Can You Bring an Empty Flask on a Plane?

Everyone has a story of a time they had to get rid of something while going through airport security, whether they absentmindedly brought a drink through the line or forgot what was in their pocket.

While full bottles of liquid aren’t allowed through security, can you bring an empty bottle or flask with you in your carry-on bag?

Empty water bottles, flasks, or canteens are allowed on planes as long as there are no liquids in them when they are brought through security. You should expect TSA to check that there are no liquids in the bottle when you go through, but you are free to bring your own flask and fill it while in the airport.

Liquids, Bottles, and Airline Security

According to the TSA’s website, an empty water bottle is allowed in both your carry-on and checked bags. 

Bottles larger than 3.5 ounces (or 100 milliliters) can not have any liquid inside of them. 

If you attempt to go through security with these items, they will either have to be thrown away or you’ll be asked to pour the contents out before proceeding. 

While alcohol flasks can be small enough to fit under this size limit, it isn’t really worth the trouble of bringing them with you. 

Extra questioning while going through security is possible and they may force you to empty a full flask even if it is under the size requirements. 

If you’re wanting to bring an empty bottle to carry some water with you, it’s no problem to bring any size flask or bottle with you. 

You may want to empty it before boarding your plane though, to avoid any hassle from flight attendants. To completely avoid trouble, consider just packing your flask in your checked bag. 

You’ll have the flask available while at your destination and you won’t need to worry about hassles at security or during your flight. 

Some items you may not consider liquids also fall under the liquid category when going through airline security. Toothpaste, lotion, and sunscreen all count. Chapstick, however, does not. 

The reason passengers can not bring liquids onto planes and the limit is set to 3.5 ounces is a bit surprising. 

In 2006, terrorists attempted to smuggle liquid explosives onto a plane in Britain, leading to the creation of the new liquid regulations. 

This is the same type of incident that causes U.S. security to require passengers to remove their shoes while going through security. 

In 2001, a man attempted to bring an explosive device onto a plane that was hidden in his shoe. 

These incidents are few and far between but are the reason such stringent and sometimes confusing rules exist for what can and can’t be brought through airport security. 

What Liquids Are Not Allowed on Planes?

All liquid or gel food items over 3.5 ounces are not allowed through airport security or on planes. If you’re traveling with these items they must be placed in checked luggage. 

Any item that alarms or can not be screened will also not be allowed through security. 

When heading through security, remove these items from your bag and separate them in the security bin. 

It’s helpful to keep all small bottles of liquids in a clear plastic bag, as they’re easier to screen and put back into your bag, making the process go faster. 

There are some exemptions to the rulings on liquids, which include medications and infant nourishment. 

For both of these exemptions, you’ll need to declare the extra items you plan on bringing with you. 

A final determination is made by TSA officers on-site regarding whether your additional liquids are reasonable for your trip.

For medications, always be sure they are clearly labeled and easily identified. The security agents may require additional testing and screening before allowing them to pass.

For child nourishment such as formula, you may be asked to open containers for small amounts to be collected for testing. Also, inform the officers if you do not want the formula to be X-rayed. 

Declaring these items and removing them from your bags can help make the process go much faster and smoother. 

Can I Bring Snacks on a Plane?

Solid food items can be brought through security in your carry-on or checked bag. You may be asked to separate these items from your bag for additional screening. 

Snacks and food purchased at the airport can be brought onto your plane with you. 

Generally, you’ll be asked to refrain from eating during the takeoff and landing portion of your flight, but once the seatbelt sign is turned off you should be free to snack. 

Make sure the snacks you’re bringing are completely solid items. Peanut butter counts as a liquid, so don’t expect to be able to bring a jar with you. 

What’s the 311 Rule?

The 3-1-1 rule is a simplified way to remember liquid regulations when going through a TSA checkpoint. 

Each passenger is allowed three liquid items that are under 3.4 ounces each. 

They must be placed in one, one-quart plastic bag and each passenger may have one of these bags in their carry-on as they go through security. 

Any liquid containers that are larger than 3.4 ounces, must either be placed in checked bags or emptied before boarding. This includes any and all liquids and gels, not just food items. 

Makeup, lotion, liquid deodorant, and toothpaste all count towards items in the 3-1-1 rule. 


Empty water bottles and flasks can be brought through airport security checkpoints, usually without issue. 

Passengers are not permitted to bring liquid containers that are larger than 3.5 ounces through security unless the container is demonstrably empty. 

If you do try to go through security with a drink, you’ll be asked to either pour the contents out or throw away the whole container. 

Bringing an empty flask allows you to fill it while inside the airport after you have passed through security.