Just make sure that the bottle is empty and then you can fill it up on the plane. Plastic or metal (we prefer metal), you can take your water bottles through TSA security at the airport – they just need to be empty.

You can take water on an international flight, but you generally cannot take it through the security checkpoint. Under the 2026 "3-1-1" rules, any liquid brought through security must be in a container of 100ml (3.4 oz) or less. To have water on board, the most common strategy is to bring an empty reusable bottle through security and refill it at the "hydration stations" or water fountains found in the departures lounge. Alternatively, you can purchase bottled water at "Duty-Free" or airport shops after you have cleared security, which is permitted on the aircraft. However, be aware of "Secondary Screening" on certain high-security routes (common for flights to Australia or the USA from some hubs), where any liquid over 100ml—even if bought inside the airport—may be confiscated at the boarding gate. A major change in 2026 is the rollout of CT scanners at airports like London Heathrow and Gatwick, which now allow containers up to 2 liters to pass through security; however, this is not yet a global standard, so always assume the 100ml limit applies unless you are at a specifically upgraded terminal.