The use of titanium dioxide nanotubes in the powder form (TNTP) has been a hot topic for the past decades in many applications. The high quality of the fabricated TNTP by various synthesis routes may meet the required threshold of performance in a plethora of fields such as drug delivery, sensors, supercapacitors, and photocatalytic applications. In this research work, the TNTP were used as an antibacterial agent for water microbial purification with different synthesis techniques of the powder form as hydrothermal and rapid breakdown anodization methods. The TNTP were characterized by SEM, X-Ray Diffraction (XRD), Raman, FTIR, and Uv-Visible Spectroscopy to study the effect of the structure, surface morphology, chemical composition, crystallinity and the optical properties of them. The antibacterial activity test was carried out using a viable count method against Escherichia. coli as a model of gram-negative bacteria in the presence and absence of solar radiation. Upon UV irradiation, hydrothermally synthesized-TNTP showed higher efficiency in deactivating E. coli (∼96.7%) than the anodized TNTP. Several factors play a significant role in determining the antibacterial activity of TNTP. These factors including the crystalline phase, surface hydroxyls, physicochemical properties of TiO2 as well as the experimental conditions.