Our monthly Event Duration Monitor (EDM) report provides a detailed summary of the monitor activations that have occurred during the month. We are publishing this data to provide easier and more timely access to the data our systems are giving us about our storm overflows. You can read more about our EDM monitors here. 

Getting accurate information about storm spills is not straightforward. In fact, we are the only country in Europe to have installed monitors on our storm overflows. The technology and monitors we’re using is still relatively new – less than five years old – and they are operating in an inhospitable environment (sewer pipes), where glitches can occur, so it’s taken a great deal of work and investment to get the most accurate information in a usable format for customers and stakeholders.     

Our monthly report provides a summary of the data published on our real-time map. This means there may be times when errors occur, and the sensors are triggered without being caused by a spill.  
  
Our fully verified data returns will still be made to the Environment Agency on an annual basis, which can be found here.