Standing in one of the largest cities of the ancient Maya civilization, Tikal, in Guatemala, visitors are surrounded by steep limestone pyramids, as high as Notre Dame Cathedral in Paris.
Tourists are also greeted by the sounds of monkeys and birds that come from the rainforest scenery behind them.
Constructed without the aid of animal carriers, metal tools or wheels, these magnificent stone carvings served as seats of power for the kings and priests who ruled in the most influential city in the Maya empire.
The city stretches across the Yucatan Peninsula of Mexico, Guatemala, Belize and parts of Honduras and El Salvador.
Tikal was the economic and ceremonial center of the Maya civilization which had a total population of 10-15 million people.
Based on a laser-based aerial survey recently revealed, there are more than 60,000 structures hidden in Tikal for centuries – beneath the dense tropical rainforest.
In front of palaces and large stone temples, each pyramid is used to observe the rotation of the sun across the sky – the greatness of the Mayans as architects and astronomers.
However, the Mayans could never have accurately predicted eclipses and other celestial momentums, without the aid of the fundamental element in their survival on Tikal: water.
There are no rivers or lakes near the town of Tikal.
The Mayans also built a network of large reservoirs to store rainwater as a reserve for sufficient time during the heavy rainy season.
At the height of the 8th century, there was a four to six month dry dry season in Tikal, which has a population of between 40,000 and 240 thousand people.
The Mayans of Tikal used this reservoir for more than a thousand years – from about 600 BC until it was abandoned in 900 AD.
The oldest filtration system in the western hemisphere
Last year, archaeologists used modern scientific techniques to uncover the deeper greatness of Mayan hydrological technology.
Sediment cores taken from reservoirs at Tikal suggest the Maya created the oldest known water filtration system in the western hemisphere.
The Mayan water purification system was very advanced where one of the main ingredients, zeolite, is still widely used in water filters today.
Zeolites are volcanic minerals made of aluminum, silicon and oxygen that are formed when volcanic ash reacts with alkaline groundwater.
Zeolites come in a variety of forms and have unique physical and chemical properties that allow them to filter out contaminants ranging from heavy metals to small microbes.
Zeolite grains have a porous structure, like a cage, so that they function as an effective physical filter.
This mineral is also negatively charged so that other elements will easily bind to it.
That is, when water passes through the zeolite, the suspended particles are physically or chemically attached to the zeolite grains, while the water continues to flow through the mineral gap.
Although archaeologists have only found zeolite in one of Tikal’s reservoirs, now called Corriental, the discovery of broken clay vessels there indicates that the pure water in Corriental was used exclusively for drinking.
Zeolite refining: Watering a thousand years of the Mayans
The researchers behind the discovery say the Mayan use of zeolites is the oldest known use of the mineral for water purification in the world.
Older than the sand filtration system developed by the English scientist Robert Bacon in 1627, about 1,800 years ago.
The Mayans invented a zeolite-powered water filtration system, which researchers say appears to have been built around 164 BC.
Earlier than the cloth filter system known as the Hippocratic arm developed in ancient Greece around 500 BC.
Although time apart, Maya’s method was found to be far more effective at removing invisible contaminants such as bacteria or lead.
“I’m a Native American and I’ve always been bothered by the view that archaeologists and anthropologists have traditionally viewed Native Americans as not developing technologies found in other ancient places like Greece, Egypt, India or China,” said Kenneth Tankersley, an archaeological geologist at the University of America. Cincinnati and lead author of a study documenting the Mayan use of zeolites.
“This system (zeolite) provided the Mayas with safe drinking water for over a thousand years and other filtration systems known in that era were primitive by comparison – like the Greek method of filtration which was just a cloth bag.”
The city of Tikal is located in northern Guatemala and in this region there are only two seasons: very rainy or very dry.
Even more challenging, during the rainy season, water is quickly absorbed into the ground which is the landscape karst – full of holes and caves.
The water was absorbed into about 200 meters below ground level, out of reach of the Mayans.
With no source of fresh water nearby, residents of this ancient metropolis in Central America must find a way to store water when the rainy season arrives.
That’s where the reservoir came in – and because Tikal was centered around a hill, the Mayans were able to take advantage of the slopes to channel water into the reservoir.
Even the large central square, situated between Temples One and Two and flanked by the main acropolis, is paved with boulders which are all placed on the slopes to drain water into the canals and then empty into the reservoirs of nearby temples and palaces.
Water reserves of tens of millions of liters
The palace reservoir is estimated to have stored 31 million liters of water. Meanwhile, the Corriental reservoir purified with zeolite is estimated to have a capacity of 58 million liters at its peak.
The discovery of the Corriental filtration system emerged from field research conducted around 2010, when researchers collected 10 sediment core samples from four Tikal reservoirs.
These cores reveal that dangerous levels of contamination from the heavy metal mercury and signs of a toxic algae explosion plagued the Palace and Temple reservoirs near the Tikal core in the 9th century.
But almost as striking as the contamination itself was the fact that the Corriental reservoir remained pristine even as the Palace and Temple reservoirs became toxic.
When Tankersley took a closer look at the Corriental sample, he found four separate layers of sand featuring chunks of crystalline quartz and zeolite that do not appear in any other reservoir.
When the team surveyed the surrounding area there were no natural sources of this type of sand, let alone zeolites, leading the researchers to conclude that the material was deliberately brought in to be used as a filter at the reservoir entrance.
Coincidentally, one of the researchers on the project noticed a depreciation some 30 kilometers northeast of Tikal that featured a similar-looking sand dune known as Bajo de Azúcar.
According to local residents, the area has crystal clear water and a sweet taste.
Tests revealed that the Bajo de Azúcar rock and sand contained zeolites. Most likely, that’s where the zeolite in Corriental came from.
“Without a time machine, we don’t know exactly what happened,” said Tankersley,
“But it doesn’t take much to imagine someone from Tikal thinking: ‘If sweet, clean water comes out of this crystalline volcanic tuff, maybe we can break it down and use it to make our water clean too.'”
The researchers hypothesized that the zeolite sand might be sandwiched between layers of woven leaves of a plant called petates to create a filter.
The filters were probably then embedded in a porous wall of limestone bricks that the Mayans installed in the path of the water flowing into the reservoir.
According to research, sand by itself will make the water look clear, but will have no impact on microbes or mercury.
With the addition of zeolites, the Maya got clear water that is also clean even by today’s standards.
“The Mayans may not have understood what zeolites were doing specifically, but they did understand the importance of keeping the water clean,” said Lisa Luce, an anthropologist at the University of Illinois.
“They use technology and environmental knowledge to purify their drinking water.”
Four layers of sand containing zeolite indicate that the filter was eroded by floodwaters during the very heavy rainy season and then rebuilt several times.
Although Corriental is the only place where the Maya zeolite filtration system was found, it does not rule out its use elsewhere.
Liwy Grazioso, director of the Guatemalan Miraflores Museum which discovered the contamination of the Palace and Temple reservoirs, hopes the findings will encourage more study of the Mayan reservoir.
“I don’t think Tikal is the only place with this technology,” Grazioso said.
“Reservoirs are everywhere in the Mayan world and very little has been learned, but if we don’t learn it, we will never know.”
For Tankersley, these discoveries represent a wealth that transcends artifacts of shiny material made of gold or jade.
He suggests that visitors to Tikal not only admire the structure, but also ponder:
“How did people 1,000 or even 2,000 years ago build it without machines or working animals.”
“Think about their achievements,” he says, “and remember that these are not extinct people, they are the legacy of Central America’s modern indigenous population.”