Drinking Water Treatment

 SODIS (Solar Water Disinfection)


SODIS (Solar Water Disinfection) is a simple water treatment method relying on solar electromagnetic radiation and temperature to inactive pathogens. SODIS capitalizes on the UV-A radiation of the solar electromagnetic spectrum to a germicidal effect. Additionally, infrared radiation raises the water temperature which has a pasteurization effect. Research has shown that SODIS is more efficient in water containing high levels of oxygen. In order to achieve maximum saturation of the water with oxygen, the bottles are filled up to three quarters and shaken for about 20 seconds before they are filled completely to the brim.


Although water supply coverage has increased remarkably in Nepal, not much attention has been given to improve the water quality. Recurring outbreaks of water borne diseases and high numbers of patients being admitted to hospitals with water borne disease ailments indicates a need to public health status via improving water quality. Additionally, the low income community are more vulnerable to such diseases and the subsequent economic repercussions. Considering the above mentioned factoids, it is essential to promote simple, low cost and effective water treatment options.


ENPHO started conducting research on SODIS in the year 2000 with support from EWAG/SANDEC of Switzerland. In the year 2003, ENPHO started promoting SODIS through its network of NGOs, municipality representatives and community groups. SODIS implementation strategy is divided into two approaches: Door to Door Monitoring approach and Awareness Package approach. As per the first approach, ENPHO conducted door-to- door SODIS promotion in Bishnumati corridor with collaboration of SANDEC/ World Vision International Nepal.


Additionally, between 2004 and 2005, ENPHO joined hands with Kathmandu Metropolitan City (KMC) and several NGOs to launch a campaign in Kathmandu. The campaign aimed to spread SODIS related messages amongst more than 50,000 households. Subsequently, more than 10,000 additional households used SODIS regularly as per the campaign. Mass education campaigns utilizing all forms of printed and electronic media as well as public exhibitions and hoarding boards helped spread the message regarding SODIS. Moreover, community mobilizers trained over 10,000 individuals, besides the individuals reached via the door- to- door monitoring approach, on the application of SODIS.


Furthermore, in 2006, ENPHO worked with various government agencies to institutionalize SODIS. ENPHO worked with the Ministry of Education and Ministry of Health for further promoting SODIS. Attempting to further scale up the program, ENPHO collaborated with governmental agencies such as Ministry of Health/District Public Health Offices (DPHO) and Municipalities to incorporate SODIS technology as part of their regular activities. Various training sessions were conducted, IEC materials were distributed and several hoarding board were set up for promoting SODIS. As per monitoring data, in the year 2006, 2375 regular SODIS users were recorded in Bhaktapur, Lalitpur, Kirtipur and Thimi municipalities. Regular monitoring and follow ups were done to ensure correct and sustained use of SODIS.


In 2008, ENPHO in coordination with UNICEF promoted SODIS in schools where a total of 6724 students were taught the specifics of SODIS technology and 123 local residents were given ToT on PoU technologies through mass media by UNICEF/DWSS in collaboration with ENPHO. Collectively, 13,980 individuals were trained in various training sessions which incorporated SODIS. In 2009, ENPHO started an investigation into the sustainable use of SODIS and explorations into new approaches. ENPHO joined hands with EWAG/SANDEC and conducted a sustainability study, as part of an international study to evaluate long term application of SODIS at grassroots levels.


ENPHO has continued to maximize the process of SODIS institutionalization and bring about positive health impact in various communities. Local stakeholders including government agencies have recognized SODIS as a simple, low cost, appropriate technology for drinking water treatment training courses. Due to simplicity and effectiveness of SODIS, communities are using the technology as an alternative method of drinking water purification. During all of ENPHO’s SODIS promotion activities, special attention has been given to the simplicity and effectiveness.