Scientists tap the sun to produce clean water

The water kiosk has been in action in Mozambique

Swiss researchers have come up with a device that harnesses the power of the sun to disinfect water - a system that has potential for developing countries.

This content was published on February 22, 2011 minutes

The SwissWaterKiosk, which is being developed by a team at the Technical University in Rapperswil, is currently being tested in Bangladesh, Mozambique and Tanzania.

Almost 900 million people worldwide do not have access to clean water, according to the United Nations.

“The concept of the SwissWaterKiosk is to use sustainable technology to disinfect water. Our main goal is to create access to safe water for people who didn’t have access before,” Lars Konersmann, the project leader, told

The system uses solar thermal technology to heat up water. Research has shown that the water does not need to be heated to 100 degrees Celsius to kill off all the pathogens, said Konersmann. In fact, 75°C over five minutes is enough. But the kiosk remains on the safe side by using 80°C.

“The lower the temperature, the more efficient we can be, the more water we can produce with the same investment or material,” Konersmann said.

The system can clean 500 litres of water daily following an initial outlay of $500 (SFr482) for the device, which the scientists say is a comparable price to other systems.

Easy to use

The kiosk is intended for use at community level rather than in individual households, with a local entrepreneur in charge of the water production and distribution. The water may be sold at a low cost as a community service or given away for free, for example in schools and hospitals.

Konersmann says the main advantage compared with other technologies is that the kiosk is easy to maintain and works straightaway – important when applying technology in developing countries.

“Since the water treatment process is the same as boiling water, the technology is also easily understood and well accepted,” he added.

The second pilot phase, following a first phase to check the technology, is assessing the social aspects, especially different operation models. Tests are being run in three countries until the end of the year.

In Bangladesh, the project, based in Dhaka, has shown that the technology is not best suited to an urban setting because there are already large central water treatment systems that are more economic and efficient. However, there has been some good feedback from rural and semi-urban areas in Africa.

Schools and beyond

Swiss non-governmental organisation Helvetas has been running a two small pilots in northern Mozambique, where it has been active in water access and sanitation projects for many years. In March another five systems will be installed.

“The first systems are in schools and we will install a few more to test it in different contexts like health centres, more schools, but also in commercial outlets, such as restaurants which are interested in testing it,” Kaspar Grossenbacher, Helvetas’ programme coordinator covering Mozambique, told

It is still very early days, stresses Grossenbacher. At first the pupils were a bit reluctant to use the kiosk, but now they take their drinking water from it. 

There were a few issues: the water was a little warm and that the system didn’t work on the few cloudy days the region had in its rainy season, said the expert. “But nevertheless they continue using it and are interested in enlarging the quantities,” he added.

Safe water access

The water access situation in this region of Mozambique - one of world’s poorer countries - is critical, said Grossenbacher. Wells are the usual solution.

Helvetas doesn’t envisage the kiosk as providing access to safe water for rural communities as a whole as these have broad water requirements. The charity believes the system is at present suited to institutions where just drinking water is required.

“It is a targeted solution which we are testing for use by specific institutions,” Grossenbacher said.

An eventual idea could be to place the water kiosk in more densely populated areas with people coming to buy drinking water there, in addition to their well requirements. This is something that would have to be tested as it is a new concept, said Grossenbacher.

Konersmann says the aim is to finish the second pilot stage in the three countries with some success stories, with a view to expanding the system in these countries and beyond.

“Safe drinking water is a basic need for every human being,” he said. “It builds the basis for quality of life.”

Water access

Almost 900 million people worldwide do not have access to clean water and a total of more than 2.6 billion people do not have access to basic sanitation, according to the United Nations.

Studies also indicate about 1.5 million children under the age of five die each year and 443 million school days are lost because of water- and sanitation-related diseases.

The UN Millennium Development Goals, a series of targets for reducing social and economic ills, all by 2015, include halving the proportion of people who cannot reach or afford safe drinking water and halving the number who do not have basic sanitation.

Swiss researchers have been involved in various projects. For example, the Sodis method involves leaving a clear plastic bottle in direct sunlight for 6 hours. The sun's UV-A radiation renders any harmful microbes inert. It has been developed by the Swiss Federal Institute of Aquatic Science and Technology (Eawag).

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Ranked at 168 out of 177 countries of the poorest countries of the world, Mozambique’s income per capita is $310 per year with the majority of the population well below the poverty line.

Subsistence agriculture continues to employ the vast majority of the country's work force. Only approximately 32% of the population has sustainable access to improved sanitation.

Life expectance is particularly low, literacy remains at only 47 %. Overall the country has around 20 million people.

Source: Helvetas

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