01 November 2011

Water from fog harvesting

When plumes of fog gather above the mountains encircling a remote South African village, children are excited, knowing they will have clean drinking water at school.

When plumes of fog gather above the mountains encircling a remote South African village, children look at them with excitement, knowing they will have clean drinking water at school.

Like many rural areas in the country, running water in Tshiavha village in Limpopo province is scarce, but the school-based fog harvesting nets have brought some relief.

Mountainous landscapes and a misty climate make Tshiavha village one of the few areas in dry South Africa where fog can be captured, with a system used in the Andes and the Himalayas that remains a novelty here.

But with experts predicting that southern Africa will become drier and hotter over the next four decades, such schemes are getting a new look as South Africa prepares to host the next round of UN climate talks in November.

Water clean and safe

Erected in 2007 with the help of a local university, the fog trapped in the nets provides up to 2,500 litres of water on a good day.

"The water is clean and safe with no chemicals added," said Lutanyani Malumedzha the principal of Tshiavha primary school.

According to Malumedzha, access to clean water had significantly improved school children's health and reduced the outbreak of waterborne diseases.

"Children used to bring their own bottles of water to school during the hot and dry months. The water was collected from muddy wells and not suitable for human consumption," said Malumedzha.

SA water among best

In some areas, communities share drinking water with cattle.

Although South Africa's water quality is rated among the best in world, rural communities lag behind when it comes to having running water.

"We have learnt to appreciate water and treat it like a precious commodity," said Malumedza.

"Not a single drop is wasted. Some of it goes there," said Malumedza pointing to a vegetable garden which provides food for the school feeding scheme.

Water scarce in SA

The four-metre high mesh net which stands outside the school's playground resembles a volleyball net, except for a gutter at the hem where water droplets fall, leading to water tank a few metres away.

There are no electronics involved and the system requires little maintenance, Malumedza said.

As a relatively dry country, water is scarce in South Africa, and remote areas with no infrastructure are hardest hit by the changing weather patterns.

"This is a cost-effective alternative which can be successfully explored, given the water challenges in the country," said Liesl Dyson, a researcher from the University of Pretoria.

Fog not enough

Limpopo province in the north, which borders Botswana, Zimbabwe and Mozambique and is home to the renowned Kruger National Park, is one of the hottest regions in the country.

But the area is one of the few places in the country with a climate suitable for fog harvesting.

"Fog only is not enough, it also needs a bit of wind," said Dyson.

"It doesn't help much if the fog just settles on the mountains without moving," said Dyson.

Half the world average

She said the system was used in a few areas in the west coast and the Transkei in the Eastern Cape Province.

According to the Council for Scientific and Industrial Research, South Africa has annual rainfall of 490 millimetres, half the world average.

Even without the effects of climate change, South Africa is expected to face water shortages by 2025, and plans to build a new dam in Lesotho to pipe more water into the country.

(Sapa,November 2011) 

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