Due to their excellent temperature retention, hydroflasks are a must if you travel often. So you no doubt want to know if you can bring a hydroflask on your next flight or not.

According to TSA regulations, you can bring a hydroflask on a plane in both your carry on and checked bags, though the hydroflask should be empty if packed in your carry on.

Bringing a Hydroflask on a Plane

The TSA have a rule in place called the 3-1-1 Rule.

The 3-1-1 Rule states that passengers are only allowed to bring water, gels and liquids in containers that are no larger than 3.4oz/100ml.

So, if your hydroflask is at least 3.4oz/100ml in size and contains liquid, it won’t be allowed in your carry on. Once you have passed airport security, you are allowed to fill a hydroflask and then bring it onto the plane.

You are allowed to pack your hydroflask in your checked bag regardless of how much liquid it contains.

Make Sure the Hydroflask is Empty

Regardless of the size of your hydroflask, you are allowed to pack it in your carry on and checked bags if it is empty.

In other words, as long as the hydroflask doesn’t contain any liquid, it can be brought past airport security, even if it exceeds 3.4oz/100ml.

Bringing a Hydroflask on International Flights

The 3-1-1 Rule is not limited to just flights within and from the USA.

As this rule applies worldwide, it means that you can only bring a hydroflask in your carry on if it is empty.

By Airline

Airlines follow TSA regulations.

This means that you can pack your hydroflask in your carry on if it is empty, and in your checked bags when it is either empty or contains liquid.

Will a Hydroflask Explode on a Plane?

Despite the changes in air pressure when flying, you don’t have to worry about your hydroflask exploding.

We do recommend slowing releasing the pressure by opening it up slowly if you filled your hydroflask before your step onto the plane.

Also, if your hydroflask has a straw and a flip-up mouthpiece, make sure that you slightly twist open the lid a bit before flipping the mouthpiece.

If you do this, the liquid inside the hydroflask won’t turn into a supersoaker and spray on your fellow passengers.

You Can Only Bring Empty Water Bottles

You are allowed to bring an empty water bottle on a plane in both your carry on and checked bags.

If the water bottle is larger than 3.4oz/100ml and contains liquid, you are not allowed to pack it in your carry on.

What About Coffee?

According to TSA regulations, you are allowed to bring coffee beans, ground coffee, and single-serve coffee capsules and pods on a plane in both your carry on and checked bags.

We go in much more detail in our can you bring coffee on a plane article.

Ella Dunham, a Freelance Travel Journalist and Marketing Manager, boasts an impressive career spanning eight years in the travel and tourism sectors.

Honored as one of "30 Under 30" by TTG Media (the world’s very first weekly travel trade newspaper), a "Tour Operator Travel Guru" and "Legend Award" winner, Ella is also a Fellow of the Institute of Travel, a Member of the Association of Women Travel Executives, has completed over 250 travel modules, and hosts travel-focused segments on national radio shows where she provides insights on travel regulations and destinations.

Ella has visited over 40 countries (with 10 more planned this year).