Second York storm overflow improvement project starts

Yorkshire Water has begun its second storm overflow project in York, reducing discharges into watercourses in the area, as part of a wider £1.5bn programme of investment by April 2030. 

The £2.5m project at Poppleton Road North combined sewer overflow (CSO) will see the installation of an underground storage tank which will be able to hold around 250,000 litres of stormwater. The additional capacity will hold back rain and wastewater during periods of bad weather, preventing it from being discharged. Flows will be sent for treatment when capacity in the network has returned to normal levels. 

The tank will be installed within the grounds of Howe Hill Allotments, within the gravel and grassed areas only – not impacting any allotment plots. 

Once completed, the project will reduce discharges to the River Ouse from Poppleton Road North CSO by 86%, to fewer than 10 per year, helping to improve the water quality in the river.  

This project closely follows the beginning of a scheme at the York Landing Lane CSO, which will also reduce discharges into the River Ouse by 49%. 

Yorkshire Water is currently planning several further storm overflow projects in the York area. 

Sam Pashley, project manager at Yorkshire Water, said: “Our storm overflows are operating more than we, and our customers, would like, and we’re committed to reducing the number of discharges taking place.  

“We’re on track with our York programme – making great progress at Landing Lane, and getting started on Poppleton Road. These are both long-term projects, but once they’re complete, they’ll have a significant impact on the health of the Ouse.” 

Contract partners Ward and Burke are expected to take around eight months to complete the project on Poppleton Road.  

The £1.5bn Yorkshire-wide storm overflow investment programme, which will see improvements at over 450 overflows, follows a £180m investment over the previous two years that helped reduce discharges to watercourses by 12% in 2024 from 2023, and by a further 24.5% in 2025. 

Storm overflows are designed to act as a relief valve for the combined sewer network, which carries both wastewater and surface water, during periods of heavy or prolonged rainfall. They discharge when the system is at capacity to prevent flows backing up and flooding homes and gardens. 

Across Yorkshire, the need for storm overflows to operate will be reduced by building new: 

· Surface water sewers, to separate surface water and wastewater so that wastewater networks aren’t impacted by bad weather 

· Underground storage tanks, to build additional capacity into the network 

· Nature-based solutions, to build additional capacity into the network 

· Sustainable drainage systems, to slow the flow of surface water into the combined network 

The storm overflow project is part of Yorkshire Water’s £8.3bn investment into its services and the environment over the next five years.