Limpopo school harvests fog to provide drinking water
Submitted by: Tholakele Nene, Thursday, April 3, 2014
Tshanowa Primary School in Thulamela District, rural Limpopo, has partnered with the University of Pretoria (UP) to implement a fog net system that provides 1,500 litres of clean drinking water every day for 171 school children, 7 staff members and the surrounding community. The system was built in 2013 on vacant land adjacent to the school.
Collecting droplets to provide water in areas of water scarcity
Tshanowa Primary School is situated in an area that suffers from water scarcity. The school is situated in the tropical part of the province, at 3347ft above sea level. The high altitude makes it difficult for the school to have running water from the nearby streams and rivers. However, this same high altitude provides an abundance of fog which can be collected and used to provide clean drinking water for the school and the community.
Project Manager Robert Maisha says that the high occurrence of fog inspired the idea to build fog nets in the area, “to assist the community as they were in dire need of clean drinking water”. He says that before the fog nets were built, the school and community had to walk long distances to collect water from streams and rivers. This water often needs to be boiled before being used.
The fog net system
The fog net system is a simple triangular structure where nets are erected between three 6metre high horizontal poles, mounted 9metres apart. As the fog moves through the nets, the water collects on the net and trickles down to a gutter at the bottom of the net. The water then goes through a sand filter to remove dirt particles. It is then emptied into a tipping bucket. From there it flows down a slope to a tank where it is stored and ready for drinking.
According to Maisha, the net collects 1,500 litres of water daily. This is used for drinking, sanitation, cleaning, and watering the vegetable garden at the school, which provides food for the school feeding scheme.
Maisha says that the fog system requires little maintenance, which is overseen by the university students and partners. Only two things require occasional maintenance: the gutters need to be cleaned and the students need to make sure that the cable ties are still intact, in case they get loose due to friction and bad weather. There are also other stakeholders that provide area based personnel to look after both the automatic weather station and the fog net.
When asked about what happens to the net during bad weather and in cases where they run out of fog. Maisha said that sometimes the area can be very dry and during that time no fog is accumulated. Therefore, the school has to depend on water that is stored in tanks and boreholes.
A work in progress
The fog net system forms part of a larger UP project that is run by Dr. L. Lyson with the help of UP students. “The project is basically about research into water availability and conservation, borrowed from a meteorological concept. In this instance, scientifically it was found that fog droplets can be collected to provide water in areas of water scarcity”, says Maisha.
Talking about the next step of the programme, Maisha said that there have been changes in the academic programme which influence the project going forward. However, he said, the University and the sponsors are exploring ways to deal with this and expand the project over the country, “paying more attention to the community need”.
When asked about which areas in South Africa are suitable for fog harvesting and what criteria they use when establishing a site Maisha explained, “We use GIS to locate high topography areas that are prone to fog. Areas include Mpumalanga, Limpopo, and parts of the Cape region (Escarpment)…Then there must be a need to provide water to that community, the area must be dry.”
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