Together with food, Man’s greatest need is for water and, when communities were established far from a riverbank, spring or well, it was necessary for water to be directed or carried to the homes; this was achieved by building an artificial channel, an aqueduct, to allow the water to flow from one place to another.
Such aqueducts were certainly used by the Babylonians in ancient Mesopotamia from 3500 BC onwards. Similar forms of open channels were used in ancient Egypt and Greece but the most famous examples were those in Rome and other parts of the Roman Empire.
The earliest Roman aqueduct was built underground during the administration of Appius Claudius Caecus in about 310 BC. Named Aqua Appia, it carried water to Rome, 16 km away.
Possibly the best known of the Roman aqueducts were those built above ground, which needed huge bridged sections high enough to allow the water to flow across wide valleys. The first of these, the Aqua Marcian, carried water a distance of nearly 90 km. It was built in 144 BC and the bridged section was 16 km long. Eventually, nine aqueducts were built, providing the city of Rome with over 170,000,000 liters of water a day.
Parts of these remain and are in current use, supplying water to the fountains of Rome. As their empire expanded the Romans built aqueducts in many other parts of Europe. Those still in existence include one at Pont du Gard at Nimes, France; another at Segovia, Spain, built in AD 109; and one at Mamz, Germany.
After the fall of the Roman Empire, water supplies were neglected for 15 centuries.
Many aqueduct systems fell into disrepair or were destroyed. It was not until the sixteenth century that there was a revival of efforts to improve the supply of drinking water in Europe.
In 1613, a channel was constructed from Hertfordshire to Islington, north London. Named the New River, this aqueduct supplied 18,200,000 liters of water a day to London. Other aqueducts built since the 1840s include the Marseilles aqueduct, 96 km long; the second Kaiser Franz Joseph aqueduct in Vienna, 231 km; and the 154 km aqueduct that supplies Manchester, England. The world’s most extensive aqueduct system is in south California, which supplies, in particular, the cities of Los Angeles and San Diego.
One of the main sources for this system is the Colorado River, from which water is carried 390 km over the San Bernardino mountains; this aqueduct has a capacity of 4,550,000,000 liters a day. Another source for this system is the Sacramento River in northern California, from which water is brought 715 km by aqueduct to a reservoir south of Los Angeles; a further 409 km for this system is expected to be completed by 1981.
Overall, the Californian aqueduct system, involving canals, pipelines and tunnels, will be almost 1600 km long and provide over 8 billion liters of water a day to southern California.