At most UK airports, a food flask filled with soup, stew or anything liquid-ish counts as a liquid for hand luggage rules — which means it is capped at 100ml, exactly like your shampoo. Pack the flask empty instead and fill it after security, and there is no issue at all. The restriction is about what is inside the flask, not the flask itself, so a good stainless steel flask is still worth packing for a trip; you just need to use it a little differently on travel days.
Does a Food Flask Really Count as a "Liquid" at Security?
Yes, if it is full of soup, stew, curry or anything with a sauce. UK government guidance on hand luggage restrictions explicitly lists "liquid or semi-liquid foods, for example soup, jam, honey and syrups" alongside drinks, gels and pastes as things the liquid rule applies to. It does not single out stews or curries by name, but they fall under the same "similar consistency" wording, so a flask of bolognese is treated the same as a flask of soup at the X-ray belt.
The 100ml Limit Still Applies at Most Airports
At most UK airports you cannot take a container of liquid or semi-liquid food larger than 100ml through security, and that still applies even if the container is only part full — a 730ml flask with 50ml of soup in it is still a 730ml container. A handful of airports have introduced newer scanners that allow containers of up to 2 litres, but this is not standard across the country, and some airports with the new equipment still enforce the old 100ml limit. There is no single UK-wide rule here: always check your departure airport's own guidance before you fly, and your connecting airport too if you are changing planes.
The Easy Fix: Travel With It Empty
The simplest way around all of this is to pack your food flask through security completely empty — an empty container has no liquid in it, so it is not restricted at all. Fill it airside instead: most UK airport terminals have a café or food outlet that will pour in a hot soup, or you can carry a dry soup sachet in your hand luggage (solid food is not covered by the liquid rule) and ask for boiling water to make it up once you are through. Either way, pre-warm the flask with a splash of boiling water for a minute or two before you add your hot filling, so you are not relying on the steel itself to heat the food — a cold flask body draws heat out of whatever you put in it.
Flying With a Baby or on a Special Diet? There Is an Exemption
Government guidance allows containers of up to 2 litres for medical purposes, special dietary requirements, and baby food or baby milk, at every UK airport, even though the standard limit elsewhere is 100ml. That exemption covers a flask of pureed baby food or a specific medical diet, though staff may ask you to taste it or test it separately at the tray. If you are travelling with a baby or toddler for half-term or Christmas, this is worth knowing before you get to the belt, since it is easy to assume the 100ml rule has no exceptions.
Checking Your Bag Instead Avoids the Problem Entirely
The liquid restriction only applies to hand luggage — there is no 100ml rule for anything packed in the hold. A filled food flask travels perfectly well in a checked bag, with the obvious caveat that you will not be eating from it until you land. A stainless steel flask with a screw-on lid, like the Good For You 730ml insulated food flask, is built to survive being thrown around a hold: it is 304 (18/8) stainless steel rather than glass, double-wall insulated, and every Good For You product carries a 2-year warranty against manufacturing defects, so a loose handle or seal fault gets replaced rather than the whole flask being binned.
Which Flask Actually Suits a Travel Day
For an adult's airport or train-station lunch, the 730ml size (available in grey or black) holds a full main meal and keeps it hot for 6 to 9 hours once pre-warmed — long enough for a delayed flight and the taxi home. For a child travelling with you, the 530ml kids' flask is sized for a primary-school portion and comes with the same foldable spoon and carry bag, which matters when you are also juggling passports and a buggy. Both use the same wide-mouth, leak-proof screw lid, so the airport-security advice above applies equally to either size — it is what is inside that gets checked, never the flask itself.
Frequently Asked Questions
Can I bring a food flask full of soup through UK airport security?
Not in hand luggage at most airports, if it holds more than 100ml of soup or anything semi-liquid. The limit applies to the amount of liquid inside, not the size of the flask, so even a half-full 730ml flask is treated as a 730ml container. A small number of airports allow up to 2 litres with newer scanners, but this varies by airport and is not guaranteed.
Does soup actually count as a "liquid" for airport security?
Yes. UK government hand luggage guidance specifically lists liquid and semi-liquid foods such as soup, jam, honey and syrup alongside drinks and gels as items the 100ml rule covers. Dry or solid food, like a sandwich, crisps or dry pasta, is not affected by this rule at all.
Can I take an empty food flask through security and fill it afterwards?
Yes — an empty container carries no liquid, so it is not restricted regardless of its size. Fill it at a café or food outlet once you are through security, or carry a dry soup sachet and ask for boiling water, pre-warming the flask first so it holds the heat properly.
Is there an exception for baby food or medical diets?
Yes. UK airports allow containers of up to 2 litres for medical purposes, special dietary requirements, and baby food or baby milk, even though the general limit is 100ml. Security staff may ask to test or taste the contents separately, so allow a little extra time at the tray.
Does the 100ml liquid rule apply to checked luggage?
No — the restriction is specific to hand luggage carried through the security screening area. A filled food flask can go in a checked bag with no liquid limit at all; a stainless steel flask with a screw-on lid is sturdy enough to travel in the hold without leaking.
How do I find out if my airport allows more than 100ml?
Rules vary by individual airport rather than being set nationally, so check the security pages for both your departure airport and any connecting airport before you travel. Government guidance on hand luggage restrictions is a reliable starting point if an airport's own site is unclear.