Dry 2025 supports drastic drop in storm spills

(by Karma Loveday)

The 2025 Event Duration Monitoring returns published by the Environment Agency show significant reductions in spill events.

Storm discharge numbers fell by 35% to 291,492 in 2025 compared to 2024, and total monitored spill duration fell by 48%. There was also a 20% reduction in average duration per spill event .

Reporting the data, the Environment Agency said: “Much of this improvement reflects unusually dry conditions in 2025 following a particularly wet 2024.”

Water UK said: "The Environment Agency and campaigners have rightly pointed to the role of the weather in driving down spill numbers. But look behind the numbers and water companies are also making progress in cutting spills in their region.” It offered some examples:

• United Utilities improved 400 storm overflows resulting in a 22% cut in spill numbers, despite rainfall across the region being 101% of the historic average. 

• Yorkshire Water invested £180m to improve more than 100 storm overflows — reducing spills by almost 25%.

• South West Water cut spills by 17% in 2025, despite the region receiving 62% more rain than England overall. 

• Anglian Water removed 340 storm overflows from its network entirely, and set out detailed improvement plans for each of the company’s 1,442 storm overflows to significantly reduce discharges. The company said its 2025 storm overflow performance was the best ever, with the total number of spills down by more than 60% and the total duration of all spills reduced by more than 80% compared to 2024.