ON A DUSTY hilltop in San Diego, the drinking water of the future courses through a wildly complicated and very loud jumble of tanks, pipes, and cylinders. Here at the North City Water Reclamation Plant, very not-drinkable wastewater is turned into a liquid so pure it would actually wreak havoc on your body if you imbibed it without further treatment.
First the system hits the wastewater with ozone, which destroys bacteria and viruses. Then it pumps the water through filters packed with coal granules that trap organic solids. Next, the water passes through fine membranes that snag any remaining solids and microbes. “The pores are so small, you can’t see them except with a really powerful microscope,” says Amy Dorman, deputy director of Pure Water San Diego, the city’s initiative to reduce its reliance on water imported from afar. “Basically, they only allow the water molecules to get through.”