Engineering Rome

The Water Revolutions in Rome

Drinking Water and the Fourth Water Revolution in Rome
emanz713 emanz713 Dec 9, 2017


Safe drinking water is arguably the most important yet underappreciated resource in the world. Although most of the world has access to filtered and/or treated drinking water, not everyone does. In the year 2015, there were still 663 million people who had to rely on “unimproved” sources for their drinking water, which is defined by the World Health Organization as surface water from lakes, rivers, and dams, or unprotected springs and wells (World Health Organization, 2015). The total world population in 2015 was 7.38 billion people (United Nations, 2017), which means that almost 10% of the world’s population did not have access to safe drinking water only two years ago. In places with water infrastructure like the city of Rome, such a disaster is not an issue – but today, “developed” urban areas are facing new water issues that come with a changing environment and a growing world population. In his book “Water 4.0”, University of Berkeley Professor David Sedlak explains the three revolutions of water systems in human history, and the need for a fourth water revolution to address upcoming problems with water infrastructure. The known history of manmade water systems spans from before the ancient Romans (~753 B.C.) to the present day. The first water revolution, named Water 1.0, was when the Ancient Romans first built piped water systems and sewer systems. The second revolution, Water 2.0, consisted of drinking water treatment. Water 3.0 was the widespread adoption of sewer water treatment in water systems. Finally, Water 4.0 is a new, potential water revolution that may include “desalination plants, potable reuse systems, graywater recycling systems, and other new forms of infrastructure” necessary to prepare us for future water challenges (Sedlak, 2014).
This article provides an overview of the history of drinking water systems in the city of Rome, and to provide insight about the future of Rome’s water supply and drinking water infrastructure. The water revolutions as defined by David Sedlak are mentioned, but the focus will be on the first water revolution and the fourth water revolution. Water features and systems that are not specifically for drinking water, including ancient Roman baths, decorative fountains, and sewer systems, are, of course, important for the development of Rome as a city, but they will not be extensively covered in this article.

Ancient Roman Water Systems

The Ancient Romans are responsible for Water 1.0 – the construction of water supply and distribution systems (as well as the first covered sewer system) in the city of Rome. But before the Ancient Romans developed intricate supply and distribution systems for water, inhabitants of the area relied on wells and cisterns for their drinking water.

Wells and Cisterns

A well is a vertical, man-made shaft built to access water that is below the earth’s surface (an underground spring, or groundwater). The most common well of the Roman empire was a well lined with masonry (see figure 1). Some of the wells had covers or lids to lift off when the wells were being used, along with well-heads to prevent people and objects from falling in. Most wells had a diameter of ½ to 2 meters, but the depth ranged from 3 to 30 meters deep, since depth depended upon the level of the water table (Hodge, 2005).

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Figure 1. Author sitting on a well in Pompeii (Anzalone, L., 2017).

A cistern is a large tank of water used to collect and store rainwater (see figure 2). This could be surface water, or rainwater runoff from building rooftops. Cisterns were commonly used for agriculture and industry more than for drinking water. They could be covered or uncovered – the most common cover was a Roman barrel-vault, which is essentially a semi-cylindrical rooftop. Some cisterns of the Roman empire were large enough to provide water for the entire city that they served, but small cisterns for individual houses also existed (Hodge, 2005).

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Figure 2. Roman cisterns in Fermo, Italy (Citta di Fermo, 2016).

Individual wells and cisterns were typically inside people’s houses. Unlike aqueducts, they were privately owned and maintained (Hodge, 2005). Some cities of the Roman empire, typically smaller settlements, never built aqueducts and always had to rely on wells and cisterns for their water. Other, larger cities, such as Rome, still had many wells even when the aqueducts were built as an additional source of fresh water. Although wells and cisterns are important water structures, they are not considered to be a part of the first water revolution. Wells and cisterns could be sufficient enough to provide some cities with all the water they needed, if there was enough groundwater or rainwater in the particular area, but they were not able to transport water long distances and deliver it into people’s homes.

Aqueducts: From Mountains to Fountains

As Rome’s population grew, local water was not sufficient enough to provide for all of Rome’s citizens. Ancient Roman engineers needed to look outside of the city walls to find a new water supply. The first step in building an aqueduct was to find a water source. The most common source was spring water, but surface water was also used to supply some aqueducts. The majority of aqueducts were channels built below ground. The channels were usually close to the surface, about ½ to 1 m below it, in order to protect the channel, but otherwise, the channels followed the topography of the land as much as possible. The three types of conduits specified by ancient Roman engineer Vitruvius are masonry channels, lead pipes, and terracotta pipes (Hodge, 2005). The size of the aqueduct channels correlates not with the amount of water that the aqueduct conveyed, but with the size of an average Roman. This was because a Roman needed to be able to fit in the aqueduct to in order to build it and later to perform maintenance on it when needed (Morabito, 2017). Because of this parameter, an aqueduct channel was often only about half to two-thirds full of water (Hodge, 2005) (see figure 3). The above-ground portions of aqueducts, called arcades, were only built in order for aqueducts to maintain a constant slope to bring the water into the city, since the aqueducts were gravity-driven. Above-ground water infrastructure was not desired, since it was more susceptible to weather, and could be targeted by enemies. Only approximately five percent of Rome’s water system (by length) consisted of the elevated aqueduct arcades (Sedlak, 2014). Some of the arcades are still standing today, and can be visited in Rome (see figure 4).

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Figure 3. Speleologists in the Aqua Virgo (Auci, 2016).

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Figure 4. Author with Aqua Claudia and Aqua Anio Novus in Parco degli Acquedotti in Rome (Shiffer, 2017).

Rome’s first aqueduct, Aqua Appia, was completed in 312 B.C. It brought clean water from its source; a spring to the northwest of the city; approximately 16.4 kilometers into Rome. This aqueduct was almost completely underground (before reaching Rome), and was constructed by the Roman censors (essentially government officers) Gaius Plautius Venox and Appius Claudius Caecus (Schram, 2010). Aqua Appia had an estimated flow rate of about 0.84 m^3/s. For comparison, the average flow rate of the Cedar River, which is one of the main sources of Seattle’s drinking water, is 18.66 m^3/s (U.S. Geological Survey, 2006). After the Aqua Appia, another ten aqueducts were built in the following 500 years to supply water to Rome’s growing population (see figure 5).

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Figure 5. Map showing the routes of Ancient Rome’s aqueducts (Sedlak, 2014).

Once an aqueduct reached the city, sometimes the water would enter a tank, essentially a cistern, which could hold approximately a day and a half’s discharge of water from the aqueduct. Next, the aqueduct would enter a smaller tank known as a castellum divisorium, which translates as “dividing tower” (see figure 6). The castellum divisorium was the start of the urban distribution system of an aqueduct; a junction box between the aqueduct channel and the beginning of city pipes, which were divided into outlet pipes for public fountains, private homes, and the baths. This distribution center was useful to prioritize water use, since the water supply depended upon the rainfall of the season. If there was excess water, the public fountains would normally receive it, since they provided most people with their drinking water (Sedlak, 2014). Further down the line, the water would reach a second castellum, which divided the water into separate pipes to supply individual citizens. 247 secondary castellum have been found in Rome (Hodge, 2005). After the secondary castellum, water would pass into these individual lead pipes through a calix, which was a bronze nozzle or tube. The calix could control the distribution and consumption of the water, but it was also used to measure the volume of water. The Roman unit of flow, the quinaria, was the smallest size of calix. The conversion from quinarian to cubic meters per second is complicated, since a quinaria is based upon a pipe diameter (2.31 cm), but most modern studies have accepted the value 4.6 x 10^-4 m^3/s based on an estimated amount of pressure head (Hodge, 2005).

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Figure 6. The remains of the castellum divisorium of an aqueduct in France (Schram, 2010).

One of the main end locations of aqueduct water was public fountains. Not to be confused with decorative fountains such as the modern-day Trevi and Fontana del Pantheon, these fountains were meant to be used by the citizens for drinking, cooking, and washing. The simplest form of fountain was a metal spout, but many fountains were more elaborate, and had stone basins for multiple people to conveniently collect water all at once (Hodge, 2005).

Water Quality

The two water sources for aqueducts; groundwater and surface water; had different quality advantages and disadvantages. Surface water that fed aqueducts could become physically polluted with dirt and anything else the water picks up from the ground before reaching the aqueduct. On the contrary, ground water was chemically altered; it became harder when it traveled through limestone and absorbed calcium (Hodge, 2005). The hardness of water a measurement of the amount of dissolved calcium and magnesium in it (U.S. Geological Survey, 2016). This is evidenced by the accumulation of calcium on the inside of aqueducts (see figure 7). Although the surface water may have looked more polluted, the surface water and other minerals could be separated by physical means, such as settling tanks or filters. These are two types of water infrastructure that the Romans did have. But the Romans did not have any way to change the chemical composition of the hard spring water. Even so, the Romans still preferred to use spring water for their aqueduct sources, probably simply because the clear water of the springs looked more desirable to drink than muddy river water (Hodge, 2005).

Figure 7. Inside Aqua Claudia, limestone accumulation is visible on the bottom portion of the channel (Author, 2017).

Basins for water that could have been settling tanks have been found attached to aqueducts. The tanks are not on the main lines of the aqueducts, but near them and connected by additional channels. Since these tanks were found near the beginning of an aqueduct’s route, they could have been used to filter dirt out of the water close to the spring source. Some tanks were also found near the end of an aqueduct’s course, close to the city. Aqueduct water was also filtered by small settling chambers cut in the channel floors of the aqueducts. Settling tanks are a common method of filtering water today.

The pipes bringing water to Ancient Roman fountains and into individual homes were made of lead. In the 1970’s, it was hypothesized that the fall of the Roman empire was due to their increased exposure to lead. This theory is not supported by classical scholars, but it is still apparent that Romans were exposed to lead via multiple sources, including by their water distribution pipes, but also from lead containers used to store food and lead salts used to sweeten their wine. The lead pipes were less likely to be a serious health risk to the Roman people since the hard spring water in the pipes formed a protective mineral layer on the inside, quite like the calcium deposits on the inside of aqueducts (Sedlak, 2014).

Renaissance and Baroque Water

Restoring Aqueducts

The first water revolution also includes the replication of Ancient Roman water systems in European cities over a thousand years after the ancient Romans used them. This occurred in several different cities, including Paris and London, but the development of water in Rome can be explored specifically (Sedlak, 2014). After the fall of the Roman Empire in 476 A.D., the aqueducts were not used anymore, partially because enemies had successfully destroyed them, but also because the aqueducts were not in good condition due to poor maintenance and material accumulation (Schram, 2010). Between the fall of the Roman empire and the restoration of the aqueducts, residents of the Roman area had to live close to the Tiber River in order to use it as a water source (Rinne, 2010). Pope Gregory I restored Aqua Virgo and possibly a couple other aqueducts by the year 602 A.D., and Pope Hadrian I repaired these aqueducts again by the end of the 700’s. Aqua Virgo was providing some water to Rome in the 1300’s, but it was not until the 1400’s that the aqueducts started to be restored to transport water at a substantial rate once again. In 1453, Pope Nicholas V renovated Aqua Virgo (one of the eleven original aqueducts feeding Rome) so that it once again brought a steady flow of clean water into the city. From then on, it was renamed Aqua Vergine. It is still in use today. Pope Nicholas V also added several conduits to the end of Aqua Vergine to direct water to fountains in the Piazza del Popolo and to the Trevi Fountain (see figure 8). This new water supply increased the quality of life of the people of Rome by improving public health and advancing hydraulic technology (Rinne, 2010). However, the Aqua Virgo is the only aqueduct, out of the eleven original, that still served Rome in the 1500’s. In sixteenth century Rome, there “were only two barely functioning aqueducts, two or three public fountains, a handful of dismal public cisterns and wells, and a murky turgid river flowing through the center of town” (Rinne, 2010). Most of Rome’s famous water features (besides the ancient aqueducts) were built after the 1500’s.

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Figure 8. The Trevi Fountain, which is fed by Acqua Vergine today (Author, 2017).

Aqua Felice was restored in 1585. With the construction of Aqua Felice, Pope Sixtus V intended to restore the abandoned Roman Hills. Restoring the Aqua Felice would “facilitate movement between the pilgrimage churches, spur development of villas and gardens on the hills, and develop the area around the Baths of Diocletian as an industrial site, with a facility to manufacture milk, an annual animal market, a huge granary, and new shops and houses” (Hodge, 2005). The original survey for the project had some elevation miscalculations due to the survey being recorded in sections, and the inaccuracy of the surveying tools of the time. This resulted in the water flowing back into the source springs instead of into the Aqua Felice. Despite this initial problem, the project continued after the upper course of the aqueduct was resurveyed. Aqua Felice was restored and routed to some civic fountains and hundreds of privately-owned garden fountains (Rinne, 2010).

At the beginning of the 1600’s, Trastevere, the Roman suburbs on the southwest side of the Tiber river, was suffering from lack of clean water. Although Aqua Vergine and Aqua Felice had been restored, Trastevere was isolated from these water sources, since it was on the other side of the Tiber river (which is the literal translation of the Italian word “Trastevere”). In 1593, a branch was built at the end of Aqua Felice to bring water over Ponte Santa Maria to provide Trastevere with some aqueduct water. However, a major flood destroyed Ponte Santa Maria in 1598, so Trastevere was once again isolated. The original Ponte Santa Maria bridge was never fixed – it was renamed Ponte Rotto (Broken Bridge) and still stands today (see figure 9). Six years after Ponte Santa Maria was destroyed, new distribution conduits were installed in the roadbeds of two other bridges, Ponte Fabricio and Ponte Cestio, to bring water to Trastevere. But this water from the east of the Tiber river was not enough to adequately supply Trastevere. In 1607, Pope Paul V decided to construct an aqueduct to serve the Vatican and Trastevere. He sent scouts to investigate mountain springs that feed Lake Bracciano, a volcanic lake about 30 kilometers northwest of the city center of Rome. This location was a reasonable choice for a source because ideally the aqueduct needed to follow a course that would not have to cross the Tiber River to reach Trastevere, and thus, the water supply would not be cut off by flooding. Pope Paul V convinced the Roman Council to pay for the entirety of the construction of the aqueduct, and to maintain the distribution of the aqueduct and its water. The Roman Council agreed, since it was a monetary advantage for the Council to be able to sell the water to the citizens of Rome. This aqueduct, now called the Aqua Paola in honor of Pope Paul V, was completed in 1612 (Rinne, 2010).

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Figure 8. Ponte Rotto on the Tiber River (Anzalone, L., 2017).

New Drinking Fountains

Until the 1870’s, Roman’s citizens were supplied with drinking water from gravity-driven aqueducts and pipes. In 1870, Pope Pius IX inaugurated a new aqueduct, Aqua Pia Antica Marcia, and pumped water to high-elevation distribution towers on hills. Now that the Romans had pressurized pipes, they did not need to depend upon the topography of their area to design their infrastructure. Individual businesses and homes gained better access to water, and thus outdoor fountains, including laundry and drinking fountains, disappeared (Rinne, 2010).
In 1872, almost all of the drinking fountains of Rome were replaced by new fountains called nasoni, or “big noses”. This type of public drinking fountain is an inexpensive, metal, free-standing fountain that was mass-produced to be widely distributed around Rome (Rinne, 2010). Nasoni are still all over Rome today (see figure 9). From my experience, not many Italians carried around water bottles, but the nasoni were popular water sources among tourists.

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Figure 9. A nasone in Campo de Fiori (Author, 2017).

Modern Roman Water Systems

Today, the water purveyor of Rome is not the Roman Public Works department, but a private utility company called Acea. Acea first started major work with Rome in 1937, when it was given the management and construction of a new aqueduct Aqua Peschiera, as well as the management of all other municipal aqueducts. In the 1970’s, Acea upgraded Rome’s aqueduct system. Aqua Peschiera, the new aqueduct, was put into service in 1971. In 1976, work began on Aqua Marcio to feed the aqueduct with new sources. In 1979, the Peschiera-Capore aqueduct was fed water from the Capore Springs (Acea, 2017). With this additional source of water, the Peschiera-Capore aqueduct system became one of the largest, exclusively spring water, aqueducts in the world. The Peschiera-Capore aqueduct has an average discharge of approximately 14 m3/s, which is equivalent to about 85% of the water consumed in Rome (Wikipedia Contributors, 2017).

Drinking Water Treatment

In 1964 ACEA gained control of Rome’s entire drinking water supply. Lake Bracciano is one of Rome’s water sources, and it is of particular interest due to its protection status and history. It was difficult to obtain information about Rome’s water supply system and treatment plants, but there is some accessible information about Lake Bracciano, likely due to public concern about it. In 1984, the Lake Bracciano sewage treatment plant opened (Acea, 2017). This is a sewer system for the bordering towns of the lake, built to protect the water quality of Lake Bracciano. The independent consulting company Hydroarch designed a new pipeline and purification plant for Acea to filter Lake Bracciano’s water before the water enters Rome’s distribution system, but it is unclear which year the construction of the plant occurred in. Along with the purification plant, Hydroarch is also responsible for building the intake at the bottom of Lake Bracciano to convey water to Rome (Hydroarch, 2009). In 1999, Il Parco Naturale Regionale di Bracciano Martignano, the Regional Nature Park of Bracciano Martignano, was formed to further protect the lake (see figure 10).

Figure 10. Lake Bracciano, a popular tourist destination northwest of Rome (Castro, 2017).

Rome Today: Current Water Challenges

Today, Lake Bracciano is still a major source of Rome’s drinking water, but it is also a popular tourist recreational area. Although motorized boats are prohibited (except for a couple commercial fishermen), visitors can still swim and kayak in the lake (see figure 11). In comparison, the Green River Watershed, the main source of water for Tacoma, Covington, Kent, and some additional areas in Pierce County, is a protected area regulated by Tacoma Water. There is no swimming permitted in the main reservoir or any other bodies of water in the watershed, including Eagle Lake (see figure 12). Although there are other landowners within the watershed, including commercial loggers, they have agreements with Tacoma Public Utilities to minimize their impact on the watershed in order to protect the water quality. The area is not open to the public. Seattle Public Utilities has even more control over their drinking water source, the Cedar River Watershed. This watershed is completely owned by Seattle Public Utilities (Seattle Public Utilities, 2016). In theory, Rome’s drinking water should not be at risk from the water activities of Lake Bracciano since it is treated before entering Aqua Paola. However, one could argue that further measures could be taken to help protect the water from human activity in case the treatment is not sufficient enough to kill certain waterborne pathogens, or if there was an unfortunate situation such as an oil spill from a commercial fishing boat.

Figure 11. Engineering Rome students swimming in Lake Bracciano (Castro, 2017).
Figure 12. Eagle Lake in the Green River Watershed (Author, 2017).

There is concern about Lake Bracciano’s water level and that Acea may be abusing the amount of water they are taking from the lake. Emiliano Minnucci, a member of Parliament for the Democratic Party in Italy, said “the continuous taking of lake water by [Acea] is dramatic. The lake is at risk of dying because of this […] for Acea our lake is a bottomless resource, but this is no longer tolerable” (Harris, 2017). By July 30th, 2017, officials had supposedly ordered Acea to stop withdrawing water from Lake Bracciano because the water level had become so low. Acea refused to comply with this – one Acea spokesman said “the drastic reduction of the flow of water into the capital’s water network will force us to introduce a rigid rotation of supplies that will impact 1.5 million Romans” (Balmer, 2017). But Nicola Zingaretti, the current president of the Lazio region of Italy, said that Lake Bracciano only supplies eight percent of Rome’s water, and Acea has time to find a solution.
Rome is currently in a drought, which has resulted in a decreased amount of groundwater. Obviously, decreased rainfall is contributing to this, but increased impervious area due to urbanization is also a factor. One study between the correlation between groundwater and stream water in Rome stated that “most of the rain drainage waters are piped to sewers, preventing stream recharge to the ground water system” (La Vigna, 2010). The lack of groundwater has caused the water table level to lower by several meters. According to this study, a correlation is present between the groundwater and the stream (surface) waters feeding Rome, which is shown by poor water quality in both bodies of water (La Vigna, 2010).

The lack of rainfall this summer has affected two-thirds of Italy’s agricultural regions, and cost the agricultural industry two billion euros (Eherts, 2017). Although most of the public drinking fountains in Rome are fed by spring water, Rome and the Vatican has chosen to shut off many of these fountains (see figure 13), likely as a statement to the public to convey the severity of the drought, but it would also make sense to ease the demand on water from Lake Bracciano.

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Figure 13. Fountain in Piazza del Biscione that was shut off (Author, 2017).

In the midst of these water supply problems, the demand for drinking water continues to grow. According to the 2013 edition of the Urban Water Census for Italy, the volume of water withdrawn from urban water for drinking use had a 3.8% increase from 2008 to 2012, which shows an increased demand for drinking water over time. The Urban Water Census also calculates the total percent of water loss between the water supply and delivered water (likely calculated through customers’ service meter readings). In 2012, 37.4% of water was lost in the water distribution system; a 5.3% increase from 32.1% in 2008 (Istat, 2014). These statistics show that Italy needs more drinking water but is increasingly losing what they have in their leaky distribution pipes. One solution for this could be an advanced leak detection program, possibly using satellite imaging. Based on my research, it is unclear what steps Acea is taking today to combat these problems, but hopefully they are attempting to improve the effectiveness of their water systems.

Learning from Ancient Rome

In order to combat future drinking water shortages and water infrastructure issues, modern day Roman engineers could possibly implement more water infrastructure designs inspired by Ancient Roman engineering. Today, some of Rome’s decorative fountains are designed to recirculate water for a week, and are then drained, cleaned, and refilled. The Trevi fountain was fitted for a recirculating pump in 1957 (Rinne, 2010). This is not the case for most of Rome’s fountains, but in the future, doing this with all of Rome’s decorative fountains could help conserve water for drinking purposes.

Private rainwater harvesting, quite like how ancient cisterns were used, could be another solution. Although reservoirs are commonly used today, they are publicly owned, maintained, and used. Individual Roman citizens or businesses could benefit from private rainwater collection. Rainfall captured in urban areas could be used for gray-water purposes, such as toilet water and irrigation. This could help conserve more fresh spring water to be used as drinking water.

Another potential solution to the water shortage in Rome is recycling the water of drinking water fountains. The nasoni of Rome are designed to constantly flow. To conserve water, these drinking water fountains could be fitted with relatively inexpensive water filters, such as ones you bring on a backpacking trip, to recycle the unused water that enters their drains. A pump could be installed to bring the filtered water back up to the spout of the fountain. Money is a hindering factor of this solution, since pumps, and future maintenance on these devices on all of Rome’s drinking fountains would add up. But with an efficient design, maybe this could be a possibility in the future.

Figure 14. Engineering Rome 2017 on Aqua Claudia (Stone, 2017).


Anzalone, Larry. Photographs taken in Rome. September 2017.

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Shiffer, Olivia. Photograph taken in Rome. September 2017.

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