Yes, CDC recommends travelers wear a mask throughout their travel journey. Travelers may be asked to adjust their mask for identity verification or remove it briefly if it alarms the security screening equipment.
Many nations, including China, Canada, France and Germany, for example, still require all travelers to wear masks on planes departing from or arriving into the country. But in Mexico and in many parts of the Caribbean it is up to the airline to set its own rules.
Both Condor and Lufthansa have announced that they will no longer require masks on planes as of October 1, 2022, with the exception of flights to & from China and India.
Safety Oxygen MaskWhen the level of oxygen in the cabin atmosphere drops below a safe level due to system failure, oxygen masks will fall automatically in front of the passengers. Pull the mask sharply, cover your nose and mouth, and put the strap over your head.
You can wear a mask if you choose, but they're no longer required on domestic flights. If you're flying internationally, whether a mask is required depends on the arrival country's mask requirements.
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.