A ZnO nanorods based water purification unit was designed which operates with solar energy as the source of activation. The purifier was tested on two model bacteria Escherichia coli and Staphylococcus aureus with concentration as high as 10¹⁰ colony forming units (CFU) per litre, which is about 10⁵ times higher than the bacterial concentration in tap water. Up to 99% (0.99 × 10¹⁰ CFU L⁻¹) removal of viable bacterial cells was achieved under sunlight activation.