21.0.1. Subject to the sampling points whose location is prescribed by a provision of this Regulation, the person in charge of the distribution system or facility must ensure that the sampling points where samples are collected enable to obtain data representative of the quality of water for the whole network. The person in charge must also make available to the Minister, for a minimum period of 5 years, a copy of the plan showing the location of sampling points and indicating, where applicable, the civic numbers of the buildings concerned, accompanied by a document explaining how the sampling points were determined, including a description of the characteristics of each sampling point. The location plan must, in addition, identify the sectors whose hydraulic features allow to have any water contamination of the distribution system or facility confined to it.