by Tim Willmott : Be the first to leave a comment
In 1987, the remote fishing village of Chungungo in Chile was transformed by the installation of a fog collecting system, after relying solely on water supplied by truck for years. With a dependable and affordable water supply, the growing population not only have domestic water but are also able to cultivate commercial crops and plant trees.
Although unconventional, the technology behind fog collection is amazingly simple: massive vertical shade nets are erected in high-lying areas close to water-short communities. As fog blows through these structures, tiny water droplets are deposited on the net, running down into gutters attached at the bottom, from where water is channeled into reservoirs and then to individual homes. In Chungungo, this system saw water flowing from local taps for the first time ever in 1992, providing more than 40 litres of water per person per day. After thirty years of development, fog harvesting initiatives have now spread throughout the mountainous coastal areas of Chile, Ecuador, Mexico, and Peru.
Like Chile, South Africa is an arid country where large sections of the population have inadequate water supply. Only 35% of the country gets more than 500mm of annual rain, most surface water sources are polluted, many ground water supplies are contaminated and water tables drop out of reach during drought. Tshanowa Junior Primary School in the Limpopo region is frequently shrouded in dense mist and rain, but the nearest water sources are a non-perennial spring located 2 kms away, and a dam 5 kms away. The school is located at the crest of one of the easternmost promontories of the Soutpansberg, 1,000 metres above sea level. Despite a relatively low elevation, the region is ideal for fog collection since moist maritime air from the Indian Ocean moves over the escarpment and against the mountains during the night and early morning.
The school obtained permission from the relevant local and tribal leaders to erect a fog water collection system on adjacent land, construction commenced in 1999 and local inhabitants were employed to assist. Each fog collector consists of three 6 metre high wooden poles, mounted 9 metres apart. Water dripping from the net into the gutter runs through a sand filter, then empties into a tipping bucket before flowing into a storage tank further down the slope. Within four days of completion, school children and members of the local community were drinking water collected by the fog screen, providing the community with an average of between 150 and 250 litres of water per day.