When flying domestically, the amount of water you can bring through airport security is strictly governed by the 3-1-1 liquids rule, which limits all liquids, gels, and aerosols to 3.4 ounces (100 milliliters) or less per container. These containers must fit into a single, clear, quart-sized plastic bag. If you attempt to bring a standard-sized water bottle or a larger container of liquid through the TSA checkpoint, it will be confiscated, regardless of whether it is sealed or unsealed. However, there are two major ways to circumvent this for your flight: first, you can bring an empty reusable water bottle through security and fill it at a fountain or hydration station once you are in the departures area. Second, any water or beverage purchased at a shop or restaurant after you pass the security checkpoint is allowed on the plane. It is also important to note that certain exceptions exist for medical necessities, such as distilled water for CPAP machines or liquid formula/breast milk for infants; these must be declared to the TSA officer for separate manual screening to ensure they do not contain prohibited substances.