Water testing reveals severe contamination in Mexico's Maya rainforest as illegal pig farming expands

Mérida, Mexico – Water testing conducted in Mexico’s Yucatán State, in an area near the state capital city of Mérida, has found that severe, widespread fecal and chemical contamination is threatening the country’s largest source of renewable groundwater, driven in part by illegal industrial pig farms, a new report by Greenpeace México and Greenpeace International has revealed today. [1] José Luis Perlasca, Campaigner at Greenpeace México, said: “For years, the rapid expansion of high-impact industrial activities has been allowed to take place in one of Mexico’s most important—and at the same time, most vulnerable—hydrological systems, causing various problems of water and groundwater contamination on the peninsula. This report offers a grim picture of the devastating effects that megafarms are having on the Selva Maya. Commissioned by Greenpeace México and conducted by an accredited independent laboratory, the study, titled ‘The Price of Pork: How Illegal Pig Megafarms Are Destroying Mexico’s Underground Springs’, investigated 17 sites across six communities, taking water samples from wells and cenotes, the iconic freshwater sinkholes that dot the densely forested Yucatán Peninsula. The results showed critical levels of fecal bacteria, with multiple sites reaching maximum laboratory quantification limits. Additional studies conducted by local Maya community group To’one Ja’o’on (We Are Water) Network in collaboration with Johns Hopkins University and the National Autonomous University of Mexico at five overlapping sites has confirmed the presence of pig fecal matter in water samples. [2] Perlasca continued: “The contamination of Mexico’s largest groundwater source not only threatens the environment and the livelihoods of nearby communities but also poses a potential public health disaster that could endanger the drinking water supply for millions of people. Environmental authorities need to realise: this is not just a local problem, but one that could jeopardise the whole region’s capacity for survival and regeneration.” Testing revealed high levels of water pollution, with nitrate concentrations in several locations exceeding World Health Organization (WHO) drinking water safety guidelines and two-thirds exceeding lower thresholds recognised as presenting health risks through long-term exposure. At peak contamination sites, chemical oxygen demand and phosphorus levels suggested direct influxes of livestock manure slurry or municipal wastewater. Nitrate contamination in drinking water has been linked by recent research to health risks like colorectal cancer and pre-term birth at levels far lower than the current WHO guideline. [3] The Yucatán Peninsula karst aquifer is the world’s most extensive interconnected cave system and supplies drinking water to 5 million people in southeast Mexico. [4] However, the region’s highly porous karst limestone provides minimal filtration against surface pollutants, meaning agricultural runoff and swine manure slurry can migrate rapidly into the subterranean system, posing severe health risks and threatening fragile ecosystems. The report highlights systemic regulatory failure, where over 90% of industrial pig megafarms operate illegally in the Yucatán peninsula without mandatory environmental impact assessments, driving deforestation and pollution. Dozens of these operations encroach directly on Protected Natural Areas and Indigenous Maya territories without free, prior, and informed consent from local communities, violating constitutional rights and destroying traditional livelihoods. Greenpeace México is calling on Mexican authorities to enforce an immediate moratorium on new and expanding industrial livestock operations across the Yucatán Peninsula, prosecute illegal megafarms, and uphold the rights of Indigenous Maya communities. ENDS Notes: Full report available here . [1] Estrada-Medina, H., & Álvarez-Rivera, O. O. (2024). Distribución geográfica y características del medio físico natural de los ambientes kársticos de México . Acta Universitaria [2] Carter et al, (2026) Establishing Methods to Monitor Swine Fecal Contamination of Surface Water, Drinking Water, and Settled Dust in Communities Neighboring Swine Concentrated Animal Feeding Operations, Yucatán, Mexico, 2022 . Environmental Justice [3] Evaluation of the parametric value for Nitrate in drinking water . Report delivered to the Ministry of Environment and Gender Equality of Denmark on November 24, 2025. [4] Global Americans, ‘ Tourism Boom, Water Bust: The Hidden Crisis Beneath the Maya Train ’, 13 October 2023 Contacts: Joe Evans, Global Comms Lead for Agriculture, Greenpeace UK, +44 7890 595387, joe.evans@greenpeace.org Sara Del Real, Oficial de Comunicación, Greenpeace México, +52 554084 5320, sdreal@greenpeace.org