Une évaluation de la performance des réseaux de distribution d’eau potable : Le cas de Nantes Métropole

Résumé Fr En

Dans un contexte de rareté croissante de l’eau, les procédés d’urbanisation doivent s’adapter aux surcoûts de l’étalement pour offrir l’accès à cette ressource. L’objet de cet article est de comprendre les déterminants du gaspillage induit par les réseaux de distribution d’eau à Nantes Métropole sur la période 2013-2017. Une évaluation de la performance en fonction des kilomètres de réseau et du nombre d’abonnés nous permet de mesurer l’impact de la densité des réseaux et du mode de gestion sur les fuites d’eau. L’étude comparée de l’efficience des communes sur le gaspillage montre que les réseaux peu denses et en régie sont moins efficaces et plus propices aux pertes d’eau lors de son acheminement. Classification JEL : L95, Q01, Q25, R10, R15.

In a context of an increasing water scarcity, urbanization processes should be adapted to the additional costs of network extension, to provide an access to this resource. This paper aims to identify the determinants of waste induced by the water distribution system in Nantes Metropole between 2013 and 2017. It raises several issues of collective interest. How to measure the relative performance of water distribution systems? Which contextual parameters influence the performance of networks and waste of water? Do some urbanization and managerial procedures should be promoted to reduce water leaks? An applied Data Envelopment Analysis benchmark based on network length and number of consumers allows us to measure the impact of network density and management structure on water leaks. Thus, the comparative study of efficiency between municipalities shows that low-density networks are subject to more water loss during water delivery, especially when subscribers are dispersed. In addition, management by the public sector in Nantes Métropole is less efficient than the private one regarding water losses. This disparity stems from the ability of the private sector to manage complex networks thanks to significant internal skills for municipalities of all sizes. These water leaks represent an economic and an environmental cost for both consumers and suppliers. If network maintenance can be profitable in the long term, short-term rationality can underpin the non-intervention of suppliers because of the very high and dissuasive costs of remediation. The current increasing water scarcity raises the question of the legal framework of these excessive losses. The discussion is therefore open on the establishment of regulatory instruments such as taxes or quotas to promote maintenance of distribution networks for a sustainable long-term remediation. JEL Classification: L95, Q01, Q25, R10, R15.