Yes, you can carry a water bottle in your luggage in 2026, but the rules differ significantly between carry-on and checked bags. For carry-on luggage, the 3-1-1 rule still applies: any liquid (including water) must be in a container of 100ml or less and fit within a single quart-sized clear bag. However, you can bring an empty reusable water bottle through security and fill it at a "hydration station" once you are in the departures lounge. For checked luggage, there are no volume restrictions on non-flammable liquids; you can pack full, sealed water bottles or other beverages as long as they are securely cushioned to prevent leaks. In early 2026, some airports with advanced 3D CT scanners have begun relaxing the 100ml limit, but until this technology is universal, the safest "pro-traveler" move is to keep your bottles empty until you pass the security checkpoint.