Even when you’re aware of the restrictions on carry on liquids, it’s easy to slip up and include something which will fall foul of the rules. Even if you travel regularly, some of the points below might refresh your memory, or suggest something you hadn’t considered before. If you have any more suggestions regarding mistakes people make when travelling with carry on liquids, please comment on this article.

Individual items over the allowed limit

Within the European Union, each item must be at most 100ml. In the United States, the limit is 3.4 oz. Most other countries which have implemented carry on liquids restrictions have similar restrictions. Any individual items larger than this are not permitted and will be confiscated at airport security. It’s important to note that this restriction also applies to the size of the container – so a 500ml bottle of water with less than100ml inside it will not be allowed through (in fact, even a completely empty container larger than 100ml will be confiscated).

Total items over the total allowed limit

All the liquid items you bring on board must fit in a 1 litre (approx 20cm x 20cm) transparent plastic bag. US TSA regulations state a 1-quart bag, about 8 inches square. This one litre limit includes the size of the bottles themselves, not just their contents.In practice, this generally means you’ll be able to fit at most500-600ml of actual liquids in your one litre bag.

Not packing liquid items in a suitable transparent resealable bag

The idea behind the bag is that all your liquid items can be easily presented together at security. It should be transparent so securitystaff can see the contents, sealable to prevent everything falling out, and resealable to allow them to remove items for closer examination before closing the bag again. And the bag must have a maximum capacityof 1 litre (or 1 quart), to limit the total liquids you’re allowed carry on board. In practice, I’ve travelled with a bag which wasn’t resealable and not had any problems. I’ve even had security staff sell me a plastic bag (!) when I’d forgotten to bring one at all. But bear  in mind that if you turn up without your liquids in a plastic bag, or the bag isn’t transparent (or too large), airport security would be within their rights to confiscate all your carry on liquids.

Not realising just how many items count as a liquid

“Liquid” has a fairly wide-ranging definition when used in terms of carry on restrictions. It includes all aerosols (e.g. deodorant), pastes (toothpaste or shoe polish) and gels. Most makeup and powders will be included, although solid lipstick is not. It also includes roll-on deodorants, creams such as suncream, lotions, ointments and foams. Many foodstuffs also fall under the “liquids” restriction: chocolate cream, fresh (soft) cheese, mayonnaise, any kind of spreads such as butter or jams are all considered liquids and can only be carried on board in quantities smaller than 100ml, in the transparent bag.

Packing carry on liquids in more than one transparent bag

Each passenger is strictly limited to only one transparent plastic bag into which all their liquids must be placed. If you’re travelling withsomeone else and they’re not bringing carry on liquids on board, that doesn’t mean you can pack two such transparent bags – instead, give them one of your bags to pack in their own luggage and present at security. If you do turn up with more than one bag, the contents of one of them may be confiscated.

Not presenting your carry on liquids separately at security

I almost missed a connecting flight before because of this one. When packing, I’d carefully checked that all my carry on liquid items complied with the restrictions and were packed in a suitable bag. However, as I was rushing to make my flight I forgot to remove the liquids bag and present it separately at security. Put my bag through the scanner, walked through the detector, turned to collect my bag – it wasn’t there. The bottles inside had shown up on the scanner and my bag had been pulled aside and left there. I had to wait nearly ten minutes until one of the staff removed the liquids bag and ran both bags through the scanner again. Barely made my flight, but I’ve learned to always present my carry on liquids separately at security. You should also always pack your resealable plastic bag near the top of your hand luggage so you can easily remove it at security.

Packing non-liquid items in your carry on liquids bag

It might seem obvious, but you only have a limited amount of space in that one transparent resealable bag. Certain items have to go into it – travel size toiletries, most makeup items, any gels or pastes count as liquids for this purpose. But just because your travel size toothpaste goes in, that doesn’t mean your travel toothbrush needs to. It only takes up space that you could use to fit a small bottle of aftershave or perfume into instead. If you’re running out space in your transparent bag, go through it and make sure that everything in it needs to be there.

Packing medicines in your carry on liquids bag

This is a bit of a tricky one. Essential medical or dietary liquids are exempt from the carry on liquids rule, in reasonable quantities, if they’re something that you will need on board. They should be presented separately at security, but need not be included in your 1 litre transparent bag. But exactly what qualifies is unclear. You may need to bring supporting evidence (e.g. a prescription) to show the medication is necessary. Baby milk is specifically permitted, in a reasonable quantity, and assuming the passenger is accompanied by a baby or small child. Milk powder is permitted, but water to go with it falls under the 100ml restriction. Contact lens solution in bottles of over 100ml is permitted in Zurich and apparently officially banned in Dublin, although I’ve taken larger bottles of it through there before and beenwaved through when I presented them. If you’re in doubt about something, either check it in, bring it in a small quantity that meetsthe airport liquid restrictions, or phone the airport before travel toconfirm that it is allowed as medicine. But if it’s a liquid that youcan prove is medicinal and necessary, then you can save space by leaving it out of your carry on liquids bag (just remember to present it separately at security).

Hopefully some of these tips might be useful to you when travelling. If you have any more to add, please comment below.