Nitrate in groundwater

Nitrate exceeds the limit value of 25 mg/l in groundwater at almost 15 % of the monitoring sites across Switzerland. In areas where arable farming is predominant, concentrations are above the limit at more than 40% of the monitoring sites.

Groundwater naturally contains very little nitrate. For groundwater that is used for drinking water or is intended as such, the Waters Protection Ordinance (WPO) prescribes a limit value ('numerical requirement') of 25 milligrams per litre (mg/l). In recent years, this limit has been exceeded at 12% to 15% of the NAQUA monitoring sites nationwide.

Nitrate in groundwater (2019) and open arable land. Maximum concentrations at each NAQUA monitoring site.

Arable areas are affected

Elevated nitrate concentrations in groundwater are mainly due to intensive agriculture. In areas used primarily for growing arable crops or vegetables, more than 40% of monitoring sites have exceeded the limit value of 25 mg/l in recent years. Mostly affected is the Swiss Plateau, with concentrations above 10 mg/l at 80% of the monitoring sites.

Further information

Last modification 08.02.2021

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