Addressing the CSO challenge to water quality
Wastewater
Sludge
Europe
Tuesday, 10 November 2020

Addressing the CSO challenge to water quality

A new report from Surfers Against Sewage (SAS) found that across the UK nearly 3,000 discharge events occurred from Combined Sewage Outfalls (CSOs) over the last year. There is a clear impact on water quality but the analysis also suggests that discharge events are anything but rare. Action is needed on several fronts to address this growing challenge, but technology innovation will play a key role.

The CSO challenge to water

According to SAS data, water companies are still discharging sewage at alarming rates.

Between 1st October 2019 and 30th September 2020, a total of 2,941 Combined Sewer Overflow (CSO) discharge notifications were issued through the Safer Seas Service (SSS) from SAS.

This not only pollutes the environment, there are also significant health risks associated with the discharge of untreated sewage.

“The water industry, led by Water UK, has been working on drainage and sewage management plans,” said Jacob Tompkins, co-Founder and CTO at the Water Retail Company.

Speaking to Aquatech Online, he said: “There are programmes in place to improve this, but the problem is every year this gets worse. They are running a race against climate change, a growing population, a growing burden upon the sewer network and the network is aging. It means that the input to the combined sewer networks are increasing.”

“Climate change, a growing population, a growing burden upon the sewer network, the network is aging. It means that the input to the combined sewer networks are increasing.”

Indeed, despite progress over the last 30 years, the UK still ranks 25th out of 30 European countries for Bathing Water quality, said SAS.

It added that the UK missed its 2020 target for UK seas to meet Good Environmental Status, failing 11 out of 15 indicators of marine health. Furthermore, some 86 per cent of rivers and inland waterways in England also fail to meet Good Ecological Status, the report adds.

The rise of open sewers

As Hugo Tagholm, chief executive of Surfers Against Sewage, said: “Water companies consistently put profit before fully protecting the environment. This report demonstrates that rivers and oceans are being treated like open sewers as combined sewer overflows are used as a routine method for disposing of sewage, instead of in the exceptional circumstances under which it is permitted.”

“Combined sewer overflows are used as a routine method for disposing of sewage, instead of in the exceptional circumstances under which it is permitted.”

The Environment Agency said it has identified over 700 overflows to be investigated and 40 overflows to be improved by 2025. 

However, only four water company prosecutions were achieved in 2019. For instance, last year an Ofwat investigation prompted Southern Water to agree to pay £126 million in penalties and payments to customers following serious failures in the operation of its sewage treatment sites and for deliberately misreporting its performance.

All water companies should provide year-round, real-time sewage discharge notifications but some chose not to release this information. 

SAS noted that Southern Water failed to provide adequate CSO discharge notifications for Bathing Waters impacted by their assets. In comparison to the 690 sewage spill notifications issued by Southern Water in 2019, they only managed to issue 78 alerts this year, according to SAS.

“In my view there should be more openness, more transparency and more admission of what’s happening,” added Tompkins.

Calls for continual monitoring in real-time

Dr David Lloyd Owen, managing director of Envisager, explained that it’s not just transparency but that a lack of data is also a major factor in addressing CSO discharge events.

Speaking to Aquatech Online, he said: “Across England and Wales, there are 17,684 CSOs where sewage and rainwater can be discharged after heavy rainfall. By the end of 2019, water and sewerage companies were monitoring 7,762 of them.”

However, while the bulk of this monitoring only offers a snapshot of conditions, this leaves around 10,000 CSOs that are not being monitored at all.

And, while not all sewer outflows need to be monitored all of the time, identifying the problematic ones, carrying out necessary remedial works and maintaining monitoring is key.

“This calls for continual monitoring in real time, so that discharges can be noticed when they occur, rather than when dead fish are found downstream.”

“This calls for continual monitoring in real time, so that discharges can be noticed when they occur, rather than when dead fish are found downstream,” added Lloyd Owen. 

He identifies opportunities for novel technology to enable positive change, highlighting a self-sufficient, remotely enabled monitoring system from Watr as an example of the type of low-cost technology that could support improved performance. 

“Water is disruptively innovative compared to conventional offerings and approaches,” he said.

Lloyd Owen added: “Cost-effective monitoring takes the guess work out of managing our waters. Keeping our waters clean and healthy will never be cheap, but at least the money can be spent where it needs to be.”

A radical approach is needed

Tompkins argues that a more radical approach is needed to solve this issue.

“You’ve got to innovate,” he said. “There are some quite interesting new machine learning and artificial intelligence programmes that can help with this, but they haven’t been implemented that much in the water industry so far.”

In a bid to address this, Ofwat has established a £200 million innovation fund designed to transform water and wastewater services in England and Wales. 

From 2021 at least two competitions will be run: a £2 million ‘Innovation in Water Challenge’ for funding projects up to £250,000 that will open for entries in January 2021 and £40 million main competition that will open in April 2021. Further competitions are anticipated each year from 2022 to 2025.

Ultimately, the challenge of CSOs and their impact on water quality and health is one which will only become more significant over time as climate change, urbanisation and a growing population all make their impact felt. 

For water companies reluctant to innovate, the regulatory regime must incentivise additional action to improve performance but as private enterprises, water companies must also manage potential commercial risks associated with CSO discharges. 

“If the regulation isn’t strict enough then that’s our fault, but I don’t see how, in the long term, that this is good for their shareholders,” concluded Tomkins. “This issue exposes them to significant business risk.”

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