Lengg lake water works
The Lengg lake waterworks is a waterworks built in 1960 and replaced in 1975 , which treats the lake water from Lake Zurich .
The plant is located on the right side of the lake in District 8 in the Riesbach district . The maximum daily output is 250,000 m 3 . It is the largest and most important plant in the city of Zurich. The Lengg plant is controlled from the Hardhof .
The water is fed in through the Tiefenbrunnen pumping station. The actual water intake is about 500 meters from the bank, 16 meters above the bottom and at a depth of 32 meters. The temperature at this depth is between 6 and 8 ° C all year round.
Six pumps enable an output of up to 13,000 m 3 per hour. In the warmer months of the year, the pipe is cleaned once a month with a chlorine solution to prevent migrating mussels from sticking. The lake water reaches the waterworks located 50 meters higher up through a 1.6 meter diameter tube via the pumping station under the Tiefenbrunnen bridge. It is processed into drinking water in an environmentally friendly manner in huge filter chambers . A double treatment with ozone removes viruses, bacteria and drug residues. An activated carbon filter removes odors and flavors. Suspended solids and particles are first filtered out in a quick filter made of gravel and pumice . At the end of the processing chain, an 80 centimeter thick slow filter made of sand and gravel cleans the water from germs. A drop of water takes about eight hours to pass through the waterworks.
In an aquarium with the purified lake water, some rainbow trout swim for a final check . In front of it is a film camera that triggers an alarm when nothing moves in the aquarium. In other water works, the trout have been replaced by water fleas , which are even more sensitive to water pollution.
Most of the actual filter systems are located underground, especially under the adjacent tennis facilities.
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Coordinates: 47 ° 20 '58.4 " N , 8 ° 34' 21.2" E ; CH1903: six hundred eighty-five thousand six hundred seventy-eight / 244918