Abstract: Well-functioning 'liveable' cities should be sustainable and their consumption of natural resources and production of waste must fit within the capacities of the local, regional and global ecosystems. It is increasingly becoming suggested that an Urban Metabolism (UM), approach could help city decision-makers (e.g. planners) take account of numerous critical influencing factors related to the inward outward flow(s) of natural resources (e.g. food, water and energy) and accumulation of waste. The paper identifies the precursory step for any UM study (Mass Flow Analysis - MFA) and applies it to a case study (Birmingham, UK) in order to show how it could contribute to the measurement, assessment and understanding of liveability, defined as 80% reduction in carbon (from 1990 levels); resource secure (an ethos of One planet living); with maintained or enhanced wellbeing. By provided focus upon an individual resource stream (i.e. water) at multiple scales (city to individual) it is shown that MFA can be used as a starting point to develop realistic and radical engineering solutions. However further work is required for it to be truly reflective of broader aspects of urban liveability.