Scientists and environmentalists have warned of a growing global water shortage – that could threaten communities around the world. Programs and policies are being studied to avert a crisis situation.

In Mexico City, one project is offering an example of how to manage the resource in one of the world’s most densely populated urban areas.

CGTN’s Alasdair Baverstock reports.

Morning rush hour in Mexico City, and above one of the capital’s busiest freeways, locals are enjoying one of the few green spaces available to them.

“Having pedestrian space that is simple, free and above all, is green, is really important,” one resident, Soledad Villa said.

But aside from a park built above a motorway, this installation is also a project in environmental sustainability.

It’s called the Ecoducto, and is engineered to collect and clean water.

By capturing both rainfall and city wastewater from nearby rivers, the installation harvests 30,000 liters a day and cleans it through biodigester tanks using natural methods.

The water is used to maintain the two-kilometer-long garden, while the plant life helps cleans air pollution from the traffic below, and what water remains is sent back to the city’s main water supply.

The project, completed in 2017, was led by Professor Alejandro Alva, a biologist at a local university.

“One of the lasting lessons we wanted to leave with this project is to show the possibility of creating wetlands inside cities, that we can rescue natural water systems in urban areas. We have to have respect, wisdom, and care when it comes to water and the life it gives us,” Alva said.

Maria Tomas from Barcelona heads up an urban planning architecture firm in Mexico City and said the Ecoducto is a good example of a modern approach to sustainable architecture.

“More and more in modern developments, we are seeing that water recycling systems are being installed. Because in the case of water crises, this type of infrastructure in your own building makes you less dependent on the main supply,” Tomas said.

As the Ecoducto now forms part of Mexico City’s landscape, there are hopes such a crisis here can be averted.

In a metropolitan area that counts 21 million residents, the rainwater harvested by the functioning Ecoducto may seem like a drop in the ocean. But its creators hope it will serve as an inspiration, both here and abroad, for innovative solutions to water shortages over the long term.