A relatively small UV light device may make a big difference in the safety of water in developing countries. Ewalb says such education is vital to ensure that the device will be used appropriately. Another drawback to the UV disinfection method is that UV light, like most other disinfection methods, does not completely rid water of viable Giardia or Cryptosporidia , parasitic protozoans that, outside of a host, form cysts that are extremely resistant to disinfection. These cysts can survive dormant for months in most environments and become active upon entering a host. Symptoms of infection for both parasites include nausea and diarrhea which can be fatal in individuals with weak immune systems.
Filtration is also a solution to the problem of using UV disinfection in turbid water.
Since the effectiveness of UV Waterworks depends on the light's ability to penetrate the water and reach all organisms present in a sample, any cloudiness or particles in the water that can shield pathogens from UV radiation will compromise the device's ability to disinfect. Filtering the water before treatment can reduce the turbidity of the influent and optimize the effect of the UV radiation. Gadgil decided not to make such a filter part of the initial design of UV Waterworks, however, because keeping the device simple and cost-efficient were the main priorities. Gadgil said that he adopted this strategy while designing UV Waterworks. The idea was to create a device with attributes that would allow it to be used by millions of people throughout the developing world, not to create one that would necessarily destroy all pathogens.