Thessaloniki Water: From the source to the glass

Thessaloniki needs in water are met by various sources, namely by the Aravissos and Axios aqueducts, after special treatment at the refinery located in the area of Sindos. The aqueducts in the areas of Narres, Sindos and Kalohori are not currently in use, but are fully operational and ready to cover any urgent needs of the population or as an alternative to failures or inadequacies of the key sources.

Main water sources

Aravissos

The springs of Aravissos, at the southern outskirts of Mount Paiko in Pella, supply the city of Thessaloniki with drinking water through the natural karstic cavity of the mountain, where the underground water outlet exits and watercourses end up. The water supply from these sources varies from 65,000 m3 to 130,000 m3 per day, depending on the annual snowfall and precipitation.

Aliakmonas

Aliakmonas and, in this case, the dam of its deflection near the village of Agia Varvara, situated approximately 40 kilometers from the estuary of the river, is the second main water suuply source of Thessaloniki. The water, through a free flow of 50 km, reaches Axios river and from there ends up in the Sindos refinery for processing. The clean, drinking water is gathered in a 75,000 m3 tank and is distributed through a 36 km pipeline network to various water tanks in Diavata, Evosmos, Polichni, Neapoli, Vlatades, Toumba and Kalamaria, as well as in the Industrial Area.

Alternative sources

Kalochori: Boreholes in this area are not currently used for water supply, as the main sources sufficiently meet current needs.

Sindos: The 26 boreholes in the area provide 30,000 m3 of water per day.

Axios: The 46 boreholes in the wider area of the River Axios (Gefyra, Chalkidona, Eleousa and Agios Athanasios) provide about 70,000 m3 per day.

Narres: This water supply starts from the bed of the River Gallikos and ranges from 5,000 m3 to 25,000 m3 per day, but is currently inactive.

Agia Paraskevi: The aquifer in the area of Chortiatis is used as a complement to meet the needs of the particular Municipal Department and is a backup source of water supply to G. Papanikolaou Hospital.

Mikra - N. Rissio: The 6 boreholes in Eastern Thessaloniki provide 4,500 m3 of water and supplement the Kalamaria water tank daily, but are not currently used.

Water treatment

At the Water Treatment Plant of Thessaloniki in the Industrial Area of Sindos, 150,000 m3 of water undergo daily treatment and chlorination so that it is potable and safe for the population. Chlorine is the most cost-effective means of water decontamination in urban water supply systems worldwide. However, both chlorine and its spinoffs, such as chloroform, give water a distinct and unpleasant taste and odor.

In cases of repairs in the water supply system due to accidental damage or permanent wear in specific pipelines (such as in 2018, when the local water supply network was damaged three times within two months), the water is hyperchlorinated by adding more chlorine to replenish the quantity that leaked out. As a result, the drinking water that reaches several households in Thessaloniki contains extra amounts of chlorine, which deteriorates its taste and smell. The purchase and installation of household water filters is an immediate, safe and cost-effective solution to this problem.

Water supply network

The water is distributed in Thessaloniki through a pipeline and pumping network, which gives it a boost to reach every part of the city. However, this water supply network is quite old, with the problems due to its deterioration becoming noticeable in recent years. All citizens of Thessaloniki remember that, in March 2018, a part of the obsolete pipeline system broke, leaving a large proportion of the population without water for 5 days.

When the Aravissos water pipeline system was completed in 1978, the manufacturers estimated its life expectancy would be 40 years. However, these forecasts appear to be quite optimistic and unreasonable as the pipeline is located at a depth of 3 meters and its length reaches 60 kilometers, which makes it extremely difficult to maintain consistently and to restore the damage promptly. If a part of the pipeline breaks or perforates, as in March 2018, the exact point of the damage must be located, an excavation must be made, the particular point must be isolated and emptied out, resulting in the water supply being shut down, then it must repaired or replaced and, finally, there is a waiting period until the water is clean. Since the water supply network in Thessaloniki is quite worn, it is very likely that events such as those in 2018 will happen again and again.