Water suppliers in England recently announced that they were ready to spend £10 billion on tackling sewage spills after apologising for the amount of contaminated water spilling into rivers and seas.

So how much sewage is actually dumped into English rivers and beaches?

FactCheck takes a look.

How much sewage is dumped in rivers and beaches?

Water companies are sometimes allowed to spill sewage into open water following heavy rainfall to prevent the system becoming overloaded, using relief valves called “storm overflows” to release extra rainwater and wastewater into rivers or seas.

But campaigners have long said that these spills are happening too often.

According to the latest data, there were just over 300,000 “monitored spill events” in 2022. A monitored spill event is a discharge to the environment and data is collected by the Environment Agency (EA).

Although still high, this was actually down 19 per cent compared to 2021, and 25 per cent lower than 2020.

Nevertheless, it’s still nearly 24 times higher than in 2016 and more than nine times higher than 2017.

But there’s a massive caveat to this data. It’s possible that the apparent upward trend since 2016 could be because the EA is collecting more data on sewage spills than it used to.

Phillip Clisham, a consultant and specialist advisor to the Institution of Civil Engineers on water and sanitation, told FactCheck that the monitoring of storm overflows has “improved greatly” since 2020 and “we now have a more accurate picture of sewage overflows and when they happen”.

But he added: “Before monitoring was increased, it was difficult to draw any definitive conclusions about sewage overflow trends because we don’t have reliable data. We also have to be careful about drawing conclusions, as the weather changes from year to year, so trends can only reliably be determined with longer term data.”

Nick Voulvoulis, professor of environmental technology at Imperial College, echoed this. He told FactCheck that “of course” the total number of monitored spill events has risen, as the number of overflows being monitored “has been increasing over the years”.

Has the action of water companies helped reduce recent sewage spills?

The average number of monitored spills per overflow did reduce from 29 in 2021 to 23 in 2022.

But the EA said this was actually “largely as a result of last year’s dry weather, rather than water company improvements”.

The EA added: “Despite claims by some water companies, there is no evidence to show it is because of water company action.”

Water companies only made improvements to 65 storm overflows last year, which is less than 0.5 per cent of the overall total of overflows in the entire system, “so we are very confident that water company action has not significantly contributed to the reduction in flows overall,” the EA said.

“What is very clear from the data they have provided is that the number of spills they are allowing on the sewerage network is far too high and totally unacceptable.”

A spokesperson for the Rivers Trust told FactCheck: “We need the government, their regulators and the water companies to take action on sewage overflows, to improve the health of our rivers and beaches for wildlife and communities.”

A spokesperson from the Department for the Environment, Food and Rural Affairs told FactCheck that the volume of sewage being discharged into open water is “unacceptable”, and that although water companies have announced action plans for more investment and greater transparency in their use of storm overflows, there is still “a great deal more to do”.