The old town of Dellys is built on a hillside, facing the sea. The place has abundant water sources: There are many underground aquifers that form springs flowing in the surrounding mountains and hills. Starting point of the water management system is located at Assouwaf site, 210 meters above sea level, where several large pools are have been constructed, one of which was staged 32 m long by 23 m wide. An aqueduct, 3 km long, collected water from Assowaf, poured it into the basins and distributed it towards several directions.
In antiquity the aqueduct would probably lead to quite many fountains. By the end of the Ottoman era, though, only a few of them remained (Ain el Mizab; Ain El Marsa in the lower Kasbah; and Ain echarchour Salem).
The number of fountains in the gardens has also been reduced. Tala Oualdoun is mentioned and is still used by swimmers then Tala Ghyal, near the cities of Ain Hmadouche and Sidi Abdelouahab.
There was no lack in water and the wells of almost all the houses of the Kasbah are supplied through the ancient network, from the medieval period to the contemporary and modern period. The wells are usually located in the yards of the houses. They have an average depth of twelve meters (12m). The outer part (60 to 80 cm) is generally solid brick masonry, wearing a ring stone at the size of the well and a thickness of about 10 cm.
In Dellys wells have a constructed part above ground, as well as an underground part. The insides of the wells are stone masonry about two meters wide in the bottom with a narrowed opening of 50-60 cm in diameter. Most of the underground part of the wells is hewn directly in rock and does not require water proof shielding. The form of the wells may vary according to their positioning: circular when they are in the middle of a yard and square when they are implanted inside a gallery or right next to a wall.
The baths & the tunnels
The inhabitants also speak often about a number of baths discovered under today’s technical school of the city. The archaeologist Anna Mascarello made known since the 1970s three tunnels: one leading to the cemetery, the other to the city and the third to Sidi Sousan. These tunnels were probably linked to the urban pipe system of antiquity (not verified). In general, restoring the route of the supply network based on discoveries was most often associated with the presence of thermal baths both public and private. Related directly or indirectly to the city supply network, the baths occupy an entire neighbourhood of high Kasbah, which still bears the name i.e. “Bath El Roum” ( = Roman bath).
Besides, this wealth contrasts with the poverty in this area during the medieval times. The baths have been reported inside as well as outside the Kasbah and in the gardens. Some stacked bricks, “the suspensurae hypocaute” (oven) and some washtubs and bathrooms confirm the Roman taste for the toilet. Although they did not know the soap that was introduced later by the Arabs in Europe, the Romans loved the baths and engaged in long hours to enjoy the water and relax in all three types of pools: the hot (caldarium) the warm (tepidarium) and the cold pool (frigidarium).