Mexico possesses a substantial inventory of water resources, primarily replenished by significant annual precipitation, yet faces a paradox of scarcity. The total quantity of water available is vast, but water security hinges critically on its accessibility and management. Understanding the reality of water availability requires examining where the water is located, how it is used, and the rate at which these resources are being depleted.
Measuring Mexico’s Renewable Water Resources
The quantifiable national water supply is primarily defined by the Annual Renewable Water (ARW), which represents the total volume of water naturally replenished each year. This figure is calculated by summing the average annual natural runoff and the mean recharge of groundwater reservoirs. The average natural water availability for Mexico is estimated to be approximately 458 cubic kilometers per year, forming the foundation of the country’s hydrological system.
The ARW figure is a net value derived from the country’s total precipitation, which averages about 1,488 cubic kilometers annually. A significant portion of this volume, estimated at around 72.5%, returns to the atmosphere through evapotranspiration and is not available for direct use. The remaining volume makes up the renewable surface and groundwater resources.
The distinction between renewable and non-renewable sources is important for resource management. Renewable water is replenished by the continuous cycle of precipitation, while non-renewable or fossil water is stored in deep aquifers with extremely slow or no recharge rates. Reliance on these irreplaceable fossil water sources, particularly in arid regions, complicates the calculation of a sustainable total supply, as the water is technically a finite resource being drawn down over time.
Geographic and Source Distribution
The physical location of Mexico’s water is characterized by a profound geographical imbalance that dictates much of the resource challenge. The vast majority of the country’s renewable water resources are situated in the humid South and Southeast regions. Conversely, the North, Central, and Northwest regions are predominantly arid or semi-arid, yet they are home to a large percentage of the population and the majority of the industrial activity.
This disparity means that two-thirds of the national territory receives low annual rainfall, concentrating the population in areas with less surface water availability. Water sources are broadly divided into surface water (rivers and lakes) and groundwater (extensive aquifer systems). Given the low surface water availability in the central and northern states, there is an intense reliance on groundwater extraction to meet demand.
Mexico has identified 653 distinct aquifers across its territory, which serve as a foundational source for nearly 40% of the national water supply. These underground reservoirs are particularly vital for major metropolitan centers, including the Valley of Mexico, which relies heavily on them despite limited local recharge. The geographical mismatch between water availability and concentrated population centers is the primary driver of the nation’s water struggles.
National Water Consumption Patterns
The available water resources are allocated across three main sectors of use. The dominant consumer by a considerable margin is the agricultural sector, accounting for approximately 76% of all water consumed nationally, primarily for irrigation purposes. This overwhelming proportion reflects the extensive need for irrigation, particularly in arid and semi-arid regions that produce a significant portion of the country’s food.
The next largest user is the public supply sector, which includes water for domestic and municipal use, accounting for roughly 14% of the total national consumption. This fraction covers drinking water, sanitation, and other household needs for the country’s growing population. The remaining volume, approximately 10%, is allocated to industrial uses, including manufacturing, power generation, and mining.
The enormous share claimed by agriculture is often compounded by systemic inefficiencies. It is estimated that a substantial amount of the water allocated for irrigation is lost due to outdated practices, leaks in infrastructure, and evaporation. Addressing this inefficiency in the primary consuming sector is a major focus for improving the overall water balance, as agricultural use places immediate pressure on other sectors.
The Reality of Water Stress and Depletion
The combined effect of uneven distribution and disproportionate consumption has led to significant water stress and resource depletion across the country. Water stress, measured as the ratio of total water withdrawal to total renewable resources, has risen sharply in recent years, reaching approximately 44.8% in 2020. This high figure indicates that the country is withdrawing a substantial portion of its renewable supply, pushing many regions toward severe scarcity.
The most tangible consequence of this sustained high consumption is the overexploitation of groundwater resources. Out of the 653 identified aquifers, approximately 115 are officially classified as overexploited, meaning extraction significantly exceeds the rate of natural recharge. Other assessments suggest that up to 245 aquifers are now in a critical state, particularly in the Northern states and the central plateau where surface water is scarce.
In the Valley of Mexico, the over-drafting of groundwater has led to measurable land subsidence, with the ground sinking between 5 and 36 centimeters annually in some areas. This depletion not only threatens long-term water security but also damages infrastructure and increases the risk of water quality issues. The current situation highlights a growing long-term challenge, where the water being used today is being borrowed from future generations, especially in regions already experiencing the highest levels of water scarcity.