From his background as a quantitative physicist, Peter van Thienen and a number of colleagues focus on the drinking water distribution network from a quantitative, model-based perspective. Key words in this are mathematical-physical models and optimisation. The starting point is to transform a simple concept into a powerful tool. A few examples include the analysis of volume flow data to understand the network and the identification of leaks (including the development of the VLPV method), the numerical optimisation of the design of networks (development of the Gondwana platform), and the initiation of the development of an inspection robot for drinking water pipelines (Ariel). These have applications in BTO, TKI and advisory projects as well as internationally in a Watershare(r) context.