A handful of studies have investigated back-calculation of biomarkers to compare with prescription rates at the community level . One study focusing on four pharmaceuticals and respective metabolites of non-communicable diseases, investigated WBE to assess compliance to pharmaceuticals within in a community . Estimating backcalculation of pharmaceuticals from wastewater and exploring elements of community compliance or incorrect disposal is not without its challenges. Several critical aspects have to be considered: i) establishing relationships between parent AAs and metabolites, ii) understanding human metabolism and establishment and use of metabolic transformation correction factors (CFs), iii) understanding stability of both AAs and their metabolites in wastewater, iv) appreciating all possible sources of AAs, e.g., veterinary usage. Prior to this study, a systematic review from our group has published a series of CFs for AAs as well as a new PrAna tool was developed to monitor community prescriptions in selected catchment . In this study, validated CFs and catchment prescription data have been applied in a longitudinal one-year study of AA usage in two urban areas from the Southwest England: 120K city of Bath and 21K town Keynsham). The primary aims of this study was to: