Tikal, an ancient Maya city in what is now northern Guatemala, is one of the largest political, economic and military centers of the pre-Columbian Maya civilization. The metropolis was inhabited from the 6th century BCE to the 10th century CE, and had a population of up to 90,000 people in its heyday. A large reservoir called the Corriental reservoir was an important source of drinking water for the city. A team of archaeologists from the University of Cincinnati has found that between about 2,200 and 1,000 years ago, the drinking water in this reservoir was filtered through a mixture of zeolite and coarse, sand-sized crystalline quartz. This filtration system is the oldest known example of water purification in the western hemisphere and the oldest known use of zeolite for decontaminating drinking water in the world.
Zeolite is a non-toxic, porous, crystalline, hydrated aluminosilicate mineral with natural adsorbent and ion exchange properties, which removes harmful microbes as well as dispersed insoluble and soluble toxins from drinking water.
Approximately 2,700 years ago, Greek and Roman engineers used zeolites as a pozzolan in cement in the construction of large scale hydraulic structures such as aqueducts, bridges, dams, and harbors.
However, it has been assumed that zeolites were not used for water purification until the beginning of the 20th century.
It also has been presumed that the oldest forms of water purification occurred in Europe and southern Asia.
“The ancient Maya created their water filtration system nearly 2,000 years before similar systems were used in Europe, making it one of the oldest water treatment systems of its kind in the world,” said lead author Dr. Kenneth Barnett Tankersley, a researcher in the Department of Anthropology and the Department of Geology at the University of Cincinnati.
“What’s interesting is this system would still be effective today and the Maya discovered it more than 2,000 years ago.”
Dr. Tankersley and colleagues used X-ray diffraction analysis to identify zeolite and crystalline quartz in the sediments from the Corriental reservoir.
They traced these minerals to steep ridges around the Bajo de Azúcar about 18 miles northeast of Tikal.
“It was an exposed, weathered volcanic tuff of quartz grains and zeolite. It was bleeding water at a good rate,” said co-author Professor Nicholas Dunning, a scientist in the Department of Geography and GIS at the University of Cincinnati.
“Workers refilled their water bottles with it. It was locally famous for how clean and sweet the water was.”
The zeolite 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,” said co-author Dr. David Lentz, a biologist in the Department of Biological Sciences at the University of Cincinnati.
“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.”
“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.”
A paper on the findings was published in the journal Scientific Reports.
K.B. Tankersley et al. 2020. Zeolite water purification at Tikal, an ancient Maya city in Guatemala. Sci Rep 10, 18021; doi: 10.1038/s41598-020-75023-7
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