Bacterial deactivation, by cell-wall rupturing, is widely described. This work further describes mineralization of Gram-positive (S. Aureus) and Gram-negative (K. Pneumonia) bacteria in water, leaving no organic species. ZnO nanoparticles are used as photocatalyst. Solar-simulated radiation (with ~5% UV) is used. Complete bacterial deactivation is photocatalyzed by ZnO nanoparticles. Mineralization of bacteria is also achievable by the process, with time. Both bacteria, with thick- and thin- peptidoglycan layers, are mineralized. Sensitization of ZnO, by anthocyanin, enhances their catalytic efficiency under purely visible light. However, simulated-solar radiation is more useful in bacterial deactivation and mineralization than purely visible light even with sensitizer. This indicates the feasibility of using direct solar radiations in photocatalytic water disinfection without the need to use other more costly and hazardous methods. The study is especially useful to many societies having limited access to safe drinking waters