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In ancient Greece, the cities were supplied with water from springs over which beautiful fountains were erected. The Greek aqueducts were not on the same grand scale as the Roman, but were usually rectangular channels cut in the rock, or made of pipes or masonry. Great care was taken in the supervision of these public works.
The first Roman aqueduct, according to Frontinus, dates from 312 B.C.
Pliny wrote of the Claudian aqueduct: "But if anyone will carefully calculate the quantity of the public supply of water, for baths, reservoirs, houses, trenches, gardens and suburban villas, and, along the distance which it traverses, the arches built, the mountains perforated, the valleys levelled, he will confess that there never was anything more wonderful in the whole world."
Frontinus, who was controller of the aqueducts in the time of Nerva and of Trajan, describes nine aqueducts, of which four belonged to the days of the Republic, and five to the reigns of Augustus and Claudius.
"The total water-supply of Rome has been estimated at 332,306,624 gallons a day, or, taking the population at a million, 332 gallons a head. Forty gallons a day is now considered sufficient."
The ancient Aqua Virgo at the present day supplies the magnificent Fontana di Trevi, and the glorious fountains in the Piazzo di Spagna and the Piazzo Navona.
The Romans not only provided great aqueducts for the Imperial City, but also built them throughout various parts of the Empire. In Rome, the aqueducts were built to supply both the low and the high levels of the city. The reason why the Romans did not build underground aqueducts, as is done at the present day, has been variously explained. Perhaps they did not fully understand that water will find its own level over a great distance. They also would have found great difficulty in overcoming the high pressure of the water.
In their conduits they built shafts at frequent intervals designed to relieve the pressure of compressed air in the pipes. The water from the neighbourhood of Rome rapidly encrusted channels and pipes with calcareous deposits. Probably the great advantage of accessibility to leaks and defects gained by building unenclosed aqueducts appealed strongly to the ancient Romans. They did not fully understand the technical difficulties involved in the "hydraulic mean gradient." No machinery was used to pump the water or raise it to an artificial level. A strip of land 15 ft. wide was left on either side of the aqueducts, and this land was defined at intervals by boundary stones. No trees were grown near the aqueduct, to avoid the risk of injuring the foundations, and any breach of the rules for the preservation of the aqueducts was severely punished by fines.
Vitruvius gives rules for testing the water, and points out that water led through earthen pipes is more wholesome than water coming from leaden ones. He states that the "fall" of an aqueduct should be not less than 1 in 200. A circuit was often made to prevent the too rapid flow of the water, and intermediate reservoirs were constructed to avoid a shortage of water in the case of a broken main. Reservoirs were also used for irrigation.
The water from the aqueduct was received at the walls of the city in a great reservoir called castellum aquarum, externally a beautiful building and internally a vast chamber lined with hard cement and covered with a vaulted roof supported on pillars. The water flowed thence into three smaller reservoirs, the middle one filled by the overflow of the two outer ones. The outer reservoirs supplied the public baths and private houses, while the middle one supplied the public ponds and fountains, so that, in the event of a shortage of water, the first supply to fail was the least important. The amount of water provided for private use could be checked, for purposes of revenue, by means of this arrangement.
At first the aqueducts were not connected with private houses, but, later, private persons were allowed to buy the water which escaped from leaks in the aqueducts. Next, private connections were made with the public mains, and, finally, reservoirs were built at the expense of adjoining households, but these reservoirs, although built with private money, were considered part of the public property. Water rights were renewed with each change of occupant. The water-supply to a house was measured by the size of the pipe through which it passed at the in-flow and at the out-flow of the reservoir.
The curatores aquarum had very responsible duties. Under their orders, in the time of Trajan, were 460 slaves who were subdivided into various classes, each of which had its own particular duties to perform in connection with the maintenance and control of the water-supply. A supply of pure water and proper drainage are of first importance in sanitation, and it is evident that the Romans understood these matters well.