The Solution: WADI

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WADI™ is a solar powered UV-measurement device that visualises the process of solar water disinfection (SODIS) in a PET-bottle. A happy smiley face on the WADI™ display indicates the point of time at which the UV-radiation of the sun has made contaminated water in a PET-bottle safe to drink.

Solar water disinfection is a natural process, in which the UV-radiation of the sun inactivates harmful pathogens in the water. The process only requires PET-bottles, which are filled with contaminated water and are then exposed to the sun. The duration of this disinfection process varies and is determined by the sun's UV-intensity. WADI™ was developed to visualise this process and to make it reliable and practicable for affected people in low-income countries.


WADI™ measures the UV-radiation of the sun and lets the user know as soon as at least 99.9% of coliform bacteria in the water have been inactivated. By the use of solar water disinfection and WADI™, the occurrence of waterborne diseases in low-income countries can be strongly reduced.

In comparison to other disinfection methods, the advantage of this technique is that it neither requires filters, chemicals, batteries nor maintenance. Solar water disinfection makes sole use of the disinfecting power of the sun's UV-radiation. In combination with WADI™, the method provides low-income households with a practicable and sustainable solution for getting access to clean water. WADI™ comes with a product guarantee of two years.

Meanwhile thousands of WADIs can be found around the global south, assisting people every day in simple and effective access to clean drinking water. Through our close cooperation with local partner organisations that help to deliver the WADI to the places where it is needed most, we know first hand about the positive impact clean drinking water can have on people’s quality of life and this does not just apply to the local population.

In addition to the decisive reduction of incidences of mortality and sickness, practising water purification with the WADI can also have strong economic and ecological components. Poverty and contaminated water tend to go hand in hand. Less water borne diseases with the WADI means less expenditure on medicine and doctors, less lost days of work, less time spent on looking for firewood to satisfy boiling the daily need for drinking water and less deforestation and CO2 emissions. Providing clean drinking water with the WADI can therefore not only leverage people to climb out oft the poverty trap, but also help to preserve the living ecosystems on which we all depend.


We thank all our partner organisations for the advancement and implementation of the targets that we have set ourselves with the WADI. It is their tireless efforts that are turning our ideas and hopes into reality.