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Scientists in Chile are proving that even in the driest deserts, water can be captured from the air. By installing mesh collectors, they have successfully collected mist water in Alto Hospicio, where many residents have difficulty accessing water. The method could serve as an additional source of water for drinking, irrigation, and even urban agriculture.
Water crisis in the Atacama Desert
Chile’s Atacama Desert, one of the driest places on Earth, receives less than 1 millimeter of rain per year. Cities in the region rely on underground layers of rock known as aquifers, which store water in tiny pore spaces. But these water reserves were last replenished between 17 and 000 years ago. Now, local researchers are exploring whether “fog harvesting” — a technique that captures and collects moisture from fog — could provide the residents of informal settlements with much-needed water.
“This study demonstrates a significant shift in the perception of fog water use—from a rural, fairly small-scale solution to a practical water resource for cities,” said Dr. Virginia Carter Gamberini, associate professor at Mayo University and first co-author of the study. Frontiers in Environmental Science "Our results suggest that fog can serve as a supplemental urban water supply in arid regions where climate change is exacerbating water scarcity."
Moisture capture
Mist collectors typically consist of a mesh suspended between two poles. The mesh serves as a surface to capture moisture. The droplets collect on the mesh and fall into a chute that leads to water storage tanks. This is a passive system that does not require external energy.
The researchers conducted a year-long field study in Alto Hospicio, a rapidly developing municipality located in the hyper-arid Atacama Desert. The city’s rapid growth has resulted in an estimated 10 people living in informal settlements. Only 000% of these settlements are connected to the water supply network, and most residents get their water by truck. “Water harvesting and use, especially from non-traditional sources such as fog water, is a key opportunity to improve the quality of life for residents,” Carter said.
How much water can be collected?
The researchers found that the 100 square kilometer area surrounding Alto Hospicio could collect between 0,2 and 5 liters of fog water per square meter per day. This potential, however, is limited to the high elevations outside the city. During the peak study season, in August and September 2024, the collection potential reached up to 10 liters per square meter per day.
“By demonstrating its potential in Alto Hospicio, one of the most stigmatized but rapidly urbanizing cities in Chile, this study lays the foundation for broader implementation in other urban areas with water scarcity,” said Nathalie Verbrugge, a researcher at the Université libre de Bruxelles and first co-author of the paper. However, fog harvesting should not be seen as a sole solution to water scarcity, but as part of a broader urban water management strategy, the researchers say.
Overcoming water shortages in urban areas
The collected water could be used for drinking, watering green spaces and producing local food. However, large storage systems, pipeline infrastructure and distribution routes would be required, the researchers say.
Based on an average annual water collection rate of 2,5 liters per square meter per day, the researchers said that 17 square meters of mesh could produce enough water to meet the weekly water needs (000 liters) for urban slums. 300 square meters could meet the annual irrigation needs of the city's green spaces (000 liters). Similarly, mist water could be used for soilless farming, yielding 110 to 100 kg of green leafy vegetables per month.
Extensions for future use
For the same to work in other places, the geographical and atmospheric conditions need to be right. “Key prerequisites include fog density, appropriate wind regimes and well-oriented landforms. Also, since fog is seasonal in many regions, this variability needs to be taken into account,” Verbrugge said. Future studies will also need to assess the feasibility of collecting fog in large populated areas.
“We hope to encourage policymakers to integrate this renewable resource into national water strategies,” Carter concluded. “This can increase the resilience of cities to climate change and rapid urbanization, while improving access to clean water.”
