Reporting on derogations under the EU Drinking Water Directive

Under the EU Drinking Water Directive (DWD; 2020-2184), Member States are “authorised, under certain conditions and in duly justified circumstances, to grant derogations from the Directive […], provided that they do not constitute a potential danger to human health and provided that the supply of water intended for human consumption in the area concerned cannot be maintained by any other reasonable means.”

In the Netherlands, water utilities can request a derogation for a specific parameter if e.g. the source water exceeds (indicative) limit values for such parameters and potentially hampers effective treatment or poses a possible public health threat. Drinking water utilities are not responsible for the source water quality, but

When the Inspectorate has granted a derogation, water utilities have an obligation to report about these parameters frequently. Such derogation reports describe in detail the monitoring efforts of the water utilities in source waters, during treatment and in the drinking water for the respective parameters, as well as any steps take to identify the causes and effects of elevated levels, and activities to optimise treatment processes and minimise concentrations in drinking water.

As water utilities often share water sources in the Netherlands, they submit combined reports to the Inspectorate, detailing their joint efforts to assess and handle elevated concentrations of parameters for which derogations have been granted.

For a number of derogation parameters, Benten has collected monitoring data, assessed trends in monitoring results, described efforts to optimise treatment steps and actions to coordinate with responsible water authorities to mitigate water quality issues and ensure improvements in source water quality. Reports produced thus far (or in progress) include: melamine, trifluoroacetic acid (TFA), glyphosate and its metabolite aminomethyl phosphonic acid (AMPA), chlorate and chlorite.