WADI: An Inexpensive and Easy Way of Water Disinfection

Background: Worldwide, almost 900 million people have no access to clean water. SODIS (Solar Water Disinfection), recommended by WHO, is an easy, efficient and economical way of water disinfection, but correct application is crucial. The aim of Helioz R&D is optimizing this method and making it more applicable for users.

Method and material: Helioz R&D developed a device (WADI: Water Disinfection) which traces the progress of solar water disinfection in a PET bottle by calculating the UV dose. WADI is mounted on the PET-bottle instead of a screwing cap. WADI is energy-self-sufficient, needs neither spare part replacement nor maintenance for an expected minimum of five years and costs less than 10 dollar per piece. Pictograms on the device facilitate correct usage.

During a two-years development process microbiological and field tests were conducted in India. In addition to tests of usability, microbiological field tests were done under Indian sunlight conditions at the Institute of Medical Sciences/SUM Hospital (Bhubaneswar, India).

Results: This study indicates a high potential for solving the drinking water problem for low-income households by application of the WADI device. Its pictograms, intelligible across cultures, reduce the risk of insufficient exposure duration of the PET bottles. Furthermore, while the recommended disinfection duration for SODIS is six to 48 hours, WADI optimizes disinfection duration thereby effectively reducing average exposure duration. Efficient disinfection is possible in only 30 to 40 minutes under bright sky and intense sun.

Conclusions: SODIS/WADI has the potential to reduce waterborne infections. An intervention study is planned to investigate the reduction of waterborne diseases by using WADI. Furthermore, the cost reduction for the health care system by the reduced burden of diarrheal diseases will be evaluated.