Learning from the past. How ancient Mayan water technology could combat modern droughts

Known for the construction of advanced water reservoirs, the ancient Mayans may hold valuable insights into dealing with current and future water crises. These ancient reservoirs were capable of providing drinking water to tens of thousands of people, making them a potential solution for present and future water challenges.

According to the latest research by experts from the University of Illinois Urbana-Champaign, these ancient Mayan reservoirs can serve as a model for reservoirs that could assist humanity today and in the future. The Mayans, an ancient civilization that resided in Central America, were adept at building structures which stored and filtered drinking water to serve large urban populations.

"Most of the major Mayan cities from the southern lowlands were built in areas lacking surface water but providing excellent agricultural soils. The residents coped by constructing reservoir systems — initially small, then increasingly larger and more complex," states Prof. Lisa Lucero, the author of a paper published in the "Proceedings of the National Academy of Sciences".

Over time, the Mayans honed their expertise in building channels, dams, locks, and barriers for storing and transporting water. They used quartz sand to filter the water, sometimes importing it from great distances to major cities like Tikal (now in northern Guatemala). They also used zeolites from volcanoes, capable of filtering out even hazardous bacteria.

"The reservoirs in Tikal could store over 237,750,000 gallons of water," stresses Prof. Lucero. It's estimated that between the years 600–800 AD, the city had a population of up to 80,000 people.

During dry periods, these reservoirs catered to the population and the cultivated fields' water requirements. The ability to provide residents with access to water was a crucial status symbol for the ruling class.

Mayan kings performed special rituals to win the favor of the rain god Chahk. Preserving the purity of the reservoir's water for potability was a major challenge. To achieve this, water plants, which are still found abundantly in local wetlands today, were used. Scientists point to bulrushes, sedges, reeds, and lilies.

Some plant remnants were discovered in the sediment collected from the reservoirs. According to Prof. Lucero, the Mayans would deepen the reservoirs and replace the plants growing in them every few years.

The accumulated sediment and biomass could then be used to enrich the soil for fields and gardens. However, lilies cannot tolerate water acidity, excessive calcium, or certain minerals like iron and magnesium. For this reason, the reservoir builders lined the water reservoirs with clay, where sediment required for the lilies to root would collect. The lilies, along with trees and shrubs on the banks, cast shadows onto the water, limiting the growth of algae. The Mayans typically did not build houses near the reservoirs to avoid water pollution.

Research suggests that reservoirs of this type were operational in Mayan culture for over a thousand years. They only failed during the most severe droughts that struck the region between 800-900 AD.

Scientists believe that this ancient solution could be exceptionally useful at present and in the future. They suggest that current climate trends may necessitate a similar approach, including the use of water plants.

"Artificially constructed wetlands offer several benefits over conventional sewage treatment systems. These advantages include economic benefits and a simple, energy-saving technology," Prof. Lucero emphasizes.