Traditional water disinfection methods such as chlorination and ozonation inevitably form harmful disinfection by-products (DBPs). UV irradiation is a safe alternative but it is very energy intensive. It makes perfect sense to enhance the utilization of photons by integrating engineered photocatalytic nanostructures in the treatment system. UV-light active photocatalytic inorganic nanomaterials, such as titania, are capable of inactivating various bacteria and viruses. They work by generating powerful but short-lived oxygen-based radicals upon irradiation. Unlike conventional chemical disinfectants, the antimicrobial nanomaterials are not consumed in the process. Photocatalytic water disinfection is a green technology because the same materials can be used over and over again. This paper reviews the recent progress in the fabrication of inorganic nanomaterials for photocatalytic water disinfection. A variety of UV and even visible-light driven water disinfection systems are introduced. Their advantages and limitations as well as the antimicrobial mechanisms are discussed.