It probably will. Consider desalination, which removes salt from seawater. It seems like something between a miracle and a no-brainer. But desalination is expensive, and only a few small plants have been built in California. It also can generate greenhouse gases and requires disposal of brine. As some skeptics have joked, desalination is a promising future technology — and it probably always will be.
Water recycling is more promising, and its technologies are advancing. State policies call for more sophisticated systems that purify reclaimed water to a drinkable state. Only a few such facilities exist in the world.
Capturing stormwater could be cheaper. Diverting runoff into treatment systems or storage basins could, according to one analysis, add as much as 630,000 acre-feet each year in coastal cities.
And if times get really hard, water might be harvested from fog by placing fine mesh screens on seaward bluffs and dunes. Stay tuned.