What are the similarities between L.A. and ancient Rome?

A time-traveling citizen of ancient Rome might find Los Angeles surprisingly familiar, barring language differences. Both cities share a culture of opulence and indulgence, a diverse blend of cultures and ethnicities, and a democratic system that occasionally sees unconventional candidates rise to prominence. However, the most striking parallel lies in their essential infrastructure: the water systems that sustain their populations.

Long before L.A.'s aqueducts were built to accommodate its booming population, ancient Rome engineered a comparable system to support over a million residents. The motivation was identical: the local water sources were insufficient to meet the needs of the growing populace.

Rome initially relied on the Tiber River for its water supply. However, the city's emphasis on hygiene and ample water access outstripped the Tiber's capacity. At its peak, Rome's aqueducts delivered water not only to affluent households but also to public baths, fountains for the less privileged, and even public restrooms equipped with sinks.

To meet the water demands of this exceptionally hygienic ancient society, Roman engineers devised a method akin to transporting water by truck, but with far greater sophistication. The aqueducts of ancient Rome, which channeled water from distant sources into the city, operated entirely on the principle of gravity.

In theory, aqueducts are straightforward: begin at a higher elevation with a plentiful water source and guide it downhill to a central distribution point. However, in practice, constructing aqueducts is far more intricate due to the uneven natural slopes of the terrain.

How did Roman engineers overcome the challenges posed by the land's topography? On the following page, we'll explore the construction techniques of aqueducts from thousands of years ago.

Ancient Aqueducts

To maintain a steady, gentle slope for the continuous flow of water, the Romans installed underground pipes and built siphons across the terrain. Laborers dug intricate underground channels and laid networks of water pipes to transport water from source lakes or basins into Rome. These pipes were usually constructed from concrete, though lead was occasionally used when sufficient funds were available (lead was a costly material in 300 B.C.). When valleys needed to be crossed, they constructed siphons—deep dips in the land that allowed water to gain enough momentum to climb uphill. Siphons also play a role in modern plumbing, such as in How Toilets Work.

However, siphons came with a significant drawback: their expense. Effective siphons required lead pipes to accelerate the water flow. This limitation led to the iconic Roman aqueduct feature—the arches. When siphons were unfeasible, arches were built to bridge valleys, with pipes running along their tops.

At various points along the aqueducts, sedimentation tanks filtered out impurities. Maintenance access points were also integrated into the system, allowing workers to inspect and repair the pipes. Engineers ensured maintenance efficiency by laying dual pipes side by side, enabling water diversion so workers could access one pipe at a time.

Among the 11 aqueducts of ancient Rome, built between 312 B.C. and 226 A.D., some transported water from as far as Tivoli, approximately 43 miles (70 km) away [source: Antiquities]. The longest, Anio Novus, stretched nearly 60 miles (97 km) [source: InfoRoma].

The fall of ancient Rome led to the decline of its aqueducts. By 537 A.D., when the Goths invaded, the water system had already been scaled back due to a shrinking population. The Goths ultimately destroyed the remaining aqueducts. However, during the Renaissance, Rome began rebuilding these structures to supply water to its new fountains. By the 1950s, eight aqueducts had been restored, and they remain standing today [source: Antiquities].

At its peak, Rome's aqueduct system provided each resident with over 265 gallons (1,000 liters) of water daily, surpassing the capacity of many contemporary water systems [source: InfoRoma].

The aqueducts in Los Angeles rival those of ancient Rome in their ingenuity, especially considering they were built without modern machinery. Similar to Rome, L.A.'s first aqueduct was constructed in response to rapid population growth. In the early 1900s, the city's water demand outstripped local supply, prompting the creation of an aqueduct system inspired by ancient Rome. On the next page, we'll explore how L.A.'s aqueducts mirrored Rome's water-delivery methods.

Modern Aqueducts

By 1904, the Los Angeles River could no longer meet the water needs of the city's 175,000 residents. For ten consecutive summer days, water usage exceeded the river's capacity by over 4 million gallons (approximately 15,141,647 liters). This crisis made finding a new water source urgent, and aqueducts emerged as the ideal solution, tapping into abundant water supplies outside the city.

The water engineers in Los Angeles chose the Owens River Valley for several key reasons. First, Owens Lake received an immense amount of snowmelt from the Sierra Nevada Mountains, often overflowing. Second, a volcanic eruption had blocked the lake's tributary, preventing its water from entering the river system. This meant a vast amount of water was being wasted, a critical concern for those tasked with securing more water for L.A. Third, before the eruption, the Owens water had naturally flowed almost directly toward Los Angeles.

To address the water shortage, Los Angeles constructed a 226-mile (364-km) aqueduct to transport water from Owens Valley to the city [source: LADWP]. Drawing inspiration from ancient Rome, L.A. engineers used underground pipes and siphons, relying on gravity to move the water. Some pipes were so large they could fit a car. The largest siphon in the system, spanning Jawbone Canyon with over 8,000 feet (2,400 meters) of steel pipe weighing more than 3,200 tons, drops water 850 feet (260 meters) to create the pressure needed for it to climb back up the canyon [source: LADWP].

However, Los Angeles' rapid growth, fueled by the abundant water supply, soon led to demand outstripping supply again. By the early 1920s, just a decade after the Owens Valley aqueduct was completed, the valley's water resources were nearly depleted.

Los Angeles' relentless demand for water devastated Owens Valley. As the lake dried up, depleting the local fish population, L.A. turned to groundwater extraction. Despite fierce opposition from valley residents, including a violent protest in 1924 where dynamite was used to damage the aqueduct, the city continued purchasing land in the valley to secure water access. This led to agricultural decline and a prolonged period of economic hardship for Owens Valley.

In 1970, coinciding with the completion of L.A.'s second aqueduct, which transported water from Haiwee Reservoir south of Owens, environmental conservation efforts began gaining momentum in the United States. A series of legal disputes led to agreements between Owens Valley and Los Angeles, enabling the valley to gradually recover. Financial support from L.A. funded the construction of fisheries, reservoirs, conservation areas, wildlife preserves, and groundwater management systems, revitalizing the region. Additionally, the aqueducts now contribute to green energy, powering several hydroelectric dams.

Despite the controversies surrounding the Los Angeles aqueducts, they remain an engineering marvel comparable to those of ancient Rome. Operating solely on gravity, the two aqueducts transport approximately 430 million gallons (1,627.7 megaliters) of water across hundreds of miles to Los Angeles daily, ensuring the city's water needs are met for the foreseeable future.