Unveiling the Flow: A Co-UDLabs survey on monitoring combined sewer overflows (CSOs)

A survey on the current state of CSO monitoring and performance assessment in Europe 

The goal of this survey is to understand what CSO* performance data (e.g. spill frequencies and duration) are available at utilities for which purpose they are being used and what the motivation of different stakeholders is to publish performance indicators on CSO (or not) [1]. 

We are particularly interested in wastewater organizations, utilities and associations which can inform us about the availability of key figures, such as the functioning of combined sewer overflows (CSO), data analysis and use in the context of “Open Government Data”. 

To this aim, we have adapted a recent survey from Switzerland [1] to the realities of the Co-UDLabs partner countries. The anonymous survey can be completed conveniently online and takes 10-15 minutes, depending on the size and tasks of your organization. 

Translations are available in several languages. Organizations from other countries are invited to fill in the English language version. đź‘‡

English: Unveiling the Flow: A survey on the equipment and functioning of Combined Sewer Overflows. 


Dansk: Hvor løber vandet? En undersøgelse af overløbsbygværkers udstyr og funktion. 


Nederlands: Zichtbaar maken van de waterstromen: Een onderzoek naar de uitrusting en werking van riooloverstorten.  


Français: DĂ©voiler les rejets : une enquĂŞte sur l’Ă©quipement et le fonctionnement des dĂ©versoirs d’orage. 


Deutsch: Was fliesst wo? Eine Umfrage zur AusrĂĽstung und Funktionsweise von RegenĂĽberlaufbecken. 


Español: Descubriendo los DSU: Una encuesta sobre el equipamiento y funcionamiento de los Desbordamientos de Sistemas Unitarios. 


The survey is coordinated by GRAIE. If you have any questions or comments, do not hesitate to contact us: contact@co-udlabs.eu  


[1] Manny, L., Fischer, M., Rieckermann, J. (2018). Policy analysis for better protection of receiving waters during wet weather. Proc. 11th UDM congress

*The majority of communities in Europe have combined sewer systems. During heavy rain events, the combined flow of wastewater and stormwater can exceed the capacity of the pipes and untreated or partially treated stormwater and wastewater is released into nearby water bodies. These releases are termed Combined Sewer Overflows (CSOs). Despite technical difficulties, major problems in CSO monitoring and performance assessment might be caused by organizational and political problems [1].