Yemeni water trader Mohammed al-Tawwa runs his diesel pumps day and night, but gets less and less from his well in Sanaa, which experts say could become the world’s first capital city to run dry.

“My well is now 400 meters (1,300 feet) deep and I don’t think I can drill any deeper here,” said Tawwa, pointing to the meager flow into tanks that supply water trucks and companies.