From groundwater to the tap

In Switzerland, households are supplied with tap water by local water treatment plants. These plants process what is referred to as raw water, sourced from various origins. After treatment, this raw water becomes drinking water. Depending on the region, approximately 40% of the raw water for tap water production comes from groundwater, 40% from springs, and 20% from surface water such as lakes and rivers, as described in this report.

The water cycle

Water is part of a constant cycle.

Due to the sun’s radiation, water evaporates from seas, lakes, and rivers and rises into the Earth’s atmosphere as water vapor. Due to temperature differences, the vapor condenses into water droplets, forming clouds. In these clouds, the droplets accumulate until they become too heavy, eventually falling as rain. This rainwater then returns to seas, lakes, and rivers.

A significant portion of the rainwater, however, falls onto the ground and infiltrates, forming groundwater. This groundwater eventually feeds into lakes and rivers. During winter, when temperatures drop, water droplets in the clouds crystallize into snowflakes. These snowflakes accumulate and fall as snow, forming glaciers. ❄️ When the sun shines again, the water evaporates, and the cycle restarts.

From groundwater to drinking water

To extract raw water, groundwater is pumped to the surface and transported to treatment plants through pipelines. If the raw water comes from springs, lakes, or rivers, it is similarly transported to the treatment plants via pipelines. Once at the plants, the water is purified and processed into drinking water, which is then transported to reservoirs and finally distributed to households.

The quality of Swiss tap water

Swiss tap water is renowned for its high quality and is among the cleanest in the world. This is partly because around 40% of it comes from spring water, which is naturally filtered through layers of soil, sand, gravel, and rock, ensuring a high level of purity. Additionally, Swiss water treatment plants are legally required to regularly test the water for harmful microorganisms, chemical contaminants, and other pollutants.

Preventing potential contamination

Despite its high quality, reports from SRF, Luzerner Rundschau, and others, like BZ Basel, indicate that occasional contamination can occur in some regions. 🧪

The causes of contamination are varied, but one weak point lies in the pipelines, which have a limited lifespan and require regular repairs or replacement. During these repairs, or due to aging pipes, contamination can occur, affecting water quality. In Switzerland, the law assigns responsibility for ensuring high-quality drinking water to property owners, who must guarantee safe water for tenants.

Regular water tests, which can be easily performed with our water analysis kits and quick tests, allow for the detection of heavy metals, contaminants, and other risk factors. These tools make it simple to take proactive measures to ensure safe drinking water. 💧