Recast Drinking Water Directive, state of play
EU JRC - June 2022
Guidance note for the analysis of microbiological parameters
The quality of drinking water in the European Union is verified by measuring parameters established in the recast of the Drinking Water Directive (DWD) 2020/2184. Compared to the former Directive 98/93/EC, microbiological parameters have been extended to additionally cover somatic coliphages as an indicator of removal efficiency following water treatment and Legionella as a parameter for the risk assessment in buildings. Implementation of these parameters and their transposition is of utmost importance for the Member States to ensure an adequate level of protection of human health. However, existing standardised methods used to measure the new microbiological parameters present technical drawbacks. For somatic coliphages, large sample volumes require a supplementary concentration step extending time of analysis, while for Legionella, the reliability of results substantially depends on the selection of a proper protocol variant, restricted choice of variants for certain drinking water types and detection limit higher than the parametric value.
Alternative methods provide a solution to overcome the mentioned technical limitations and significantly reduce time to results allowing an early action in case of detected contamination. According to DWD 2020/2184, such methods can be implemented for analysing somatic coliphages and Legionella if their reliability is at least equal to that of the standard method. The Guidance Note presents an overview of current and novel methods for testing the new microbiological parameters and provides recommendations for harmonising the choice of alternative methods used across the Member States with the aim to support the European Commission and Member States in the implementation and transposition of the mentioned parameters, taking into account the parameters formerly established in Directive 98/93/EC.
Rationale of the Guidance Note
New microbiological parameters included in DWD 2020/2184
Method specifications for the new microbiological parameters (Annex III)
EMEG proposals for the next steps in implementing the new microbiological parameters
Other microbiological parameters in DWD 2020/2184 established by DWD 98/83/EC
Clostridium perfringens including spores
Colony count 22°C
List of tables
Metodi chimici controllo delle acque destinate al consumo umano
Acque potabili - Parametri Nitrato e nitrito