He’s Pulling Water Out of Thin Air in the Atlas Mountains

High in the Anti-Atlas Mountains of southwestern Morocco, the air is thick with a mystery the local Berber people call "tagut." For centuries, this dense, rolling fog was seen as a nuisance, a damp blanket that made paths slippery, rusted tools, and, according to local legend, stole the rain before it could reach the parched earth. But where others saw a curse, Dr Aissa Derhem saw an equation for survival. A mathematician by training and a visionary by nature, Derhem has spent the better part of two decades proving that the very mist the community feared was actually the solution to their most desperate problem: a lack of water.

Derhem’s journey as a maker didn't start on a mountain peak, but in the cold libraries of Canada in 1989. While studying for his PhD in mathematics, he stumbled across research on fog-harvesting projects in Chile’s Atacama Desert. It was a "eureka" moment that bridged two worlds. He realised that the unique microclimate of his home region, where the cold Atlantic currents meet the warm African landmass, created a persistent anticyclone perfect for "milking" the clouds. When he returned to Morocco, he didn't just bring back a degree; he brought back a mission to save the villages that were emptying because the wells had run bone-dry.

The path from theory to reality was anything but smooth. Making something that works in the laboratory is one thing; making it survive the brutal 70 km/h winds of Mount Boutmezguida is another. Derhem’s first attempts involved traditional woven "Raschel" nets, which were quickly shredded by the fierce gusts. Instead of giving up, he leaned into the failure, searching for a more resilient material. He eventually partnered with German engineers to implement the "CloudFisher" technology, a robust, industrial-grade 3D mesh supported by a frame that can withstand winds up to 120 km/h. These nets don't just sit there; they are engineered to move with the wind, trapping millions of tiny droplets that condense and trickle down into collectors.

Today, the summit of Mount Boutmezguida, sitting at 1,225 meters above sea level, looks like a field of giant metallic spiderwebs. It is the largest functioning fog-collection system in the world. These nets harvest an average of 22 litres of water per square metre on a foggy day, which adds up to roughly 37,000 litres of pure, potable water. Because this "cloud water" is naturally distilled and lacks minerals, Derhem engineered a system to blend it with underground water, ensuring it tastes right and provides the necessary nutrients for the 1,600 people it serves.

For Derhem, this isn't just about pipes and mesh; it’s about restoring the dignity of the Berber people. Before the nets, women and girls would spend up to four hours a day trekking to distant, contaminated wells. Now, that time is spent in schools or producing argan oil. "Fog is like aeroplanes at the start," Derhem often says, "at the beginning they were only little toys, but with effort, things have changed". He has turned the invisible moisture of the air into a visible future for his people.

Lessons for Budding Makers

Dr Aissa Derhem’s decade-long quest to harvest the Moroccan mist offers vital insights for any creator tackling environmental challenges:

1. Look for the "Invisible" Resource: Derhem realised that the fog, which his community considered a nuisance, was actually a latent resource waiting for the right tool to unlock it.
2. Prototype for the Extreme: When his first nets were destroyed by high winds, he didn't abandon the project; he went back to the drawing board to find materials like the CloudFisher mesh that could survive the actual environment of the mountain.