One third of the drinking water in the Netherlands comes from surface water. Increasingly, new chemical substances are being found in this water. The RIVM assessed 65 substances to determine if they could affect drinking water quality. For five substances, concentrations in surface water are already higher than the drinking water threshold. These substances are also not easily removed from the water. Therefore, the RIVM advises water managers to ensure concentrations of these five substances decrease. To prevent future drinking water problems, it is important that fewer chemical substances enter surface water.
More and more chemical substances enter surface water, for example from industry, medicine residues, and pesticides. One third of the drinking water in the Netherlands comes from surface water. It is important that drinking water quality remains good. However, this means drinking water companies must increasingly work to remove chemical substances from the water.
Early detection is important
Water managers and drinking water companies therefore monitor whether chemical substances are present in the water for which no standard yet exists. To detect these substances as early as possible, the Water Framework Directive (KRW) sets a signaling value of 0.1 micrograms per liter. Above this concentration, it is investigated whether the substance poses a health risk via drinking water.
Risk assessment of 65 substances
Based on measurements from 2017 to 2020, the RIVM analyzed which chemical substances exceed the signaling value of 0.1 micrograms per liter. In total, the RIVM conducted a risk assessment for 65 substances. The RIVM advises water managers to take action for five substances: bromate, dibromoacetic acid, lithium, N,N-dimethylsulfamide, and trichloroacetic acid.
Less discharge prevents costly purification
The RIVM calls for even less discharge of chemical substances into surface water. This is not only better for the environment but also important to keep our drinking water safe. It is also necessary to comply with the Water Framework Directive. The WFD Water Framework Directive (Water Framework Directive) obliges EU member states to ensure that surface water quality does not deteriorate. This means the water should be so clean that only simple purification is needed to make drinking water.
Recommendations for drinking water research
The RIVM only investigated surface water used for drinking water, not the purified drinking water. The RIVM advises doing so and assessing possible health effects. For one substance, lithium, this research is already completed. The RIVM concludes that lithium in Dutch drinking water poses no health risks, even for people using lithium as medication.
The RIVM conducted this risk assessment for the Ministry of Infrastructure and Water Management (IenW) to assess the goals of the Water Framework Directive.