In sewerage asset management, there has been a concerted move away from primarily assessing system capacity or physical performance, to focus on “serviceability” as a key performance indicator. After identifying flooding due to blockages as a key failure mode, this paper documents the development of a tool which can contribute towards efficient sewerage asset management within the context of maintaining “serviceability” to customers, the public and the environment. Against the background of poor availability of reliable data, the reported project provides a process based on FMECA which can be implemented with limited information and without the need for additional data gathering. Land use and network characteristics data have been used alongside a hydrodynamic model to determine critical points in a network. Based on this, a methodology for identifying where blockage likelihood lies is outlined alongside an approach which allows failure consequence to be quantified. The text then outlines a framework which allows failure likelihood and consequence to be combined to prioritise sewerage asset maintenance.