UK Health Officials Warn Against Swimming at 12 of 14 River Bathing Sites

In May 2026, the UK government designated 13 new bathing sites across England, including the first-ever on the River Thames in London, bringing the total number of monitored bathing waters to over 460 [1]. The announcement arrived alongside a fact that undermines its celebratory framing: 12 of England's 14 existing river bathing sites carry "don't swim" warnings after being rated "poor" for water quality by the Environment Agency [2]. Signs advising people to stay out of the water have been installed at these locations after tests found bacteria linked to human and animal faeces at levels exceeding safe thresholds [3].

Only two river sites — the River Stour in Suffolk and a stretch of the River Thames in Oxfordshire — met acceptable standards [3]. The remaining 12 were contaminated by a combination of sewage discharges, agricultural runoff, urban drainage, and misconnected plumbing [4].

Source: Environment Agency

Data as of Nov 25, 2025CSV

What the Tests Measure — and What They Miss

England's bathing water classification system uses two bacterial indicators: Escherichia coli (E. coli) and intestinal enterococci (IE), both markers of faecal contamination [5]. The Environment Agency takes up to 20 water samples at each designated site during the May-to-September bathing season [5].

For inland waters, the thresholds inherited from the EU Bathing Water Directive (2006/7/EC) — which England adopted into domestic law post-Brexit — set the boundary between "sufficient" and "poor" at 900 colony-forming units (CFU) per 100ml for E. coli and 330 CFU/100ml for intestinal enterococci, measured at the 90th percentile [6]. The "excellent" classification requires readings below 500 CFU/100ml for E. coli and 200 CFU/100ml for enterococci at the 95th percentile [6]. Classifications are based on four years of sampling data [5].

But independent scientists argue this testing regime captures only part of the picture. A 2024 University of York study, conducted in partnership with Surfers Against Sewage and Watershed Investigations, sampled 23 river and lake bathing sites across the UK and tested for approximately 100 chemical pollutants [7]. Chemical contaminants were detected at every site. The River Nidd at Knaresborough and Sheep's Green on the River Cam in Cambridge recorded the highest numbers, with 48 of the 100 monitored chemicals present [7]. Five substances — caffeine, nicotine, metformin (a diabetes medication), metconazole (a pesticide), and lincomycin (an antibiotic) — were found at all 23 sites [7].

PFOA, a banned "forever chemical" associated with cancer and immune system disruption, appeared in 95% of samples [7]. Antimicrobial resistance genes — including genes coding for resistance to last-resort antibiotics — were detected at 22 of the 23 sites [7]. None of these contaminants are captured by the official pass/fail criteria.

"Bathing waters across the UK are awash with pharmaceuticals, pesticides, industrial chemicals, harmful bacteria and genes that can create superbugs resistant to antibiotics," the York researchers concluded [7]. Contact with contaminated natural waters can cause ear infections, skin rashes, respiratory illness, diarrhoea, and stomach cramps [8].

The River Wharfe: A Case Study in Persistent Failure

The River Wharfe at Ilkley in Yorkshire, England's first inland bathing water when it was designated in 2020, has been classified as "poor" in each of the three seasons since its designation [9]. It was one of three sites to receive five consecutive poor classifications by 2025, alongside the coastal sites Tynemouth Cullercoats and Weston Main [10].

Yorkshire Water, which holds the discharge permits for wastewater treatment works upstream of the Ilkley site, pumped sewage into bathing waters for almost 8,000 hours during the 2025 bathing season [11]. The company has been named alongside Thames Water and Southern Water as responsible for 81% of serious pollution incidents in recent Environment Agency performance assessments [12].

The Wolvercote Mill Stream in Oxford, another river bathing site, has also been classified as poor. The Environment Agency investigated bacterial sources at the site from June 2022 to 2024, finding sewage pollution — particularly from storm overflows — as a significant contributor [13].

Storm Overflows: 3.6 Million Hours of Untreated Sewage

The scale of sewage discharge from storm overflows provides context for the river bathing failures. Storm overflows are designed as safety valves that release a mix of rainwater and sewage during heavy rainfall to prevent flooding of homes and treatment works. In practice, they have become a routine source of pollution.

In 2024, untreated sewage was discharged through storm overflows for a total of 3,614,427 hours across England — a record, exceeding 2023's total by 8,558 hours [14]. While the number of individual spill events fell 2.9% compared to 2023, the total duration of discharging rose 0.2% [14]. The average number of spills per overflow was 31.8 in 2024, down from 33.1 in 2023 [14].

Source: Environment Agency EDM Data

Data as of Mar 27, 2025CSV

The Environment Agency described these levels as "unacceptably high" and attributed them to "longstanding underinvestment and poor asset maintenance" [14]. Monitoring coverage has improved — the proportion of storm overflows fitted with event duration monitors increased from around 10% in 2015 to 100% at the end of 2023 [15] — meaning the scale of the problem is now visible, but far from resolved.

Follow the Money: Dividends, Debt, and Infrastructure

The financial structure of England's privatised water industry is central to understanding why river water quality remains poor. Since privatisation in 1989, water and sewerage companies in England and Wales have declared £52.7 billion in statutory dividends over 32 financial years, according to Ofwat data [16]. In 2022 alone, companies paid £1.4 billion in dividends, up from £540 million the previous year [17].

The industry disputes claims of underinvestment. Water UK, the trade body, states that companies have invested £236 billion since privatisation and that in every year since privatisation, investment has exceeded dividend payments [18].

Source: Ofwat / University of Greenwich

Data as of Jan 1, 2024CSV

Critics counter that this framing obscures how that investment was financed. Research from the University of Greenwich found that privatised water companies generated enough cash to cover their capital investment without taking on debt, but instead funded spending with borrowing — enabling £56 billion in dividends to flow to investors while aggregate company debt ballooned [19]. Total spending on infrastructure fell 15% to £4.8 billion between 2020 and 2021, with the decline most pronounced for wastewater and sewage networks [19].

Thames Water, Southern Water, and Yorkshire Water — companies whose operational areas encompass several of the failing river bathing sites — were flagged for the worst environmental performance in the most recent Environment Agency assessment [12].

Enforcement: Few Prosecutions, Small Fines

The Environment Agency's enforcement record against water companies has drawn scrutiny. Since 2015, the Agency has concluded 63 prosecutions against water and sewerage companies, securing fines totalling over £151 million [20]. In 2021, seven prosecutions resulted in fines of £90 million, though this figure was dominated by a small number of large cases [20]. In 2022, five prosecutions yielded combined fines of just £841,000 [20].

Notable recent cases include a £2 million fine for Severn Trent Water for raw sewage pollution of the River Trent, and a £3.3 million fine for Thames Water for polluting rivers near Gatwick Airport and killing thousands of fish [20]. In November 2023, Yorkshire Water paid £1 million to charities after polluting Hookstone Beck in Harrogate [20].

The Agency has also secured over £15 million for environmental projects through enforcement undertakings since 2014 [20]. Its largest criminal investigation to date — examining potential permit breaches at more than 2,000 wastewater treatment works across all water and sewerage companies — remains ongoing [20].

The Environment Agency has called for prison sentences and higher fines in water pollution cases [21]. But campaign groups argue existing penalties remain trivial compared to the economic benefit companies derive from non-compliance — a position reinforced by the scale of dividends paid even in years of significant environmental failure.

Europe's Laggard: How England Compares

England's 86% failure rate among river bathing sites stands in contrast to the broader European picture. In 2024, 78% of inland bathing waters across the EU were rated "excellent," according to the European Environment Agency [22]. Germany achieved 91% excellent ratings for its inland sites; France recorded approximately 75% [22].

Source: European Environment Agency

Data as of Jul 1, 2025CSV

Overall, 392 of England's 449 designated bathing sites (87%) were rated "excellent" or "good" in the 2025 classification [10]. But this headline figure is overwhelmingly driven by coastal sites. Strip out the coast and focus on rivers alone, and the picture inverts: only 2 of 14 river sites (14%) met minimum standards [2].

The Liberal Democrats described England as the "sick swimmer of Europe" in response to the data [23]. The comparison is complicated by scale: France designates hundreds of inland bathing waters; England had just 14 river sites until this month's expansion. The small sample size amplifies the failure rate, but also raises the question of why so few rivers have been designated.

The Designation Paradox

Surfers Against Sewage has called for the government to designate at least 200 inland bathing waters by 2030, arguing that designation is "one of the most effective tools for forcing water companies to reduce sewage spills" [24]. The group describes the current system as "too polluted to protect" — a dynamic in which rivers remain undesignated precisely because they would fail the standards that designation triggers [25].

The logic of the campaigners' argument: without designation, there is no legal obligation to test water quality, identify pollution sources, or invest in improvements. Designation places a statutory duty on the Environment Agency to monitor and on polluters to act. In 2024, the Environment Agency itself acknowledged that of the 34 waters designated since 2021, 19 were classified as poor, including 17 of the 27 designated that year [10]. This suggests a pattern in which newly designated sites expose pollution that was previously invisible to regulators because no testing was required.

Water UK has pushed back. "Designating an area as a bathing water before it is suitable for bathing risks confusing the public, who will rightly believe it is safe to swim there," the trade body said [3]. The industry argues that improvements should precede designation, not follow it.

Surfers Against Sewage has launched a judicial review against the Secretary of State for Environment, Food and Rural Affairs, challenging proposed reforms it says could reduce the number of designated sites and weaken public health protections [26].

Meanwhile, an estimated 7.5 million people in the UK swim outdoors in rivers, lakes, and the sea — a number that surged during the pandemic, when the Outdoor Swimming Society's membership grew by 75,000 [27]. The vast majority swim at locations that have no official monitoring or designation.

Who Bears the Health Risk

The expansion of wild swimming during and after the COVID-19 lockdowns has concentrated health risks among populations that may not have access to official water quality information. For many communities, river swimming during lockdowns offered free exercise when gyms were closed and travel was restricted [27]. One fifth of local authorities in England face a shortage of public swimming facilities, and 37% of these water-deprived areas overlap with zones of high social deprivation [28].

The 12 failing river sites are spread across England, from Yorkshire to Oxfordshire to the West Country. The River Wharfe at Ilkley, for instance, is a popular summer destination in a town where swimming has been a tradition for generations. The absence of safe river swimming options falls most heavily on communities without easy access to the coast or private leisure facilities.

Documented health effects from contact with contaminated river water include gastrointestinal illness, ear infections, skin rashes, and respiratory problems [8]. The Bureau of Investigative Journalism reported in 2022 that MRSA and antibiotic-resistant E. coli strains had been found in British rivers, including those used by swimmers [29]. Around 70% of antibiotics taken as medicines eventually reach the natural environment through excretion and disposal [7].

The Road Ahead: PR24 and the £104 Billion Question

Ofwat's 2024 Price Review (PR24), finalised in December 2024, authorises £104 billion in investment across the water sector for the period April 2025 to March 2030 — a quadrupling of new investment [30]. Of this, approximately £10 billion has been allocated specifically to tackle storm overflows, with a target of reducing spills by 44% from 2021 levels and bringing the average number of spills per overflow down to 16 per year by 2029 [30].

Whether these targets will prove sufficient to bring the 12 failing river sites to "good" or "excellent" status is uncertain. The Environment Agency has stated that identifying pollution sources at river sites typically requires more than one year of monitoring data, and implementation of improvements — from land management changes to wastewater infrastructure upgrades — "can take several years" [4].

The gap between current performance and the stated ambition is large. Storm overflows discharged for a record 3.6 million hours in 2024 [14]. Bringing that figure down by 44% would still leave over 2 million hours of untreated sewage entering waterways each year. For river bathing sites sitting close to discharge points, with multiple upstream pollution sources and limited natural dilution, meeting minimum standards will require not just fewer overflows but fundamental changes to agricultural runoff management, private drainage systems, and wastewater treatment capacity.

The government's decision to designate six more river sites in 2026 — while 12 of the existing 14 carry "don't swim" warnings — represents a bet that designation drives improvement. The evidence from the first three years of the River Wharfe's designation suggests the process is slower and more contested than campaigners had hoped. But without designation, the Environment Agency has acknowledged, the pollution simply goes unmeasured [4].

England's rivers are being used for swimming whether they are designated or not. The question is whether the regulatory framework will expand fast enough to match the reality of how millions of people already use them — or whether the current 14-site system will remain a fig leaf that exposes the problem without resolving it.