The inactivation of Escherichia coli (E. coli) was studied in presterilized surface water sample using titanium dioxide as the photocatalyst under irradiation of BLF Fluorescent lamps. Inactivation of E. coli (10 3 CFU/mL) was achieved in 60 min in the presence of 1.0 mg TiO 2 / mL. Photocatalytic inactivation data was evaluated in terms of first order rate equation N/N 0 = e (-kIt). The reaction rate constant k, 1.22 * 10 - 2 (mW min/cm 2 ) - 1 was calculated.