Analysis suggests most sewage spills in England may have been illegal

Most of the sewage spills into England's waterways in the last two years may have been illegal but gone unpunished, according to new analysis.

UK law states that raw sewage should not be released during "normal" weather conditions, yet until now the regulator has not clarified exactly what that means.

But campaigner Prof Peter Hammond obtained a definition in secret court papers, and said it shows that for more than 80% of the time sewage was being spilled, the weather was "normal" - making the spills possibly illegal.

The water companies and the regulator, the Environment Agency (EA), rejected the analysis and said they were working to reduce spill numbers.

The last few years have seen growing awareness and mounting public anger at the amount of raw sewage that is being discharged into England's rivers, lakes and seas.

The country's sewage issues are, in large part, caused by the fact that drains usually take rainfall into the same network of pipes that remove waste from homes.

This means that when it rains, if there is not enough spare capacity, the system and sewage treatment works can be quickly overwhelmed.

But until now, it has not been clear what amount of rainfall there must be before water companies can legally spill raw sewage into waterways. Campaigners have said this has allowed the industry to spill routinely with no consequences.

Earlier this year, a source at the EA sent Prof Hammond undisclosed documents from a court case against Southern Water for illegal sewage spilling in 2021.

It included a previously undisclosed definition of "heavy rain" conditions. And accompanying internal EA documents confirmed that water companies can spill sewage when there is "heavy" rain i.e. beyond the "normal" weather conditions.

Prof Hammond, a retired academic and campaigner whose work on sewage spills has been cited in Parliament and in economic regulator Ofwat's enforcement decisions, used the definition to run an analysis of water company spill data.

He looked at more than 350 storm overflow outlets in England and whether there had been heavy rain when they were spilling sewage.

The outlets include all of the largest sewage treatment works and a representative selection of smaller ones, across all England's nine water companies serving more than 30m people.

Hammond said he found about 86% of the raw sewage spilling hours took place when there had not been heavy rain, meaning those discharges could be potentially illegal.

None of England's water companies did well in Hammond's analysis, with even the best having a potential illegality rate of over 70% for the last two years.

"It's totally outrageous, both from the point of the water companies who are exploiting the weak regulation but also from the Environment Agency's point of view, where they've not been doing their job properly," Prof Hammond told BBC News.

It is not the first time the Environment Agency's enforcement regime has been called into question.

In 2024, the Office for Environmental Protection (OEP), an independent public body, ruled that the EA was not applying legislation properly as to when sewage could be legally discharged. It said the EA was allowing water companies to spill in "normal" weather rather than "exceptional circumstances" - as the law states.

In light of the OEP report the EA issued new guidance last year, external making it clear that spills should not take place during normal weather.

But in an email exchange with the BBC the EA refused to confirm that spills should only take place during "exceptional circumstances", but said it would "always take action" if there had been a breach of the law.

"However, to meet the strict legal requirements needed to pursue a criminal conviction we must consider a wide range of factors including specific site and permit conditions, as well as rainfall totals," its spokesperson said.

Asked to provide details of completed or ongoing enforcement action related to spills in "normal" weather a spokesperson for the EA said they could not, citing "ongoing legal proceedings".

In response to Prof Hammond's analysis, a spokesperson for Water UK, which represents the water companies, told the BBC: "As confirmed by the High Court and the Office for Environmental Protection, discharges should only occur in 'exceptional circumstances' or if preventing them is technically possible but would involve excessive cost.

"In any case, we want to end all discharges and are working to end them as fast as we physically can."