
Temperature test: 0 hrs 90°c, 90 mins 83.9°c, 4 hrs 74.1°c, 6 hrs 67.5°c, 8 hrs 61.8°c, 24 hrs 31.6°c