[Source ΕΥΔΑΠ]
From antiquity, Athens connects its history and life with a basic problem: water scarcity, ie the lack of water. This is because surface water has always been scarce as there are no large rivers and lakes in Attica. Thus the water supply of the city was mostly from springs and wells. At the same time there were many fountains scattered throughout the city, as well as a number of tanks, in which rainwater was collected (rain gutters).
One of the most famous ancient aqueducts was Peisistratio, which was built by the tyrant Peisistratos in 530 BC, 2,800 m long and which drew water from the springs of Hymettus. Of course, there were other smaller aqueducts in various parts of the city carved in slate or newly made of lead-connected ceramic pieces as well as aqueducts assisted by micro-dams.
However, the most important historical project for the water supply of the city of Athens was the Hadrian's Aqueduct built by the Roman Emperor Hadrian (134 - 140 AD). It started at the foot of Parnitha and ended at Lycabettus where the Hadrian's Reservoir was built, in which the waters of the aqueduct were stored.
The water was channeled by water bridges in the city of Athens. The aqueduct functioned satisfactorily until the enslavement of Athens by the Turks, who inactivated the aqueduct. After the liberation of Greece from the Turks, Hadrian reopened but could not meet the increased needs of the Capital. These came to cover the beginning of the last century the construction of the dam of Marathon and the creation of the homonymous artificial lake.
The construction of the dam was undertaken by the American Company ULEN while its supervision and subsequent management was undertaken by the Hellenic Water Company.
The Water Supply of Athens from antiquity to modern times [Source ΕΥΔΑΠ]
Water Sources
Marathon Reservoir
Material Reservoir
Mornos ReservoirEvinos Reservoir
Bogiati Tunnel
Evinos Reservoir
Drillings
Drilling also plays an important role in the water supply of Athens. The underground aquifers are not used every day, but they are valuable reserves in case of need. These are 105 boreholes in the northeastern Parnitha, in the area of Yliki and around the Boeotian Kifissos.
The drillings in total have the potential to yield 600,000 sq.m. water per day for controlled periods but must be safeguarded as a safety factor for the uninterrupted water supply of Athens.
Water treatment plants
The water, after being collected in the reservoirs, reaches through the aqueducts to the Water Treatment Units. There it undergoes a treatment that makes it drinkable.
There are four Water Treatment Units in the Attica Basin.
1.ΜΕΝ Γαλατσίου
2.ΜΕΝ Αχαρνών
3.ΜΕΝ Πολυδενδρίου
4.ΜΕΝ Μάνδρας (Ασπροπύργου)
Water treatment stages
The water that reaches the Water Treatment Units is raw. It contains various solids (branches, soil, mud) that it has carried away, as well as germs and microorganisms that are not visible to the naked eye..
The water with the treatment to which it is subjected (flocculation, precipitation, refining, disinfection), is freed from the above elements.
In Water Treatment Units the following sequence of steps in water treatment is followed:
Stage 1: Add chlorine and disinfect
Prechlorination kills germs in the water and facilitates its subsequent treatment.
2nd stage: Addition of aluminum sulfate and clarification
The aluminum sulfate solution helps the solid particles present in the water to aggregate with each other and, after gaining more weight, (flocks) to settle. The whole process is called flocculation. Flocculation takes place in two stages that differ in the intensity of mixing of water caused by mechanical means (stirrers) and hydraulic means (by the vortex of water from its impact on the walls of special tanks).
3rd stage: Sedimentation tank
In this tank the water calms down and the accumulated solids (flocks) settle to the bottom of the tank. In this way the water is purified at a rate of 80%.
4th stage: Cleaning filters (sand filters)
Very light particles and colloids (20%) that do not precipitate, are retained in special sand filters from which the water comes out clean to be given to consumption.
If the pre-chlorination is not satisfactory, we add additional chlorine when the water leaves the closed storage tanks and before it enters the water network.
ΜΕΝ Γαλατσίου
ΜΕΝ Αχαρνών
ΜΕΝ Πολυδενδρίου
ΜΕΝ Μάνδρας (Ασπροπύργου)
Water quality control
The water leaving the refineries for distribution to the consumption is safe and drinkable water, while it meets the conditions of the relevant sanitary provisions.
The water of Athens is of excellent quality. It is considered one of the best in Europe, considering that in Europe bottled water is widely used as drinking water.
Drinking water is characterized by water that is physically, chemically, biologically and microbiologically pure and can be consumed without endangering human health. Drinking water should be colorless, odorless, cool and with a pleasant taste. It should not be too harsh because it causes difficulties in its daily and industrial use.
It should not contain large amounts of organic matter, heavy metals or pathogenic parasites or germs. The water temperature should be constant at 10-15 degrees C (Celsius).
The following characteristics are mainly investigated during water quality control:
Smell - Taste - Color
Turbidity
Temperature
Alkalinity - Acidity - pH
Germs
Hardness
Various chemical compounds, chlorides, sulfates, etc. are also investigated extensively.
Chemical laboratories of ΕΥΔΑΠ
Each Water Treatment Unit has its own chemist-laboratory, which is equipped with the most modern equipment of analytical instruments and devices. In these laboratories, analyzes and tests are performed on water samples, which are collected from the entire water supply system of ΕΥΔΑΠ.
The laboratories carry out every year, among others, about 300 complete analyzes of samples from the lakes, 10,000 microbiological tests from points of the water network and on-site control of residual chlorine in about 20,000 samples.
The most modern and newest laboratory is the Chemical and Biological Laboratory of Polydendri. This Laboratory is a real acquisition for ΕΥΔΑΠ.
The main object of the chemical laboratory of Polydendri is the determination of metals in water samples. The laboratory has a state-of-the-art metal detection system and can detect 30 different metals in a water sample.
In the Biological Laboratory of Polydendri, water samples are analyzed from the reservoirs of ΕΥΔΑΠ, in order to ensure that the reservoirs meet the requirements of the EU Directives. in terms of biological and limnological parameters. The main biological parameter studied in the Biological Laboratory is the phytoplankton of the reservoirs, which reflects the general condition of the lakes and their eutrophication stage..
Water supply network
When we say water supply network we mean all the pipes that transport the refined water from the local M.E.N. up to consumer water meters. The network that operates today had started to be built after 1926 by the E.E.Y. in parallel with the construction of large water supply projects (Marathon dam, Bogiati tunnel, etc.).
The total length of the network today is 7000 km. It consists of 1500 km of main supply lines (from Φ 400 mm and above) and 5500 km of secondary distribution pipes.
65% of the total length of the pipes consists of asbestos cement pipes, 15% of steel pipes, 15% of cast iron pipes and 5% of PVC pipes.
The operating pressures of the pipes have a maximum of 25 bar (atmospheres) and a minimum of 1 bar. EYDAP is obliged to provide water with a pressure of 1 to 12 bar at the location of the hydrometer, according to the water regulation. Optimal desired pressure: 6 bar.
EYDAP provides water in areas with ground altitudes from 0 to 600 meters above sea level. Territorial areas per 30 meters of altitude difference, are water supply zones.
The total number of water meters is about 1,600,000.
Forty-five city tanks with a total capacity of 190,000 sq.m. are scattered in high places of the city from where the water through the distribution network reaches the consumers.
Automatic remote control system monitors the operation of the water supply network.
At 100 points, pressures, levels and benefits are constantly monitored and recorded. However, most of the manipulations are done on the spot by the EYDAP staff.
The total volume of storage tanks of EYDAP that serve the water supply network amounts to 1,022,000 sq.m. water.
Maintenance
The Preventive Network Maintenance Service belongs to the Directorate of Sewerage Network and is headquartered in the area of Akrokeramos of the Municipality of Keratsini within the facilities of the Psyttalia Sewage Treatment Center.
Staff - Equipment
The Service employs 63 people who work in three shifts (A, B, C) 24 hours a day and are of the following specialties:
a. Engineer: 1
b. Foremen: 5
c. Administrative: 6
d. Craftsmen: 30
e. Workers: 21
Categories d and e are a crew of tankers and pipeline inspection and repair vehicles.
The equipment available is as follows :
a. Four (4) biaxial sewage recycling tanks of new technology SUPER 2000 with sewage tank 6m3 and water tank 5m3 for cleaning pipes.
b. Two (2) three-axle sewage recycling tanks of new technology SUPER 2000 with 7m3 sewage tank and 6m3 water tank for pipeline cleaning.
c. Two (2) reconstructed biaxial mixed pressure-suction tanks with 3m3 water tank and 3m3 sewage tank with the main object of cleaning the sewage pumping stations and water supply network installations (refineries, van stations, etc.).
d. One (1) Pipeline Television Control Vehicle with all the necessary equipment for the control and detection of invisible faults of the sewerage network.
e. Two (2) small vehicles closed for the support of the pumping station cleaning workshop and the TV pipeline control workshop.
