With nearly 22 million people living in its surrounding areas, Mexico City is one of the biggest urban centers in the world. But due to climate change and a local water crisis, the city - built 7,800 feet above sea level - is collapsing.
Nearly 20% of residents lack access to clean water, so Mexico City keeps drilling deeper for more, weakening the ancient clay lake beds on which the Aztecs first built much of the city.
Some areas of the city are sinking at a rate of 9 inches per year. Sidewalks in neighborhoods like Iztapalapa resemble broken china, and 15 elementary schools have crumbled or caved in.
Isla Urbana has designed a rainwater harvesting system to enable communities to catch rain, filter it and use it for the greater part of the year. The organization believes that rainwater harvesting could provide up to 30% of the capital's water supply.
