It almost never rains here Fog harvesting to combat water shortages in the Atacama Desert

In the Atacama Desert, a research team is testing an unusual source of water: Fog. Special collectors could help cities without a water network - a solution with potential, but also limitations.

In the extremely dry Atacama Desert, fog could be a new source of water. A Chilean-Belgian study shows that special collectors could produce several liters of water per square meter every day.

With less than one liter of precipitation per square meter per year, the Atacama Desert is considered one of the driest regions in the world. Many cities use groundwater that comes from rainfall that last fell on a large scale between 10,000 and 17,000 years ago.

A research group has now investigated whether fog harvesting - a process for collecting and storing fog water - could be a simple and cost-effective solution for supplying water in the desert. The results have been published in the journal "Frontiers in Environmental Science".

Two posts, a net and a gutter

Special collectors are needed to collect fog water: These typically consist of a net that is stretched between two posts and collects moisture. The droplets collect on the surface, flow into a channel and from there into water tanks - without any external energy.

The concept is already being tested in rural regions of South America and Africa. The current study was designed to test the potential of the method for an urban environment.

The research team set up several fog collectors in and around Alto Hospicio, a rapidly growing city in the north of the Atacama Desert. Around 10,000 people live here in simple dwellings, of which only 1.6 percent are connected to the water network. Most of the inhabitants are dependent on water deliveries by truck. "Collecting water from unconventional sources such as fog offers a valuable opportunity to improve the quality of life," lead author Virginia Carter Gamberini from Chile's Universidad Mayor is quoted as saying in a press release.

The scientists found that in an area of 100 square kilometers around Alto Hospicio, between 0.2 and 5 liters of fog water per square meter could be collected daily. However, this was limited to higher areas outside the city limits. In August and September 2024, a collection potential of up to 10 liters per square meter per day was even determined.

Fog harvesting alone is not enough

The research team calculates that, based on an average water collection rate of 2.5 liters per square meter per day, a net area of 17,000 square meters would be sufficient to provide 300,000 liters of water per week for the urban slums. To irrigate the green areas (100,000 liters per year), 110 square meters of net area would be enough.

"By demonstrating the potential in Alto Hospicio, one of Chile's most stigmatized yet fast-growing cities, this study lays the foundation for wider application in other water-scarce urban areas," says study author Nathalie Verbrugghe from the Free University of Brussels. However, the method alone is not enough; it must be integrated into a more comprehensive water strategy.

The approach also offers opportunities for other arid regions of the world - if the geographical and atmospheric conditions are right. "The most important prerequisites include fog density, suitable wind patterns and well-aligned elevated landforms," says Verbrugghe. As fog is often seasonal, this variability must also be taken into account.

The collected water could be used for drinking as well as for irrigating green areas and for local food production. However, large storage systems and suitable pipelines would be required.