New analysis suggests that the majority of raw sewage discharges into England's rivers, lakes and seas over the past two years may have been illegal, despite going unpunished. Under UK law, sewage should not be released during "normal" weather conditions, but the Environment Agency has never publicly clarified what that threshold means, leaving campaigners to argue that water companies have been able to spill routinely without consequence. Water companies and the regulator have rejected the findings and say they are working to cut spill numbers.

The analysis, by retired academic and campaigner Prof Peter Hammond, drew on a definition of "heavy rain" contained in previously undisclosed court documents from a case against Southern Water. Applying this to data from more than 350 storm overflow outlets across all nine English water companies, serving over 30 million people, Hammond found that around 86% of sewage-spilling hours occurred without heavy rain, meaning those discharges could be unlawful; even the best-performing company had a potential illegality rate above 70%. The Environment Agency said the "heavy rain" definition applied only to Southern Water's sites and that rainfall thresholds vary regionally, though Hammond said adjusting for regional rainfall did not significantly alter his findings.