Chemicals in European surface water and groundwater (Signal)

Chemicals in European surface and groundwater bodies are monitored under the Water Framework Directive (WFD). This includes chemical status assessments, reported by EU Member States under their River Basin Management Plans (RBMPs) since 2010. In surface waters, detected chemicals are assessed against a list of 33 ‘priority substances’ and groups of substances that pose a significant risk to, or via, the aquatic environment. Concentrations are compared to Environmental Quality Standards (EQS). 

In groundwater, EU standards for nitrates and pesticides are determined by the Groundwater Directive, while national thresholds are used for other pollutants.   

The second RBMP in 2016 showed that only 33% of surface water bodies in the EU-27 have good chemical status. This is primarily due to a small number of ubiquitous, persistent, bioaccumulative and toxic substances such as mercury and brominated flame retardants. ​However, their persistent properties mean that they will remain in the environment for a long time even after they are no longer released. If excluded from the analysis, 77% of surface water bodies would achieve good chemical status. Meanwhile, around 23% of the area of groundwater in the EU-27 failed to achieve good chemical status. In the EU, 65% of the drinking water is derived from groundwater.  

The European Commission published a proposal in 2022 to, among other things, expand the list of priority substances for surface waters with additions such as 24 per-and polyfluoroalkyl substances (PFAS) as a group (widely used synthetic chemicals) and bisphenol A. The proposal also includes amendments to the Groundwater Directive that would introduce additional EU standards for a series of pharmaceuticals, non-relevant metabolites of pesticides, as well as the group of 24 PFAS. The selection of priority substances is informed by monitoring – in a limited number of sites – substances on a ‘watch list’. This list is regularly updated with substances that could pose a risk to water quality at the EU level. The 2022 update added several new substances, including some pesticides and antibiotics.   

River basin-specific pollutants (RBSPs) – substances discharged in significant quantities into a river basin – are identified and monitored by Member States. These contribute to the ecological status of surface water bodies, with classifications ranging from ‘bad’ to ‘high’. The four pollutants most reported as failing EQSs across Member States in the second RBMP were zinc, copper, arsenic and ammonium, with substantial differences in the used EQS. Other monitored substances in specific river basins include legacy and currently used pesticides, such as imidacloprid, diflufenican and glyphosate, as well as industrial substances including pyrene and bisphenol A.   

It is important to note that status assessments are based on individual substances, which can overlook potential risks from chemical mixtures.   

In 2022, the Commission published a proposal to revise the Urban Wastewater Treatment Directive. It includes steps to tackle micropollutants and microplastics in wastewater treatment by requiring the monitoring of micropollutant removal, reducing releases of untreated sewage during periods of intense rainfall and tracking the source of industrial pollution. These measures would help reduce the occurrence of substances of concern in effluent from wastewater treatment plants and their upstream introduction into surface water bodies. They would also support the transition to the production of safer and more sustainable chemicals.