The port city of Tianjin is in desperate need of water. The surface and groundwater supplies of this sprawling northeast Chinese metropolis have shrunk to dangerously low levels due to decades of reduced rainfall and overexploitation of the Hai River that flows through the city. According to the Tianjin Environmental Protection Bureau, the city’s per capita water resources are one-twentieth of China’s national average, far below the UN benchmark for a water-stressed region. Despite promoting water conservation and metering among residential and industrial users, Tianjin still faces shortages that drive its reliance on large-scale water-supply infrastructure like the South-North Water Transfer Project and seawater desalination. 

In the United States, a similar situation is unfolding. After a prolonged drought between 2011-2015, California’s investment in desalination solutions to supply fresh water to the state’s dry south grew exponentially. While most American desalination plants are used to purify less-saline “brackish water” from rivers and bays, large-scale seawater operations have begun to proliferate in California, as well as Florida and Texas. California alone has 11 municipal seawater desalination plants, with 10 more proposed. Southern California-based Poseidon Water LLC opened America’s largest desalination facility in Carlsbad in 2015, which currently meets about 10 percent of San Diego’s water demand. With the capacity to produce 54 million gallons of water a day, this new desalination plant, as well as another one currently in the works at Huntington Beach, could ensure water security in Southern California.