WADI is a sustainable and cost-efficient point-of-use solution for the lack of safe drinking water to reduce waterborne diseases, child/infant mortality, and health care expenditures and equally increase social development.
The WADI device traces the progress of solar water disinfection in a PET bottle by detecting and calculating the UV-A rays of the sun, indicated by a status bar and smiley face. WADI makes the SODIS procedure attractive, calculable and visualizes the method for end-users. WADI, developed in cooperation with the ETH Zurich, is going to significantly ease the usability of solar water disinfection, making the SODIS procedure calculable and strengthen the acceptance of the SODIS method.
With its built-in solar panel, WADI is energy-self-sufficient, affordable and needs neither spare part replacement nor maintenance for at least two years (guaranteed). In the near future, WADI will have a guaranteed lifecycle of five years and will be made of recyclable plastic, in line with cradle to cradle design which stands for eco-efficient production. The device can be used and shared by several persons and families since many bottles of water can be disinfected simultaneously. Internationally understandable pictograms on the device facilitate correct usage. WADI is not only meant to be a life-saving tool which satisfies basic human needs but also a lifestyle product which brings easy and inexpensive solar water disinfection to remote low-income households
WADI facilitates the consumption of safe and clean water in an efficient and affordable way, it improves health and environment and contributes to the Millenium Development Goals and the human rights.
Solar disinfection is a simple, ecological and affordable solution for lack of safe drinking water. Contaminated water is filled in a transparent PET-bottle and exposed to the sun for some time, depending on the UV intensity. For example, near the Eastern coast of Central India, the microbiological disinfection takes only about 30 to 40 minutes under bright sky and relative intense sun during the month of April. The water must be relatively clear (max. 30 NTU - Nephelometric Turbidity Unit) and the bottles must be transparent, clean and unscratched. Solar water disinfection is approved by the WHO for being the simplest and cheapest water disinfection system.
How it works:
Contaminated water is filled in a transparent PET-bottle, the WADI device is put on the bottle like a screw cap and both are exposed to the sun for some time, depending on the UV intensity. A progress bar indicates duration and as soon as the display shows a smiley face, the water is ready for drinking.
WADI itself was designed for usage without any training. In most of the Southern countries especially children and women are responsible for procuring water and sometimes cannot read nor write. Helioz has designed self-explanatory pictograms which are located on the device to ensure easy implementation and enhance the usability of the water disinfection tool.
Tests and usage in Kenya, Rwanda, India and Mozambique have shown that
WADI is easy to handle and that the use of it soon integrates in the daily routine. Furthermore these tests have shown that the use of WADI alleviates the daily chores of the users. Still, awareness building and behaviour change are critical factors for spreading and fostering the use of this simple and cost-efficient tool on a sustainable and longterm basis.
Solar water disinfection (SODIS) is a method for disinfecting water using only sunlight and plastic PET bottles. At a water temperature of about 30°C (86°F), a threshold solar radiation intensity of at least 500 W/m2 [Watt per square metre (all spectral light)] is required for about 5 hours for SODIS to be efficient. This dose contains energy of 555 Wh/m2 (Watt hours per square metre) in the range of UV-A and violet light, 350 nm-450 nm. At water temperatures higher than 45°C (113°F), synergistic effects of UV radiation and temperature further enhance the disinfection efficiency.
SODIS is a free and effective method for decentralized water treatment, usually applied at the household level and is recommended by the World Health Organization (WHO) as a viable method for household water treatment and safe storage.