Can you use sunlight to clean water? The smile on WADI says yes

Contaminated Water is still one of the main causes for the diseases of millions of people worldwide. We’ve asked Lukas Landerl from HELIOZ some questions about it.

Why is it, in your opinion, so difficult to tackle this problem?

Lukas: Realizing the devastating effects that the consumption of contaminated drinking water has, the United Nations adopted the provision of access to safe drinking water into its Millennium Development Goals in 2000. Only ten years later, the access to safe drinking water was declared a basic human right. However, according to UNICEF/WHO (2014), 750 million people worldwide still do not have access to an improved drinking water source. The majority of these people lives in rural South- and Southeast-Asia and Sub-Saharan Africa.

In our eyes, there are several factors that simultaneously hinder disease control. The sheer size of the problems seems to impede both local and international politics to come up with a well-designed strategy of how to improve the situation both on a local and on a global scale. Creating awareness about waterborne pathogens and their effect on human health is the fundamental challenge that the public and the private sector need to tackle first, in order to make people sensitive to the drinking water issue. Insufficient infrastructure, including electricity, roads, sewage and of course water pipes, aggravates the problem and increases the people’s dependence on household water treatment. While too many people are still without access to safe water, a lot of progress has been made in the past 15 years and the UN has achieved its goal of halving the number of people without access to safe water by 2015.

WADI, an easy-to-use solar powered UV measurement device that is used as an indicator for the solar water disinfection (SODIS) method.

WADI, an easy-to-use solar powered UV measurement device that is used as an indicator for the solar water disinfection (SODIS) method.

Solar water disinfection already fascinated you during your studies. How did Helioz come up with WADI (Water Disinfection), an attachment to water bottles that can help people to properly disinfect water and how does it work?

Lukas: WADI is an easy-to-use solar powered UV measurement device that is used as an indicator for the solar water disinfection (SODIS) method. A happy smiley face on the WADI display indicates the point in time at which the UV-radiation of the sun has made contaminated water in a PET-bottle safe to drink.

SODIS is a natural process, in which the UV-radiation of the sun inactivates harmful pathogens in PET-bottles filled with water. The process only requires PET-bottles, which are filled with contaminated water and are then exposed to the sun. Over time, the sun’s UV-radiation will deactivate the harmful pathogens in the water. While this is as simple as it can get, a major limitation is that the duration of this disinfection process varies and is determined by the sun’s UV-intensity. WADI, which is placed next to the bottles, was developed to indicate this process and to make it reliable and practicable for affected people in low-income countries. Its happy smiley face on the display guarantees at least a 3 log10 (99.9%) reduction of coliform bacteria in the water.

How important is education and training for the effectiveness of WADI?

Lukas: As with SODIS; education and training is vital for the effectiveness of WADI. In a first step, people need to be made aware of the link between waterborne pathogens and diseases such as diarrhea. Only then, they may be convinced to use water treatment technologies to prevent future contractions of diseases. Consuming safe water is particularly important for children, who are most prone to contracting diseases. In a second step, people must be trained on SODIS and WADI. It must be clearly communicated what WADI does and what it does not do. It is also essential to know about the advantages of WADI as compared to SODIS alone, and to know the limitations of both SODIS and WADI (incl. its non-effectiveness against metal and chemical water pollution and its limited effect with turbid water). When selling larger volumes of WADI, we at Helioz offer complementary train-the-trainer session, in which we cover all the above mentioned topics. Whenever single orders are placed, we provide training via video call, phone or in person.

The measurement device you developed has a very unique display. How do people perceive your idea of using smiling faces to show the level of disinfection?

Lukas: We came up with the smiling face to indicate the completion of the disinfection process, because we believed it to be a universally understood sign. So far, we have received almost exclusively positive feedback on the sad and smiling faces, and people clearly know that they should only drink their water upon appearance of the smiling face. Only once we experienced that the smiling face was misunderstood, when people confused the smiling mouth with a mustache.


In which countries is WADI already in use? Can you estimate how many people already use the device?

Lukas: As of today, more than 2,000 WADIs are in use, spread over five continents. Estimating the size of the average household in our target countries at five people, it can be said that more than 10,000 people are currently using WADI. The majority of these WADIs are in India, Kenya, Papua New Guinea, Philippines, Thailand and Uganda. A part of the WADIs is also used by individuals for outdoor-purposes such as hiking or mountain-climbing.

While two large-scale projects in Mexico and Africa were planned for 2014, they had to be postponed because of unforeseen problems at our production partner site and because of the Ebola outbreak.

How much does the WADI cost? Can people afford to buy it?

Lukas: Depending on the order quantity, WADI costs between EUR 10.00-12.50 net ex works, Austria. Because of additional costs for international transport, import duties and taxes, distributor margins and national transport, the final purchasing price for the end customer typically adds up to about EUR 13.00-20.00. Considering the fact that one WADI can be used by an entire family, and that it neither requires batteries, spare parts nor maintenance for a period of at least two years, its total costs of ownership are relatively low when compared to competitive products. At the end of the day, affordability of WADI still heavily depends on the ruling importation regulations, and on the income level in the country in question.

WADI is part of the “empowering people. Network”. What benefits do you see for your work in being part of a network like this?

Lukas: By being part of the “empowering people. Network”, we are listed alongside some of the most innovative and promising water and waste water technologies on the market. Information about our WADI is therefore available for a large range of people, ranging from technology providers, development organizations, international organizations and private companies.   The epN therefore supports us in our efforts in taking WADI to the people who need it.

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