SODISMETHOD Mike Janich


Sunlight and an ordinary plastic water bottle are all that is neces- sary to disinfect drinking water for many sur- vival situations.


One of the greatest concerns in any


survival or disaster situation is ensur- ing that you and your family have an adequate supply of clean drinking water. Note that the two key words in that sentence are adequate and clean. Having enough is a matter of either storing water or drawing it from what- ever sources might be available. Clean means ensuring that the water you do have or can get is free of contami- nants, including harmful bacteria, vi- ruses and protozoa. Natural disasters like hurricane


Katrina are a stark reminder that it is very possible to have plenty of wa- ter with none of it safe to drink. Out- breaks of coliform bacteria, giardia- sis, cryptosporidiosis and hepatitis A, have also prompted increased concern about the safety of public water sup- plies and a greater focus on water dis- infection methods appropriate to this type of threat.


Solar Water Disinfection Water-borne pathogens can be de-


stroyed by boiling or chemical treat- ment. In places or circumstances where fuel and chemical resources are abundant, these methods are conve- nient and practical. However, devel- oping countries not only have limited resources, they also have a much more critical need for water disinfection. According to the World Health Orga- nization, more than 2 million people per year die of water-borne diseases worldwide, and 1 billion people lack access to a source of improved drink- ing water. In response to this critical need,


scientists began searching for alter- native methods of water disinfection that are inexpensive and highly fuel- effi cient. One result of this search was the SODIS method, short for solar wa- ter disinfection. In simple terms, this method uses the UV-radiation of the sun to kill harmful pathogens. SODIS was fi rst discovered by Pro-


CLEAN, DRINKING WATER FROM THE


POWER OF SUN 62


fessor Aftim Acra at the American University of Beirut in the early 1980s, but the bulk of the research on SO- DIS — as well as the refi nement of the method — was done by the research groups of Martin Wegelin at the Swiss Federal Institute of Aquatic Science and Technology (Eawag) and Dr. Kev- in McGuigan at the Royal College of Surgeons in Ireland. Thanks to their efforts, and the implementation of SO- DIS programs in developing countries worldwide, there has been signifi cant progress in the reduction of sickness from water-borne pathogens.


How Does It Work? There are three primary ingredi-


REALITY CHECK • 2012 SPECIAL EDITION


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