From the well to the tap
Nine waterworks supply Berlin and the surrounding areas with drinking water. The waterworks are located near lakes and rivers, or in extensive forest areas, and utilise groundwater reserves. Groundwater comes from percolated stormwater and surface water, called the “bank filtrate”. As percolation (seepage) is a slow process involving many different layers of soil, our water undergoes a thorough natural cleaning. The result is top-quality groundwater.
Each of Berlin's residents uses an average of 110 litres of water per day. Each day, an average of 580,000 cubic metres of drinking water is made available to households, industry and businesses. A maximum of 1 million cubic metres is possible. Groundwater is pumped from approximately 700 wells – each between 30 metres and 170 metres deep – to the waterworks, where it is further processed and stored in clean water tanks. Depending on demand, water is then pumped from the tanks into our extensive pipe network. The waterworks and intermediate pumping stations are connected via a dense network of transport pipes, which is why the drinking water in the network almost always comes from several waterworks at the same time.
Metering – an exact science
A building connection pipe runs from the water main in the road to the shut-off valve behind the water meter. Everything behind the meter that flows into the house is then the obligation of the customer. Building connection pipes are serviced and maintained by Berliner Wasserbetriebe.
At the end of each connection pipe, there is a water meter that keeps track of the level of water consumption in the respective property. The water meters are the property of Berliner Wasserbetriebe. They are checked and calibrated every five years. This is the responsibility of our state-approved testing facility for cold water measuring instruments.
By the way: a water meter can also be used to detect leaks in building pipes. If all water taps and tapping points in the building have been shut off, the small cog wheel on the water meter should stand still. If it doesn't, then there is a leakage at some point in the system and a plumber should be notified.
Most people in Berlin, primarily those who live in a block of flats, rarely even see their water meters. Water consumption in Berlin is usually charged as part of the rent, depending on the size of the flat. We at Berliner Wasserbetriebe charge the respective property owner for the water consumption, based on the entire property.
Supply on demand
Supply bottlenecks are prevented by the waterworks working together. Even if one of the waterworks fails, it will not lead to a local collapse in the water supply. From the three large waterworks, Tegel, Friedrichshagen, and Beelitzhof, two smaller waterworks and the pumping stations in the supply network are also monitored and controlled. A centralised control system enables remote control for all plants. Berlin's geographically lowest district is Wannsee, in the southwest, at 32 metres above sea level (Normal Null or Amsterdam level); Buch in the northeast is the highest district, at 64 metres above Normal Null. Due to these differences in altitude, the pipe network is divided into a northern and southern high city zone and a low city zone in the area of the glacial valley.
Today, there are more than 7,900 kilometres of drinking water mains beneath Berlin's roads. Most of these, around 6,400 kilometres, are water supply mains with a diameter of 5 to 30 centimeters. The remaining 1,500 kilometres of mains have a diameter of up to 1.40 metres; 52 % of these are made from grey cast iron, 26 % from ductile cast iron pipes, 12 % from reinforced concrete, 9 % from steel, and the small number of remaining ones are made of plastic. Building connections are mainly made of steel or plastic. The average age of a water main in Berlin is 52 years; the oldest pipes are around 120 years old. When new mains and supply pipes are laid today, ductile cast iron pipes are used for pipes up to a size of 30 centimetres; steel pipes are the material of choice for larger crosssections. These are lined with cement mortar to prevent corrosion. Plastic pipes are used for building connections.
Keeping an eye on the pressure
In Berlin, there are around 300,000 building connections to the supply mains. In addition, there are approx. 68,000 hydrants and more than 96,000 shut-off valves. Pressure and flow rates are constantly monitored at numerous points along the network. The average pressure lies between 4.5 and 5.5 bar. This pressure ensures that even the top floor of a five-storey building can be easily supplied with fresh water. High buildings or buildings situated on higher ground have their own booster stations to support this process. Berlin no longer operates water towers.
On the way to the customer
At Berliner Wasserbetriebe, we have divided our supply area into four “water districts”. Each district has a service network operating centre, whose staff are responsible for the servicing and maintenance of the mains and pipes. Each year, they perform around 5,000 repair jobs, of which 2,000 jobs alone are due to pipe bursts in supply and building connection pipes. To prevent damage from occurring, Berliner Wasserbetriebe employees annually check the fittings in the pipe network with regard to their accessibility and proper operation, and also replace numerous signs. In addition to this, around 2 kilometres of pipes are cleaned annually and lined with cement mortar in order to improve their flow rate. To service the network, the water mains are also checked systematically for leaks every four years. As a result, Berlin has a very low rate of water losses – less than four percent.