The water network is comprised of all the primary transfer and distribution pipelines for treated water from the WTPs to the consumers’ water meters, as well as the support facilities, such as the regulating-storage tanks and the pumping stations.

EYDAP is responsible for the supply of water to the greater Attica region with a population of more than 4.000.000. The altitude of its jurisdiction areas ranges from 0m to +600 m. The WTPs operational water levels range from +159 m to +248 m.

The total length of the network is approximately 7.500 km and is made up of 1.800 km of primary water supply mains ranging in diameter from 400 mm to 1.800 mm, and 5.700 km of water distribution pipes with a maximum diameter of 300 mm. 65% of the water network consists of asbestos-cement pipes, 15% of steel, 15% cast-iron and 5% of PVC or Polyethylene (PE). The pipes’ nominal operational pressure ranges from 1 to 25 bars.

The water network also consists of several components, which ensure its stable operation and allow for the immediate resolution of any problems. There are about 150.000 cut-off valves and more than 500 control valves (pressure reducers) at various points of the network for the supply of the pressure zones.

The SCADA system has been successfully in operation since 1993. The SCADA system monitors the WTP operation, the water network, the storage tanks, the pumping stations and all major hydraulic nodes of the supply network. The system includes 100 monitoring stations and continually logs the water network’s operational data, such as pressure, tanks’ water levels, and other supply information. Even though the system has the ability to operate facilities via remote control, most operation is still performed manually by EYDAP personnel.

In order to ensure the stable and uninterrupted supply of the consumer, the water network includes 50 regulating/storage tanks of a total capacity of 249.000 m3, as well as 76 pumping stations with total installed power of 27.267 HP in various locations throughout Attica. The network has been divided into pressure zones for its stable operation and control. Pressure zones are designed to service areas differing in altitude by 30 m intervals. They are supplied either from the regulating/storage tanks via gravity flow, or from a pumping station, or from a zone of higher pressure.

Based on the water network operational guidelines (as published in the Government Gazette No. 1396/22-10-2001), EYDAP has the responsibility to supply potable water based on Greek and European standards. EYDAP is required to provide its customers with a continuous operational pressure of at least 2 atmospheres at the water meter, and never higher than 12 atm. EYDAP’s goal is for the water supply pressure zones to operate at a pressure of 6 bars.

It is important to point out that the Geographical Information System (GIS) for the water network is under development, with phase A completed by 60%. The GIS System, once completed, will be greatly enhance EYDAP’s ability to manage and monitor its water network, and will also prove extremely useful in the design of new projects.

The current book value of the water network and supplies, based on SOE’s (Certified Public Accountants) 1999 valuation, is estimated at 73,3 M€, and its average age is estimated at 20 years, while its average lifetime is at 30 years.

Water Supply Distribution  Network Pumping Stations

EYDAP is responsible for the smooth operation of the electromechanical equipment of the water supply network. Most of the equipment concerns pumping stations, which have been divided into three regions: Athens (SA), Menidi-Heraklion (SH) and Piraeus (SP). The operation of these pumping stations differs according to the needs and peculiarities of the network.

They can be grouped into two basic categories according to operation principle:

1. Pumping stations that supply tanks or other pumping stations: Their aim is to transfer quantities of water to a particular altitude in order to cover the needs of the network.
2. Pumping stations that supply the water network directly (Booster): Their aim is to maintain constant pressure in the network, which is accomplished by modulating the pumps’ operation.