One third of the drinking water in the Netherlands comes from surface water. More and more new chemicals are found in this water. For 65 of these substances, RIVM has assessed whether they could impact the quality of drinking water. For five substances, the concentrations in surface water are above the limit value for drinking water. Moreover, these substances are not easy to remove from the water. RIVM therefore advises water managers to ensure that the concentrations of these five substances decrease. To prevent problems related to drinking water in the future, it is important to reduce the amount of chemicals that end up in surface water.
More and more chemicals are ending up in surface water, originating from sources such as industrial activities and residues of medicines and pesticides. One third of the drinking water in the Netherlands comes from surface water. It is important to ensure that our drinking water is of a sufficiently high quality. However, this means that drinking water companies will need to make increasing efforts to remove chemicals from the water.
Early detection is crucial
That is why water managers and drinking water companies test the water for chemicals that are not yet subject to any standards. To detect these substances at the earliest possible stage, the Water Framework Directive (WFD) stipulates a signalling value of 0.1 micrograms per litre. Any value exceeding this concentration prompts an investigation to see whether the substance might pose a health risk if found in drinking water.
Risk assessment of 65 substances
Based on measurements from 2017–2020, RIVM analysed which chemicals exceeded the signalling value of 0.1 micrograms per litre. In total, RIVM completed a risk assessment for 65 substances. For five substances, RIVM recommends that water managers take action. These substances are bromate, dibromoacetic acid, lithium, N,N-dimethylsulfamide and trichloroacetic acid.
Reducing discharges prevents the need for expensive purification
RIVM calls for a further reduction of discharges of chemicals in surface water. This would not only benefit the environment, but also keep our drinking water safe. It is also necessary in order to comply with the WFD. The WFD requires EU (European Union) Member States to prevent any decline in the quality of surface water. This means, among other things, that the water should be clean enough to produce safe drinking water through simple purification processes.
Recommendations for drinking water research
RIVM only assessed surface water used as a source of drinking water, not the purified drinking water itself. RIVM recommends assessing the latter to identify the possible impact on public health. Such an assessment is already completed for lithium. RIVM concludes that lithium in Dutch drinking water does not pose any health risks, including for people who use lithium as a medication.
The Ministry of Infrastructure and Water Management commissioned RIVM to carry out this risk assessment in order to measure progress against the WFD objectives.