The Los Angeles River in 2013. Engineers turned it into a narrow concrete channel in the 1940s, after a flood destroyed homes and left 100 people dead in 1938.
Credit: Steve Lyon/Flickr

For thousands of years, city planners have engineered water into submission — think aqueducts.

“That’s really the core of modern water infrastructure,” says David Sedlak, the author of Water 4.0. “It’s the ancient idea that the Romans gave us. Collecting water somewhere on the outskirts of the city, sending it with gravity into the city, and then when we’re done with it, we put it back underground in a sewer and send on its way.”

It’s the way most cities are designed. And you can hear the echoes of that ancient plumbing in Los Angeles, where rain answered prayers last month amid an epic drought. But that […]