Since 9/11 most major airlines have increased security measures to help prevent airliner terrorist attacks. Additional scrutiny was paid to liquids and gels following the discovery of a potential terrorist plot using these items in August 2006. In the United States, the Transportation Security Administration (TSA) is responsible for security and setting guidelines about what is and isn't permissible on a plane. These rules particularly apply to carry-on baggage which can be accessed by a passenger during flight.


The 3-1-1 rule is a handy way to remember what quantity of liquids, gels or aerosols TSA permits on a plane. The "3" indicates that each individual bottle of liquid should be 3.4 ounces (100 ml) or less. Even if the bottle is only half full, the size of the bottle, not the amount of liquid present, is what determines whether it is acceptable. The first "1" means that all of your bottles should fit inside one clear plastic zip-close bag. The second "1" is that only one bag per passenger is allowed. This bag should be removed from your carry-on luggage to make it easier to screen.

Liquid Exceptions

All Getaways

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Several items including breast milk, baby food and formula are allowed in your carry-on luggage and do not have to abide by the 3-1-1 rule. Diabetics or people with medical conditions can carry medications, water or juice but must explain this. Declare any liquids in these categories to the officers conducting the screening. They may choose to examine them more closely.

Checked Luggage

With the exception of prohibited items, such as gasoline, paint thinners and pepper spray, you can pack any size liquid or gel item in your checked baggage. Just remember that most airlines charge fees for a second bag and some for a first bag. To save on space, consider purchasing what you need at your destination.


You can purchase a beverage to drink and carry onto the plane once you have cleared security. In fact, you can buy liquid or gel items of any size in an airport after you have passed through clearance. These items are new, unopened and are guaranteed not to be a risk.

Making a Mistake

You may throw a bottle of water in your bag intending to drink it on the way to the airport and then forget about it. Or, you may accidentally pack something too big. Security will seize any items that do not fit into the established guidelines. You will be allowed to return to the counter to see if you can add items to your checked luggage. You can also mail the item to your home or destination if the airline has a post office. Many people simply choose to discard the item at the security checkpoint.