Asset management policies for drinking water networks are mainly applied at network level. However, the scope of these policies covers a much larger scale, particularly when it comes to water preservation through leak reduction. In France, the two main instruments used by public authorities to encourage water suppliers to apply sustainable asset management are regulation (at national level) and subsidies (at Water Agency1 (WA) level). At present, knowledge of networks at both of these scales is insufficient to allow thorough optimisation of these policies (EPA, 2013) (Ernst & Young, 2012). At the request of the French Ministry for Ecology and AFB (French Agency for Biodiversity) Irstea has developed a method to enhance technical asset knowledge at both national and WA level.