The Rivers Trust

Sep 12, 2023

Hundreds of thousands of raw sewage discharges were recorded last year. These maps show where these were and what the impact is Last modified on Tue 12 Sep 2023 09.29 EDT More than 384,000 discharges of raw sewage were reported by water companies across England and Wales in 2022, official figures show, in what the Rivers Trust has described as “extremely bad news for environmental and human health”. However, the true scale may be even greater, as a new legal challenge has claimed. Meanwhile, another set of water firms are under investigation by the regulator Ofwat and the Environment Agency for alleged illegal dumping of sewage from treatment works, and an independent watchdog is now saying that the government and even the regulators themselves may have broken the law by letting firms discharge raw sewage more often than law allows. As the inquiry continues, exclusive data seen by the Guardian reveals how one company, Thames Water , appears to be dumping raw sewage outside the permitted conditions at two of its sites. Dumping outside these conditions – for example, in dry weather – is a breach of the regulations and the discharges are considered to be illegal. The charts and maps below show how much recorded sewage has been released in English and Welsh rivers in the past year, what the impact of this is and whether dumps at four sites in England met legal requirements. The vast majority of sewerage services in England and Wales are provided by 11 large water companies. Six of those companies now face a class action legal claim alleging that they have failed to reveal the true scale of raw sewage discharges. A spokesperson for Water UK, the industry body, has described the claim as “entirely without merit”. More than 384,000 raw sewage discharges were reported by water companies across England and Wales in 2022, adding up to 2.3m hours of spilling. In the vast majority of these cases, including the ones highlighted here, we do not have the data to analyse whether any specific discharge was legal or illegal. The lawsuit alleges that the true number of spills is higher, with official data being skewed due to a lack of accurate reporting to the Environment Agency and Ofwat, the regulator for England and Wales. Knowing how much of what we flush down the toilet actually ends up in rivers and seas is complicated by the fact that publicly available information is scarce. Thames Water is one of the few companies that shares information on spilling events in real-time, through their storm discharge map . And the volume of raw sewage released through overflow systems, as far as this is measured, is not published for the majority of them. There have been attempts at estimating though. A recent study suggested that a sample of 30 wastewater treatment works spilled as much as 11bn litres of raw sewage in 2020. The number of discharges that breach permit regulations – and are therefore illegal – is disputed, and reliable data is not readily available. However, the Guardian has seen data on four out of more than 350 wastewater treatment works operated by Thames Water, which released the data on these selected works in response to environmental information requests. All four had previously been accused of spilling outside permitted criteria, and should not be seen as representative of Thames Water or the wider country. Those four treatment works collectively spilled 1,839 hours in 2022 — the equivalent to almost 77 days, according to public records. Mogden, close to the River Thames, also tracks the volume of raw sewage it discharges. Between early 2019 and May this year it spilled 20.6bn litres – the equivalent to roughly 8,000 Olympic pools, according to data released by Thames Water in response to an environmental information request. Importantly, those numbers cannot be extrapolated to the rest of the country, as it serves about 2.1 million people and is many times larger than most treatment works. When spills occur at Mogden, untreated sewage is piped to a discharge point that feeds directly into the River Thames. Combined sewer overflows (CSOs) were designed as a release valve to be used during periods of “unusually heavy rainfall”, to prevent excess water from backing up into the system. Environmental permits specify the conditions that water companies must meet to be allowed to spill raw sewage through these CSOs. One of these conditions is known as the “overflow setting”, which specifies a minimum volume to pass through full treatment while a CSO is in use. Failing to treat the required amount of sewage is known as “early spilling”. Our analysis suggests that last year, the majority of raw sewage discharges at Mogden and Oxford works fell into this category. No evidence of early spilling was found at the other two works last year. Analysis suggests Mogden and Oxford works did not treat the legally required amount of sewage during most spills in 2022 Volume of treated sewage during spills AllowedNot allowed Loading... Guardian graphic. Source: Guardian analysis of data released by Thames Water in response to environmental information requests Violating permit conditions can carry hefty fines when prosecuted. Anglian Water was recently fined £2.65m after releasing 7.5m litres of untreated sewage into the North Sea. The impact on rivers in England and Wales Agriculture and rural land management is the biggest single contributor to river pollution in England, according to figures from the Environment Agency, as excess nutrients from fields and livestock end up in the water. But the water industry, with discharges of both treated and untreated sewage, is a close second. The most recent ratings for England and Wales, from 2019 and 2021 respectively, show that rivers are in poor chemical and ecological state. Only 15% of rivers in England achieved good ecological status in 2019, down from 23% in 2009. In Wales, things are a little better, with 45% of rivers achieving good ecological status in 2021. This was an improvement from 2009, when only 27% made the mark. A spokesperson for the Rivers Trust said: “Spilling raw sewage into rivers is extremely bad news for environmental and human health, sending all sorts of unpleasant substances into waterways that shouldn’t be there. As well as bacteria, such as E coli, anything that goes down the drain in our combined sewer system, could end up in rivers, so that includes excess nutrients like nitrogen and phosphorus, forever chemicals commonly found in household items, and microplastic particles, which are now ubiquitous in our environment. “If these discharges are happening when minimum volumes at treatment works are not being met, or when river levels are low, these pollutants will be even more concentrated in the water, allowing algae to proliferate and meaning plant and animal life won’t have enough oxygen to survive. The current situation is absolutely unacceptable and will get even worse if investment doesn’t go into our grey and green-blue infrastructure.” Grey infrastructure refers to human-made structures such as dams, pipes and water treatment plants. Green-blue infrastructure is a network of natural and semi-natural features designed to deliver societal benefits, such as flood protection and climate regulation. A Thames Water spokesperson said: “Thames Water Utilities Limited is aware of a claim threatened by Prof Carolyn Roberts. Thames Water Utilities Limited has engaged cooperatively with Prof Roberts to explain that the threatened claim is without merit and no claim has yet been issued against Thames. “We believe it is unacceptable for untreated sewage to enter rivers and we take this matter very seriously. We’ve published an action plan to radically improve our position in order to protect and improve the environment. “We’ve recently published plans to upgrade over 250 of our sewage treatment works and sites and we have planned substantial investment in our local sewage treatment works to reduce the need for untreated discharges, including South Leigh, Stanton Harcourt and Oxford. We have also started the £100m upgrade of our Mogden sewage treatment works. “Addressing discharges will take time and sustained investment, however each step we take on this journey is a move in the right direction.” A United Utilities spokesperson said of the lawsuit and the wider issue of spilling: “With the largest combined sewer network in the UK and highest levels of rainfall, we are planning the biggest programme of storm overflow reduction in the country. By 2030 we will have invested £3bn to tackle the issue, with more to follow.” A spokesperson for Dŵr Cymru (Welsh Water), who reiterated that the company was not part of the legal action, said: “We absolutely understand and accept public concern about any sewage pollution impacting our rivers and so improving river water quality is our absolute priority. “The total removal of storm overflows from our system is currently unaffordable and would take decades but what is in our control is the ability to target investment to storm overflows which have the biggest impact on river water quality so that we can improve their performance. That is why we are investing significantly to improve storm overflows, with £140m being invested between 2020-25 with a further £420m planned from 2025 to 2030. “We have been working in the river catchment at Pontyrhyl and Llangeinor and have discovered points where river water is finding its way into the sewer. Work is ongoing to remove this, which will have a material effect on spill numbers. “Many different factors contribute to river and sea water quality – of which wastewater is one element. We have a strong environmental record and have invested heavily to improve water quality in both our rivers and seas. This has delivered real improvements and helped ensure that 44% of our rivers meet good ecological status compared to 14% in England, and that Wales has over a third of the UK’s Blue Flag beaches while only having 15% of the coastline.” On the lawsuit and the wider issue of spilling, a Yorkshire Water spokesperson said: “We are aware of an alleged claim being pursued by Leigh Day solicitors. Given the nature of the proposed proceedings, it would be inappropriate for us to comment any further.” In response to the class action legal claim, a Severn Trent spokesperson said: “This is a highly speculative claim with no merit which we strongly refute. Should pollutions ever occur, they are always reported to the Environment Agency . Any claim to the contrary is wholly and completely wrong. “Our regulators, the Environment Agency and Ofwat, set strict targets and performance measures that deliver for our customers and the environment. Severn Trent is recognised as a sector leader by both regulators across operational and environmental measures. We consistently deliver for our customers, and recently received the highest 4* status for environmental performance from the Environment Agency for the fourth year running.” Anglian Water and Northumbrian Water were approached for comment but declined to make a statement. Methodology Data on the total spilling duration of different treatment works was compiled by the Rivers Trust . Figures for England were sourced from the Environment Agency , and data for Wales was provided by Dŵr Cymru. Data on the four wastewater treatment works in the Thames River basin was sourced from environmental information regulation requests. These are four selected treatment works out of more than 350 operated by Thames Water. All four had previously been accused of spilling outside permitted criteria, and are by no means a representative sample of all wastewater treatments works. Data on the ecological status of rivers was sourced from the Environment Agency for England and Natural Resources Wales for Wales. Note that ecological status is not the same as overall water quality. We use ecological status as a proxy for water quality because overall water quality cannot be directly compared between England and Wales. The overall quality is determined by combining a water body’s ecological and chemical status. Explore more on these topics