According to the World Health Organization, “Globally, there are nearly 1.7 billion cases of diarrhoeal disease every year”. Diarrhea is the number one cause of malnutrition in children under 5. It kills 760,000 children under five years old each year. Diarrheal illness can be caused by contaminated food or water, or lack of sanitation practices. Children come into contact with feces through many routes, like unwashed hands, open sewage, groundwater, or insects. The major route that SODIS closes off is contamination through water. SODIS stands for solar disinfection, and the type of disinfection referred to here is using Polyethelene Terephthalate bottles and UV radiation to kill off bacteria. PET bottles allow sun rays to reach the water without releasing chemicals from the bottle. Several bottles at a time are filled with contaminated water and placed on roofs or tables. After six hours water is safe to drink. My only concerns are the cost (it appears as though the people who use SODIS were given a donation of PET bottles) and the quantity of clean water that is typically produced with this method. Nevertheless, this is a simple solution that can be easily implemented.
Here is more information: SODIS document.
The image of the SODIS bottle has changed a lot since 1991. Here is a more modern website: Solar Bottle.