Sustainability of Mexico City’s Water Supply. Measuring SDGs 6, 8, and 13

Cities are seen as agents of social and technological progress, and engines of global economic growth. It is estimated that 55 percent of the world’s population lives in urban areas, and this rate is expected to increase to 63 percent by 2050 (UN, 2025). This expansion of cities puts pressure on water resources and implies urgent attention to the challenges of achieving sustainable water management.

Urbanization processes alter the natural hydrological system of waterheds and decrease water availability in other territories (Cotler et al., 2010). In addition, they generate pollution of water bodies by discharging of wastewater that contains sediments, nutrients, organic matter, heavy metals, pathogens, and hydrocarbons, which cause the decrease of aquatic fauna, generates eutrophication (excess of nutrients in water), and increase health risks for those who live adjacent to the riverbeds (Spellman, 2014).

URBANIZATION PROCESSES ALTER THE NATURAL HYDROLOGICAL SYSTEM OF WATERHEDS AND DECREASE WATER AVAILABILITY IN OTHER TERRITORIES

In the social realm, cities present inequalities in access to water services, promote vulnerability to climate change (Choueiri et al., 2022; Choueiri & Vantaggiato, 2023), and lead to the lack of water availability in other territories since water required in cities is transferred from them.

Sustainable water management involves measuring the environmental and social impacts of city water systems and identifying improvement strategies that allow them to move towards meeting the Sustainable Development Goals (SDGs).

SUSTAINABLE DEVELOPMENT GOALS AND WATER SYSTEMS
To move towards the sustainability of city water systems, it is necessary to measure the limitations in the fulfilment of at least three of the 17 SDGs: SDG 6, which is directly related to sustainable water management and consists of ensuring equitable, affordable, and secure access to drinking water and sanitation services to all city dwellers; SDG 8, which establishes the need to have decent jobs and economic growth, which, applied to the agencies and institutions responsible for the provision of drinking water and sanitation services, implies ensuring that human resources required for operation, functioning, and managing of water infrastructure have decent jobs (WWAP, 2016), and SDG 13, which establishes climate action that seeks to adopt urgent measures to face climate change and its effects, implying that water systems in cities should reduce greenhouse gas (GHG) emissions generated by the use of energy in their processes.

This article presents an assessment of sustainability of Mexico City’s drinking water supply, considering the impacts of climate change by quantifying GHG emissions to meet SDG 13; assessing SDG 8 decent work indicators, and quantifying equitable and safe access to drinking water that corresponds to SDG 6. All this, based on a life cycle approach that allows us to assess impacts, from the extraction of the resource to its distribution as drinking water.


MEXICO CITY’S WATER SYSTEMS
Mexico City (CDMX) is the capital of Mexico and has a population of 9.2 million inhabitants, besides that of 47 co-urban municipalities, where 12.6 million people live. Mexico City receives a drinking water supply of 32 cubic meters per second on an annual average. 67.5 percent of this resource is groundwater (wells and springs within Mexico City) and 32.5 percent is surface water, coming mainly from the Cutzamala System in the State of Mexico, which contributes an annual average of 9.4 cubic meters per second, and to a lesser extent from the Magdalena River, within Mexico City, which contributes 0.63 cubic meters per second on an annual average.

Groundwater and surface water sources within the territory of Mexico City include 512 wells, 17 springs, and the Magdalena River. The water extracted is treated in 56 small water treatment plants in the city (with an installed capacity between 0.037 and 0.205 cubic meters per second), mainly through direct filtration or reverse osmosis. Subsequently, drinking water is distributed through 268 pumping and repumping plants (figure 1).

The drinking water supply system of Mexico City comprises three life cycle stages: raw water intake and extraction; water treatment; and water pumping for distribution. The energy and chemical inputs and operational personnel requirements for the functioning of dams, water treatment plants, and pumping systems are shown, both for groundwater extraction and distribution, and the local community is included as one of the sectors that form part of the system.

 Modificado de García-Sánchez et al., 2023

On the other hand, water from the Cutzamala System—with infrastructure located in the municipalities of Amanalco, San José del Rincón, Valle de Bravo, Ixtapan del Oro, Villa de Allende, and Villa Victoria in the State of Mexico, and those of Ciudad Hidalgo and Zitácuaro in Michoacán— has a flow of 15.7 cubic meters per second; 9.4 of them are sent to Mexico City and the rest is used in the State of Mexico. This water resource is captured and stored in seven dams in the State of Mexico (including the Villa Victoria Reservoir) and then purified at the Los Berros Plant (municipality of Villa de Allende). Subsequently, water is pumped through six pumping stations of the Cutzamala System, that raise it more than 1100 meters, and transport it more than 240 kilometers away, until it reaches Mexico City (CONAGUA, 2025).

Measuring the environmental and social impacts of drinking water provision in Mexico City requires a systemic approach in which the processes involved, the environmental contributions of the inputs used in each process, and the emissions to the environment are visualized.

GREENHOUSE GASES EMISSIONS
To generate an inventory of GHG emissions of Mexico City’s drinking water supply system, we quantified the electricity required by each stage of the life cycle: collection and extraction, purification, and distribution. The inventory is based on the electricity consumed because it is considered the main input (Amores et al., 2013; García-Sánchez & Güereca, 2019). This information was obtained from the Secretariat of Integral Water Management of Mexico City (SEGIAGUA) for the infrastructure of Mexico City, and from the National Water Commission (CONAGUA) for the data referring to the Cutzamala System. Once the information was obtained, the electricity required for each cubic meter and for each stage of the life cycle was calculated. GHG emissions were calculated based on electricity use (table 1).

The unit of measurement for GHG emissions is carbon dioxide equivalent, a standard for the synthesis of various types of emitted gases.

 Elaboración propia con datos de SEGIAGUA y CONAGUA

The results show that for every cubic meter of drinking water that reaches homes in Mexico City, 2.81 kilograms of carbon dioxide equivalent (CO2 eq) are generated. This value is 326 percent higher than what was calculated, for example, for the city of Tarragona, Spain, where 0.86 kilograms of CO2 eq are emitted per cubic meter (Amores et al., 2013). This difference comes from the high electricity requirement of the Cutzamala System in the distribution stage (4.86 kilowatts per hour per cubic meter), while the electricity required for pumping in the distribution stage in Mexico City is 0.56 kilowatts. Another factor influencing the system’s carbon emissions is the national energy matrix, which includes more than 70 percent of fossil fuels. 

If we consider that the estimates of water lost through leaks in Mexico City range between 12 and 14 cubic meters per second (between 35 and 43 percent of the total), it can be argued that the flow that arrives from the Cutzamala System—and that generates most of the GHG emissions—escapes. This is an indicator of the need to reduce water leaks in Mexico City, while the country advances in the generation of cleaner energy. These actions, although they constitute a great challenge, are essential for Mexico City’s water supply system to advance in the fulfillment of SDG 13. 

SOCIAL LIFE CYCLE ASSESSMENT
Life Cycle Assessment (LCA) is a methodological approach that evaluates the potential environmental and social impacts of a product, service, or organization throughout its life cycle. It is based on a systemic approach where inputs and emissions from every unique process are quantified to generate the Life Cycle Inventory (LCI), from which potential environmental impacts are modeled. When LCA studies focus on analyzing social impacts, they are called Social Life Cycle Assessment (S-LCA) and they consider the social impacts that affect or benefit the sectors involved in the life cycle of the product: workers, local community, or chain of value (instead of considering supplies and emissions of energy, materials, and chemical compounds).

García-Sánchez et al. (2023) carried out a S-LCA study focused on the urban water cycle in Mexico City, establishing the water supply system as a reference, with its life cycle stages of collection and extraction, purification, and distribution. SDGs 6 and 8 were adopted as references, as well as sustainability criteria based on the intrinsic value of the well-being of those involved (Sala et al., 2015).

To assess the progress of SDG 6, the study quantified the social impact in the category of local community, specifically analyzing the municipalities of Villa de Allende and Villa Victoria because they have key infrastructure, such as the Los Berros purification plant and the pumping system for distribution from the Cutzamala System, and also because in their communities social conflicts have appeared due to the lack of drinking water supply. To carry out the evaluation, the category of access to water resources was considered including the following indicators: 1. Access to drinking water in frequency, quality, and availability; 2. Access to drainage infrastructure, and 3. Availability of an exclusive, complete bathroom (figure 2).

El diagrama muestra los sectores involucrados y las categorías y subcategorías de indicadores del ACV-S utilizadas para la evaluación.

 García-Sánchez et al., 2023

To analyze the degree of compliance with SDG 8, the social impact on workers of the drinking water supply system was evaluated, considering the working conditions necessary for decent work in the Cutzamala System and the CDMX system. This was carried out by measuring three subcategories: 1. Income, 2. Job stability (considering the type of contract and time in the position), and 3. Working conditions: working hours and social security (figure 2).

To obtain information from the local community, databases of the surveys of The National Institute of Geography and Statistics (INEGI) and telephone surveys were used. The telephone surveys were based on simple random sampling for people over 18 years of age and included 13 questions; they were made to random cell phone numbers obtained from the National Numbering Plan of the Federal Telecommunications Institute (IFETEL). The sample considered a total of 384 homes surveyed in the municipalities of Villa Victoria and Villa de Allende, with a confidence level of 95 percent and a margin of error of plus/minus five percent.

Regarding data on workers’ wages, job stability, social security, and working hours, the monthly remuneration databases published by the Secretariat of Integrated Water Management (SEGIAGUA) transparency website were used. Information on the number of overtime hours, requests for access to information were made to obtain databases at the plant level. Information on workers of the Cutzamala System was obtained through requests of access to information to the Aguas del Valle de México Basin Organization.

Processing of the SDG 6 information, referring to social impacts on the local community, is presented as social risk and is based on a 0-1 scale obtained from the normalization of the social performance found for each indicator. The scale has three levels: low risk (0-0.24) when households have limited access to water services in a maximum of two indicators in 24 percent or less; medium risk (0.25-0.44) if households have limited access to water services in two or more indicators, with deprivation values of 25 percent or more, and high risk (0.45-1), if households have limited access to water services in the three indicators with deprivation values greater than 25 percent.
Assessment of SDG 8—decent work—is also presented as social risk and, as in the local community category, analysis of this dimension is also based on normalized values and presented on a three-level scale: low risk (0-0.24) when in a maximum of two indicators of decent work there is a maximum of 24 percent of the workers under precarious conditions; medium risk (0.25-0.44) when in two indicators of decent work, between 25 and 44 percent of workers are in precarious conditions, and high risk (0.45-1) when 45 percent or more of workers are in precarious working conditions in all three labor indicators. 

Based on the above, in Villa de Allende and Villa Victoria, average levels of social risk of 0.55 in water precariousness were obtained, which places both municipalities at high risk, although Villa de Allende has a higher value (0.58) than Villa Victoria (0.51). This is because in Villa de Allende 59 percent of households do not have a drinking water connection inside their homes and 22 percent obtain water from other sources, such as other homes, rivers, or wells. In this municipality there is a lack of quality water because the parameters of manganese, fecal coliforms, and total coliforms are out of limits and 61 percent of households buy bottled water.
In Villa Victoria, 48 percent of households have a water connection, but not inside the house. In this sense, 39 percent of households obtain water from other sources. Water quality is poor due to turbidity and the presence of iron and manganese. It was also recorded that 77 percent of households consume bottled water.

This contrasts with the level of drinking water supply in Mexico City and is a sign of inequity and lack of social justice between Mexico City and the municipalities that provide it with water, while at the same time makes the need evident to move in a fairer and more balanced way towards the fulfillment of SDG 6, conceiving water supply in Mexico City as an integral system, both technically and socially, that not only benefits Mexico City, but all the municipalities and communities that make it up.

On the other hand, regarding SDG 8, workers in Mexico City face high social risk (0.6), due to working hours, since 80 percent of workers reported earning less than 366 U.S. dollars per month, an insufficient salary to cover their needs and those of at least one person in their care (Sehnbruch et al., 2015). In addition, 92 percent work an average of 14.38 hours overtime per week (higher than the maximum of nine hours established by the Federal Labor Law). The Cutzamala System has low social risk (0.24), because 98 percent of its 286 workers reported income between 366 and 544 U.S. dollars per month (overtime not considered) and this level of income is conducive to a lower social risk.

The different levels of social risk in Mexico City’s drinking water supply system show the need to improve working conditions: a more dignified wage for Mexico City that does not require people to work so many overtime hours to “make up for expenses.”

The results of this study coincide with some studies carried out in different countries in the field of water and sanitation, where the following human-resources problems have been identified: loss of experienced personnel, lack of financial resources to hire new personnel, lack of trained personnel and continuous preparation programs (Saravia-Matus et al., 2023). Therefore, it is necessary to have efficient training and education programs for workers of both Mexico City and the Cutzamala System in a comprehensive effort.
CONCLUSIONS
The supply of drinking water in Mexico City has a much higher level of GHG emissions than other cities’; this must be addressed by reducing leaks and moving towards an electricity system powered by a higher proportion of clean energy. 

The distribution stage generates the highest GHG emissions, mainly due to pumping at the Cutzamala System to Mexico City and to the distribution within it.

There is a high social risk in the local communities of Villa de Allende and Villa Victoria, in the Cutzamala System, due to water precariousness. This reflects inequity and lack of social justice between Mexico City and the municipalities that provide it with water, which speaks of limited progress in terms of SDG 6 for Mexico City’s water supply system.

There is also a high social risk due to job insecurity for workers who operate the drinking water infrastructure of Mexico City, mainly due to low wages and excessive weekly working hours. This reinforces the need to make progress in achieving SDG 6 targets. 

Based on the above, it is recommended that water supply systems work on the generation of metrics that allow the evaluation and reporting of comprehensive progress in the level of sustainability, including in an integrated way the progress in SDGs 6, 8, and 13.

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