Water is a crucial chemical compound made of two hydrogen atoms and one oxygen atom, existing in solid, liquid, and gaseous states. The water cycle continuously recycles water on Earth, while purification processes, including pre-chlorination and filtration, are necessary to make water safe for drinking. Wastewater is collected and treated at a municipal plant to ensure environmental safety.

1. THE WATER

2. THE DEFINITION Water is the most widespread chemical compound which is necessary for all known forms in our planet. The molecule of water is consists of two atoms of hydrogen and one atom of oxygen , the chemical substance of water's molecule is proved by the french chemist Antoine L a voisier .

3. PHYSICAL CONDITIONS OF WATER I n nature the water exists in three states The solid state (below 0 C.) The liquid state (between 0-100 C.) And the last one, the gaseous state (about 100 C.)

4. THE NAME The water in Greek “nero” got its name from the byzantine phrase “νεαρό ύδωρ” “nearo ydor”(= young water) which means flowing water. This phrase comes from the ancient greek phrase “ νήρον ύδωρ” “nyron ydor”

6. the water cycle, also known as the hydrologic cycle, is the continuous recycle of water on, above and below the surface of the earth.

7. The water of the earth can change states , from solid, such as ice  To liquid, such as the water on lakes and rivers  And to gas, such as the water steams. 

8. the water steams condense to clouds , become water and then they fall as rain or snow , enriching the stores of water on earth , that are either on the surface , like the sea and the lakes , or underground.

9. THE WATER CYCLE NEVER STOPS.. That’s why everybody should take care of the environment and keep it clean

10. Water purification

11. The water, which is received with pipes from the dams( particularly from the one in Marathon) is dirty as it contains pieces of solid debrids ( like mud, brunches, dust e.t.c.) which are carried away while passing. Also, micro-organisms such as bacteria, which can’t be traced with a bare eye are transferred through water. That’s why, the water must go through some treatment in order to become drinkable.

12. Firstly, the water is collected in holding tanks and gets to the Water treatment plant (W.T.P.),through the aqueduct. The water’s treatment in Attica’s basin take place in four plants : a) W.T.P. Galatsiou, b) W.T.P. Aharnon, c) W.T.P. . Poludendriou, d) W.T.P. Mandras. These four W.T.P. have a purification capacity of 1.9 million cm 3 . (cubic metre) everyday.

13. The steps for water purification are: 1. Pre-chlorination in order to kill bacteria and algae and arresting any biological growth 2. Flocculation a process which clarifies the water by adding aluminium sulfate in order to remove any turbidity or colour so that the water is clear and colourless .

14. 3. Sedimentation water exiting the flocculation basin may enter the sedimentation basin, also called a clarifier or settling basin. It is a large tank with slow flow, allowing flock(small particles ) to settle to the bottom.

15. 4. Filtration the water is filtered through sand filters as the final step to remove remaining suspended particles and unsettled floc.

16. 5. Additional disinfection of water take place by adding disinfectant chemicals in the last step in purifying drinking water. The most common disinfection method involves some form of chlorine or its compounds. That stage is called meta-chlorine

17. The drinkable water is the water which is completely purified from every natural, chemical, biological and microbiological view and can be drank by people without them being in danger(of getting sick). The drinkable water can’t have any colour or smell, but it’s cool and has pleasant taste.

18. The drainage of water after use, carried by rain water follow the natural flow into the sea.

19. Domestic wastewater is collected and transported via a network of pipes to a municipal treatment plant, in the island of Psitalia, where a two stage treatment take place.