To desalinate or divert? A comparative supply cost analysis for north coastal China

Seawater desalination is largely presented as a last resort to address water scarcity in closed basins. The question of whether seawater desalination can substitute for other costly measures, specifically large-scale diversion, has not been adequately assessed. To this end the full unit cost of supplying water to Beijing from the South-to-North Water Diversion Project, the largest in the world, is compared to desalination. Desalination appears to be much more cost-efficient than diversion, even when the diversion’s environmental externalities are excluded. By implementing desalination and water management options, China could substantially reduce water costs; this suggests that desalination should not be viewed only as a last resort.