The Mexican capital is built on the spongy soil of a former lake bed. So much water has been extracted from shallow near-surface wells that the city is sinking.
Mexico City Mayor Miguel Angel Mancera visited the new drilling site Wednesday. He says more drilling is needed to explore the deep limestone strata and determine how much water is there.
The city also has to pump in water from outside sources to supply more than 21 million people living in the greater metropolitan area.
Paradoxically, the city is also plagued by periodic flooding because it sits in a mountain-ringed valley with no natural outlet.