The effects of scarcity

The higher value ascribed to water has less to do with depletion and scarcity than cost. While there's as much water on the planet as there has ever been, cheap water is in short supply. "All the easily tapped sources have already been tapped," by damming up rivers and other methods, says Neil Berlant, lead manager of the PFW Water Fund (PFWAX), the only open-end mutual fund focused exclusively on water-related stocks. What remains are more expensive sources of water—from oceans, groundwater, or reclaimed used water—which require either desalination, chemical disinfectants, or other processes to be made suitable for drinking.

There's plenty of technology available to clean up water to meet increasingly strict public safety standards, but consumers will have to get use to paying higher rates to local water systems to pay for the necessary treatment. People in the developing world have long had little access to clean drinking water because of how much it costs.