Water Industry News

Water Crisis: What Is Dry Spilling?

The poor quality of the UK’s waterways is now very well documented and it seems as though not a day goes by that sewage spills and pollution don’t hit the headlines for some reason or other.


One area of growing concern is the practice of dry spilling, where untreated sewage is discharged into streams, rivers and the sea during periods of dry weather.


Combined sewer overflows are purposefully designed to be used as an emergency release valve during periods of exceptionally heavy rainfall so as to reduce pressure on the sewer network and prevent sewage from backing up into homes and businesses.


However, it seems that illegal dry spilling incidents are becoming increasingly common, with water companies discharging raw sewage even when there has been no rainfall to speak of.


An investigation by campaign group Surfers Against Sewage found that between 1st October 2021 and 30th September 2022, there were 143 dry spills affecting the nation’s most popular surf and swimming spots and, of these, 92 took place at locations classified as ‘excellent’ for water quality.


As well as being largely unnecessary, dry spills put the environment at increasing risk, at a time when the water crisis is really starting to take hold and protecting freshwater resources is fast becoming a global priority.


When sewage is discharged during periods of dry weather, pollution becomes more concentrated because there’s less water to dilute it, which increases the contamination risk from infectious organisms.


In fact, just over a month ago, at least 57 people came down with sickness and diarrhoea after competing at the World Triathlon Championship Series in Sunderland, an event that took place along a stretch of coastline that has been at the forefront of a battle between campaigners and the government relating to sewage discharges and regulatory failures.


At the time, Eva Perrin – science and research officer at Surfers Against Sewage – was quoted by the Guardian as saying: “The sample taken on 26th July showed unprecedented levels of E coli well over what is natural for this water body or safe for human recreational use and urgently needs to be investigated.”


New data


A new BBC inquiry has found that three of the biggest water companies in the UK illegally discharged sewage hundreds of times in 2022 on days when there was no rain to speak of.


It was found that Thames Water, Wessex Water and Southern Water collectively engaged in dry spills for 3,500 hours in breach of their permits, releasing sewage on dry days 388 times… including during the summer, when all three regions were classified as being in drought.


What’s more, all three companies appear to have discharged sewage on July 19th, the hottest day ever recorded, with temperatures topping 40 degrees C in some parts of the country.


Although all nine water companies in England were sent environmental information data requests by the investigatory team, only Thames, Southern and Wessex sent in details relating to when spills started and stopped.


It’s likely that fewer spills were recorded by Thames water last year because it only monitors 62 per cent of its overflow points, in comparison to Wessex Water (91 per cent) and Southern Water (98 per cent).


The other six firms said that they were unable to provide the requested information because they are already under investigation for potential illegal dry spills by regulator Ofwat and the Environment Agency.


Why is this happening?


Environmental barrister and water industry expert Nicholas Ostrowski explained that there are three main reasons why dry spilling incidents may take place… maintenance problems, insufficient hydraulic capacity where there isn’t enough room for water to go through the pipes and deliberate releases of effluent during dry weather.


Any and all illegal spills should be looked into by the Environment Agency, with enforcement action ranging from warnings to unlimited fines. Last year, 115 cases of illegal spills were recorded by the agency, which is less than a third of what the BBC investigation has found


John Leyland, chief executive of the agency, told the news source: “The funding for the Environment Agency is a matter of public record … and we’ve seen a steady decline in some of our funds and so we’ve had to change.


“We’ve been focusing on digital monitoring, but earlier this year we announced a programme of increased investments in real people on your riverbank. We are committed to increasing our regulatory presence to hold the water companies to account.”


What is the impact of sewage pollution?


Sewage pollution, regardless of whether the discharge is legal or if it is a dry spill incident, can have a devastating impact on nature and the environment, as well as posing serious risks to human health.


One consequence for waterways is the development of algal blooms, which take place when large amounts of nutrients like nitrogen and phosphorous (found in sewage) enter the water. This has a big impact on the ecosystem, blocking out light required for photosynthesis, reducing oxygen in the water and killing aquatic life.


The overall biodiversity of waterways is also affected because while algal blooms may negatively affect some species, they can actually help support other groups, which can have a long-lasting effect.


Chemicals have also been found to cause physiological changes in fish… and once sewage has been released into the water, there isn’t much that can be done to prevent the impact this will have.


However, it is possible that waterways and ecosystems can recover, depending on what kind of spill it is. Chronic pollution, for example, can make recovery impossible, which can lead to the eradication of certain species in some locations.


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