Reuters UK writes about water scarcity in Mexico City in an article entitled Mexico City battles water crisis with taxes, pleas.  Among other issues, they write

Leaks and theft mean nearly 40 percent of Mexico City water is lost before it reaches the tap and only half of what is left is metered. Officials are in a desperate battle to serve the 20 million residents and the business community at a time of declining rainfall.

Officials limited water service to many Mexico City neighborhoods last spring in the face of a dry spell not seen in nearly 70 years.