0923 Testing of the Measuring Device and Assessment of Overflow Activity of Stormwater Tanks URM

Purpose of the study and service

How do you recognize a well-functioning combined sewage overflow tank? Is ‘my’ stormwater tank okay? The measured overflow activity of the tank is an important indicator for its correct function.

An evaluation of the overflow duration and frequency allows a statement without further hydrological data or even a simulation of the actual status. Normal overflow activity usually indicates correct operation. If the overflow activity, however, is significantly above or below average, the reasons should be investigated separately.


Possible reasons for particularly long or frequent overflows:

  • reverse flow into the stormwater tank caused by flooding for a few days
  • particularly strong inflow of infiltration water, especially in winter and spring
  • particularly high rainfall and relatively short monitoring period
  • outlet flow too low due to a partially blocked flow control unit
  • stormwater tanks still needed further up the network
  • fault in the design of the tank volume or in the discharge

Possible reasons for particularly rare or short overflows:

  • especially dry or short monitoring period
  • the catchment area of the stormwater tank is only partially drained using a combined system, but using alternative drainage systems instead
  • flow control discharge too high