The Democratization of Water From the Rooftops of Mexican Cities

The national debate on water advances through two opposing views. One suggests that the country faces a crisis caused by an absolute lack of the resource, while the other argues that the problem emerges from insufficient management.

My experience in the development of water solutions aligns with this second position, because Mexico receives water but lacks the infrastructure necessary to capture it, direct it, and use it efficiently. A city becomes fragile when it allows millions of liters to be lost during a single day of rain and then faces scarcity weeks later.

In recent years, rainwater harvesting has expanded strongly across urban environments. It began as a domestic response from families seeking autonomy during supply failures, but today the evidence shows a broader and deeper scenario. Harvesting no longer occupies a marginal space. It now forms part of the strategies that sustain the operational continuity of businesses, commercial areas, logistics centers, and public buildings. This transition changes the entire scope of the tool, since a domestic system offers months of independence while an industrial system can relieve pressure on an entire public network.

Mexico City provides an illustrative example. In 2024, harvesting programs installed over recent annual cycles collected more than 918 million liters of water, a volume sufficient to cover the basic consumption of thousands of households for months. This figure not only demonstrates efficiency but also raises questions about the size of the opportunity when these results extend to shopping centers, industrial parks, warehouses of more than 20,000 square meters and complexes with constant flows of people.

The potential of rainwater harvesting multiplies when analyzed at an urban scale. A household with an average roof can achieve five to eight months of independence with a well-installed system, without affecting the public network and without interrupting basic activities. Industrial or commercial spaces with larger surfaces can significantly reduce their consumption of the network for nonpotable uses such as restrooms, equipment cleaning, or cooling systems. The city strengthens its resilience while businesses reduce the risk of interruptions.

Since 2003, Mexico City’s construction regulations have required large buildings to include rainwater harvesting systems. This requirement does not aim to satisfy a formality, it responds to an evident reality. A roof produces water, and urban infrastructure must enable its storage. The transition toward more resilient cities does not depend solely on drilling new wells or constructing dams, but on using what already exists across the urban landscape.

Mexico faces a level of water stress that places it 26th worldwide, and this condition creates clear risks for industries, logistics hubs and commercial establishments that depend on public supply. Industrial rainwater harvesting positions itself as a defensive strategy that protects operational continuity, stabilizes costs, and reduces exposure to partial or total supply cuts. Resilience stops being an abstract concept and becomes a decision reflected directly in day-to-day operations.

The integration of harvesting with reuse processes expands this potential even further. Industrial rainwater harvesting and treatment projects in Mexico already reach water recovery rates between 74% and 68.5%, supported by processes that comply with official quality standards. This shows that captured rainwater and treated wastewater meet the needs of various industrial operations. The economic benefit appears immediately because every cubic meter recovered eliminates the need to purchase water from the network, reduces operating costs, and increases the ability to respond to periods of water stress.

For many years, Mexican cities expanded through systems designed to expel water as quickly as possible. The priority was to prevent flooding, but that vision no longer matches current climatic conditions. Rains have grown more intense, dry periods have lengthened, and the drainage network no longer withstands this variability. The city does not need to expel all the water, it needs to store a significant fraction. The roof becomes a key piece of a silent infrastructure that reduces flooding and preserves water for later periods.

Industrial rainwater harvesting does not operate in isolation. It forms part of a broader ecosystem that includes drainage systems, treatment plants, wells, elevated tanks, pumping stations, and distribution networks. All of these elements face simultaneous stress, and harvesting provides an additional layer of support. A building that stores thousands of liters during a rainfall prevents that volume from entering the drainage network. A logistics center that uses that stored water the next day reduces its dependence on the system. An industrial park that integrates harvesting and reuse reduces external demand and adds balance to the urban system.

In recent years, I have seen projects where harvesting ceased to be experimental. Supermarkets, retail chains, manufacturing companies, educational institutions, and hospitals already incorporate rooftops that function as storage platforms. This experience shows that engineering evolves and society now recognizes the strategic value of water. The future city will not rely solely on megaprojects. It will also depend on existing rooftops that require only adequate design, filtration, pumping, and storage.

The democratization of water emerges when a city enables households, companies, and buildings to contribute to resilience. It does not appear when a single actor concentrates control of the resource but when thousands of distributed points contribute scalable solutions. Rooftops, courtyards, parking lots, logistics warehouses, and commercial centers already form part of this distributed water architecture. Harvesting does not divide, it unifies. It gives industry autonomy, reduces pressure on the public network, and brings households closer to a more stable way of living.

In this context, it is essential to mention that Rotoplas promotes engineering that strengthens this vision and enables rainwater harvesting to advance toward industrial levels that once seemed distant.

Rainwater harvesting can transform the relationship with water and reshape urban resilience. It does not arise from theories; it emerges from real rooftops, verified data, and available solutions. The future of cities will not depend solely on new supply sources, but on decisions that relieve pressure on the public network, reduce vulnerability, and convert rain into a resource that generates stability and development.