In the Mediterranean countries, all of which have a long dry season and rocks largely of porous limestone, the regular supply of water to cities and villages, as well as for irrigation, has always been a problem. The Romans excelled in this branch of engineering and their great aqueducts, whether underground or spanning deep valleys, are among the most striking relics of antiquity.
Rome itself was supplied by nine great stone aqueducts which were subsequently increased to eleven. Three of them were more than fifty miles long. They were lined with cement and were up to 3 or 4 ft wide; although they were in fact tunnels, they were high enough for a man to pass through them. The distribution of the water to fountains and dwellings from the large reservoirs which were fed by these aqueducts was sometimes by means of lead pipes and sometimes by wood; but as early as 27 B.C. the architect Vitruvius pointed out the danger to health from lead poisoning; and in his book De Architectura he adds, 'Therefore it seems that water should not be brought in lead pipes if we desire to have it wholesome'. (9) Bronze was too expensive at that time for piping; but the Romans, who were complete masters of all matters relating to pumping, etc., frequently used copper or bronze pumps, stopcocks, valves and other fittings.