Cisterns

The Romans made extensive use of cisterns, so that herein I will only be able to explore a very few of the many that were built. Cisterns were used extensively for storing water from rainfall collection and from aqueducts. One example of a cistern (Fig. 7.8a) is at the Roman city of Ilici (La Alcudia de Elche) near present day Elchi, Spain. Figure 7.8b Shows a Roman cistern at the base of the Acropolis in Athens, Greece. In the Roman town of Pompeii, with the extensive water distribution system including both aqueduct water and well water, the roofs of houses collected rainwater that flowed through terracotta pipes down to cisterns where water was stored for domestic use.

The Piscina Mirabilis, near Naples, Italy, is one of the largest Roman cisterns (capacity of 12,600 m3 of water). The cistern was supplied by water from the Augustan aqueduct, the Serino aqueduct that was built from Serino to Miseno. The Serino aqueduct, 96 km long with seven branches, supplied many towns including Pompeii, Herculaneum, Acerra, Atella, Nola, and others. The total elevation drop in elevation from the source, the Acquaro-Pelosi spring in Serino to the Piscina

Fig. 7.8 Roman Cisterns (a) Cistern in Illici, Spain (b) Cistern below Acropolis in Athens. (Copyright permission with L. W. Mays). Color version available in Appendix

Mirabilis is 366 m (0.38%). This large cistern is 72 m by 27 m in plan and is 15 m deep (according to Hodge, 2002).

In Roman North Africa vast cistern complexes were used in conjunction with the aqueducts (Wilson, 2001). These cisterns had capacities that were often several thousand m3, that were much larger than the domestic cisterns. They were typically located where the aqueducts reached the edge of towns. Wilson (2001) describes two types of common cistern complexes in North Africa, both of which were used at Uthina in Oudna, Tunsia. Large cross-vaulted chambers, with a roof supported by piers, is one type of cistern. A second common type of cistern complex includes several barrel-vaulted chambers with a transverse chamber set across them.

In the cisterns at Tuccabor and Djebel M’rabba in Tunsia, the transverse chamber was placed between the inlet and the parallel chambers and the chamber serves as a settling tank before water enters the storage chambers (Wilson, 2001). At Thugga, Thuburnica, Thapsus and Uthina (Fig. 7.9), the transverse chamber is placed between the parallel chambers and the outlet, with no settling (Wilson, 2001). At Thuburnica and the Ain el-Hammam cisterns at Thugga the entrance of the aqueduct channel runs along an internal wall of the cistern so that it distributes water to the cistern chambers. Cisterns at Dar Saniat at Carthage were constructed with three settling basins and two storage reservoirs each of two compartments with a total storage capacity of 2,780 m3 (see Fig. 7.10). Primary settling tank A (oval in shape) received water from the aqueduct and water entered the two-chamber cistern (D and E). Water also flowed from settling tank A into secondary circular settling tanks B and C before entering the second cistern chambers F and G. The water in F and G obviously would have been cleaner. A circular tap chamber (H in Fig. 7.10) received water through two lead pipes from D and E at floor level. It also received the higher quality water from G and F in a third lead pipe a meter higher than floor level.

Fig. 7.9 Plans and sections of the small (top) and large (bottom) cisterns at Uthina (Oudna, Tunsia) (after Babelon and Cagnat 1893, text to f. XXVIII, Oudna; as presented in Wilson (2001))

The story of cisterns continues to the magnificent cisterns built by the Byzantines. These include one of the largest and most magnificent cisterns of all, the Yerebatan Saryi or Basilica Cistern in Istanbul, Turkey. Other great cisterns and even cistern systems were built. In Aden, Yemen, built on the cone of a huge extinct volcano, tunnels and channels were built to transport water to a series of 50 large open air cisterns. Even today the use of cisterns remains a very important aspect of water supply in many parts of the world.