Water was supplied for a Roman city in three ways. Collection of rainwater in cisterns; wells that took up groundwater; water carried by aqueducts. Although we know that the Romans preferred fresh running water, the use of water collected in cisterns was widespread, especially in areas where water sources were scarce.

Tharros had an aqueduct, that carried water to the castellum acquae in the centre of the city, which had a public fountain; some diversions must have taken water to the thermal baths lower down, that needed a large amount of water (figs. 1-2).

Fig. 1 - The castellum aquae (photo by Unicity S.p.A.)

Fig. 2 - The castellum aquae (C) and the thermal bath buildings (T) (from Google Earth. Review C. Tronchetti)

Cisterns were common in Tharros, belonging to the so-called “open” type; i.e. With short rounded sides, from the Punic world, but that were still used in Sardinia during the Roman era. These cisterns collected rainwater and may have had a domestic use, for daily needs (figs. 3-4) or were linked to public buildings, such as the temple of semi-columns (fig. 5).

Fig. 3 - Roman open cistern (photo by Unicity S.p.A.)

Fig. 4 - Open cistern (photo by Unicity S.p.A.)

Fig. 5 - Cistern of the temple of semi-columns (photo by Unicity S.p.A.)

The cover for the cisterns has now normally been lost, but what remains of them allows us to believe they were dual sloping covers (fig. 5).

Sometimes the larger cisterns had a lateral area jutting out that was used as a well to draw water from (fig. 6).

Fig. 6 - Sector of a cistern used as a well to draw water from (photo by Unicity S.p.A.)

The cisterns were filled using terracotta pipes, which have now been lost, that directed rainwater into the tanks. Small channels dug into the rock, sloping outwards, were often created from the tanks, acting as overspills, to drain excess water.

A large number of wells were found, eighteen, (ten of which no longer draw from the groundwater), which integrated the water from the aqueduct and the cisterns (fig. 7).

Fig. 7 - Curb of a well (photo by Unicity S.p.A.)

In addition to the water gathering and distribution system in the city, we must also consider the outflow of waste water.

An effective sewer system ran under the main and minor roads on the slopes of San Giovanni, and then ended up discharging their contents into the sea. The sewers were dug out of the rock, with an integration of blocks when the rock was too deep (figs. 8-10)

Fig. 8 - Roman road: modern covering in wood in the centre lines the sewer cavity (photo by Unicity S.p.A.)

Fig. 9 - Sewer in a minor road of Tharros (photo by Unicity S.p.A.)

Fig. 10 - Sewer heading to discharge into the sea (photo by Unicity S.p.A.)