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First DWD Watch List adopted

The European Commission adopted an implementing Decision containing the first Watch List under the new Drinking Water Directive on 19 January 2022.

The document does not come as a surprise though, since according to art.13 (8) of the new Drinking Water Directive “the first watch list shall be established by 12 January 2022” and “Beta-estradiol and Nonylphenol shall be included in the first watch list in view of their endocrine-disrupting properties and the risk they pose to human health”.

As Recital 5 of the Directive recalls, the WHO recommended that “three representative endocrine-disrupting compounds may be considered as benchmarks, for assessing the occurrence of endocrine-disrupting compounds and their treatment efficacy where necessary, with values of 0,1 μg/l for Bisphenol A, 0,3 μg/l for Nonylphenol and 1 ng/l for Beta-estradiol”.

It is important reminding the whole reasoning at the basis of the WHO recommendations from the 2017 report: “Drinking Water Parameter Cooperation Project” (page 81) is the following:

“Routine monitoring for the full range of EDCs would currently be difficult, expensive and not effective at preventing contamination of drinking-water.

It is therefore not recommended to include provisions for EDCs in Annex I Part B. If Member States, however, wish to provide reassurance to consumers regarding oestrogenic and other EDCs in drinking-water, it would be possible to use precautionary, arbitrary benchmark values which are close to the proposed environmental quality standards, or possible future environmental quality standards, for the protection of aquatic life. Aquatic life is much more sensitive to the effects of oestrogenic EDCs than mammals, including humans.

The following three representative EDCs and benchmark values could be considered:

  • 17-Beta-oestradiol: 0.001 µg/L;
  • Nonyl phenol: 0.3 µg/L; and
  • Bisphenol A: 0.1 µg/L.

These three substances were chosen as benchmarks because they are known to be present in surface water sources impacted by treated sewage effluent and other discharges. [...]

The values are below those that would be of interest for human health [...].

The purpose of such benchmark values is to determine if the (surface water) source is impacted by treated sewage effluent or other effluents known to contain oestrogenic EDCs. If any of the three substances is detected above the precautionary benchmark value, then these values can be used to verify the efficacy of treatment since all of these EDCs are of low water solubility.”

Water operators supported the idea of the watch list in the Drinking Water Directive as a way to investigate contaminants of emerging concern in water resources/raw water and inform the Risk-Based Approach where they are likely to be present in water intended for human consumption and could pose a potential risk to human health.

This is reflected in the wording of Recital 17: “Where surface waters are used for water intended for human consumption, Member States should pay particular attention in their risk assessment to microplastics and endocrine-disrupting compounds, such as Nonylphenol and Beta-estradiol, and should, where necessary, require water suppliers to also monitor and, where necessary, carry out treatment for those and other parameters included in the watch list if considered a potential danger to human health. Based on the risk assessment of the catchment areas for abstraction points, management measures to prevent or control the risks identified should be taken to safeguard the quality of the water intended for human consumption. Where a Member State finds, through the identification of hazards and hazardous events, that a parameter is not present in catchment areas for abstraction points, for instance because that substance never occurs in groundwater bodies or surface water bodies, the Member State should inform the relevant water suppliers and should be able to allow them to decrease the monitoring frequency for that parameter, or to remove that parameter from the list of parameters to be monitored, without carrying out a risk assessment of the supply system”.

It is worth to point out that the Directive, in art.13 dedicated to ‘Monitoring’, describes clearly some features of the Watch List that would:

  1. Address “substances or compounds of concern to the public or the scientific community on health grounds (‘the watch list’), such as pharmaceuticals, endocrine-disrupting compounds and microplastics. Substances and compounds shall be added to the watch list where they are likely to be present in water intended for human consumption and could pose a potential risk to human health. To that end, the Commission shall make use, in particular, of scientific research of the WHO. The addition of any new substance or compound shall be duly justified under Articles 1 and 4”.
  2. Indicate “a guidance value for each substance or compound and where necessary a possible method of analysis that does not entail excessive costs. Member States shall put in place monitoring requirements with regard to the potential presence of the substances or compounds which are included in the watch list, at relevant points of the supply chain for water intended for human consumption. For this purpose, Member States may take into account the information collected under Article 8(1), (2) and (3) of this Directive and may use the monitoring data collected in accordance with Directives 2000/60/EC and 2008/105/EC or other relevant Union legislation, in order to avoid overlapping of monitoring requirements.”
  3. Outlining the possible measures, “where a substance or compound included in the watch list is detected, under Article 8(2) or under the fifth subparagraph of this paragraph, in concentrations exceeding the guidance values set out in the watch list, Member States shall ensure that the following measures are considered and that those measures considered relevant are taken”:
  1. preventive measures, mitigation measures or appropriate monitoring in the catchment areas for abstraction points or in raw water as set out in points (a), (b) and (c) of the first subparagraph of Article 8(4);
  2. requiring water suppliers to carry out monitoring of those substances or compounds, in accordance with point (a) of the second subparagraph of Article 8(5);
  3. requiring water suppliers to check whether treatment is adequate to reach the guidance value and, where necessary, to optimise the treatment; and
  4. remedial actions in accordance with Article 14(6) where Member States consider it necessary to protect human health. The implementing acts provided for in this paragraph shall be adopted in accordance with the examination procedure referred to in Article 22.

It should be observed that according to art.8 (4) prevention measures at the level of the catchment have priority in the Risk-Based approach.

One year after entering into force the new legislation is already being implemented and Member States still have 12 months to transpose it into national legislation. This will contribute to ensuring that tap water remains safe and affordable for European citizens.



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