What is SODIS?

Water School provides simple, strategic and sustainable clean water solutions to the developing world. Our program integrates health and sanitation education programs with the Solar Disinfection (SODIS) technique which effectively changes contaminated water to safe-drinking water.

(SODIS) is a simple and well-established method of improving the  quality of drinking water. Contaminated water is collected and placed in clear plastic PET (polyethylene terephthalate) bottles which are left in direct sunlight on a hard surface for one full sunny or partly cloudy day or two full days if fully cloudy.

The sun’s UV rays kill the micro-organisms in the water making it safe for human consumption. It is a simple, sustainable and affordable method that when implemented correctly, has been proven to change the lives of thousands of people. The project focuses on water treatment at the point of consumption because this provides the least opportunity for re-infection of the water with pathogens subsequent to other treatment methods (e.g. filters).

In order for SODIS to be effective, several conditions must be met:

a) Adequate health and sanitation practices MUST be applied alongside SODIS training.

b) The target area must be 35 degrees above or below the equator (the completed continent of Africa).

c) A ready supply of plastic bottles, free from scratches, must be available.

d) The water in the bottle should be clear enough to see spread fingers of one’s hand on the other side.


Visit our FAQs for more info!


Eawag Aquatic ResearchEawag supports the improvement and spread of the SODIS method through research in microbiology, health, educational strategies and PET bottles. However, the field work in individual SODIS projects is not part of Eawag’s core business. Water School is pleased to partner with Eawag to implement their important research in areas of the world that desperately need clean water. Visit the Eawag website for more information.