By Marcia Anderson
A: Aqueducts and Great Water Transport Systems.
The New York City water system is not only a modern engineering feat; it is also a return to the technology of the ancient Romans.
As ancient Rome grew, early Romans drew greater quantities of water from the Tiber and from wells sunk in the city. Similarly, early New Yorkers drew their water from the surrounding rivers and from wells tapping ground water aquifers. The hidden half of Rome’s water system, the sewers, took water overflow and flushed refuse into the river, which damaged the river, but kept Rome clean. The water over time became polluted and insufficient for the population. Inadequate water supply and contaminated wells also plagued New Yorkers in the 1700s and 1800s. The Croton aqueduct system was built in response to the fires and epidemics that repeatedly devastated NYC.
In the Roman Empire, aqueducts were invented to bring pure water from the hills which surround Campania. Neither the Romans, nor New Yorkers could have built their big cities without aqueducts. Both of our societies would have been very different without fresh imported running water that this system provided.
By 200 BC, Romans developed a highly effective system of bringing water in conduits to their cities from sources many miles away. The conduits were either open channels, or pipes made of clay, bronze or lead laid underground. Because the system relied on gravity, the water source had to be higher than the city served. Roughly 4/5ths of Rome’s aqueducts run underground, in covered trenches which were quick and easy to build as they did not require the construction of arches or the burrowing of tunnels. Romans built underground to hide their water from enemies and to protect the pipes from the stresses of wind and erosion. Covered trenches and tunnels were also less disruptive to life on the surface than walls or arcades.
The channel itself was a trough of brick or stone, lined with cement, and covered with a coping, which was almost always arched. The water either ran directly through this trough, or it was carried through pipes laid along the trough. The pipes were 10 feet or more and were cemented together at the joints. When a channel came to a dip in the landscape, such as a valley, the Romans built an arcade to take the water over it. The water had to be kept at a certain level because if they lost that level, it was hard to get pressure back up again.
In New York, from 1837 to 1842, the Croton River was conveyed through an artificial channel, built with square stones, supported on solid masonry, and carried over valleys, through rivers, under hills, on arches, through tunnels and bridges, for 40 miles, to supply NYC with fresh water. It was arched over to keep it pure and safe and flowed at the rate of 1.5 miles per hour towards NYC.
The Croton Aqueduct brought NYC its first supply of clean, plentiful water and thus contributed to its development as a great metropolis. The first Croton water entered the aqueduct on June 22, 1842 and carried water from the Old Croton Dam in Westchester County to two reservoirs in Manhattan. One was on the present site of the Great Lawn in Central Park, and the other site was where the New York Public Library is on Fifth Avenue from where it was distributed. The New Croton Aqueduct went into service in 1890, with its tunnels running deep underground and currently supplies about 10 percent of NYC’s water.
The Croton Aqueduct is a National Historic Landmark and is considered one of the great engineering achievements of the 19th century. The tunnel was designed on principles dating from Roman times, is gravity fed, and on a steady gradient dropping gently 13 inches per mile. Its builders had to cut the conduit into hillsides of varied terrain, set it level on the ground, tunneled through rock, and carried it on massive stone and earth embankments and across arched bridges.
The next time you drink fresh, clean, NYC water thank the NYC Water authority and adapted Roman ingenuity.
About the Author: Marcia is the bed bug and vector management specialist for the Pesticides Program in Edison. She has a BS in Biology from Monmouth, second degree in Environmental Design-Landscape Architecture from Rutgers, Masters in Instruction and Curriculum from Kean, and is a PhD in Environmental Management candidate from Montclair – specializing in Integrated Pest Management and Environmental Communications. Prior to EPA, and concurrently, she has been a professor of Earth and Environmental Studies, Geology and Oceanography at Kean University for 14 years.