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Exe Estuary Management Partnership

For people, for wildlife, for the future

Water Quality: The Sewage Issue


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Water Quality: The Sewage Issue

Current Situation

While not the primary source of water pollution (Fig.1), sewage entering the estuary via Combined Sewer Overflows (CSOs) affects water quality and has been high on the agenda for various stakeholders who use the water for different purposes and are concerned about its state.

Figure 1: Major pressures that cause water bodies to fail to achieve good ecological status. Source: 25 Year Annual Environment Plan Annual Progress Report.

In its annual reports on progress against the targets set in the 25 Year Environment Plan, DEFRA identifies the major pressures that cause water bodies to fail to achieve good ecological status. The most recent progress report indicates that after the physical modification of rivers (a factor unavoidable in many urban environments), the main three drivers preventing water bodies achieving good status are agricultural pollution from rural areas (40%), sewage and wastewater (36%), and run-off from towns, cities, and transport, referred to as urban diffuse pollution (18%).

On the Exe, CSOs have been a topic of concern for various user groups and bought to the Exe Estuary Management Partnership (EEMP) as an issue to address. This has often been in the form of reported specific incidents of raw sewage entering the estuary. As such, it is important to understand that the EEMP does not hold a regulatory role and can only facilitate sharing information and holding regulatory bodies accountable.

The purpose of this section of the State of the Exe Estuary, therefore, is to:

  1. Explain the current situation, with a focus on the Exe Estuary, as well as signpost to relevant data sources.
  2. Introduce relevant bodies and organisations which are working to monitor, regulate, and improve water quality.
  3. Recommend ways in which members of the public can get involved in citizen science projects and other activities aimed at testing and bettering the condition of water bodies.

Combined Sewer Overflows (CSOs): Explained

The UK has a combined sewage system made up of thousands of kilometres of sewers built by Victorians. Clean rainwater and wastewater are conveyed in the same pipe to a sewage treatment works. During heavy rainfall pipe capacity often exceeds the possible inundation of sewage works and the potential to back up and flood. CSOs were developed as overflow valves to reduce the risk of sewage backing up during heavy rainfall. An overflow of diluted sewage during heavy rain is NOT a sign that the system is faulty. CSOs are a necessary part of the existing sewage system and prevent sewage from flooding our homes and businesses. You can read more about CSOs and recent headline figures on the government website.

Figure 2: During large storms, stormwater is combined with sewage in the same pipe, and the increased volume overflows straight into nearby waters. Source: ECOSS Combined Sewer Overflows.

Government Plan for Sewage Outflows

In September 2023, the UK Government expanded their previous Storm Overflows Discharge Reduction Plan document and published an updated version to include all coastal and estuarine sites. The revised version of the document states that Marine Protected Areas (MPAs) and shellfish water protected areas will be made a priority in terms of reducing sewage outflows. It also outlines a plan to drive a £60 billion capital investment over next 25 years, making it the biggest infrastructure programme in water company history.

The Plan additions mean that MPAs, shellfish, and bathing waters will be added to ‘high priority sites’, alongside Sites of Special Scientific Interest (SSSI) and bathing waters. The newly updated document is part of wider Plan for Water, which lays out the government’s strategy to hold water companies accountable and to manage the multiple pressures on our water resources through increased investment, stronger regulation, and tougher enforcement. As part of robust government action, the targets set out in the new Plan will apply to every storm overflow in England, representing an increase from 91% to 100% coverage. The targets include requirements for water companies to:

  • Improve 100% of storm overflows discharging into or near every designated bathing water; and improve 75% of overflows discharging to high priority sites by 2023.
  • Improve all remaining storm overflows, regardless of location, by 2050.

Environment Act 2021

The government’s Storm Overflows Discharge Reduction Plan aligns with the Environment Act 2021, in which the government placed a legally binding duty on water companies to progressively reduce the adverse impacts of discharges from storm overflows. Under the Environment Act, the government set out the following policies:

  • There are event duration monitors on over 90% of the sewerage network. By the end of 2023, there will be 100% coverage. This will provide a complete picture of when, and for how long, each storm overflow operates. The Environment Act 2021 introduced new requirements for water companies to publish this information annually, and for the Environment Agency to publish an annual summary report for all the water companies in England. All water companies must provide data about the frequency and duration of storm overflow discharges for all storm overflows in near real time and make this available to the public no later than 2025.
  • Under section 82 of the Environment Act 2021, water companies must monitor the water quality impact of their assets that discharge sewage, including storm overflows and continuous discharges from wastewater treatment works. This will provide continuous data and will significantly increase our understanding of the water quality of our rivers. This information will allow us to measure water companies’ progress to achieve the targets detailed in this Plan and other objectives. This duty shall apply to inland watercourses.
  • The scope of the statutory duty under section 82 of the Environment Act 2021 is limited to watercourses through which water flows. We appreciate that there will be increased interest in monitoring storm overflows that discharge to other water bodies such as lakes, groundwater and coasts, and the impacts they have on ecology and public health. However, these sites present unique monitoring difficulties, including the failure of sensors due to salinity of coastal waters and the difference in parameters for good water quality for different types of water body. We will work with the Environment Agency and the water industry to pilot approaches and encourage water companies to bring forward monitoring at complex sites where it is clear they have consumer support to do so to improve transparency of all storm overflow operations.
  • The government will consider what further steps can be taken to improve the timeliness and usefulness of information that the public are given about bathing water quality, including through the monitoring measures in the Environment Act. Bathers are currently informed of the water quality through signs which display the annual classification of a bathing water, alongside other information. The Environment Agency also issue daily pollution risk forecasts during the bathing season at over 170 bathing waters. We will consider what further steps we can take so the public can make informed choices before they enter the water.
  • In addition to adding Shellfish Water Protected Areas to the list of high priority areas, special consideration is given to areas of shellfish production to support shellfish life and to contribute to the high quality of shellfish products suitable for human consumption. The government has designated 101 Shellfish Water Protected Areas in England where water quality is monitored for harmful bacteria and action taken to meet the strict microbial standard. The government and the Environment Agency have identified waters which can achieve compliance with the microbial standard by 2030, and where there is significant economic production of shellfish and where action is needed to prevent deterioration. The Environment Agency will require water companies to explore the need for action (improvement, prevention of deterioration or investigation) at 63 shellfish waters (63%) between 2025-2030. This will lead to reductions in sewage discharges from storm overflows and disinfection of treated sewage.

South West Water is the relevant water company for the Exe Estuary area. In terms of their 2025 commitments, they are committed to reducing discharges to an average of 20 per year. For their river quality commitments, they have promised a 100% coastal bathing water compliance and one third reduction in impact on rivers by 2025. By 2030, all storm overflows at beaches and 50% overflows which are environmentally sensitive on rivers will be in line with new targets. 100% of overflows should be in line with new targets by 2040.

Figure 3: 100 selected CSOs located around the Exe estuary.

The map above illustrates 100 CSOs located around the Exe estuary. The location data were extracted from the Catchment Based Approach (CaBa) dataset. The Event Duration Monitoring (EDM) data presented below, adds context to this information.

Event Duration Monitoring (EDM)

South West Water (SWW) have now installed EDMs on 100% of their storm overflows. EDM data provides valuable information that helps SWW to understand sewer performance and helps the Environment Agency (EA) ensure that sewerage systems are compliant. EDM data also helps to improve the transparency of sewerage network performance for SWW customers and stakeholders.

Summary reports are consistently produced by SWW and provided to the EA on an annual basis (and seasonally for Bathing Waters) with the date/time duration of each overflow. All overflows are included in the annual return which covers the period 1 January 2022 to 31 December 2022 inclusive. These data were submitted at the end of February 2023. Overflows which have a potential impact on Bathing Waters also have a seasonal return each year covering the period 1 May to 30 September inclusive. These data are submitted by 31 October. The data from this return can be used to help determine Bathing Water classifications. For Shellfish Waters, the annual written report is sent to the Local Food Authority (LFA) and the Environmental Health Officer (EHO). In some cases, notifications of overflows affecting Shellfish Waters are required and made to the LFA, EHO and EA within 24 hours to help protect shellfish quality.

The entire SWW 2022 EDM Return dataset is publicly available and can be downloaded from the CaBa website. Overall, the average number and duration of spills for SWW CSOs was down in 2022 from 2021 numbers (Fig.4). However, a key reason for this may have been a dryer-than-average year.

Figure 4: South West Water 2022 EDM Return Data. Source: Event Duration Monitoring Annual Report 2022

From the 2022 EDM Return Data, we selected for the 100 CSOs located around the Exe estuary (Fig. 5).

Figure 5: 2022 EDM data for 100 CSOs located around the Exe estuary.

The data illustrates that the 98 CSOs (for which data was available) spilled 1621 times amounting to a total of 9,017 hours and equalling 375.7 days. The data also showed that, on average, 91% of the EDMs were operational. The top worst 10% of sites are listed above along with their total duration of spills in hours. The data showed that the spills affect Exe Shellfish Waters and Exmouth Beach Bathing Waters.

WaterFit Live

As Bathing Waters at beaches are so crucial for everyone in the South West, SWW has now introduced a WaterFit Live map designed to share information about the region’s bathing beaches, location and performance of storm overflows, and SWW’s plans to improve water quality.

The interactive map allows users to see if any storm overflows have been operating at local beaches to the extent that they may have temporarily affected bathing water.

Users are able to insert a place name into a search bar and click on a coloured pin (Fig. 6) to check Bathing Water status. The pin colours change according to the data SWW receives, detailed local knowledge of the bathing water environment, and how storm overflows may affect them.

Figure 6: Pin colours and their meaning for the SWW WaterFit Live Map.

Organisations working to regulate, monitor, and improve water quality

Regulating the water industry

Environment Agency

Within England, the Environment Agency (EA) is responsible for issuing permits and regulating all discharges from storm overflows. This is done by issuing permits for individual storm overflows that outline when they can operate and under what circumstances, as well as how they should be monitored and maintained.

The EA focusses regulatory and enforcement action:

  • On activities that cause the greatest risk of serious environmental damage;
  • Where the risks are least well controlled;
  • Where a breach undermines a regulatory framework; and
  • Where they suspect deliberate or organised offending.

The additional information on storm overflow discharges from the new monitoring and reporting requirements will improve the ability of the EA to enforce unlawful storm overflow discharges and permit breaches.

The EA has a range of enforcement actions it can apply when permits are breached. The EA can also persecute a water company in line with its Enforcement & Sanctions Policy. In deciding how to take enforcement decisions, the EA considers the facts and circumstances, testing the evidence against the interests of the public. The EA acts proportionally when they apply the law and will take account of, and balance, impacts on the environment, people, and business.


Ofwat is the independent economic regulator for the water and sewerage companies in England and Wales. Ofwat is responsible for making sure that the regulated companies provide consumers with a resilient and efficient service at a fair price. To support these actions, Ofwat will:

  • Challenge, support and enable water companies to meet the targets set out in the Defra Storm Overflow Reduction Plan;
  • Enable investment to follow investigations as quickly as possible without waiting for the next 5-yearly water company planning cycle;
  • Incentivise companies to meet these targets as quickly as possible and go beyond these targets if this is supported by customers, provides best value and is affordable;
  • Challenges companies to meet their public commitments;
  • Actively support companies in the use of green infrastructure where it is the most appropriate and best value approach.

Ofwat has a range of enforcement powers that it can use to ensure companies comply with their statutory obligations to provide and maintain a sewer system in relation to storm overflows. These include enforcement orders to ensure water companies take all appropriate steps to ensure compliance. Ofwat can also impose financial penalties on water companies to a maximum of 10% of their turnover (in a relevant year) if they are in breach of their relevant statutory duties or license conditions. All financial penalties are borne by shareholders rather than customers. The new monitoring and reporting framework will support Ofwat’s ability to decide when to take enforcement action as it will be very clear to all when storm overflow discharges exceed legal limits.

Providing water

South West Water

South West Water provides water and sewerage services to Devon, Cornwall, and part of Somerset and Dorset.

Ofwat and the EA monitor water companies’ performance against a range of metrics and rate them annually. As part of the price review process Ofwat and water companies agree a set of performance commitments. Ofwat monitors the industry and publishes annual reports summarising water companies’ progress against the commitments. Its most recent report, the Water Company Performance Report 2022-23, was published in September 2023.

In 2021-2022, South West Water was given the lowest of three ratings – ‘lagging behind’ – alongside five other companies. Ofwat concluded that it was performing below its commitment level in five of the twelve categories:

  • Customer satisfaction;
  • Number and duration of interruptions to water supply;
  • Water quality;
  • Pollution incidents;
  • Treatment work compliance.

It performed at or above its commitments for other metrics, including reducing leakage and mains asset repairs.

Ofwat says that it will require underperforming companies to present action plans setting out how they will improve performance.

South West Water published its action plan in March 2023. Ofwat have deemed SWW to have moved out from the ‘lagging behind’ category this year but expect any improvements to be sustained over time.

Companies that miss their performance targets can face financial penalties, which are taken off customers’ bills (customers pay less) in the following financial year. This is intended to compensate customers for lower-than-expected service levels. Conversely, companies that outperform expectations can charge more. Based on its overall performance in 2022-23, SWW will be required to reduce bills by a total of £11.8 million in 2024-25 (Fig.7).

Figure 7: Total final determination adjustments. Source: Sector-overview-Final-determinations-of-in-period-outcome-delivery-incentives-for-2022-23.pdf

The EA compares performance between water companies through its Environmental Performance Assessment. It looks at performance across six metrics, including pollution incidents and delivery of the Water Industry National Environment Programme (WINEP), and assigns each company an overall rating out of four stars. The Environmental Performance Report 2022 was published in July 2023.

SWW was given the lowest rating, two stars. This is up from one star in 2021.

Ofwat announced in June 2022, as part of the investigation into sewage discharges from wastewater treatment works, it had opened an enforcement case against SWW.

Campaigning for better water quality

Surfers Against Sewage (SAS)

Surfers Against Sewage is one of the UK’s most successful marine conservation and campaigning charities. SAS is made up of water lovers who protect the ocean and all it makes possible. Through their multiple campaigns and education programmes, SAS is building a caring community, passionate about the ocean.

Surfers Against Sewage began 30 years ago as a response from the surfing community to the shocking state of our coastline. Back then, anyone who ventured into the water often found themselves swimming in raw sewage.

What had started as a local uprising in now a vital community of nationwide Ocean Activists fighting to see a thriving ocean. SAS’s numbers are now way beyond just surfers, from swimmers to beachgoers, dog walkers, and everyone who cares about the coastline.

Apart from an environmental focus, SAS also concerns itself with the human health impacts of spending time in sewage-ridden waters, weather surfing, swimming, or carrying out any other water sports and activities. Sewage pollution puts water users at risk of contracting dangerous illnesses including viruses and antimicrobial resistant bacteria. A report by the European Centre for Environment and Human Health (ECEHH) highlighted that sea bathers in the UK are just as likely to become ill from seawater as they were in the 1990s. Poor water quality also prevents individuals enjoying the mental and physical wellbeing benefits associated from engagement with the ocean environment.

SAS is calling to end sewage pollution to guarantee safe seas and rivers. The charity challenges the Government and water companies to end sewage pollution in rivers and the ocean. SAS also provide the only national real-time water quality service that protects all water users from pollution.

During the 2022 bathing season alone, SAS issues over 2,000 sewage discharge notifications for designated bathing waters through the Safer Seas & Rivers Service.

The Safer Seas & Rivers Service (SSRS) app is available for everyone to download for everyone for Apple or Android. The app makes it easy for water users to search out a swim, surf or sail spot, and be served the latest pollution forecast compiled from the Environment Agency, Natural Resources Wales (NRW) and Scottish Environment Protection Agency (SEPA) for 200 locations across the UK. The app also allows you to check rivers and streams, alert your local MP to pollution in your area, and report an illness by filling out a health report.

Each year, SAS also publish a Water Quality Report, the 2023 report is available now. This year’s report delves into water quality issues across all four of the UK’s nations.

You can join SAS Campaigns, help them fundraise and sign up to their newsletter and mailing list to get the latest information and help end sewage pollution.

West Country Rivers Trust (WRT)

West Country Rivers Trust is on a mission to improve water quality in rivers. Along their partners: South West Water, Devon Wildlife Trust, Cornwall Wildlife Trust and Exmoor National Park Authority, West Country Rivers Trust is working to improve water quality in rivers for the Upstream Thinking project. The project initially ran between 2010 and 2015, and, after proving successful, underwent a second phase from 2015 to 2020. You can read SWW’s final review of UST2 and the results of the 2019 survey.

Currently, WRT run a very successful citizen science scheme – the Westcountry Citizen Science Investigators (CSI) programme which equips members of the public with tools to detect signs of healthy or unhealthy rivers and streams. CSI members can send the WRT team observations, photos, wildlife sightings and evidence of pollution that helps build a picture of what is going on in our rivers and helps focus action.

End Sewage Convoys and Poollution Exmouth (ESCAPE)

ESCAPE was established to tackle the importation of sewage sludge by tanker into Exmouth and to reduce the dumping of untreated sewage into the Exe estuary and coastal waters. The group’s activity is primarily focussed on the local area covering the estuary and coastal region in and around Exmouth, but ESCAPE have also taken a wider view across the country looking to understand the impact the whole wastewater treatment system has on our rivers and seas. Their strategy is to use a range of tools to engage and hold those responsible for pollution and damage to account and to provide information to water users or anyone interested in protecting our special and sensitive environment.

ESCAPE’S Facebook group was created in October 2022 and its membership rose from 200 to 700 from December 2022 to December 2023. Over the year, they have created a large body of content, guides to specific issues related to their campaign and generated over a thousand posts. Through regular lobbying, monitoring of spills and activity they have established direct links with South West Water in order to raise Exmouth-specific issues resulting in increased activity and better communications ahead of planned maintenance and upgrade activity. ESCAPE’s campaign has also extended to holding regulators and policy makers to account by representing the views and experiences of water users and customers as plans for the next five years are drawn up and considered.

To get involved, you can become a member of the ESCAPE Facebook group and read more about their 2023 achievements in their end of year report.

Friends of the River Exe (FORE)

Friends of the River Exe acts as a voice for the river, bringing together grass roots organisations and people who live, work, and play along the Exe and its tributaries – to protect, restore and celebrate it.

FORE was launched in 2023 in response to the anger about the state of the River Exe with a Transition Network Seedfunding grant which bought together the River Exe Transition Partnership (Sustainable Tiverton, Transition Exeter and Transition Exmouth).

FORE work in partnership with WRT on citizen science, and with Sea-Changers on an Oral History project to record memories of the Exe in partnership with Tiverton Museum.

FORE are informed by ESCAPE and inspired by other friends groups across the UK. FORE volunteers organise a wide variety of activities including citizen science to help bring community evidence to polluters. They also ran a Festival of the Exe in September 2023 to celebrate all the activities happening along the Exe. You can get involved with FORE and partner activities by signing up for updates and visiting their website.

  1. How YOU can get involved and help

There are actions we can all take to make a difference and help improve water quality. Through small changes, we can reduce the amount of rainwater entering the sewers and make sure they can flow freely. According to the Storm Overflow Discharge Reduction Plan, all members of the public can play a part through:

  1. Using permeable surfaces and alternatives for drainage

Construction of impermeable surfaces like patios or plastic grass in our gardens concentrates rainwater in the drainage system and prevents its natural drainage. Using permeable surfaces, such as grass, and alternatives for drainage, such as soakaways and rain gardens, helps to reduce the problem. Permeable surfaces can prevent sewage systems from being overwhelmed and help to protect homes and business from flooding.

  1. Good use of drains

Misuse of drains and sewers by disposing of fats, oils, greases, wet wipes and nappies down sinks and toilets can cause pollution and flooding as they can build up in sewer networks and limit or even block the flow in the pipes. Water UK research has identified that wet wipes flushed down the toilet are a frequent cause of sewer blockages. Wet wipes, mostly comprising baby wipes, make up 93% of the material that causes sewer blockages, which cost the water industry in England and Wales £100 million a year to fix.

  1. Reducing use of wet wipes

The government are currently exploring options to address the issues caused by wet wipes and ensure that consumers dispose of them appropriately. In November 2021, the Government launched a call for evidence on commonly littered and problematic plastic items which explored future policy action on wet wipes. A summary of responses to this call for evidence will be published in due course. The Government is now undertaking a research project on wet wipes to better inform future policy proposals, including the scope of any potential ban. The research project will consider the effect of wet wipes on the sewage system, whilst also considering the effects of plastic pollution from them. The outcomes of the project will be published and inform next steps.

West Country Rivers Trust have also got a campaign to help everyone improve water quality. Apart from signing up to become a Westcountry CSI, you can:

  • Not put fats and oils down your sink – pouring excess fats down the sink can lead to blocked sewers and subsequent pollution of our rivers and beaches.
  • Check your septic tank – If a septic tank hasn’t been emptied frequently enough, it can overflow during high rainfall and cause sewage to leak out into the river. Find out more!
  • Only 3 Ps down the loo – Poo, pee and paper.
  • Reuse water – Whether it’s a little water left in the bottom of a glass or leftover water from your soak in the bath, letting it slip into the plughole is not your only option. Why not use this water to water your house plants or in the garden?
  • Food waste – We’ve all been there, watching a cluster of leftover food disappear down the plughole. Sadly, the decomposition of this organic matter in our rivers uses up the oxygen and so impacts ecosystems. Put it in the compost or use your brown bins instead.

Below is a list of all the campaigns/groups/citizen science and volunteer schemes that you can get involved with to help tackle the sewage issue and help improve water quality:

If you spot a sewage outflow, this must be reported to the Environment Agency through their hotline 0800 807060. They will likely ask you a few questions including location and extent and notify South West Water, as well as The District Council.

You can also file a complaint to your local MP.