Long before it was CDMX, this valley was Lake Texcoco — a shallow, saline lake ringed by mountains, with the Mexica capital of Tenochtitlan built on an island near its center, connected to the shore by causeways. When the Spanish arrived in the 16th century, they began draining the lake, a process that continued in fits and starts for the next four hundred years. By the 20th century, most of it was gone, replaced by the city we know today.

That history isn't just trivia: it's still shaping the ground under your feet, and, indirectly, the water coming out of your tap.

Why Mexico City is still sinking into its old lakebed

Mexico City is famously sinking. In the worst-affected areas, it's dropping by close to 50 centimeters a year, a consequence of decades of groundwater extraction from the aquifer beneath the old lakebed the city sits on. A 2021 study in the Journal of Geophysical Research: Solid Earth found the subsidence is effectively irreversible and ongoing. That uneven settling doesn't just crack sidewalks; it stresses buried municipal pipe and building risers, and reporting on the city's water system has documented residents dealing with water that arrives dirty, arrives at reduced pressure, or doesn't arrive at all, with utility crews fixing the same lines only for them to fail again later.

Why CDMX tap water is treated but still varies by building

Here's the part that surprises most people: Mexico City's tap water is treated at the source. The city's water utility does treat and monitor what enters the system. The problem isn't the treatment plant. It's everything the water passes through after that: aging building pipes, rooftop tinacos (storage tanks) that don't always get cleaned on the schedule they should, and plumbing that's sitting on ground documented to be settling unevenly. None of that shows up on a city-wide water quality report, because none of it is the city's water quality problem to report: it happens after the water is already legally "safe," inside infrastructure the utility doesn't own or inspect.

What it means for water filtration in your apartment

This is why we treat water filtration as a building-plumbing problem, not a city-water conspiracy. You can't control what happens to water between the treatment plant and your building. You can control what happens in the last few meters, right at your own tap.

That's the whole premise behind what we do: point-of-use filtration that doesn't ask you to trust the entire chain, just the part you can actually see, install, and maintain yourself. In practice that means an ultrafiltration or reverse osmosis system under your kitchen sink, which is what we install across Roma Norte, Condesa, Juárez, and the neighborhoods around them, in buildings sitting on exactly the ground this article is about.

If you want to see which water filter actually fits your building, have a look at our Drinking Water Systems comparison, check what your own building's water pressure is, or read why the garrafón you're buying now has a tradeoff of its own. Or if you'd rather just ask, message us on WhatsApp.

Sources

  • Chaussard, E., et al. “Over a Century of Sinking in Mexico City: No Hope for Significant Elevation and Storage Capacity Recovery.” Journal of Geophysical Research: Solid Earth, 2021.
  • “Why Mexico City's Water Crisis Is Causing It to Sink,” The Washington Post, June 2024.