What is a aqueduct

An aqueduct is a canal, a pipe, or a tube that is built to carry large quantities of water from one place to another. The name comes from the Latin words iiqua, meaning "water," and ductus, meaning "canal." Most aqueducts bring water to people living in large cities. The first aqueducts were built by the Greeks, more than 2,500 years ago. The Greeks dug canals and cut tunnels through the hills and rocks to bring water from the hills to their cities. One Greek aqueduct was a tunnel almost a mile long, cut through a hill. The tunnel was 8 feet wide and 8 feet high, and a stream of water 3 feet deep ran through it. The most famous aqueduct-builders were the ancient Romans.

They also dug canals and cut tunnels. But the Romans did something else that no one else had done. They built long stone bridges to help carry water to their cities. These bridges themselves have become known as aqueducts. Sometimes when people use the word "aqueduct," they mean a bridge that carries a tube of water on its top. The Roman water-carrying bridges often stretched for mile after mile across valleys and fields. These Roman aqueducts were marvels of engineering and architecture. They were built of stone and brick, and the water tube on top was large and usually lined with cement. The Romans could have built their aqueducts on top of solid walls, but people would not have been able to get through these walls.

So the Roman aqueducts consisted of hundreds and even thousands of arches, one after the other. Some of the Roman aqueducts were built with one row of arches on top of another, and some even have three rows of arches. Today there are still ruins of ancient Roman aqueducts in Italy, France, Spain, and North Africa. A few Roman aqueducts are still in use. Aqueducts bring water to many large modern cities. Water is brought to New York City through aqueducts. The Croton Aqueduct was finished in 1842. Since the Croton Aqueduct is able to bring 60 million gallons of water to New York City every day, it was natural for people to think that no more water would ever be needed. But New York grew and grew and grew.

Today the people of New York often use twenty times as much water as the Croton Aqueduct, large as it is, can supply. New York's water is brought from as far as 100 miles away. The people of Los Angeles need and use less than half the water needed by the people of New York City. The aqueduct bringing water to Los Angeles, however, is over twice as long as the longest New York City aqueduct. The water brought by aqueduct to Los Angeles comes from the Sierra Nevada Mountains, more than 230 miles away. Modern aqueducts are not built above ground as were the Roman bridge aqueducts. Most modern aqueducts are either tunnels drilled through rock or large pipes laid underground.