What is the truth about Mexico City possibly running out of water and reaching its “zero day”?


For weeks, it has been one of the most frequent topics of conversation among its inhabitants: could Mexico City soon run out of water?

The scarcity is a fact, and proof of this is that, although the lack of water in some neighborhoods is not new, there have been an increase in temporary supply cuts in various areas of the capital and its metropolitan area in recent months.

A prolonged drought, the absence of rain, and temperatures much higher than usual for the time — even reaching 30 °C in recent weeks — have caused the water stored in the dams to be at a minimum and alarms to be raised.

The situation is so critical that specific dates were even spread about when the Valley of Mexico could reach its “zero day,” that is, the moment when it would be without enough water to meet the basic needs of the 22 million people that make up its population.

The news spread like wildfire on social networks, but the Mexican government denied that it was real.

Despite everything, the concern is evident, and some companies that sell containers for storing water saw their sales skyrocket due to the citizens’ unease.

To understand the severity of the situation, its causes, and whether it is true or not that the Mexican capital could be close to a general water shortage, BBC Mundo consulted several experts on the subject.

Dams at Minimum Levels

“We were already coming from three years of drought due to the ‘La Niña’ phenomenon, and now with ‘El Niño’ [which began in June 2023] the rains that were expected from January to date have not occurred, so we have a precipitation deficit in almost the entire country of 41.4%,” explains meteorologist Christian Domínguez Sarmiento.

“This is unusual and puts us in a tight spot.”

This climatic situation caused the Lerma-Cutzamala dam system, one of those that supply water to Mexico City and its metropolitan area, to be unable to store the necessary water and is currently at only 37% of its capacity “when historically at this time it was at 70%,” emphasizes Jorge Arriaga, coordinator of the UNAM Water Network.

The scarcity in these dams, located in the State of Mexico and Michoacán, caused the authorities to progressively reduce the volume of water they deliver to the Valley of Mexico over the last two years, going from 14.8 cubic meters per second to only 8 at present.

This reduction is the main reason why more areas of the capital — regardless of their location or other characteristics — have recently suffered more water cuts, because their supply comes directly from Cutzamala.

“What is different with other droughts in the city is that the regions that we previously considered to have a surplus of water, today also face drought. And that in the capital it is not only affecting traditionally less fortunate groups: everyone, rich and poor, is coming out to demand access to water,” highlights Roberto Constantino Toto, coordinator of the Water Research Network of the Metropolitan Autonomous University (Red AgUAM).

However, it is important to note that the Lerma-Cutzamala contributes just over a quarter of the water consumed in Mexico City and its metropolitan area.

Another 5% comes from the rivers and springs found in the valley, while the vast majority — more than two-thirds of the total — comes from wells that extract water from the aquifers.

Although the current major crisis is centered on the great visible scarcity in the dams, the groundwater is also affected by the lack of rain, which is necessary for its recharge.

“We are expanding urban areas excessively in places where we would have to put natural catchment systems that allow this water infiltration, because today we extract 215% more than what we are recharging,” warns Arriaga in conversation with BBC Mundo.

The Water Paradox in CDMX

Paradoxically, the problem of Mexico City throughout history was not the lack of water but the floods, having been built on an ancient lake and surrounded by mountains.

To face this risk, over the years, a set of outlets for the basin’s water and the drying of the lakes were artificially constructed, until in the last century the rivers were piped.

Thus, Constantino Toto points out, the capacity for reinjection and recharge of the underground sources became very poor because most of the rainwater that falls on the city is evacuated by the drainage system.

“We are victims of effective success in protecting the city, and the result is that, to be able to complete the rainwater that we send to the drainage, we have to import it from those regions where it does rain through this dam system that we have built,” he details to BBC Mundo.

The truth is that, currently, the infrastructure to supply water to a constantly growing population is totally insufficient and has great deficiencies.

“Today, 40% of the water is lost in leaks in the distribution networks. And the same Cutzamala system was planned for a 20-year horizon and continues operating after 40, without giving it major maintenance according to the needs,” exemplifies Arriaga.

The problems and damages that the underground water infrastructure presents also have to do with the fact that the Valley of Mexico is so vulnerable to earthquakes and suffers constant changes and movements in the ground.

Not to forget the sinking that Mexico City presents, motivated in part precisely by the water that is extracted from the aquifer and that causes the soils to compact and increase the speed of said collapse.

These characteristics of the Mexican capital have made water problems constant for many of its citizens for years. Thus, some areas normally have water service by rotation, which means that they only have supply at home during a limited schedule per day, or they receive it directly through tanker trucks or pipes.

This scenario has continued to worsen in recent years.

According to Constantino Toto, “at the beginning of the year 2000, there were barely 50 neighborhoods in Mexico City subject to the rotation regime, and today we have 386.”

And his forecasts are not at all optimistic. “Before the current crisis, the capital’s water system calculated that 20% of the city’s population was subject to this distribution. Now our estimates tell us that, if we continue the way we are functioning now, by the year 2030 it will be 70%. And that figure is worrying.”

Is it correct to talk about a zero day?

Despite being a historical problem, it was in recent weeks that the concept of a hypothetical zero day began to be heard loudly.

Among the first mentions is an initiative presented three years ago in the Congress of the capital, which states that this milestone could be reached by 2028, citing the United Nations as a source.

However, it is not specified in which document or statement of the international organization this estimate was announced.

But the most replicated forecast in media and social networks was that of the Organismo de Cuenca Aguas del Valle de México, dependent on the National Water Commission (Conagua), by which zero day could arrive this very June 26, 2024.

In response to questions from BBC Mundo, Conagua’s communication area assured that this date was “a misinterpretation” of the different scenarios that were presented at a press conference last November about the filling of the Cutzamala based on the water extracted from the system, which was then 9 cubic meters per second and was reduced to 8 last January.

“The Cutzamala contributes only a quarter of the water to the metropolitan area and complementary works are being carried out such as drilling and rehabilitation of wells, of water treatment plants… Therefore, it is not foreseen that there will be a point at which the city will not have water,” clarified said source.

Another recurring critical voice on this point was José Luis Luege, former head of Conagua and now part of the team of the opposition presidential candidate Xóchitl Gálvez, who assured in several interviews that even in April there could be very little availability to pump water to the Valley of Mexico.

“An opposition figure started a campaign to sow fear and uncertainty among the inhabitants of Mexico City by declaring that zero day was approaching (…). They lie, zero day is an invention,” stated in a press conference on February 21 Elizabeth García Vilchis, in charge of one of the sections of the ‘mañaneras’ of President Andrés Manuel López Obrador.

The experts consulted by BBC Mundo agree in ruling out that there is a near moment when the Mexican capital could run out of water, although they emphasize the seriousness of the current situation.

“Talking about that zero day and even placing it in June is irresponsible because what is now being affected the most is the Lerma-Cutzamala system, but we still have aquifer supply,” says Arriaga.

“But of course we are in a critical situation because it is not raining. And it is also serious that it has been calculated that there is underground water storage for between 40 and 50 more years. So, we might see that zero day then, but only if we do nothing and continue under this same situation,” he adds.

“It is worrying that if the rains are delayed, we will have to adjust to a situation of less water availability that we will have to share among all. Is this zero day for Mexico City? No. But it does bring us close to the zero day of Cutzamala, so it is important to resolve this crisis,” agrees Constantino Toto.

When will the rains increase?

One of the big unknowns now is whether the Cutzamala will be able to recover during the next rainy season, which usually runs between June and October.

However, meteorological models do not yet allow predicting what will happen on those dates.

“What we can know is that this season from March to May is going to be hotter than normal, causing more evaporation of water from the dams, and it is going to rain less than in other years,” explains Domínguez Sarmiento, a researcher at the Institute of Atmospheric Sciences and Climate Change of UNAM.

“This is going to get us into trouble because there is still a long way to go for the rainy season that usually starts in June, but it could also start in August… all this aggravates the drought conditions we were already coming from.”

Aside from the long-awaited arrival of rainfall, experts point to other initiatives that could be launched, in addition to raising public awareness about responsible water use.

Thus, the UNAM Water Network recently presented a study with different actions to ensure water security in the Valley of Mexico that range from improving infrastructure to the management and financing system for the coming decades.

“We need to separate stormwater drainage from wastewater [sewage] and recharge our aquifers with that rainwater. We need to reuse water. And now that elections are coming, it is a great time to guarantee a budget that allows us to rehabilitate the infrastructure to accelerate leak control programs and recover the hydrological balance of the basin,” says Constantino Toto.

“My great concern is that, when it rains again, water will cease to be an important social issue, because the dams will fill up and it will seem that it was not necessary to change for everything to remain the same. And it will be a great opportunity lost,” he concludes.

Source: BBC