The intervention from David Black, Ofwat's new interim chief executive, comes following mounting concern about the increased use of storm overflows in recent years and the impact they can have on waterways, biodiversity and local communities.
Raw sewage was released in streams and rivers for 3.1m hours in 2020. Storm overflows are intended to prevent sewers becoming overloaded by sewage and high rainfall, through the release of wastewater into waterways. But their increased use has been the subject of campaigns from green groups and water charities.
Black called on water companies to “build on progress they have made on other fronts” with a focus on meeting the challenge from the use of storm overflows. In the most recent price review, Ofwat, the financial regulator for the water sector, approved £1.2bn of investment to reduce the use of storm overflows.
Ofwat is seeking specific assurance that water company boards are closely monitoring performance, using the right data, and providing the appropriate check and challenge on the use of storm overflows. It warned water companies that where they do not have the right measures in place, it could take action against them.
Black said: "Caring for our rivers is a complex and multi-sector issue, but it is clear to me that the positive strides the water sector has made in other areas of environmental performance are not evident when it comes to storm overflows.
"This is a sector with genuine ambitions to be, and be seen as, leaders when it comes to caring for the environment. The challenges from the use of storm overflows present an opportunity for water companies to show they mean business and can meet the growing expectations on them."
In March, DEFRA said measures to reduce sewage discharges from storm overflows would be put into law. These measures include requiring the government to publish a plan by September 2022 to reduce sewage discharges from storm overflows. It must also report to Parliament on its progress in implementing the plan and water companies must publish data on storm overflow operations on an annual basis.
Environment minister Rebecca Pow added: “I have made it very clear to water companies that they must improve their environmental performance – with a particular need for reducing sewage discharges from storm overflows. To this end we have added new legally-binding obligations on water companies and the government in the Environment Bill to tackle pollution in rivers.”