Fog harvesting could ease water shortages in the world’s driest places

Fog harvesting may provide a crucial water source for people living in some of the planet’s driest regions. 

By capturing moisture from passing fog, this technique gathers droplets and channels them into storage, potentially easing shortages for those who have little or no connection to traditional water infrastructures.

Urban water solutions

The study was carried out by researchers at Chile’s Universidad Mayor, who examined whether fog harvesting could meet the needs of residents in informal settlements in the Atacama Desert. 

“This research represents a notable shift in the perception of fog water use – from a rural, rather small-scale solution to a practical water resource for cities,” said Virginia Carter Gamberini, an assistant professor at Universidad Mayor and first co-author of the paper.

“Our findings demonstrate that fog can serve as a complementary urban water supply in drylands where climate change exacerbates water shortages.”

Characterized by annual rainfall below one mm, Chile’s Atacama Desert has extremely limited water resources. Cities in the region often rely on groundwater reserves that were last recharged between 17,000 and 10,000 years ago. 

The goal of the research was to see if fog harvesting – a passive system that collects atmospheric moisture on mesh panels – could help alleviate the water needs of rapidly expanding urban areas.

Capturing moisture from the air

Fog collectors usually feature a mesh stretched between two posts. As fog rolls in, tiny droplets attach to the mesh, then trickle down into a collection gutter and onward to storage tanks. Because this setup requires no external power, it offers an appealing option in remote or infrastructure-poor environments. 

The research team conducted a year-long study in Alto Hospicio, a municipality in the hyper-arid Atacama with a fast-growing population. Approximately 10,000 people in Alto Hospicio reside in informal settlements, and most depend on truck deliveries for their daily water.

“The collection and use of water, especially from non-conventional sources such as fog water, represents a key opportunity to improve the quality of life of inhabitants,” Carter said. 

In the surrounding 100-square-kilometer area at higher altitudes, the researchers estimated a daily harvest potential of 0.2 to 5 liters of fog water per square meter, although fog density peaks in certain seasons. At times – such as August and September 2024 – fog yields jumped up to 10 liters per square meter each day.

Broader adoption of fog harvesting

“By showcasing its potential in Alto Hospicio, one of Chile’s most stigmatized yet rapidly urbanizing cities, this study lays the groundwork for broader adoption in other water-scarce urban areas,” said researcher Nathalie Verbrugghe of Université libre de Bruxelles, also a first co-author of the article. 

While the team emphasizes that fog harvesting alone will not solve chronic water shortages, they believe it can become part of a larger strategy for sustainable urban water management.

The scientists envision multiple uses for harvested fog, including drinking water and irrigation for communal gardens. They estimate that installing 17,000 square meters of mesh – capable of generating an average of 2.5 liters of water per square meter per day – could meet the weekly water needs (about 300,000 liters) for urban slums. 

For irrigating city green spaces, 110 square meters would cover an annual requirement of approximately 100,000 liters. Even small-scale food production is possible: according to the study, fog water could fuel soil-free agriculture, producing 15 to 20 kg of leafy vegetables a month.

Prerequisites for fog harvesting

Fog harvesting is dependent on specific geographical and climatic conditions. “Key prerequisites include fog density, suitable wind patterns, and well-oriented elevated landforms. Additionally, since fog is seasonal in many regions, this variability should be considered,” Verbrugghe said. 

Storage tanks, piping infrastructure, and distribution systems are likewise necessary to deliver the collected water where it is needed.

For large settlements, scalability becomes a critical question. If successful, fog harvesting would require significant planning, funding, and collaboration among local communities, government authorities, and possibly private sector partners. 

Yet the technique’s minimal energy demand and adaptability make it an appealing option, especially for regions forecast to face ever more severe water stresses under climate change.

Fog harvesting and resource planning

Encouraged by their findings, the researchers aim to integrate fog harvesting into broader, renewable water resource planning.

“We hope to encourage policymakers to integrate this renewable source into national water strategies,” Carter concluded. “This could enhance urban resilience to climate change and rapid urbanization while improving access to clean water.”

In places like the Atacama Desert, where traditional water supplies are both ancient and limited, fog harvesting could serve as a practical complement to existing resources. 

By combining multiple solutions – from groundwater to desalination to advanced conservation methods – communities may be better equipped to cope with the increasingly harsh realities of water scarcity.

The study is published in the journal Frontiers in Environmental Science. 

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