Article 4 1.

Member States may derogate from Article 3 only if the establishment of a collecting system or the connection to a collecting system is not justified because it would produce no environmental or human health benefit, is not technically feasible or would involve excessive cost. If derogating from Article 3, Member States shall ensure that individual systems for the collection, storage and when applicable, treatment of urban wastewater are used in agglomerations of 1 000 p.e. and above, or part of those agglomerations.