• WADI uses simple progress bars and smiley faces to visualise the process of solar water disinfection.
  • Solar-powered, maintenance-free, portable UV measurement device that uses simple progress bars and smiley faces to visualise the process of solar water disinfection.


WADI is a solar-powered, portable UV measurement device that uses simple progress bars and smiley faces to visualize the process of solar water disinfection (SODIS). It measures the UV-A and UV-B radiation of the sun and indicates the point of time at which at least a 3 log10 reduction of coliform bacteria has taken place. The visualization of the progress of the solar disinfection process eliminates user uncertainty. 

WADI revolutionizes the way safe water is obtained, providing a cost-effective and sustainable solution for households, schools and communities of the Global South. It provides people with safe water for many years to come, using nothing more than WADI and the power of the sun. At the same time, WADI also makes a positive contribution towards the reduction of CO2 emissions, as the most common way to disinfect water continues to be boiling using wood or gas.

WADI has been tested by the WHO and meets their microbiological performance criteria for household water treatment technologies.

Worldwide, there are over 780 million people without access to an improved drinking water source. The problem is usually not water shortage as such, but lack of disinfected, drinkable water. In many countries, drinking water is contaminated with harmful bacteria or viruses. 80% of all illnesses and deaths caused by diseases in developing countries derive from insufficient or contaminated drinking water supply. Globally, an estimated 2000 children under the age of five die every day from waterborne diseases.

The sales price for WADI (ex works) is around 15 EUR. HELIOZ offers customized projects for NGOs as well as companies, including corporate social responsibility (CSR) and CO2 compensation projects. For detailed offers contact HELIOZ via office(at)helioz.org.

Stage of development: produced in serial production

WADI is a solar-powered UV measurement device that visualizes the process of solar water disinfection (SODIS). It is placed alongside bottles that are filled with contaminated water and exposed to the sun. Once the process is completed, a happy smiley face on the WADI display indicates that the UV-radiation has made the contaminated water safe to drink.

Solar water disinfection is simple: Contaminated water is filled into a transparent PET-bottle, which is then exposed to the sun. The UV radiation of the sun kills pathogens in the water and can thereby reduce waterborne diseases (e.g. Cholera). The SODIS method is approved and endorsed by WHO and by UNICEF.

Advantages of WADI:

Sustainable: no maintenance, no spare parts needed, 2-year warranty

Practicable: water resistant and dust proof (IP65), easy to transport

Scalable: simultaneous use of many bottles

Environmentally friendly: no batteries, no chemicals, no CO2 emissions

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Key Facts

Organization: Helioz GmbH - Austria
Website: www.helioz.org
Contact: Martin Wesian
Email: office@helioz.org
Operating in: Austria, India, Bangladesh, Uganda, Kenya, Ethiopia

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Water & Sanitation