…can’t speak for all major airports, but most as a rule have either a “tank farm” on site or an underground pipeline supplying for the whole airport. Our home base Vancouver International (CYVR) has a pipeline from a suburban area where there is a refinery and storage tanks. I’m not certain how the fuel is alloted, as there are numerous potential users in multiple airlines, private users, and corporate aviation departments. Two operators have contracts with various airlines to provide fuel. Some of the fuel is pumped into trucks/bowsers and delivered to the aircraft, some is pumped from underground outlets at the gates directly into the aircraft.
Smaller airports with less fuel requirements have fuel trucked in and stored on site, these are the ones that would probably have the most likely problems re the protests over fuel going on as we speak in Europe.
“You screw up just this much, and you’ll find yourself flying a cargo plane full of rubber dogshit outta Hong Kong!”