There were 403,171 spills of sewage leaked into England’s rivers and seas in 2020 due to ‘storm overflows’, Environment Agency figures have revealed.
During heavy rain, storm overflows prevent sewers becoming overloaded with a combination of sewage and rain – but they do this by releasing the diluted wastewater into rivers, polluting waters.
Use of storm overflows has also increased in recent years as climate change has led to greater rainfall – and water infrastructure has not kept pace with population growth, according to the government.
The new figures from Environment Agency, released today, also reveal there were more than 3.1 million hours of spillages in 2020.
The data has been published proactively for the first time as part of a pledge to increase transparency around the issue.
The UK government has already this week announced new legally-binding duties for water companies and government to reduce sewage discharged into waterways.
England has a combined sewage system made up of hundreds of thousands of kilometres of sewers, built by the Victorians, in many urban centres. This means that clean rainwater and waste water from toilets, bathrooms and kitchens are conveyed in the same pipe to a sewage treatment works. But during heavy rainfall the capacity of these pipes can be exceeded
‘Storm overflows are designed to discharge diluted sewage to rivers or the sea at times of heavy rainfall to prevent it backing up into homes and streets,’ said Environment Agency chief executive Sir James Bevan.
‘But a growing population and climate change means they will discharge more often.
‘The Environment Agency is working actively with the water companies to ensure overflows are properly controlled and the harm they do to the environment stopped.’
Event duration monitoring (EDM) data, which ‘lifts the lid’ on storm overflows, has always been available from Environment Agency by request.
But due to a commitment made by the government’s Storm Overflows Taskforce (set up in September 2020) to increase the transparency and accessibility of this data, it’s now on gov.uk.
Increased monitoring and reporting of storm overflows is part of the solution, according to Bevan.
It means everyone can see exactly what is happening and it will help drive improvements and investment.
The data shows that the total number of recorded spills for last year (403,171) is up more than 70 per cent from 292,864 in 2019.
However, this increase is due to the higher number of overflows being monitored, Environment Agency said.
A growing number of the storm overflows are now being monitored due to the combined risk of ocean pollution and sewage backing up into homes and roads.
EDM data for 2020 has come from 12,092 of the 14,630 known outlets from the nine English water companies and Welsh Water sites that flow into England.
This figure is up from 8,276 in 2019, 6,182 in 2018, 2,515 in 2017 and just 862 in 2016.
On average, there were 33 spills per storm overflow, slightly lower than 35 in 2019 when fewer outlets were monitored, with each one lasting an average of eight hours.
The data also shows that almost one in five overflows are discharging more than 60 times a year.
UK environmental charity the Rivers Trust has called for publication of real-time monitoring of those overflows spilling sewage more than 20 times a year, so action can be taken to improve them, and for more real-time data to help river users as well as people swimming at the coast.
‘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,’ said Christine Colvin, director for partnerships and communications at the Rivers Trust.
EDM data for 2020 has come from 12,092 of the 14,630 known outlets from the nine English water companies and Welsh Water sites that flow into England. This figure is up from 8,276 in 2019, 6,182 in 2018, 2,515 in 2017 and just 862 in 2016
Accelerated investment in fixing overflows and other infrastructure to improve the sewage system is needed, as well as action by households about what goes down the drains, and pollution from industry and agriculture.
The rate of spills varies between water companies – United Utilities reported the highest level of an average of 59 spills per storm overflow in 2020.
United Utilities said it has invested £1.2 billion in improving storm overflows over the past two decades, and that the North West has a greater proportion of combined sewers which take sewage from homes and water from storm drains through the same system, increasing the risk of spills.
‘Looking ahead, we are reviewing the performance of all our monitored storm overflows to help direct further investigations or to inform where investment may be needed,’ a company spokesman said.
A spokesman for industry body Water UK said water companies have massively increased monitoring of overflows, with plans for 100 per cent coverage by 2023.
And firms are investing £1.1 billion over five years to improve storm overflows as part of a wider £5 billion programme of environmental improvements.