(mib) "Following the tsunami in South East Asia, one of the biggest problems is the supply of drinkable water to the populations, lack of which can trigger serious epidemics," writes Cornelia Kirchweger in an Energy Globe press release. "However, a simple method exists to avert this danger: just two plastic bottles per person, a piece of corrugated iron and six hours of sunshine turns contaminated water into water that is safe to drink."

The underlying research that led to the development of the system began in 1991 at the Swiss Federal Institute for Environmental Science and Technology (EAWAG) (1) . A PET bottle is filled with water and laid in the sun for a number of hours, preferably on a corrugated iron roof. Exposure to ultraviolet solar rays and the warming up to around 50 degrees Celsius killins pathogens. "Faecal Coli concentrations in the water are reduced by 4–5 powers of ten and the dangerous cholera pathogen (Vibrio cholerae) gets inactivated. UV-A rays play havoc with the genetic code of bacteria and viruses and these organisms are either destroyed outright, or at least so badly damaged that they can no longer proliferate," as it says in the description of method in EAWAG's project information.

The EAWAG project, Sodis (Solar Water Disinfection) (2) , has now been awarded the Energy Globe Special Prize 2004 (3) , one of the world's most renowned environmental prizes. The formal award ceremony will take place on 27th April 2005 at EXPO 05, the World Exhibition in Japan.

"The organisers of Energy Globe tested this astoundingly simple system in field trials in Kenya. All tests show that after six hours the water in the bottle is really germ-free and safe to drink," writes Cornelia Kirchweger. "With this very simple method, the people who were affected by the flood disaster can be supplied with clean drinking water. In addition to other places, survivors of the tsunami in Asia are using Sodis in parts of Indonesia, India and Sri Lanka."

At least a third of populations in developing countries have no access to clean water. Lack of safe drinking water poses the greatest health risk to millions of people; Sodis can help.

Solar water disinfection is a simple way to improve the quality of drinking water. Solar rays help to destroy pathogenic agents in water. Picture: Energy Globe