This master thesis data validation is used to gain a better understanding of urban sewer systems. For this, an evaluation tool consisting of three levels is used. Level 1 and 2 are in focus throughout the thesis. At level 1 a tolerance band is used as data validation. The tolerance band is based on an exponential projection. This tolerance band aims at capturing sudden changes in data, as all changes in drainage systems are considered to have an explanation. At Level 2 it is validated whether the sudden change has a logical explanation via a context-classified tolerance band. This tolerance band uses information from multiple sensors, so the active context can be defined.

The evaluation tool has subsequently been used on collected data from Viby at Aarhus. It is not possible to make a generic data validation. Therefor a calibration of the methods is required. After the calibration, the evaluation tool were useful to provide a better understanding of the urban sewer system as the tolerance band clearly detected sudden changes in data and subsequently validates whether these changes were expected.
However, data validation is not better than the calibration performed.