Storm overflow discharges up 54%

The number of discharges from combined sewer overflows (CSOs) rose by 54% in 2023, in what the Environment Agency has described as a “disappointing […] but not surprising” year.

Environment Agency figures show 464,056 sewage spills were reported in England in 2023 – the highest number since records began in 2016.

However, this was the first year with complete event duration monitor (EDM) coverage, which was a legal requirement by the end of 2023 for all CSOs in England.

Rainfall during the year was also significantly higher year-on-year with some areas receiving more than 20% higher rainfall than the long-term average.

The regulator reported the average number of spills per overflow rose from 23 in 2022, to 33 last year.

For last year, the Agency’s data shows 40% of storm overflows spilled fewer than 10 times in 2023 compared to 48% in 2022.

In 2023, 13.9% of storm overflows did not spill at all, compared to 18% in 2022 and 13% in 2020.

“Whilst it is disappointing that water companies have reported an increase in sewage spills in 2023, it is sadly not surprising,” said Helen Wakeham, Environment director of water.

“We are pleased to see record investment from the water sector, but we know it will take time for this to be reflected in spill data – it is a complex issue that won’t be solved overnight.”

She highlighted that England is ahead of the curve in its monitoring, with no other country yet monitoring all of its overflows.

She added that the sector has begun work to reduce the number of discharges from overflows, beginning with the most sensitive catchments. Proposals over the next five years should cut spills by 40% by 2030, which is more than double the target set by government.

Also responding to the latest figures, a Water UK spokesperson labelled the results as “unacceptable” adding that they “demonstrate exactly why we urgently need regulatory approval to upgrade our system so it can better cope with the weather”.

They added: “We now need the regulator Ofwat to give us the green light so that we can get on with it.

“The government should do its bit by delivering the ten commitments it has previously made, which would eliminate tens of thousands of sewage spills.”

Rivers Trust called for greater use of blue-green infrastructure to improve the health and water quality of rivers, which are impacted by pollution from agriculture, highway runoff and other industries as well as sewage.

“This is just one source of pollution we can identify and rectify – and we must – because this effluent is making our rivers and our people sick,” Rivers Trust chief executive Mark Lloyd said.

“We must make good decisions to solve this problem, looking for integrated solutions that tackle the sewage problem along with other sources of pollution, and deliver more benefits to society too. That means working with nature as much as possible and not relying exclusively on expensive, carbon-hungry measures which transfer a large cost onto customers.”