Ancient Mayan societies built sophisticated water filters using materials used in modern purification systems

Almost 2,000 years ago, the ancient Maya living in what is now known as Guatemala were filtering drinking water with a sophisticated number of compounds still used in modern commercial filters.

In the once-bustling city of Tikal — the ruins of which still stand in rainforests in northern Guatemala — the Mayan people used natural materials imported from miles away in order to remove impurities from water.

Researchers from the University of Cincinnati discovered evidence of an ancient filter system at the region’s Corriental reservoir, which was an important source of drinking water for the Maya.

A team of scientists including anthropologists, geographers, and biologists working together identified crystalline quartz and zeolite, both of which would have had to have been imported to Tikal.

The scientists said the quartz would have been found in coarse sand, while the zeolite — a crystalline compound consisting of aluminium and silicon — would have been added together to create what they described as a “natural molecular sieve”.

Both zeolite and quartz are used in modern water filtration.

The filters would have removed harmful microbes, nitrogen-rich compounds, heavy metals such as mercury and other toxins from the water, said Kenneth Tankersley, associate professor of anthropology and lead author of the study.

“What's interesting is this system would still be effective today and the Maya discovered it more than 2,000 years ago,” Dr Tankersley said.

Similar systems have only been used in Europe since the end of the 20th century, making the Mayan system one of the oldest water-treatment facilities of its kind in the world, Dr Tankersley said.

Researchers from UC's College of Arts and Sciences traced the zeolite and quartz to steep ridges found around the Bajo de Azúcar — a geological feature about 18 miles northeast of Tikal.

They used X-ray diffraction analysis to identify zeolite and crystalline quartz in the reservoir sediments.

At Tikal, zeolite was found exclusively in the Corriental reservoir.

The researchers noted that finding ways to collect and store clean water was of critical importance to the ancient Maya.

Tikal and other Maya cities were built on porous limestone which made access to drinking water difficult for much of the year during seasonal droughts.

UC geography professor and co-author Nicholas Dunning, who has studied ancient civilizations most of his career, found a likely source of the quartz and zeolite about 10 years ago while conducting fieldwork in Guatemala.

"It was an exposed, weathered volcanic tuff of quartz grains and zeolite. It was bleeding water at a good rate,” he said.

“Workers refilled their water bottles with it. It was locally famous for how clean and sweet the water was.”

Professor Dunning took samples of the material at the time, and the UC researchers later determined the quartz and zeolite closely matched the minerals found at Tikal.

“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,” Professor Dunning said.

UC anthropology professor emeritus Vernon Scarborough, another co-author, said most research on ancient water management has tried to explain how civilisations conserved, collected or diverted water.

“The quality of water put to potable ends has remained difficult to address,” he said.

“This study by our UC team has opened the research agenda by way of identifying the quality of a water source and how that might have been established and maintained.”

Of course, reconstructing the lives, habits and motivations of a civilisation 1,000 years ago is tricky.

“We don't have absolute proof, but we have strong circumstantial evidence,” Professor Dunning said. “Our explanation makes logical sense.”

“This is what you have to do as an archaeologist,” UC biologist and co-author David Lentz said.

“You have to put together a puzzle with some of the pieces missing.”

Professor Lentz said the filtration system would have protected the ancient Maya from harmful cyanobacteria and other toxins that might otherwise have made people who drank from the reservoir sick.

“The ancient Maya figured out that this material produced pools of clear water,” he said.

Complex water filtration systems have been observed in other ancient civilizations from Greece to Egypt to South Asia, but this is the first observed in the ancient New World, Dr Tankersley said.

“The ancient Maya lived in a tropical environment and had to be innovators. This is a remarkable innovation,” Dr Tankersley said.

“A lot of people look at Native Americans in the Western Hemisphere as not having the same engineering or technological muscle of places like Greece, Rome, India or China. But when it comes to water management, the Maya were millennia ahead.”

The research is published in the journal Scientific Reports.