Gulf states are among the most water-scarce in the world. With few freshwater resources and low rainfall, many countries have turned to desalination (where salt is removed from seawater) for their clean water needs. But Gulf states are heading for “peak salt”: the more they desalinate, the more concentrated wastewater, brine, is pumped back into the sea; and as the Gulf becomes saltier, desalination becomes more expensive. “In time, it’s going to become impossible to use desalination in a way that makes economic sense,” says Gökçe Günel, an anthropologist at the University of Arizona.