Waternomics is an EU-funded research project that addresses key challenges regarding the efficient management of, and decision support tools within, the water supply sector. A novel aspect of the Waternomics project is to apply Fault Detection and Diagnostics (FDD) to building water networks in order to identify faults (leaks, malfunctioning equipment, inefficient operation etc.). FDD is a measurement science which has traditionally been used in buildings for Heating Ventilation and Air-Conditioning (HVAC) systems to identify and rectify faults at the earliest possible stage and thus reduce maintenance costs, increase efficiency and result in energy savings of between 10 and 30%. To date, these FDD tools have not been applied systematically to building water infrastructure. This Waternomics project aims to develop and implement FDD systems, in a number of large scale pilots; (i) a municipal water based demonstration in the National University of Ireland, Galway engineering building and a school in Galway City (both in Ireland) (ii) a corporate operator in Linate airport, Milan, Italy and (iii) domestic users in Thermi, Greece. This paper specifically describes the standard based methodology to be used in applying FDD to a building, which has been developed thus far from the NUI Galway Engineering pilot site.