IN 2023, private water companies in England more than doubled the amount of sewage they discharged into the country’s rivers and seas.

It amounted to around 3.6 million hours of sewage spills in total, up from 1.75 million hours in 2022.

However, as environmental campaigners have pointed out, sewage dumping is also an issue in Scotland.

Yet a key difference stands out when comparing the figures between the two countries.

While 100% of combined sewage pipes in England are monitored, in Scotland, that figure stands at around 5%.

But just how big of a problem is sewage dumping and how much would it cost to install monitors on every overflow pipe in Scotland?

What is ‘sewage’?

TO begin, it’s important to understand what is defined as “sewage” in this context.

“What people consider traditional sewage - literally what goes down your toilet and sink - that gets combined with the run-off from houses, pavements and roads into a combined system,” said Rachel Wyatt, a policy and advocacy manager at the Marine Conservation Society.

“When the sewer network gets too full of rainwater and there’s just no capacity left, the water has to go somewhere and so it gets discharged through Combined Sewage Overflows (CSOs).”

The pipes then release the water into rivers and seas across the UK.

There are around 3600 Combined Sewage Overflows in Scotland(Image: BBC Panorama)

In England, where privately run water companies were mandated to install monitors by the UK Government before December 2023, nearly 100% of CSOs are monitored.

Meanwhile in Scotland, the publicly owned Scottish Water only monitors around 5% of CSOs.

However, Scottish Water maintains that only around 1% of the water discharged through CSOs comes from toilets, with the vast majority of it being run-off and "grey" water from appliances like washing machines.

The issue

THE ageing nature of Scotland’s sewer system and increased instances of extreme rainfall linked to climate change means that there are times when discharging sewage into waterways becomes necessary in order to stop it backing up into homes and businesses.

This, inevitably, has an impact on the environment.

“It isn’t just what goes in your toilet,” said Wyatt. “It’s everything else you’re using in your home, too.

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“Microfibres from clothes, microplastics and chemicals from household products, it can all impact marine wildlife.”

The resulting damage to the marine environment also impacts things such as bathing water quality and shellfish farms.

The numbers

THAT instances of sewage releases into Scotland’s rivers and seas occur is demonstrably not for lack of investment.

Between 2022 and 2023, £886 million was invested by Scottish Water to maintain or improve the system, with former chief executive Douglas Millican stating that the utility company needed “to decide which areas are the greatest priority for investment with the resources we have”.

He added that despite investment levels increasing significantly since 2021, Scottish Water was still only investing around 40% of what was necessary to ensure long-term assets were replaced when needed.

There are around 3600 CSOs in Scotland with only about 7% equipped with Event Duration Monitors (EDM), which record the occurrence and length of sewage releases into rivers.

(Image: Stock)

Scottish Water told the Sunday National that the cost of installing a single EDM on a CSO is £7500, although it can be more depending on other issues such as location and the need for traffic management.

That means an estimate to install EDMs on all CSOs currently without them is about £25 million which, given the priorities of Scottish Water, would likely have to come in the form of extra funding from the Scottish Government.

The politics

SCOTTISH Labour MP Chris Murray accused the Scottish Government of being “missing in action” on the issue of sewage releases following a warning issued by the Scottish Environmental Protection Agency (Sepa) advising swimmers not to take to the water in Portobello earlier this month.

On Friday, Sepa confirmed that the bacterial pollution which caused concern on July 10 was not related to CSO releases but instead to “human, dog and gull waste” left on the beach.

Still, Murray has said that the dumping of sewage in Scotland’s waters makes him “so angry” and that he would be “pushing hard” to stop the sewage.

In a letter to acting net zero minister Gillian Martin, he asked her to work “urgently” to address the issue and commit to “adequate monitoring of sewage overflows”.

However, a request from the Sunday National asking Murray to detail where the £25 million would come from to fund full-scale monitoring of CSOs received no response.

Similarly, the Scottish LibDems leader Alex Cole-Hamilton said the SNP and the Greens had “utterly failed to get to grips with the sewage crisis in our rivers” during their time in government.

When asked to detail where the £25 million to fund CSO monitoring would come from, they pointed the Sunday National to their General Election manifesto, which implied the money would be found from an increase in capital funding from the UK via tax increases on banks, energy companies and tech giants.

When asked to detail how it could be financed by the Scottish Government given the fact the LibDems did not win the General Election, the Sunday National once again received no response.

The future

ACCORDING to Sepa, around 67% of Scotland’s waterbodies were classified as being in good or better condition in 2022. Evidently, there are improvements to be made in both monitoring and preventing sewage releases.

But, as the Marine Conservation Society acknowledges, the fixes aren’t cheap.

So-called grey infrastructure involves building large storage tanks to hold sewage at times of heavy rainfall which can then be treated later.

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Green infrastructure, meanwhile, would involve more soft engineering solutions like wetland creation which can hold rainwater currently being diverted into our sewers.

“All of that can be very expensive,” said Wyatt. “But it can be done and in a way that can have multiple benefits for people and the environment.

“As this problem is only going to get worse in the future, ultimately the cost of doing nothing will be greater.”

What the stakeholders say

A SCOTTISH Water spokesperson said: “We treat 1.07 billion litres of wastewater every day and deliver services which meet or exceed our regulatory requirements.

“Environmental standards are being maintained or enhanced. Overflow points are a fundamental part of the public sewer system and operate, as designed, during heavy rain to prevent properties from flooding when sewers reach capacity.

“The vast majority of overflowing water is ‘run-off’ from roads and roofs, and ‘grey’ water from household appliances. Only about 1% comes from toilets. 

“Scottish Water has invested £2.7 billion in the drainage system over the past decade and is committed to further investment of up to £500m. As part of this, we are on track to install 1000 new monitors and other improvements by the end of 2024.

“Customers can play their part by not flushing wet wipes and other items that cause blockages down toilets.”

A Scottish Government spokesperson said: “Our waters are monitored by the independent Scottish Environment Protection Agency (Sepa).

“Sepa assesses 87% of waterbodies in Scotland as having ‘high’ or ‘good’ water quality, up from 82% six years ago.

“However, we are not complacent, [and we] seek ongoing improvement and continue to work closely with SEPA and Scottish Water to monitor and improve water quality.

“Overflows from sewers are wastewater which has been highly diluted by rainwater and which normally consists of less than 1% toilet waste. To suggest otherwise is a misrepresentation.

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“Scottish Water is taking action and is committing up to £500m to improve water quality, increase monitoring of the highest priority waters and tackle debris and spills.

“This includes a commitment to install at least 1000 new monitors on the network by the end of 2024 – good progress is being made, with around 800 having already been installed by the end of March.

“We are also determined to limit the amount of rainwater entering sewers to reduce overflows and have recently published an analysis of the responses to our public consultation on water, wastewater and drainage which asked the public for their views on how we achieve this.”