A water generation system for the generation of water on board an aircraft comprises a fuel cell device having an exhaust for an exhaust gas, a condenser and an outflow valve for discharging cabin air, which is drawn off through the condenser due to the pressure difference between the cabin pressure and ambient pressure without extensive cooling circuits or pumps, for example. The condenser may be coupled to the exhaust such that the exhaust gas is cooled by cabin air, and the outflow valve is connected to the condenser and to the environment of the aircraft, such that, when the aircraft is at cruising altitude, the cabin air is drawn through the condenser and is discharged into the environment.