A look inside Zurich’s water treatment system

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The control room of Zurich's main water supply sits in a bunker in the Hardhof district. Keystone

Groundwater, pumped from a horizontal filter, is of such quality that it can be delivered directly into the distribution grid. Keystone

In this facility water is run through natural sand and carbon filters before being treated with ozone to get rid of micro-organisms and promote oxidisation. Keystone

This facility treats up to 250,000 m3 of drinking water a day. Keystone

A water pipe leading into the Lengg facility in Zurich with a diameter of 1.6 metres. Keystone

These water pipes lie 123 metres under the earth and have a diameter of 2.2 metres. Keystone

A view into the water at the lake facility of Lengg in Zurich. Keystone

Fish act as biosensers to test the water quality; computers monitor for any change in their behaviour. Keystone

A view into the reservoir of Lyren in Zurich Altstetten. Keystone

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Switzerland has a reputation for pristine waters. Voters will have a chance to make it even cleaner when the popular initiative "clean drinking water for all" comes to ballot in the next years. 

Here we take a behind-the-scenes and below-the-ground look at how Zurich’s water supply system is treated and routed from lake to home. Often invisible, the pipes and technologies cleaning and transporting the source of life are critical backbones of any urban infrastructure.