Clean water is a human right

One of the biggest problems in many developing countries is the lack of clean, hygienically safe water. It is estimated that about half of the people in these countries suffer from diseases caused by polluted drinking water or lack of hygiene. It is particularly tragic that contaminated water is the second most common cause of death among children worldwide.

Since 2011, the Swiss "WaterKiosk Foundation" has therefore set itself the goal of providing as many people as possible with safe access to clean drinking water. To this end, the Foundation commissioned the Swiss Institute for Solar Technology in Rapperswil to develop a solution. This is called "Solar Water Disinfection" (SoWaDis) and has been used since 2011, mainly in Bangladesh and Tanzania. Without need for conventional electricity, purely solar-powered, and without additional operating materials, the systems are self-sustaining. They do not require chlorine or time-consuming cleaning of filters – it is a robust and inexpensive technical solution that is easy for the local people to understand and maintain.

The water treatment technology "SoWaDis" is based – somewhat like the boiling of water – on a thermal disinfection powered by solar energy. The water first flows through a heat exchanger and is heated to 65 degrees. It is then heated up further to 82 degrees in a solar collector. In this process, pathogens such as bacteria, viruses and protozoa are reliably killed within a few minutes; a thermally controlled valve and the construction-dependent residence time of the hot water ensure adequate cleaning. Up to 600 litres of drinking water can be produced daily in this way, and for larger quantities, the system is modular extendable.

Wieland Thermal Solutions supports the "WaterKiosk Foundation": In 2011, 70 coaxial heat exchangers for the "SoWaDis" heat treatment plants were donated to the Swiss foundation. Robust and low-maintenance, they are still making a valuable contribution to clean water and thus a healthier life in numerous schools, hospitals and villages in Tanzania.