Defra and the Environment Agency have worked with water companies through the 21st Century Drainage Programme to develop a process to identify storm overflows that spill frequently. It is also agreed that investigations will be conducted to assess the cause, the environmental impact and whether it is cost beneficial to reduce the spill frequency. If it is cost beneficial then a spill reduction scheme will be promoted, which will be reviewed annually.
Through the planning for the next round of water company investment in the period 2020-2025, over 700 storm overflows have been identified for investigation and some of these will result in identified requirements for spill reduction. From investigations carried out to date, more than 40 storm overflows have already been identified as requiring spill reduction, and improvements will be secured through the investment programme.
In addition, storm overflows are monitored for how often and for how long they operate. By 2020 some 11,500 out of 15,000 storm overflows in England will have that monitoring to help inform further assessment and improvement work.