Winterthur Drinking Water: Source and Water Quality Explained

The drinking water in Winterthur comes from the groundwater stream of the Töss River in the areas of Linsental and Zell. Around 30,000 m³ of water per day – approximately 30 million liters – are extracted from these groundwater resources. The water quality in Winterthur is so high that no additional treatment is required before it enters the public supply network.

Water Supply in Winterthur

The Winterthur public utility (Stadtwerk Winterthur) supplies not only the city itself but also eleven surrounding municipalities with drinking water. The water originates from nine protected groundwater catchments and is pumped into two central reservoirs.

A significant advantage of the Winterthur water supply system is the efficient use of natural elevation differences. About two-thirds of the water reaches households through natural gravity flow – completely without pumps. The remaining third is transported to higher reservoirs via twelve staged pumping stations.

Through the Kemptthal pumping station, the system is also connected to the Zurich water supply network. This connection increases supply security and ensures stable water availability even during peak demand or technical disruptions.

In addition to domestic consumption, the network provides water for approximately 3,880 hydrants, firefighting reserves, and around 130 public fountains across the city.

Water Quality and Hardness in Winterthur

The water hardness in Winterthur is about 28 °fH (approximately 15.7 °dH), which corresponds to moderately hard water. A water hardness conversion table is available here.

A detailed chemical and physical analysis of the Töss groundwater used for Winterthur’s supply can also be viewed here.

Water quality is continuously monitored by the public utility. However, the responsibility of the water supplier ends at the building connection. Inside the building, the property owner or operator is responsible for maintaining water quality in the plumbing system.

Why a Drinking Water Test Can Be Useful

Even though the public Winterthur water supply meets very high quality standards, changes can occur between the house connection and the tap. Old pipes, fittings, or stagnant water may release heavy metals, bacteria, or other contaminants into the drinking water.

A professional drinking water laboratory test provides certainty about the actual water quality in your household. This can be especially important for sensitive groups such as infants, pregnant women, or people with weakened immune systems.

• Stadtwerke Winterthur
• Swiss Association for Gas and Water (SVGW)
• Swiss Drinking Water Ordinance (PDF)