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A primitive way to obtain water was its storage; before the construction of aqueducts, the Romans obtained water from the Tiber river, from the rain or from wells and water was scarce in summer.  So, the water storage was very important in the first times of the city and in manycities around the empire where a system of flowing water through aqueducts took a long time to exist or never existed.

The primitive private houses used to have only one room blackened by the smoke called atrium –“black room”-; its roof was inclined to the interior so that the rain water felt inside and was collected in a small pool; when the houses evolved and the wealth allowed it, the Romans made new rooms, separating the kitchen from the rest of the rooms, but the small pool to store rain water remained in the centre, but it became bigger in the centre of a porch courtyard –atrium with peristylum-; so, the houses were organized around the atrium, with a compluvium –an opening in the roof in the centre of the house where the light and the rain water entered- and under the compluvium an impluvium –the small pool to collect the rain water- with a size proportional with the compluvium.  The impluvium was decorated with marble or mosaics that need to be cleaned often  to avoid an accumulation of impurities, moss and so on.  The impluvium has often a drain hole in a height to avoid that the pool overflowed.

Impluvium in the peristylum of the domus of Antas in Glanum (Provence, France)

(Photo:  Roberto Lérida Lafarga 8/8/2007)

Impluvium en la domus de Dolfin in Vasio (now Vaison la Romaine, Provence, France)

(Photo:  Roberto Lérida Lafarga 6/8/2007)

Other method to storage water in a higher scale was the cisterns to a private use or to a common use.  In the first case, the Roman used to collect normally the water that remained from the impluvium of their houses in small cisterns whose capacity only reached some tens of cubic metres.  In the case of public storage the Roman built along their empire cisterns with high capacity that they filled up with rain water or water from channels or aqueducts.  The big buildings for public events (theatres, amphitheatres, circus) stored water for their own maintenance collecting the rain water that flowed through their tiers, thanks their pitches and storing in a tank at the bottom of the steps;  so in the theatre of Pompeii there was a cistern for 7.000 litres and the theatre of Arausio (now Orange, in Provence, France) had a cistern in an angle of the scenery.

A permanent problem was the water purity; the best method to clean the cisterns was to decant, although they were usually provided of spiked gates and grids that blocked the entry of big residues.  The ground and the sand were used as filters to purify water, but they were not enough, so the cisterns were divided in channels –the piscine Mirabilis in Miseno had 5 longitudinal naves and 13 transverse naves-: the water flowed from one channel to other, especially to a central channel deeper, and the impurities remained in the channels; finally the water was completely filtered.  Some cisterns had a colossal size: in Rome one of its cisterns, today called Sette Sale, was 56 metres long and 42 metres wide; in Constantinople (now Istambul) the cisterns, today called Yerebatan Sarayi, was 140 metres long and 70 metres wide, with a roof supported by 336 columns with Corinthian capital and profuse decoration, like Medusa’s heads reused as basis for a column.

Details of the cisterns Yerebatan Sarayi in Istambul

(Photographies: Roberto Lérida Lafarga 26/9/1992).

Architecturally these big cisterns were a challenge for the Roman engineers, because in their building they had to bear in mind an additional factor: the water pressure on the constructive elements; at the same time they had to bear in mind to build decantation channels and to fight against the pernicious effects of the water in all kind of constructions:  the waterproofing of the cisterns became essential.  In all hydraulic building the walls and the ground were recovered with a thick layer of opus signinum, i. e., a red mortar waterproofing made by mixing lime with tile sand

Cistern in the Caracalla's Thermae (Rome)

(Photo:  Roberto Lérida Lafarga 29/12/2004)

Finally, the cisterns could belong to three different types: first, cisterns with vaults supported by columns –the most spectacular-, like the Yerebatan Sarayi in Istambul; these cisterns received water from aqueducts and they had a decantation system; second, cisterns with vaults without columns, with only a nave with thick walls that supported the vault, longer than wider; they had not too much capacity; and third, cisterns made by juxtaposition of cisterns of the second type, usually terraced to allowed the decantation; they had a advantage over the other two types: it was not necessary to empty them completely to clean the residues, mud and moss; probably this type was the most used by the Romans (Carthage, Capri, Sette Sale in Rome, etc.).

However, with the progress of the hydraulic works, in the Roman dams, in the aqueducts and in the arrival of water to the cities it was usual and necessary that the specus drained in cisterns to the urban distribution of water: these cisterns are called in Latin castella, i. e., cisterns of distribution.  We know the castella of Pompeii and Nemausus (Nîmes, in Provence, France).  About the castellum of Nîmes Malissard said “its walls have disappeared completely; in the middle of the houses of the Rue –street- de la Lampèze only the cistern of the castellum and its rooms remain.  Protected by grilles and sometimes covered by weeds, these remains seem to be there only to offer to an obstinate visitor, who looks it for and finds it, an almost perfect plan of a distribution tower” (I subscribe these words, because I suffered an “odyssey” to find it).  A circular cistern 1 metre deep receives the water from a rectangular specus 1,20 high and it divided the water into 10 tubes of 0,40 metres provided of grilles that obstruct the big residues.

Details of the castellum in Nîmes where it is visible the specus of water entry from the aqueduct of the Pont du Gard and the semicircular exits to distribute the water in the city. 

(Photographies:  Roberto Lérida Lafarga 14/8/2007)




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- BELTRÁN LLORIS, Miguel: “El agua profana en la cuenca media del valle del Ebro:  AQUA DUCTA.  La captación del agua, presas, embalses, conducciones”, en AA. VV.: Aquaria: Agua, territorio y paisaje en Aragón, Zaragoza, 2006

- CONNOLLY, P. y DODGE, H., La Ciudad Antigua.  La vida en la Atenas y Roma clásicas, Madrid, 1998