Efficient monitoring of water systems and proper use of the collected data in further applications such as modelling, forecasting influent water quality and real-time control depends on careful data quality control. Given the size of the data sets produced nowadays in online water quality monitoring schemes, automated data validation is the only feasible option. In this paper, software tools for automatic data quality assessment with a practical orientation are presented. The developments from three organizations ranging from simple to more complex methods for automated data validation are described and evaluated for water quality measurements collected at the inlet of wastewater treatment plants, where probably the hardest measurement conditions are found. The objective of this collaborative effort is to come up with better tools and improved approaches for implementing a successful automatic data quality control procedure.