Storm Overflow Data ‘Still Unacceptably High’
The Environment Agency has published its water supplier event duration monitoring annual return data for 2024, revealing spill frequency and duration from storm overflows in England, with a 2.9 per cent drop in the number of incidents over the year compared to 2023.
The average number of spills for 2024 per overflow was 31.8, down from the 33.1 registered in 2023 and the 32.6 in 2020. However, spill durations – the number of hours that overflows were in operation – were up by 0.2 per cent… and, as the Agency notes, this analysis shows that both spill counts and duration are still unacceptably high.
Progress does appear to have been made, however, with 39 per cent of overflow sites spilling less than ten times last year, compared to 40.5 per cent in 2023 and 40 per cent in 2020. Furthermore, 12.5 per cent of overflows didn’t spill at all, down from the 13.9 per cent in 2023 and the 13 per cent in 2020.
The Environment Agency has permits in place for storm overflow use to ensure that they’re only utilised legally during periods of intense rainfall or to mitigate for snowmelt. More monitoring of these sites is in place than ever before, with data-driven analytics helping the organisation to map discharges against rainfall more effectively.
This, in turn, allows the agency to understand just what scale of problem they’re dealing with, as well as providing the industry with a clear framework within which they can focus their investments and push forward with the necessary improvements.
Commenting on the report, Alan Lovell – chair of the Environment Agency – said: “This year’s data shows we are still a long way off where we need to be to stop unnecessary sewage pollution.
“But it also provides vital intelligence that drives targeted investment. Using our event duration monitoring analysis, we have worked with partners to secure £10.2 billion from water companies to improve storm overflows in England.
While these improvements get underway, we expect water companies to do what customers pay it to do: ensure their existing assets are maintained and operating properly. We will continue to protect our precious water quality and resources by holding water companies to account.”
Part of the £10.2 billion of investment will be used to implement nature-based solutions to help reduce the amount of rainfall that reaches storm overflows, such as wetland creation, tree planting, permeable pavements, rain gardens and river meandering to help slow the flow of water.
In order to meet the Environment Agency’s requirements, water suppliers have now committed to upgrade more than 2,500 overflow sites. This, it is hoped, will reduce annual sewage spills by 85,000. Furthermore, 3,500 monitors will be installed at emergency overflow facilities to protect and enhance 13,500km of river.
Storm overflow pollution
Much of the UK’s sewer network is a combined system, where sewage water and surface water both flow through the same pipe system before reaching treatment plants.
When this system becomes overloaded during periods of intense heavy rainfall, for example, sewage overflows (including combined sewer overflows) and pumping stations can be used to discharge untreated sewage and wastewater into local environments.
Sewage overflows are only meant to be used in exceptional circumstances to prevent sewage from flooding properties. While this is permissible and legally allowed, illegal sewage discharges during dry periods are also increasingly taking place, putting the natural world increasingly at risk.
Untreated sewage contains bacteria and pathogens that can cause serious infections, with sewage pollution leading to a range of different illnesses, including E.coli and hepatitis.
Environmentally, raw sewage is also a cause for concern, having a significant impact on our rivers, lakes, streams and oceans. Algal blooms, for example, can develop as a result of increased nutrients that make their way into the water via untreated sewage.
This can cause changes in biodiversity and affect the delicate balance of the ecosystem, putting aquatic life at serious risk, including fish, plants and insects.
Once sewage enters a waterway, there isn’t much that can be done to prevent the consequences, but these ecosystems can restore themselves – as long as they’re not overwhelmed.
The problem lies in chronic pollution, which can lead to the complete eradication of certain species – and this is why it’s so essential to prioritise sustainable water management to ensure the safety of one and all.