Today, we take water filtration for granted. From city sewer systems to storm drain ponds and water treatment plants, we’re fortunate to have virtually unfettered access to clean, safe water. But where did it all start? How (and when) did humans devise and deploy systems that made this kind of water purification possible? The Maya city of Tikal offers a look back in time to the Western Hemisphere’s first filtered framework.

Let’s dive in.

On a Molecular Mission

The goal of any water filtration system is to trap and remove problematic particles, from heavy minerals to harmful bacteria. Filtrating frameworks — often called molecular sieves, according to Smithsonian Magazine — are typically made using porous crystalline compounds capable of capturing these particles without negatively impacting overall water flow. The practice hasn’t changed much in the past few millennia; according to the CDC, two key stages of current water treatment systems include sedimentation (the process of heavier particles settling to the bottom of water supplies) and effective filtration.

And while archeological evidence shows that ancient civilizations were more than capable of building aqueous transport systems, molecular sieves were largely absent, especially in the Western Hemisphere. However, according to a paper published in Scientific Reports, new research suggests that Mayan engineers dealing with unique landscape and weather challenges devised and implemented a filtrating framework using a type of volcanic mineral — which is still used today — in city water systems, bottled water and wine.

The Technology of Tikal

The city of Tikal — also called Yax Mutal — contained more than 3,000 buildings and supported more than 60,000 people during its most populous period in 750, and it remained occupied until around 1100. Now part of a rainforest in Guatemala, the natural environment of Tikal came with unique water challenges, including a porous limestone base and reoccurring droughts. As a result, Mayan engineers needed a way to not only transport and store water but also to ensure this water didn’t sicken and kill its population during times of drought.

Accomplishing this goal meant creating the Corriental reservoir, which, despite high mercury content in other nearby water storage systems, was free of contamination. According to the Tikal researchers, the reason is simple: zeolite.

Zeolite is a compound of silicon and aluminum, and as the CDC notes, it’s still used in water filtration systems across the United States for its ability to collect and capture harmful microbes, especially when paired with crystalline quartz. The Tikal system had both, allowing it to naturally filter mercury and bacteria-heavy water before it was used by the populace.

Worth noting: There’s no naturally occurring zeolite in Tikal. Instead, the research team believes that the Maya likely found this combination some 18 miles northeast of town, near the Bajo de Azúcar — which contained naturally pure and filtered water. According to Nicholas P. Dunning, co-author of the Scientific Reports paper, “It was probably through very clever empirical observation that the ancient Maya saw this particular material was associated with clean water and made some effort to carry it back.” Once they brought it back, they would place it in settling tanks to clean and purify the water before it reached the Corriental reservoir.

Not only does this system represent the earliest known example of water filtration in the Western Hemisphere, but it also predates the use of this compound for water decontamination anywhere in the world. As ScienceAlert notes, while the Romans did use a variant of zeolite — called pozzolan — as part of their cement mixture for building bridges and aqueducts, not even these famed ancient builders repurposed zeolite to remove water contaminants.

Engineering Equivalence

This Mayan water work also raises an important point: While ancient engineering efforts of Eastern Hemisphere civilizations point to the human preoccupation with clean, easily accessible water (such as the Roman Empire’s still-standing Aqueduct of Segovia), these Eastern efforts are often regarded in isolation and ignore the efforts of their Mayan and Aztec counterparts.

Case in point? The Maya city of Tikal. Not only were the builders tasked with transporting water across great distances to account for the problem of porous limestone foundations during droughts, but they also needed a way to correct for cyanobacteria and other disease-delivery microbes. As lead author of the Tikal study Kenneth Barnett Tankersley notes, “When it comes to water management, the Maya were millennia ahead.” And that’s not the only Western claim to fame. The post-Mayan Inca civilization was also responsible for creating one of the most complex and enduring roadway systems in the world — the Qhapaq Ñan — which stretched more than 25,000 miles down the western coast of South America, and parts of it are still in use to this day.

Water, Water Everywhere

We all need a drink. It’s no exaggeration to say that civilizations live and die on their access to clean, fresh water — and when it comes to functional filtration frameworks, the Mayans were way ahead of the curve.