The inhibition efficiency (IE) of CTAB - Zn(2+) System in controlling corrosion of carbon steel in well water has been evaluated by weight loss method. Enumeration of microorganisms from well water and biocidal efficiency of inhibitor system (CTAB-Zn(2+)) were also determined by serial dilution technique and spread plate method. The formulation consisting of 200 ppm of CTAB and 5 ppm of Zn(2+) shows an IE of 98%. Potentiodynamic polarization curves indicate that the CTAB - Zn(2+) system functions as anodic inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. FTIR spectra suggest that the protective film consists of Fe(2+)-CTAB complex and Zn(OH)(2). The optimum concentration of CTAB for destroying the bacterias viz. E.coli, Salmonella and Shigella is >= 25 ppm. At 25 ppm of CTAB, it shows 100% biocidal efficiency in well water containing 5 ppm of Zn(2+).