The Difference is Drinkability: the SODIS method

Access to water is easy, but for billions of people, it isn’t always safe. Drinking straight river and puddle water can cause serious diarrhea and even death. In many countries, unsafe water conditions lead to children’s absence from school because of water-borne illness.

While some people in these hard-hit places – particularly South and Central America, much of the continent of Africa, and southern Asia – have cookers to purify the water, most people either do not have access to easy purification or cannot afford the fuel needed.

That is where SODIS comes in. SODIS is a Swiss acronym for solar water disinfection, a process of purifying water using only sunlight and plastic bottles.

Essentially, the method goes like this: Fill clean PET bottles with water and leave them out in the sun for 6 hours (more depending on conditions). Keep the water stored in those bottles, and drink from them when needed!

The SODIS method is becoming widely recognized for its possibilities for households around the world. It currently provides clean water for over 3 million people and counting.

SODIS projects around the world

But more research and education are needed if the method is to work perfectly. For example, scratched or old bottles, or water stored in the bottles for too long, can hurt the efficiency of the project and not be safe. And some people still have some concerns about the chemicals released during radiation.

But the simple and free access to clean water has already led to a wide increase in school attendance and a decrease in diarrhea anywhere from 30%-80%, depending on the community.

SODIS projects are coordinated by the Swiss Federal Institute of Aquatic Science and Technology (Eawag), and are funded by many groups, including large foundations and various Lion’s Clubs and Rotary Clubs. To learn more about the method, or how individuals and groups can get involved, visit the SODIS website.

Join In!

The SODIS method has been around for over 10 years and Eawag has SODIS projects in over 33 countries. Have you heard about this method before? Do you know any people or groups who have used it?

Projects like SODIS obviously cannot solve all health problems. What other factors contribute to illnesses such as diarrhea in underdeveloped countries?

3 Responses to “The Difference is Drinkability: the SODIS method”
  1. Darrell says:

    Ihaven’t experienced Sodis but the tablets we used to put in a cantein would allow us to drink rice paddy water or water polluted with water buffalo urine.

  2. Michael says:

    Wow. So simple. Is there something very unique about PET plastic bottles? What are they? I wonder how it works. If they are not too expensive I’d like to buy a few to use for camping.

    • Joanna says:

      They’re just plastic bottles – the kind used most for soft drinks. And SODIS works best with a lot of sun, and even better on slanted, metal roofs.

      So for camping, filling up hard plastic or aluminum bottles ahead of time will probably always be easier and better. But if you really want to rough it, I suppose you can give it a shot. I will probably bring a couple of Nalgenes and sit back while you work.

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