New figures published by the Environment Agency have revealed that the ten water and wastewater companies in England and Wales discharged raw sewage into rivers in England more than 400,000 times for more than three million hours last year.

Event Duration Monitoring (EDM) data shows the number of recorded spills from storm overflows rose to over 403,000 in 2020 - up from nearly 293,000 in 2019. 

The Agency has been working with water companies and has concluded a programme to install monitors on the vast majority of storm overflows – just over 12,000 – by the end of 2020.

By the end of 2023, the remaining number will be monitored to provide a complete picture of permitted storm overflows in England.

Headlines figures from the 2020 data include:

• 14-fold increase in the coverage of monitors, from 862 in 2016 to 12,092 in 2020;
• The number of storm overflows with monitoring devices has increased from 8,276 in 2019 to 12,092 in 2020 providing intelligence on over 80% of the sewerage network;
• The average number of spills per storm overflow was 33, although there was significant variance between water and sewerage companies (min/max average 21/59);
• The average duration of each overflow event was 8 hours, (min/max average 5/12 hours).

EA storm overflow table from the 2020 EDM return

The Agency uses the EDM data to inform the Water Industry National Environment Programme (WINEP), developed by the Environment Agency – a framework to prioritise where water companies need to improve and where they should focus their investment.

Rivers Trust - discharges are “a shocking volume of untreated contaminated wastewater”

The Rivers Trust, the umbrella organisation for 60 local member Trusts, described the discharges as “a shocking volume of untreated contaminated wastewater” reaching rivers which showed that the current approach and infrastructure, managing storm water in particular, needs “a radical overhaul.”

However, it welcomed the first public release of the data by the EA. The increase from 862 (6%) to 12,092 SOs being monitored since 2016 was also an important step, as monitoring was now in place for 80% of the known SOs in England.

“Data indicates that, appallingly, almost 1 in 5 overflows across England are discharging more than 60 times per year - a staggering statistic"

Michelle Walker, Deputy Technical Director of The Rivers Trust, said:

“It’s good to finally see this data in the public domain, and in particular the significant increase in the number of overflows being monitored over the last four years. …

“Whilst we know we can’t make a direct comparison to last year’s EDM data due to the 50% increase in the number of overflows being monitored, the data raises alarm bells. If storm overflows work as designed, they will discharge less than 20 times per year – when there has been extreme rainfall….”

“The 2020 data indicates that, appallingly, almost 1 in 5 overflows across England are discharging more than 60 times per year, a number which is supposed to trigger an EA investigation. This is a staggering statistic and The Rivers Trust is now calling for greater transparency and publication of real-time monitoring of overflows which are discharging more than 20 times per year so the appropriate measures can be taken to improve the situation.”

Christine Colvin, Director for Partnerships & Communications at The Rivers Trust, added:

“The sector has made progress in monitoring sewage pollution in a relatively short time, but the urgent work to clean up our rivers has barely begun. As government guidance identifies that extreme rainfall intensity will increase by 10% by 2050 and 20% by 2080, so the SO issue will only get worse and business as usual is not an option.”

According to the Rivers Trust, the water companies’ commitment to investigating and improving 800 overflows before 2025 (at a cost of £1.1 billion) will deal with only 5% of the +14,000 SOs that are declared by water companies.

The Trust is calling for an accelerated investment in fixing overflows and the upstream problems that cause them to spill more frequently than they should.

“ Significant investment in infrastructure, including innovative implementation of nature-based solutions, is required to ensure that we have a capable and resilient sewage system for the 21st Century”, the Trust said.

Responding to the publication of the 2020 EDM data, a spokesperson for Water UK, the body which represents all the water companies in the UK, said:

“Water companies are committed to playing their part in reducing any harm from storm overflows. As the data shows, we have massively increased monitoring, with the aim of getting 100% of the 14,630 overflows in England monitored by the end of 2023.

“This data is invaluable and allows investment to be targeted where it’s needed most. A total of £1.1bn is being invested by water companies to improve storm overflows over the next 5 years as part of a wider £5bn programme of environmental improvements. In addition, we are playing a leading role in the Government taskforce that is looking at long-term alternatives to storm overflows.

“What we all want to see are improvements in the health of our rivers. Storm overflows account for only around 4% of all the reasons for rivers and waterways not achieving good ecological status, so it’s essential to deal with all the other sources of harm, and all sectors involved will need to play a part in addressing this complex challenge together.”

Last week the Government confirmed that new measures to cut water companies' reliance on storm overflows to discharge sewage into rivers are to become law.

The latest measures build on the work already underway by the Storm Overflows Taskforce, set up in September 2020 to bring together government, the water industry, regulators and environmental NGOs to accelerate progress in this area.

Earlier this year the Taskforce – made up of Defra, the Environment Agency, Ofwat, Consumer Council for Water, Blueprint for Water and Water UK – agreed a long-term goal to achieve this.