From Groundwater to the Tap – How Drinking Water Reaches Our Homes

Where Does Our Tap Water Come From?

In Switzerland, tap water is supplied to households by local water utilities. These utilities treat so-called raw water, which originates from several natural sources. After treatment, this raw water becomes safe drinking water.

Depending on the region, approximately 40% of the raw water comes from groundwater, 40% from natural springs, and about 20% from surface waters such as lakes and rivers.

The Natural Water Cycle

Water moves continuously through the natural water cycle.

Solar radiation causes water from oceans, lakes and rivers to evaporate and rise into the atmosphere as water vapour. As temperatures change, the vapour condenses into droplets that form clouds.

When these droplets become heavy enough, they fall back to Earth as rain. Some of the rainwater flows into rivers and lakes, while a large portion seeps into the ground and forms groundwater.

During winter, water droplets can crystallise into snowflakes that fall as snow and may accumulate into glaciers. When temperatures rise again, the water evaporates once more and the water cycle continues.

From Groundwater to Drinking Water

To obtain raw water, groundwater is pumped to the surface and transported through pipelines to water treatment plants. Water from springs, lakes or rivers is also delivered to these facilities through pipelines.

At the waterworks, the water is purified and treated to become drinking water. After treatment, it is typically stored in water reservoirs before being distributed to households and businesses through the water supply network.

The Quality of Swiss Tap Water

Swiss tap water is considered among the cleanest in the world. One reason for this is the large share of spring water, which is naturally filtered through layers of soil, sand, gravel and rock, resulting in exceptional purity.

In addition, Swiss water utilities are legally required to regularly test drinking water for microorganisms, chemical contaminants and other pollutants.

Avoiding Potential Contamination

Despite the generally high quality, reports from sources such as SRF, Luzerner Rundschau and BZ Basel show that contamination can occasionally occur in some regions.

One potential vulnerability is aging water pipes. Over time, pipelines may corrode or release particles during maintenance work, which can affect water quality.

In Switzerland, homeowners are legally responsible for ensuring the quality of tap water within buildings and must provide tenants with safe drinking water.

Regular water analyses, which can easily be carried out using water analysis kits or quick tests, help detect heavy metals, pollutants and other potential risks in drinking water.

These tools allow households to identify problems early and take targeted action to maintain safe drinking water quality.