In thousands of rural areas in the developing world, contaminated drinking water remains a significant source of dysentery and other water-borne illnesses. World health and development officials are now looking to SODIS (Solar Water Disinfection) as a simple, inexpensive and effective method that allows local inhabitants to remove bacterial contamination from their water.
The system requires only sunlight and PET bottles. Clean, empty PET bottles are filled with the local water and capped, then exposed to direct sunlight for anywhere from six hours to two days, depending on weather conditions. The sun's ultraviolet radiation destroys the cell structure of various bacteria, while the warmth of the sun heats the water to speed the disinfection process.
PET bottles are used not only because they are inert, lightweight and shatterproof, but because the clarity and chemical structure of PET allows both UVA and UVB rays to reach the water. Because the effectiveness of the sunlight in killing bacteria decreases as the depth of the water increases, the PET bottles are typically placed on their sides when exposed to the sun.
The SODIS system, endorsed by the World Health Organization, is now being successfully used by approximately two million people in more than 30 countries around the world, primarily in portions of Central and South America, sub-Saharan Africa, the Indian subcontinent and areas of Southeast Asia.
To learn more about SODIS, visit www.sodis.ch/index_EN