No, you cannot carry a standard unopened bottle of water through airport security in your carry-on luggage if it exceeds the standard liquid limit. Under the TSA's "3-1-1" rule (and similar international regulations), all liquids, gels, and aerosols must be in containers of 3.4 ounces (100 milliliters) or less, and all containers must fit in a single quart-sized, clear plastic bag. Since most standard water bottles are 12 to 20 ounces, they will be confiscated at the checkpoint, even if they are factory-sealed and unopened. The only major exceptions are for medically necessary liquids, such as distilled water for CPAP machines, or for "breast milk, formula, and juice for infants," which must be declared for separate screening. To save money and stay hydrated, the most efficient "travel hack" is to bring an empty reusable water bottle through security. Once you are in the "airside" departures area, you can fill it for free at a water fountain or a dedicated bottle-filling station. Alternatively, you can purchase a new bottle of water from a terminal shop after you have cleared the security screening process, as items sold inside the secure area are already cleared for flight.