Recent developments in on-line sensor technology supplying high temporal resolution data and advanced data quality control (DQC) tools ease the task of understanding in-sewer processes, allowing for better integrated management of sewer systems and wastewater treatment plants (WWTP). The present study illustrates how data with high temporal resolution and advanced DQC tools can be used to: (i) detect unexpected shock loads during dry weather due to an on/off pumping strategy, (ii) understand the processes in upstream sewer systems under wet weather, and (iii) take the necessary actions to reduce the shock loads at the WWTP. The results for a selected week show that the on/off pumping strategy creates unnecessary peaks with 50-200% increased flows. This affects the water quality arriving at the WWTP, particularly with respect to the total suspended solids concentrations, which increased by 150-200%, making up a TSS-load increase by up to 400%. The dissolved concentrations increased only by 10-20%. The data from on-line sensors, upgraded by DQC procedures, are currently forming an information-dense basis for calibration of a sewer water quality model, which will be used to better understand the processes taking place upstream the plant and to reduce their impact on the performance of the WWTP.