Commission issues methodology to measure microplastics in drinking water


May. 23, 2024

The Commission has issued a delegated act to harmonize the methodology for measuring microplastics in water intended for human consumption across member states. Many of these substances will eventually be included in a watch list and monitored for their potential risks to human health.

Regulatory background

  • The EU’s Directive (EU) 2020/2184 on the quality of water intended for human consumption (DWD) sets the standards for drinking water quality throughout the European Economic Area (EEA). Its primary objectives are to ensure that all people in the 30 EEA member countries have access to safe drinking water, and member-state authorities, water suppliers and relevant economic actors are held to uniform standards that safeguard sustainable, secure water delivery and management.
  • The scope of the legislation encompasses the entire water supply chain, starting where water collects (i.e., catchment areas), continuing through the abstraction, treatment and storage stages, and ending with the distribution of drinking water to the “point of compliance.” This means that the scope of the directive ends, for example: a) at the faucets of a household, b) the spout of a tanker carrying water intended for human consumption, c) the point where drinking water is filled in bottles at a bottling facility, or d) drinking water is used to cook at a restaurant.
  • Several exemptions are laid out in Article 3 of the DWD, including natural mineral waters, waters which are medicinal products, and water from private, small-scale individual suppliers.
  • The DWD affects a broad swath of economic operators. Above all, these encompass EU-based water suppliers and companies up and down the value chain that produce materials, component parts or products that are – or are meant to be – used in contact with water intended for human consumption (i.e., drinking water contact substances, materials, or products). Examples of such in-scope products include pipes, taps, valves, coatings, hoses, and gaskets, as well as water heaters or coolers, water meters, filters, treatment devices, water tank linings, sealants, pumps, and many others. Accordingly, all substances and materials that contribute to the final composition of these products, as defined under the DWD and supplementing legislation, are also in scope.

2020 update to the Drinking Water Directive

  • The current version of the DWD was introduced in 2020 after a thorough evaluation by the Commission determined that the previous framework – last revised in 1998 – contained major shortcomings. As documented in the Commission’s impact assessment, the shortcomings included obsolete parametric values to measure and assess drinking water quality; insufficient monitoring methods and a lack of systematic risk assessment requirements; inadequate information available for consumers; and a patchwork of inconsistent obligations to authorize substances and materials for use in drinking water contact applications, resulting in burdensome differences from member state to member state and, ultimately, exorbitant regulatory compliance costs.
  • The 2020 version of the DWD sought to eliminate these identified weaknesses. Changes aimed at doing so include updated Annex I parameters according to the latest science for assessing drinking water properties; water monitoring requirements fleshed out in Article 13 and Annex II; and new member-state obligations under Articles 7-10 underpinning a “risk-based approach to water safety” and providing risk assessment and risk management measures designed to prevent continually evolving threats to water quality. The updated directive also clarified and added more types of information that must be made available to consumers so that they, for example, are able to easily access (e.g., online or by phone) the amount of water they consume over time, and the per-unit price of water consumed versus if they were to consume bottled water.
  • Article 11 was incorporated to harmonize the hitherto disjointed procedure for authorizing substances and materials in contact with drinking water, establishing four yet-to-be-finalized positive lists of starting substances, compositions and constituents. Notably, ECHA is charged with the technical and scientific evaluation tasks related to the authorization and continuing management of these materials intended for drinking water contact. This includes the assignment of the opinion-making duty on evaluations to the agency’s committee for risk assessment (RAC).
  • Because the EU introduced these new rules in the form of a directive, each country was required to transpose, or implement, its provisions individually into national law, meeting the minimum obligations set out by the directive. Article 24 of the DWD established transposition provisions, mandating that member states implement and comply with the lion’s share of the rules by January 12, 2023, the same day that the previous framework was repealed.
  • Transitional conditions are given in Article 25, which set January 12, 2026 as the deadline for member states to ensure compliance with the parametric values for bisphenol A, chlorate, chlorite, haloacetic acids, microcystin-LR, uranium, and total and sum values of per- and polyfluoroalkyl substances (PFAS). Accordingly, water suppliers are required to begin Article 13 monitoring operations by the same date in 2026 for this list of substances.

DWD establishes “watch list” to monitor substances of concern

  • The 2020 DWD mandated that he Commission set up a watch list “addressing substances or compounds of concern to the public or the scientific community on health grounds […] such as pharmaceuticals, endocrine-disrupting compounds and microplastics.” A separate provision required that the EU executive establish, by January 12, 2024, a methodology “to measure microplastics with a view to including them on the watch list.”
  • The directive explains the purpose of this list, stating that it is intended to address “growing public concern about the effects of emerging compounds […] on human health through use of water intended for human consumption.” Likewise, it indicates that the list will serve as a useful mechanism enabling authorities “to respond to growing concerns in a dynamic and flexible way,” allowing for “follow-up on new knowledge about the relevance for human health of those emerging compounds and on new knowledge about the most appropriate monitoring approaches and methodologies.” Finally, the list represents a “response to various relevant Union policies,” presumably including ambitions like the Commission’s Plastics Strategy, which calls for research to better understand how microplastics affect human health.
  • The first version of the watch list – published in April 2022 – included two substances with endocrine-disrupting properties. The list provided guidance values, a limit of quantification, and method of analysis, where available, for both substances (17-beta-estradiol and nonylphenol).

Now the Commission has published legislation introducing a methodology to measure microplastics in drinking water

  • On May 21, 2024, Delegated Decision (EU) 2024/1441 was published in the Official Journal of the EU, establishing the methodology for measuring microplastics in water intended for human consumption. This Decision meets DWD’s Article 13(6) statutory requirement to deliver this legislation, albeit almost two months late.
  • The recitals of the Decision provide details on the rationale behind the creation of this methodology. The detection, identification and quantification of microplastics is a complex task given the heterogeneous nature of these substances. As noted in the Decision, microplastics have “widely variable dimensions, compositions and shape,” can contain additives, and “their physicochemical characteristics are influenced by their degradation history.” To fully grasp the extent to which people and the environment are exposed to and impacted by these substances, Recital 4 states, “it is necessary to understand better the occurrence of microplastics throughout the supply chain for water intended for human consumption, by means of quality-assured methods and harmonized reporting criteria, and to determine the concentration, shape, size and composition of the microplastics.”

Highlights of the methodology

  • The Decision’s Annex lays out the framework of the methodology, which the Commission designed to meet the DWD’s objective to monitor these emerging substances of concern in drinking water supplied throughout the EU.
  • Section 1: Definitions. At the outset, the Commission offers an extensive list of definitions for 24 terms used within the methodology. Several noteworthy terms are microplastic, microplastic particle (which defines size and dimensions), microplastic fiber (which also defines size and dimensions), polymer, natural polymer, and synthetic polymer. This section also contains a list of 10 priority polymers, which “are to be considered in the identification of microplastics:” polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polyvinylchloride (PVC), polyamide (PA), polyurethane (PU), polymethylmethacrylate (PMMA), polytetrafluoroethylene (PTFE), and polycarbonate (PC).
  • This first section also defines a handful of techniques to be employed in the methodology, including Raman spectroscopy, Infra-Red (IR) spectroscopy, Fourier-Transform IR micro-spectroscopy, Raman micro-spectroscopy, and Quantum Cascade Laser-IR microscopy.
  • Section 2: Methodology to measure microplastics in water intended for human consumption. This section describes in detail the protocols and procedures for collecting, sampling, treating, storing and analyzing microplastic materials. At a high level, a filter cascade – or a sequence of four filters “placed in series to collect particles from liquid flowing through the filters” – is required to collect particles and fibers from the drinking water under examination. Individual particle size and shape is to be determined from images generated through optical microscopy or chemical mapping, whereas particle compositions are determined using vibrational micro-spectroscopy. Particles and fibers from acquired spectra are to be identified by comparing them “with spectra of known materials contained in a spectral library.” This library is required to contain examples of the 10 priority polymers, as well as examples of “proteins and minerals and natural polymers such as cellulose that might commonly be present in water intended for human consumption.”

Analysis and next steps

  • By adopting this methodology, the Commission seeks to harmonize the way microplastics in drinking water are detected, categorized and measured across all EU member countries. In turn, these unified measures will make the collected data easier to analyze and more meaningful, allowing member states to learn from each other’s experiences and to more easily apply lessons learned from the outcomes of individual countries’ measurement activities.
  • The Commission is mandated under the DWD to report by January 12, 2029, and “where appropriate thereafter […] on the potential threat to sources of water intended for human consumption from microplastics, pharmaceuticals and, if necessary, other contaminants of emerging concern, and on the relevant associated potential health risks.” Clearly, this methodology is expected to assist in populating and maintaining the watch list, which will contribute to the Commission’s report.
  • Beyond the guidance values provided in the watch list, it is not clear in the mid- to long-term what regulatory compliance implications, if any, this list of substances of concern in drinking water could have for potentially affected companies.

To contact the author of this analysis, please write Scott Stephens (
To contact the editor of this analysis, please write Chelsey McIntyre (

Key Documents and Dates


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