A steam-augmented gas turbine engine system generally includes a compressor (3), first and second combustors (4a, 4b), a compressor turbine (6) and a power turbine (7). A heat exchanging system (8b) removes heat from an exhaust product from the power turbine (7) and preheats water which has been desalinated by a water purification system (12). The desalinated water is provided to the first combustor (4a), as a predetermined quantity of ...