Agencies SANTIAGO (Chile)

Capturing water from fog - on a large scale - could provide some of the driest cities in the world with drinking water, according  to researchers in Chile. After studying the potential of fog harvesting in the desert city of Alto Hospicio, on the edge of the Atacama desert which is the world’s driest desert,  lead researcher Dr Virginia Carter Gamberini from Universidad Mayo said, "The city also has a lot of social problems. Poverty, drugs, many slums.

" With no access to water supply networks, people in the slums rely on drinking water that is delivered by truck. Average rainfall in the region is less than 0.19in (5mm) per year. However, clouds of fog that regularly gather over the mountain city are an untapped source, researchers say. The researchers  published their findings in the journal, Frontiers of Environmental Science.

Capturing fog water is remarkably simple - a mesh is hung between poles, and when the moisture-laden clouds pass through that fine mesh, droplets form. The water is then channelled into pipes and storage tanks. It has been used at a small scale for several decades, mainly in rural South and Central America,  in places with the right foggy conditions. One of the biggest fog water harvesting systems is in Morocco, on the edge of the Sahara Desert.

Carter and her colleagues carried out assessments of how much water can be produced by fog harvesting, and combined that information with studies of cloud formation in satellite images and with weather forecasts. Alto Hospicio's fog forms over the Pacific Ocean - when warm, moist air flows over cold water - and is then blown over the mountains. The reliably foggy conditions here allowed Carter and her colleagues to pinpoint areas where the largest volumes of water could be harvested regularly from the clouds.