The synergistic effect of phosphonates with Sodium Tungstate - Zn2+ on the inhibition of corrosion of carbon steel in well water environment has been evaluated in the present study. The phosphonates chosen in the present study are sodium salts of:2-Chloroethylphosphonic acid (2-Cl EPA ), 1-Hydroxyethane-1,1-diphosphonic acid (HEDP), Amino(trimethylenephosphonic acid)(ATMP) and Diethylene triamine pentamethylene phosphonic acid (DTPMP). The mechanistic aspects of corrosion inhibition are discussed based on the results obtained from the classical mass-loss method, potentiodynamic polarization study, AC impedance spectrum and surface analysis techniques like Fluorescence, FT-IR spectroscopy and scanning electron microscopy. The biocidal efficiencies of these systems in the presence and absence of suitable biocides have been evaluated.