Lima, Peru has some rather unusual suburbs. Rural villagers who move into the capital often end up living on the outskirts of town — steep hillsides that envelop the city. The land is cheap, but it comes with risks and downsides, namely landslides and a lack of water.

In order to help remedy both problems, the government has set up a sort of homesteader’s law. If new residents squat on unclaimed land, after a time, they’re allowed to obtain the land’s title by planting trees uphill, an insurance policy against landslides. More trees also help re-establish the area’s natural water cycle, returning the precipitation that they don’t absorb themselves back into the groundwater.

The only problem is there’s not much water around for irrigation, or anything else for that matter. Residents of Lima proper rely on Andean lakes for their water needs — the city only gets about 0.5 inches of rain per year, according to National Geographic News. While some hillside residents can obtain access to that same water, it costs about 10 times as much.

So German conservationists and biologists Kai Tiedemann and Anne Lummerich have helped small developments set up fog collectors, snatching hundreds of gallons of water out of the Pacific fogs that roll in from June to November.

The simple collectors — nets made from a widely available mesh strung between two posts — trap the tiny, airborne droplets. As the droplets group together, they drip into a gutter. The most basic nets can collect more that 150 gallons a day; special multilayer nets can collect more than 600 gallons a day. With such lush water supplies, residents are better able to take care of their government-required groves, earn their titles and stabilize the hillside ecology.

More:
How do trees affect the weather?
How do fog machines work?
How Weather Works