Tip #2: Reduce waste and save some money by bringing a reusable water bottle. So you can't bring H₂0 or any other liquids more than 3.4 oz. (well there are some exceptions) through security, but you CAN bring an empty bottle. Just fill it up on your way to boarding your flight after screening.

You can carry a water bottle on a flight, but it must be completely empty when you go through the airport security checkpoint due to the "3-1-1" liquid restrictions (which limit liquids to 100ml or 3.4oz). Once you have cleared security, you can refill your bottle at a water fountain or a "hydration station" inside the terminal before you board. Carrying a reusable metal or BPA-free plastic bottle is highly recommended as a sustainable and cost-effective alternative to buying expensive bottled water inside the airport. If you are traveling with an infant, you are generally allowed to carry larger quantities of water or "nursery water" for formula, but you must declare this to the TSA or security officers for specialized screening. On the plane, the air is notoriously dry, so having your own full bottle allows you to stay hydrated without waiting for the cabin crew's beverage service. Just be sure to close the lid tightly, as the changes in cabin pressure can sometimes cause a "leak" if the seal isn't secure. Many modern airports now feature specialized "draining" stations before security to make this process easier.