2024 data shows spill numbers down but durations up

There was a 2.9% decrease in storm overflow spill numbers to 450,398 in 2024 compared to 2023, and the average number of spills per overflow was down from 33.1 to 31.8. But spill durations were up marginally (0.2%) and totalled 3,614,428 hours across the year.

Contextual factors included that 2024 was one of the wettest years on record, albeit not as wet as 2023; and that the year was the first ever in which 100% of storm overflows were monitored, making the dataset a baseline for future performance to be judged against.

In their commentaries, Defra and the Environment Agency highlighted forward factors that should lead to better future results, including the £10.2bn being spent across 2025-30 on storm overflow improvements; new storm overflow policy and Storm Overflow Assessment Framework guidance; deterrents in the Special Measures Act; and more active inspection and enforcement.

Environment secretary Steve Reed described the data as “disgraceful” and The Rivers Trust highlighted that there had been “no significant progress”.