(10)Member States should establish national, regional or local registers to identify individual systems and temporary storage used on their territory and take all measures necessary to ensure that the design of such systems is adequate, that the systems are properly maintained and that they are subject to a regular compliance control on the basis of a risk-based approach. In particular, Member States should ensure that individual systems used for the collection, storage or treatment of urban wastewater are impervious and leak-proof, and that monitoring and inspection of the systems are carried out at regular and fixed intervals. Taking into account the disproportionate costs for adapting the design of such systems to the new design requirements, those new design requirements should not apply to systems established prior to the entry into force of this Directive. Where individual systems are used to collect and/or treat more than 2 % of the urban wastewater load at national level from agglomerations of 2 000 p.e. and above, Member States should provide the Commission with justifications for the use of individual systems instead of collecting systems, demonstrating compliance of those systems with established standards under this Directive and describing the measures taken to reduce the use of such systems.