Experts say that Mexico City could run out of drinking water by the end of June, an event locals call “Day Zero.”

Mexico City has long struggled to bring water to its millions of residents, but three consecutive years of low rainfall and high temperatures have created a serious emergency.

The Cutzamala water system — a series of treatment plants, reservoirs, and canals that provide water to tens of millions of people — is running dry.

Conditions are so bad that the North American Drought Monitor classified the federal district containing Mexico City as “severe” on April 30. Locals expect “Day Zero” could come as soon as June 26, according to Mexico Business News.

While local politicians downplayed the water crisis for months, several neighborhoods have already seen their water run out, CNN reported.

The Mexican government to describes the Cutzamala system as “vital to the lives of millions of Mexicans” living in the Mexico City Metropolitan Area and the Valley of Toluca Metropolitan Area.

The system normally moves about 15 cubic meters of water a second and provides service to about 22 million people. It’s now operating at 28% capacity, The Washington Post reported.

Crumbling infrastructure is also contributing to the problem. About 40% of Mexico City’s water is lost due to leaky pipes and other issues, the Post reported.

Gabriel Quadri de la Torre, a federal congressman for the Mexico City district of Coyoacán, told the outlet that fixing the pipes would cost billions and that it’s “very difficult to think” the city will have the money to pay for it.

With June 26 fast approaching, the city desperately needs rain. But rainfall might cause a “false sense of security,” Christina Boyes, a professor at the Center for Economic Research and Teaching in Mexico City, told the Post.

Researchers from the National Autonomous University of Mexico said in a study that intensive water capture, using treated residual water for agriculture, and refilling aquifers with surface water, could save the Cutzmala system, according to Mexico Business News.

The study found that only 75% of farms in the area use irrigated water, and most do not reuse the water when they can. Still, the study’s plan would cost an estimated $5 billion, the report says.

Mexico’s National Water Commission announced in February that it’s working on projects to improve the Cutzamala system and help supplement some of the water it is losing. As part of the action, the Mexico City Water System introduced a plan to improve infrastructure reliability, strengthen programs for private company participation in the water network, and harvest rainwater in schools, the agency said.