From Antiquity to the Turkish Rule
Athens has always been an area with little rainfall since antiquity. Ancient Athens was primarily supplied with water from springs and local wells. Thus, its inhabitants had to develop basic water collection and distribution systems for the water supply of the city.

Between the years 540-530 B.C., Pisistratos constructed an underground aqueduct, that collected additional water from the Hymettus Mountain. Thanks to the project completed by Pisistratos, water reportedly flowed in abundance, meeting the needs of the city residents.

But the most important work for the water supply of Athens, the Hadrian Aqueduct, was built by 134 A.D. up to 140 A.D. by the Roman Emperor Hadrian. The Hadrian Aqueduct began at the foot of Mount Parnitha in the area of Tatoi and transported water by gravity to a stone reservoir on the hill of Lycabettus in the city of Athens.

The Hadrian Aqueduct and Reservoir were the main sources of water for the city of Athens in the years that followed. It operated without change until the time of the Turkish Occupation (which began in 1456). From this point on, the Roman aqueduct and reservoir were left to deteriorate.

In such circumstances, the Athenians during the period of Turkish Rule turned to the construction of wells in their homes.

1833 - 1925
The retreating Turkish Army destroyed many water supply works during the war for the liberation of Greece (1821). Hence, at the time of Athens’ liberation in 1830, the city’s water supply problem was critical and demanded immediate attention. The new city authorities commissioned a number of projects to rebuild and renovate existing local water supply works, such as the ancient Hadrian Aqueduct systems.

The Hadrian Aqueduct was cleaned of accumulated debris, repaired, and put into operation again in 1840. In 1870 the remains of the Hadrian Reservoir were uncovered. The new Hadrian Reservoir was reconstructed and operated up until 1940.

However none of the above endeavours provided a real solution to Athens’ water problem. The municipal taps, 55 in number, that existed in Athens contributed little to no on daily water consumption needs and were totally inadequate. The men, who were carrying and selling water in Athens from the neighbouring villages, such as Kifissia and Maroussi, were very popular and earned lots of money during that period.

From the Marathon Dam until today
In 1922 with the huge influx of refugees from Asia Minor, Athens underwent a sharp increase in population that had a devastating effect on the city’s water supply.

In 1925 a contract was signed between the Greek Government, the Bank of Athens and the American Firm ULEN for the financing and construction of the new water supply works. The first major project was the construction of Marathon Dam (1926-1929). Over 900 people were involved in the construction of the dam, which is considered unique because it is entirely paneled externally with Pentelikon white marble.

The Boyati Tunnel (13,4 km) was constructed to transport water from the Marathon impounding reservoir to a new water treatment plant in Athens.

In the years that followed (1950’s) Athens’ population continued to grow and the need for additional sources of water once again became pressing. Yliki Lake in the nearby prefecture of Viotia had a significant amount of available water. It was joined in water supply system of Athens in 1956. Yliki is situated on a lower altitude compared to Athens. So, it required the construction of pumping facilities in order to transport the raw water to Athens. The Yliki pumping station is the biggest in Europe.

With Athens continuing need to increase raw water supplies, a new project was proposed which involved the damming of the Mornos River. The dam’s construction began in 1969, but operation of the Mornos dam and new Mornos aqueduct officially began in 1981.

The Mornos dam is one of the highest earth gravity dams in Europe with a height of 126 m. The Mornos aqueduct that transports water from the Mornos reservoir to Athens is the second longest aqueduct in Europe.

Another major project, which has provided Athens with additional water, is the Evinos River diversion to the Mornos Impounding Reservoir. The project consists of the Evinos Dam and a diversion tunnel. Work began on the Evinos project in 1992 and was completed in 2001. The diversion tunnel was completed in just two years, which is considered to be a significant achievement given the project scale. The tunnel has a length of 29,4 km. The Mornos and Yliki Aqueducts are joined by a system of interconnecting aqueducts that provide alternative supply schemes for the maintenance and repair needs of the works. The network of interconnecting aqueducts also offers EYDAP greater overall control and water resource management capability.

Via the Mornos, Yliki and other interconnecting aqueducts, raw water is transported from various sources to the four water treatment plants in the Athens area: Galatsi, Polydendri, Acharnon, and Aspropirgos.