There were many components to the Roman urban water distribution system. Figure 7.2 Illustrates how the water distribution system connects to the aqueduct system. Water flowed by gravity through enclosed conduits (specus or rivus), which typically were underground, from the source to a terminus or distribution tank (castellum). Above ground aqueducts were built on a raised embankment (sub-structio) or on an arcade or bridge. Settling tanks (piscinae) were located along the aqueducts to remove sediments and foreign matter. These pipes were connected to the castellum by a fitting or nozzle (calix). These pipes were placed below ground level along major streets.
Pompeii (located on the Bay of Naples, south-southeast of Mt. Vesuvius in Italy) had a water supply system that is representative of Roman urban water distribution systems. Sources of water for Pompeii included wells, cisterns and other reservoirs, and the Serino aqueduct. This aqueduct received water from springs at Serino, near Avellino, and then was routed via Sarno around the north side of Mt. Vesuvius to serve Naples and two large cisterns of Cento Camerelle (Baiae) and the Piscina Mirabilis (Misenum). From Sarno a branch aqueduct was routed to Pompeii terminating at the castellum at Porta Vesuvii, shown in Fig. 7.6. According to Richardson (1988, p. 51) there were no springs within the city of Pompeii. The water table was tapped within Pompeii using wells as deep as 38 m below the surface (Maiuri, 1931, pp. 546-557).
Two approaches to laying out the pipe network were followed: (a) using a main pipe from the secondary castellum with smaller branch pipes attached to serve individual customers, and (b) not using main pipes but using individual pipes laid from the secondary castellum to the individual customer, which was the normal Roman practice (Hodge, 2002). Pompeii’s water distribution system consisted of pipes along the main streets connecting the main castellum at Porta Vesuvii (Fig. 7.6a) to the various water towers (secondary castella) (Fig. 7.7a), from which smaller pipes (Fig. 7.7b) were placed under the sidewalks and streets and served the various customers. Not all customers had individual lines from a secondary castellum but instead received their supply from taps into the system at their locations.
A water tower (secondary castella) that had a lead storage tank placed on top of the tower with a public water fountain on the street is shown in Fig. 7.7a. Public water fountains, supplied from the secondary castella, were placed somewhat evenly around the urban center, being about 50 m apart. The fountains had an overflow weir so that the water would flow onto the streets and then into the drainage system. Terracotta pipes were not used in the water distribution system in Pompeii (Jansen, 2001). Lead pipes (Fig. 7.7b) in Pompeii are of the same construction and appearance as found in other Roman cities. The water taps found in Pompeii were also similar to those found in other Roman cities. Only a small number of houses had a water pipe that supplied a private bath or basins in the kitchen. Overflows were drained into cisterns for rainwater.
The households and public buildings both had very interesting systems to collect and store rainwater. Buildings with peaked roofs had gutters along the eaves to collect the rainwater and downspouts to carry the water to the cisterns located under the building. Downspouts were made of terracotta pipes and were often set inside the wall.
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