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Water cy­cle: The path taken by water

© Unsplash

The path taken by water

The residents of Graz are supplied by the competence centre for water management with outstanding and untreated drinking water – which is permanently monitored by the company’s own water laboratory. The competence centre also ensures the collection, drainage and cleaning of waste water in the entire municipal area.

In order to preserve the high reliability of supply and the high quality, the pipeline network covering 1,393 kilometres including building connections is permanently controlled and renewed as a precautionary measure. To safe costs and work efficiently, half of the investments required for this are coordinated with other infrastructure companies and form the subject of joint requests for proposals, which are also handled jointly.

By its very nature, the sewer network of the city of Graz, which is currently 860 kilometres long, requires permanent extension and renovation. From tests carried out together with Graz University of Technology, the average life cycle and renovation requirements are known. To maintain a proper disposal of waste water and to eliminate sources of danger for the environment, the sewer system is inspected in sections and sewer renovation concepts then formulated. In the process, the majority of the construction volume is implemented by construction methods that do not require any excavation.

However, collecting and draining the waste water is of course not all.  Via two main collection sewers to the left and the right of the Mur, the murky load enters the sewer plant of the city of Graz in Gössendorf which was designed for the waste waters of half a million people. The treatment there is carried out according to the self-cleaning principle of natural waters in a  mechanical and biological way and above all without any chemical additives, before the water which has been purified to a level of 98% is introduced into its normal cycle again and directed into the Mur.

© Holding Graz