In Yucatán, what goes down the drain doesn’t go far.
That is the warning from Francisco Bautista Zúñiga, a soil and karst specialist at UNAM, Mexico’s national university, who says Mérida’s rapid growth is moving ahead without enough regard for the porous ground the city sits on, putting the region’s only freshwater source at risk.
“Here, our aquifer starts at the kitchen sink, at the bathroom drain,” he said. “Everything we pour there will reach the groundwater.”
A water supply with little protection
Unlike much of Mexico, the Yucatán Peninsula has no surface rivers. It rests on a flat shelf of limestone, known as karst, riddled with cracks, caves and cenotes. Rain soaks straight through the thin soil into the aquifer below, and so does almost anything else.
Bautista Zúñiga said groundwater here has little natural protection compared with other regions. Having plenty of water, he noted, does not mean it is safe to drink, and cleaning up a polluted aquifer is a difficult job.
He also said there are not enough studies, and no proper system to monitor groundwater quality.
That matters because Mérida drinks from the same source it drains into. The city’s tap water comes from well fields on its outskirts, known as Mérida I, II and III, all drawing from the shallow aquifer. Municipal planners have long noted that the aquifer and cenotes are the only water sources available.
A city that keeps spreading
Mérida’s footprint has grown fast. Its urban area went from about 15,000 hectares (37,000 acres) in 2019 to 34,000 hectares (84,000 acres) in 2023, according to figures published earlier this year by Por Esto! in a report on sprawl. That is more than double in four years.
Much of that growth has come as gated subdivisions and housing on the city’s edges. Mérida has no citywide sewer system, so many homes rely on septic tanks. Rainwater drains into storm wells that send runoff directly into the subsoil, untreated. Paving over open land also cuts the amount of rain that can soak back in and recharge the aquifer.
Other specialists have raised similar alarms. Earlier this year, a local architects’ group said the loss of open land has pushed the city’s storm drainage past capacity, raising both flood risk and the threat of contamination. Environmental groups have pointed to pig farms, poultry operations and mass tourism as additional pressures on the water table and the cenotes it feeds.
Bautista Zúñiga’s main point is that planning has not caught up. New developments, he said, are advancing without fully weighing the conditions of the karst beneath them.
Yucatán Magazine has reported on the state’s water warnings before, including the limited capacity of Mérida’s treatment plants.
Fast Facts
- The Yucatán Peninsula has no surface rivers; nearly all fresh water is underground.
- Mérida’s tap water comes from three main well fields: Mérida I, II and III.
- Mérida’s urban area grew from about 15,000 ha (37,000 acres) in 2019 to 34,000 ha (84,000 acres) in 2023.
- Many homes depend on septic tanks rather than a sewer system.
- Avoid pouring oil, paint, solvents or medicines down household drains.
With reporting from Diario de Yucatán and Por Esto!, with background from Mérida’s municipal planning institute, Implan.
Facebook teaser
Mérida has no rivers, only the water underground. A UNAM soil scientist says the city’s growth is outpacing what that porous ground can handle, and that nobody is consistently checking the water’s quality.
Source links (for Lee only, not for publication)
- Diario de Yucatán (primary, Nov. 9; fetch-blocked, quotes from search excerpt): https://www.yucatan.com.mx/merida/2026/11/09/crecimiento-urbano-de-merida-amenaza-el-agua-subterranea-de-yucatan.html
- Por Esto! (external link, urban-area figures, April 4): https://www.poresto.com/yucatan/merida/2026/4/4/alertan-por-contaminacion-del-acuifero-ante-expansion-desordenada-en-merida.html
- Diario de Yucatán, architects’ group on drainage (July 1): https://www.yucatan.com.mx/merida/2026/07/01/capacidad-rebasada-experto-senala-que-a-merida-le-urge-un-nuevo-sistema-de-drenaje.html
- Implan Mérida drainage study: https://www.merida.gob.mx/implan/content/documents/resiliencia/propuesta_SUDS.pdf
- UADY study on Mérida well fields: https://www.revista.ingenieria.uady.mx/volumen8/delineacion.pdf
- Internal link: https://yucatanmagazine.com/yucatan-water-warning/
Note: I couldn’t read the full Diario piece. The quote and points attributed to Bautista Zúñiga come from the excerpt available; check the full text for any additional remarks or his exact title.