Modelling of the integrated urban water system is a powerful tool to optimise wastewater system performance or to find cost-effective solutions for receiving water problems. One of the challenges of integrated modelling is the prediction of water quality at the inlet of a WWTP. Recent applications of water quality sensors have resulted in the availability of long time series of sewer water quality and WWTP influent quality. This time series contains a lot of information on the response of sewer water quality to, for example, storm events. This allows the development of empirical models to predict sewer water quality. This paper proposes a new approach for water quality modelling, which uses the measured hydraulic dynamics at the influent of the WWTP to derive the (measured) influent water quality. This model can then be used as a WWTP influent generator using either measured or simulated influent hydraulics as input.