Water Footprint in Mexico: How to Measure It Without a Dedicated Law

In Mexico there is no specific law regulating the corporate water footprint, unlike carbon emissions, which do have a mandatory framework under the General Law on Climate Change. That does not make water a minor risk: industry is one of the most significant concession holders after agriculture and public supply, and much of the centre and north of the country operates under water stress.

Why measure the water footprint even if it is not mandatory

The absence of a law does not remove the risk. Investors, corporate clients and international reporting schemes increasingly ask for evidence of water use, and in a water-stressed area the future availability of the resource is an operational risk, not just a reputational one. The concept and its boundaries are in the entry on water footprint.

The three components of the water footprint

• Blue footprint: freshwater withdrawn from surface or groundwater sources and consumed in the production process.
• Green footprint: rainwater stored in the soil and used by crops or vegetation.
• Grey footprint: the volume of water needed to dilute the pollutants generated to meet quality standards.

Each is calculated differently, and the detail is developed in the guides to the blue water footprint and the grey water footprint.

What is mandatory: the National Waters Law

The fact that there is no water footprint law does not mean your company's water is unregulated. Any use of national waters requires a concession title from the National Water Commission (CONAGUA), and the National Waters Law, amended in December 2025 alongside the enactment of a new General Water Law, imposes obligations on concession holders that look a lot like a water inventory:

• Measure: install meters or other direct measurement devices within 45 working days of notification of the title, keep them in good working order, give written notice if they stop working and repair or replace them within 30 calendar days. If the concession holder does not install them, the authority can do so at its expense.
• Do not exceed volumes: do not extract, use, exploit or discharge volumes greater than those authorised in the title, and meet the requirements for rational and efficient use of water and for reuse.
• Pay the fees: pay the fees for extraction, consumption and discharge on time. Non-payment for more than one fiscal year is grounds for suspension and, in case of recidivism, revocation of the concession.
• Control discharges: anyone discharging wastewater into receiving bodies needs a discharge permit, must treat the water where necessary to meet the permit and the NOMs, install meters and sampling access points, keep monitoring records for at least five years and file, every two years, a report with chronological analyses and quality indicators of the water discharged, carried out in certified or accredited laboratories.

The 2025 reform also introduced the concept of water responsibility, defined as responsible management and good practices by concession holders and users to improve the handling, reuse and efficient, sustainable use of water without exceeding the volumes granted, and provides for the authority to regulate what counts as responsible water management. It also made it an offence to transfer concession titles and to change the use of the water outside what the law allows.

Penalties are expressed in Units of Measurement and Update (UMA). Using volumes greater than those authorised, failing to install or tampering with meters, using national waters without a title or polluting them carries fines of 2,160 to 30,000 UMA; discharging wastewater in breach of the law or wasting water, fines of 1,750 to 7,200 UMA; and failing to deliver data requested by the authority or obstructing its inspections, fines of 260 to 2,160 UMA. Closure and suspension or revocation of the concession can be added, and in case of recidivism the fine rises by up to one third.

There is one more connection with federal environmental reporting: discharging wastewater into receiving bodies that are national waters makes the establishment subject to RETC reporting, so its water use, its extraction sources and its discharges must be declared every year in the Annual Operating Certificate (COA).

Where your company's water use actually is

The most common mistake is measuring only the water that comes through the plant's meter. In many sectors, most of the water footprint sits in the sustainable supply chain: raw materials, agricultural inputs and supplier processes. Ignoring that part leaves out most of the real impact.

How to measure it with the ISO 14046 methodology

• Define the scope: which facilities, processes and suppliers are included in the calculation.
• Collect consumption data by site: especially critical for groups with several plants or subsidiaries. The meters required by the National Waters Law and the readings that support fee payments are the natural starting point.
• Assess the local context: the same litre of water does not carry the same weight in a water-stressed area as in one with abundance, and that weighting is what distinguishes a water impact assessment from a simple consumption inventory.
• Verify and report: with auditable data aligned with frameworks such as GRI, CDP or the European standard on water and marine resources.

The full procedure is in the guide to water impact assessment under ISO 14046 and in how to measure the corporate water footprint.

From manual measurement to centralised data

For a group with several sites, consolidating water consumption by hand in a spreadsheet is close to unworkable: the data arrive in different bills, for different periods and with no common criteria. Centralising consumption by plant, with the origin of each reading recorded, is what lets you move from an annual number to a report that withstands verification. You can see it in Manglai's water footprint software.