How ancient water systems inspired today’s water technologies
Where there is water, there is life. The history of civilization is the history of water technologies. To thrive, society must engineer technologies to harness the essential resource: water. The life of civilization flows as the world explores ways to store, transport, and purify drinking water and smartly eliminate or recycle wastewater. Water is the fountainhead of culture and innovation.
Civilizations face two main water problems: abundance and distribution. Where there is too much water, the rule of survival is to stay above. But also, how do you survive when and where there is too little water?
Like in the ancient Fertile Crescent, the Middle East is watered by rain falling in Turkey’s mountains and northern Iraq. In Mesopotamia, the “land between two rivers,” the Tigris and the Euphrates, early civilizations capitalized on a gravity-fed system of irrigation canals. That was the first form of irrigation. It boosted food production, especially grain, which fermented a Sumerian innovation – beer.
As ancient fans of beer, the Egyptians also prioritized safe drinking water. In Khem, people used a gravity filter to purify muddy water drawn from the Nile with alum. The coagulating effect of aluminum sulfate, Al2(SO4)3, causes suspended particles to clump. This speeds up filtration, making more water available. It is the first known chemical water treatment.
Another drinking water system was developed in ancient India and China. As ancient Hindu texts indicate, they used heat, sunlight, and copper to purify water. Filtration using cloth, sand, and charcoal was also used to capture other contaminants. Purified water was then stored in earthen vessels. This enriched it with minerals and increases its alkalinity, improving its bioavailability.
Storing water is the “savings account” for civilization. The Nabateans saved water by using clay pots to limit evaporation when watering crops. Surviving dry times was possible in Istanbul, Turkey, mainly because of the Cisterna Basilica, the largest of several hundred ancient cisterns. In Rajasthan, Northern India, Chand Baori provided water throughout the year.
In arid landscapes, water storage and flood protection go together. Dams and diversion structures built nearly 6,000 years ago at Jawa, in modern Jordan, prove this. The Ma’rib Dam, built by the Sabaeans in Yemen, relied on natural drainage patterns to create an artificial lake, watering crops in their domain.
Ancient civilizations constructed water supply systems by applying two basic hydraulic principles – “water flows downhill” and “water finds its own level.” Early Roman engineers supplied water through extensive hydraulic aqueduct systems. They used the inverted siphon, a hydraulic structure that creates a pressurized flow in a pipe, to overcome gravity and transport water across valleys. An efficient delivery system means that a civilization spends less time and energy transporting water, letting it grow and become more complex.
A more-effective water system means more free energy for a civilization. In mountainous landscapes, this means slowing water down, reducing its erosive power, and capturing it for irrigation. Terracing creates long, complex groundwater flow paths, giving crops’ root systems a chance to absorb water in dry mountain landscapes. In Lebanon nearly 3000 years ago, the people divided the terraced fields into small, shallow basins to irrigate the famous cedar forests for this reason. The ancient Chinese and Inca, in South America, similarly terraced their mountain fields. Today, the “Djessure” irrigation technique in Tunisia is still widely used, allowing olive and other tree species to grow in areas where it rains less than 250 mm per year.
Many of the great cities of the world suffer from the opposite problem: too much water. When and where there is too much water, there are two main choices: work around the water or make the water work around you. The ancient inhabitants of the Beni savannah in the Upper Amazon basin in Bolivia built mounds and causeways to avert disaster by working around floods. Banks composed of earthenware fragments and charcoal were created as fertile green islands sustaining pockets of life in the floodplain matrix. As ecological engineers, the people of the Beni fostered the growth of the forest found there today.
Once a civilization has enough water, it has to learn how to get rid of it. Another testament to the genius of Roman engineering is the Cloaca Maxima. Began 2,600 years ago, it is one of the world’s most ancient and reliable sewage systems, operating to this day. This semi-artificial sewer, created by enclosing, canalizing, and augmenting natural streams, was later emulated in London, Buffalo, New York, and other cities in the 19th century. Sewer systems protect a population from disease, keeping a civilization healthy. A prime example comes from mid-19th century England. During a cholera epidemic in London, in 1854, British scientist John Snow determined that a water pump contaminated by raw, cholera-bearing sewage was the source of the epidemic. This paved the way for water disinfection when chlorine was first used in the late 19th century to combat typhus, cholera, and other water-borne pathogens.
Today, 150 years after Dr Snow’s work in spatial epidemiology, wastewater surveillance helps predict and forestall coronavirus outbreaks. Idrica’s GoAigua, a waste water surveillance platform, uses GIS and AI/machine learning to track COVID-19 in Europe and the U.S.
Sampling sewage allowed Eau de Paris to detect a change in the concentration of SARS-CoV-2 corresponding to the COVID-19 curve in the capital region. Using a similar approach, the University of Arizona was able to detect SARS-CoV-2 RNA in waste water from a dorm. Early detection of coronavirus in sewage flowing from that dorm led the university to test all 311 students living there. Two asymptomatic individuals were quickly identified and quarantined, preventing unnecessarily harsh and disruptive measures, like lockdowns.
Avoiding unnecessary disruptions keeps civilization humming. Many ancient water technologies could be catalysts for solving the world’s water problems today. They could help deliver water to growing megacities, like Lima, Peru. With over 10 million people in its metro region, Lima is the second-largest city in a desert, exceeded only by Cairo, Egypt. Only 1 in 10 people living in Lima have access to potable water. By 2030, water demand is likely to outstrip supply there, leaving most people in Lima thirsty. That is why Aquafondo is restoring kilometres of amunas, a type of ancient, pre-Incan water collection and delivery system. Like Rajasthan’s Chand Baori stepwell and water collection system, amunas provide water during the dry season and protect mountain soils. That’s why the Peruvian government is investing $24 million in natural infrastructure.
But ancient water systems high in the Andes cannot deliver enough drinking water for a modern megacity like Lima. That’s why hybrid approaches combining modern engineering with ancient wisdom and nature-based solutions are increasingly popular. In the United States, the U.S. Army Corps of Engineers’ Engineering with Nature initiative has investigated how mangroves and islands built from dredged sediment can protect coastlines from hurricanes and typhoons. Built using ancient principles, New York City’s water supply system is a prime example of engineering with nature. Serving nine million people, the city’s water is delivered by aqueducts and tunnels from up to 200 km away. Even more impressive, this water is so pure that only 10% requires filtration. Natural forest ecosystems surrounding NYC’s reservoirs filter water naturally, keeping it pristine. Combined with smart water technologies, like robotic buoys monitoring water quality and computational models, NYC’s system reliably delivers water to nine million people. All it takes to make New York’s water safe to drink is treating it in the world’s largest ultraviolet germicidal irradiation plant, capable of disinfecting over eight billion litres of water each day. Ultraviolet irradiation is, of course, also a service naturally provided by the sun. Solar water disinfection, or SODIS, is also a reliable way to disinfect water, as recommended by ancient Hindu texts and the World Health Organization, thousands of years apart.
These Ayurvedic texts also recommended storing water in copper and earthen vessels. Copper is still a practical point-of-use method for purifying drinking water. It remains an especially important tool for many people in the developing world. Natural copper (I) oxide (Cu2O) steals electrons from bacterial cell walls and membranes and inhibits intracellular processes responsible for energy production and DNA replication. Recent research has even shown that copper and Cu2O can remove viruses and bacteriophages from drinking water, solving a modern problem with a bronze age technology.
Other modern water technologies also function much like ancient ones. Earthen vessels made of clay naturally exchange ions with the water stored in them. Ion exchange is a process by which minerals and nutrients with an electric charge, positive cations, and negative anions bind to clay particles. This absorption, binding to the surface of a substance, is also a characteristic of carbon and modern ion-exchange resins. Today activated carbon and ion exchange resins perform the water purifying function of earthenware, replacing ancient charcoal filtration. Even more importantly, ion-exchange resins can selectively bind specific contaminants, including novel and emerging contaminants. This makes them a flexible and scalable tool for water purification.
Far less complicated than ion-exchange resins, clay pots also have the advantage of limiting evaporation and delivering irrigation water where it is needed. Like the Nabataeans’ water pot irrigation, the humble watering bag and modern drip irrigation systems are a low-tech way of saving water. AI could optimize this but, just like the wheel, sometimes the original innovation is hard to improve on.
Avoiding disruptions keeps civilization humming. Ancient water technologies can be catalysts for solving the world’s water problems today.
Even ancient civilizations collected data to manage their water systems. Flow data collection and time measurement is the earliest form of smart water technology. Song, dance, and ritual art was likely the first form of record-keeping for water. Songlines in Australia were used by the locals to record geospatial water data essential to their survival. With ritual acting as a mnemonic device and by using star maps as a guide to the landscape, the aborigines navigated reliably across thousands of kilometres. Using this 40,000-year-old technique, they could reliably find water in the desert. There are even stories that accurately record the sea level rise observed in Australia approximately 13,000 years ago, preserving high-fidelity data using only the human mind and natural features for over 400 generations.
The Wardaman people’s oral tradition incorporates an annual cycle of “dreaming stories” oriented to the Southern Cross throughout the year. The yearly cycle is the basis for predicting weather patterns and water availability at different times. Having a calendar is necessary for managing water in civilization to provide for agriculture and specialized labour. What we know from Babylonian sources is that Sumerian astronomers observed the sky to develop a calendar to predict water availability. Using this calendar, they could determine approximately when the Tigris and Euphrates could be expected to flood. This information allowed farmers to prepare for flooding and plant crops, stabilizing Sumerian civilization and allowing it to persist for millennia. After the Australian aborigines’ songlines, the Sumerian calendar coupled with observations of the Tigris and Euphrates’ flow stage may be the second earliest example of predictive analytics for modelling water availability.
Instruments measuring a river’s flow stage were likely among the next significant innovations in smart water technology. In its various forms, the Nilometer was not just an instrument for describing the state of the Nile; it became a tool for predicting the economic implications of the great river’s level. If the annual flood of the Nile was less than ideal, famine would likely ensue. If it were excessive, infrastructure would be washed away. In either case, this measurement was an early example of an attempt to predict and prepare for disaster. Hidden behind the mystique of the ancient Egyptian priesthood was the age-old adage: Be Prepared.
Later measurements of a river’s stage in Europe told a similar story of feast-or-famine. The Hunger Stones of central Europe were set in dry riverbeds as reminders of famine. One found in the Elbe river in the Czech Republic is inscribed “Wenn du mich siehst, dann weine.” meaning “When you see me, weep.” These stones marked significantly lower water levels in European rivers, portending failed crops, starvation, and disaster. True data and accurate interpretation mean survival now, as in the past. A message that all leaders should hear, especially in times like today.
Some modern water technologies function like ancient ones. Clay earthen vessels naturally exchange ions with the water stored in them.
Since Nilometers, hunger stones, calendars, and songlines, we have made tremendous progress towards accurately predicting water availability. For over 125 years, the United States Geological Survey (USGS) has collected data on rivers in the US, collecting almost 250 million observations from 26,000 stream gauges. This high-resolution data collection capacity deployed across thousands of kilometres allows Americans to anticipate, predict, and sustain water stress. Digital water technologies today represent a refinement of this system scaled to ultra-local, ultra-high resolutions. It is truly amazing to think that we can now see a building as a watershed because our ancestors told sacred stories about how the stars would help us find water in the desert.
What will help us find “water in the desert” today? One of the earliest and most-influential technologies that we developed was the story. Going back to the beginnings of civilization, it starts with the stories we tell about water. How we live and work with it. How we share it. The circular economy is really about integrating externalities and closing the loop, especially for water. In the blue economy, value is created by managing water cyclically to save time, effort, and energy. And the economy is fundamentally a story we tell ourselves about how to share, live, and work together. Like the Australian aborigines, it is our stories that map our world and tell us how to survive. Our first water technologies are reflections of these stories. They provide the social, economic, and ecological foundation for sustainable water management now and in the future.
The question is, do we hear what those stories are telling us today?