Yorkshire Water reduces storm discharges to watercourses by 24.5% in 2025
26/03/2026
The number of discharges into watercourses in Yorkshire decreased by 24.5% in 2025 when compared to the previous 12 months.
Discharges fell from 68,164 to 51,404 and the duration of the discharges into watercourses fell from 430,263 hours to 285,230 hours – a decrease of 33.7%. The average number of discharges per storm overflow also decreased from 31.4 in 2024 to 23.6 in 2025.
The decrease in 2025 follows a 12% reduction in discharges in 2024.
Richard Stuart, director of asset delivery and engineering, said: “A reduction in the number and duration of discharges across the region in 2025 is a positive. The dry weather in 2025 contributed to the reduction, but we also saw above average rainfall in the region in January, September, November and December. Our £180m investment over the last two years targeted over 100 storm overflows and is delivering a reduction in storm overflows across the region.
“Some of the work as part of this investment was completed in early 2025, so we are yet to see the full benefit during an entire 12-month period, but we are seeing the investment beginning to make an impact. Of course, there is more to do and we’re underway with a further £1.5bn investment to continue tackling the performance of storm overflows.
The £180m investment into more than 100 storm overflows across the region has delivered improvements from the 2021 benchmark for the project, including:
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£2.4m investment at Cudworth No2 CSO near Barnsley has seen a drop from 41 discharges into the river Dearne in 2021 to zero in 2025
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£835k investment at Marton Bridge CSO near Pickering to separate and divert rainwater from the wastewater network has reduced discharges into the river Seven to zero in 2025, compared to 24 in 2021.
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£1.3m investment at Esplanade Whitby CSO to divert rainwater from properties and surface water from highways directly into the sea, rather than combining with wastewater, has seen a 75% reduction in discharges.
Richard added: “We know we need to continue driving down the number of discharges to our rivers and seas and we’re committed to delivering those improvements over the next few years and beyond. By April 2030 we will invest £1.5bn to upgrade and improve more than 450 storm overflows, tackling those discharging the most frequently, for the longest time and those that have a significant impact on the receiving watercourse.
“There are more than 2,000 overflows across our region, protecting homes and businesses from sewage backing up in the network, and we have analysed the performance of all of them to ensure our investment is targeted and will make the biggest difference to the health of our rivers and seas. All projects are underway - many are in the planning and design stages, but construction is taking place at a number of sites across Leeds, Barnsley and Sheffield, with many more to come in the months and years ahead.
“As we complete more investment this year and over the period to 2030, we will see the improvements we’ve already made begin to scale up and we will continue to report our performance transparently so people can hold us accountable. We have also significantly improved collaboration between all stakeholders interested in river health and will continue to work closely with organisations that want improvements to be made to our region’s watercourses.
“As well as the major infrastructure work completed in recent years and what’s to come by 2030, our teams are out and about across Yorkshire every day carrying out activity to improve the operation and efficiency of our networks to continuously reduce the discharges to our region’s watercourses.”
Storm overflows projects currently under construction as part of the £1.5bn investment include:
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Darton Church Street/CSO, Darton, Barnsley – £5.3m new underground storage tank capable of holding 190m3 of storm water to reduce discharges into the river Dearne
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Butterthwaite Road/CSO, Ecclesfield, Sheffield - £2.6m new storage tank capable of holding 460m3 of storm water to reduce discharges in Blackburn Brook
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Genn Lane/CSO and West Street Worsborough/CSO - £4.8m project to increase storage, reroute sewers and rebuild a CSO to reduce discharges into the river Dove
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Millshaw CSO, Beeston, Leeds – £1.2m new storage tank capable of holding 260m3 of storm water to reduce discharges into the river Aire
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Fraser Avenue CSO, Horsforth - £1m investment will create 300m3 of storm water storage to reduce discharges into the river Aire
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Preston Street, Bradford - £30m new underground storage tank capable of holding 13,500m3 of storm water to reduce discharges in Bradford Beck
More than 450 storm overflows, including those at the wastewater treatment works in Scarborough and Bridlington, will receive investment by April 2030. The work will continue to build on the success of recent investment and aims to bring down storm overflow discharges throughout the region.
Yorkshire Water will continue to invest in storm overflows beyond 2030, again prioritising those discharging the most frequently of the 2,184 overflows across the region.