The European Commission adopted a Delegated Regulation establishing a non-exhaustive list of essential services based on the sectors identified by the CER Directive.
In particular, the CER Directive provides for obligations on Member States to carry out risk assessments and identify those critical entities that provide essential services. In this context, pursuant to Article 5 of the CER Directive and in accordance with the conditions laid down in Article 23 of the Directive, the Commission was empowered to adopt a delegated act in order to supplement the Directive, by establishing a list of essential services in the sectors and subsectors set out in the Annex to the Directive. This list will be used by competent authorities, in accordance with the CER Directive, for the purpose of conducting risk assessments and thereafter to identify critical entities pursuant to the Directive.
You can find the delegated act here.