Some 80% of the water used for drinking and for industry in Switzerland comes from groundwater.

The nationwide groundwater monitoring system set up in 2002 has shown that many sources are contaminated with nitrates, pesticides and hydrocarbons, particularly in the densely populated plateau area.

Although the water is safe to drink, precautions need to be taken to protect it.

The major pollutant is nitrate. The highest concentrations occur in the areas of intensive farming. Agriculture is the most important source, but leaking sewage pipes and heavily fertilised green spaces in towns also play a part.