Collecting Fog Could Help Provide Water in Arid Cities, Study Says

Researchers have determined multiple ways that harvested fog could help meet water demand in arid cities, particularly those within the driest area on Earth, the Atacama Desert. From providing drinking water to irrigating landscapes to supporting hydroponic gardening, the new research shows promise in fog-harvesting technology.

In the study published in Frontiers in Environmental Science, scientists investigated the potential of fog collection in Alto Hospicio, Chile, an area threatened by water scarcity. The region receives less than 0.19 inches, or 5 millimeters, of rain per year, the BBC reported. Further, the Alto Hospicio region relies on underground aquifers for drinking water, and those aquifers have not been replenished in 10,000 to 17,000 years.

While fog harvesting for water has been considered previously, the study authors noted that this method is typically considered for rural areas. However, the scientists found that fog harvesting could also supplement the water supply in larger urban areas.

“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,” Virginia Carter Gamberini, co-author of the study and assistant professor at Universidad Mayor, said in a statement. “Our findings demonstrate that fog can serve as a complementary urban water supply in drylands where climate change exacerbates water shortages.”

Fog harvesting in Chile's Atacama Desert shows potential as a supplementary urban water source, collecting up to 10 liters per square meter daily, aiding water-scarce regions with sustainable solutions.

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— Science X / Phys.org (@sciencex.bsky.social) February 20, 2025 at 12:32 AM

Researchers used Standard Fog Collectors (SFC), originally described in a 1994 study, to capture fog and measure the water harvested from it. The SFC is a mesh device suspended between two posts and attached to a metal channel with a coating to protect from corrosion. The metal channel then funnels that water into storage tanks with rain gauges that could measure the amount of water harvested from the fog every 10 minutes.

The team conducted their observations from October 2023 to October 2024 and coupled the results with modeling to further determine the fog collection potential.

They found that they could harvest an average of about 0.2 to 4.9 liters of water from fog per square meter per day within a total area spanning 100 square kilometers. During peak fog times of the year, the SFCs collected up to 10 liters of water per square meter each day. In December, fog water collection was zero.

They found that early mornings, between midnight and 9 a.m., yielded the most fog, with about 140 milliliters per square meter collected every 10 minutes.

“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 Nathalie Verbrugghe, co-author of the paper and a researcher at Université libre de Bruxelles.

These insights allowed the researchers to explore potential use cases for this water, especially if governments place the SFCs in areas with higher fog potential. The authors determined that about 17,000 square meters of mesh would be necessary to meet 300,000 liters of water demand. While this option wouldn’t be a sole solution to water scarcity, the authors emphasized it could offer an additional source of water to help meet demand.

In addition to providing potable water to households, the authors found that this collected water would be useful for irrigating farms and hydroponic gardens because it typically doesn’t require much treatment. With an average collection of 2.5 liters of water per square meter each day, this water could yield about 15 to 20 kilograms of hydroponically grown vegetables per day in Alto Hospicio, according to the study.

However, the authors wrote that the fog water quality will be dependent on air quality, so testing will be important in evaluating the potability of the harvested water. Further, cities would need to invest in infrastructure to collect, store and distribute the collected water.

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