In this study, the variations in refractive indices of Zamzam, bottled drinking, and distilled waters with wavelengths and temperatures in the range of 20oC to 80oC have been measured by computer simulation phase shifting digital interferometry at six discrete wavelengths across the visible spectrum. The computer simulation phase shifting digital interferometer have been used to design an experimental setup to investigate the wrapped images of the correlation fringes. By having the derivatives of the refractive index of the liquid with respect to the temperature T, and the wavelength, , respectively from the new equation of refractive index, the dependence on temperature and wavelength was obtained. In this paper, a new theoretical model about the temperature dependence of the refractive index of liquid is presented, and it is in agreement with the previous experimental results. In summary, bottled drinking and distilled waters do not have the unique and distinctive optical refractive index that Zamzam water does.