Groundwater quality

Groundwater does not naturally contain any persistent synthetic substances. Nitrate and residues of plant protection products have a long-lasting adverse impact on groundwater quality. Along watercourses, micropollutants from industry, commerce and households are also found in groundwater.


Nitrate exceeds the limit value of 25 mg/l in groundwater at well over a tenth of the monitoring sites across Switzerland. In areas where arable farming is predominant, concentrations are above the limit at almost 40% of the monitoring sites.

Plant protection products

Residues of plant protection products (PPPs), i.e. their active substances as well as their degradation products, occur at over half of the groundwater monitoring sites across Switzerland. In intensive arable farming areas, residues of PPPs are detected at over 90% of the monitoring sites.

Volatile halogenated hydrocarbons

Volatile halogenated hydrocarbons (VHHs) exceed the limit of 1 µg/l at 3% of monitoring sites across Switzerland. In urban catchment areas, the concentrations of VHHs are above this value at almost 11% of the monitoring sites.


Pharmaceuticals occur in groundwater at around 13% of the monitoring sites throughout Switzerland. Groundwater resources in unconsolidated aquifers next to rivers are the most affected. The pharmaceuticals enter rivers and streams via sewers and sewage treatment plants, and finally infiltrate into groundwater.

Perfluorinated chemicals

Residues of perfluorinated chemicals occur primarily at groundwater monitoring sites near rivers. The discharge of treated or untreated wastewater into surface waters and the subsequent infiltration of these waters into groundwater appear to be the major source of PFC in Swiss groundwaters.

Further information



Last modification 22.05.2020

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