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Very high E.coli levels discovered on Thames ahead of Henley Royal Regatta

Sir Steve Redgrave, Chair of the Committee of Management for Henley Royal Regatta. © Jim Donahue/ River Action

Water quality testing by River Action citizen scientists has revealed alarmingly high levels of E.coli bacteria from sewage pollution along the River Thames used for next week’s Henley Royal Regatta – with qualifying races today involving approximately 4,000 rowers.

With the General Election next week, River Action want urgent action from politicians on the UK’s water pollution emergency. The campaign group calls on whichever party forms the next government to adopt its five-point plan to save the UK’s rivers, including prosecuting the polluters, and properly resourcing and reforming the environmental regulators which have allowed the desecration of rivers like the Thames for more than a decade.

The regular testing on the Thames – near Fawley Meadows where the effluent from the Henley sewage treatment works enters the river – by the Henley and Marlow River Action group started on the 23rd May and continues until 7th July, the last day of the Regatta. Using a Fluidion World Health Organization verified E.Coli analyser, and results analysed by Earthwatch, the tests revealed levels of E.coli up to 25,000 CFU (colony forming units) per 100ml. This is more than 27 times higher than what the Environment Agency grades designated bathing waters as poor, the bottom of four categories.  When bathing water is graded ‘poor’ the Government’s advice is against bathing. The testing locations suggest that the source of pollution is from Thames Water discharging treated effluent containing bacteria, and untreated sewage directly into the river and its tributaries.

Safety guidelines issued by Henley Royal Regatta

As part of its ongoing commitment to ensure the safety and well-being of participants of the Henley Royal Regatta, the event organisers have included the latest ‘Guidance on rowing when water quality is poor’ to all rowers entering the competition. The guidance was written by British Rowing, River Action and The Rivers Trusts, with the aim of minimising the risk of illness due to proximity to polluted water.

Included are helpful tips on the importance of covering cuts, grazes, and blisters with waterproof dressings, taking care not to swallow river water that splashes close to the mouth, wearing suitable footwear when launching or recovering a boat, and cleaning all equipment thoroughly.

CEO of River Action James Wallace said, “It is shocking that we have had to issue health advice to the competitors of the Henley Royal Regatta. Thank goodness the organisers are showing a duty of care to the rowers by issuing guidance that will help to keep competitors safe.  Clearly, rower and river user health is a priority. We applaud them for their actions and hope everyone competing in the Regatta stays healthy. As we saw at the recent university Boat Race in London on the River Thames, there is a risk that rowers can become unwell from waterborne pathogens which not only affects their race but puts their health and sport at risk.”

Mr Wallace blamed the river pollution on Thames  Water. “The river pollution is most likely the fault of Thames Water.  On behalf of rowers and Thames communities, we demand that they stop this deluge of raw sewage, which threatens river users with serious sickness and the river’s biodiversity. This is a health emergency. The new government must get a grip of the water pollution crisis and ensure that water companies, including Thames Water, invest urgently in upgrading wastewater treatment plants and fix their leaky infrastructure before someone becomes seriously ill, or worse. 

“Rivers should come with a health warning. Citizens are doing the job of regulators and industry because there is insufficient testing – even at international sporting venues – and no duty of care shown by the Environment Agency or the Department of Health and Social Care. During this election week we urge the public to vote for clean rivers.”

Responding to the results of water quality testing on the River Thames at Henley, Sir Steve Redgrave, the most successful male rower in Olympic history and Chair of the Committee of Management for Henley Royal Regatta said, “Today’s findings provide a stark reminder of the impact that sewage pollution is having on our rivers. Henley Royal Regatta supports the research undertaken by River Action, which highlights the essential work that needs to be done to improve the cleanliness of our waterways for all to enjoy. Our rowers train daily all around the country. Our waterways are vitally important to our competitors racing, but also to all those athletes training on a daily basis nationwide. Our top priority has been, and always will be, the safeguarding of our competitors. This year, as part of the documentation provided to all entrants competing in the Regatta, everyone is being given the latest guidance from British Rowing on how to protect themselves.”

Citizen Scientist Dave Wallace from Henley and Marlow River Action Group who conducted the testing said, “The river in Henley is internationally famous and has one of the highest levels of recreational and sporting uses of any stretches on the Thames. It is so badly polluted by dangerous levels of E.coli and other pathogens primarily from sewage, as shown by our testing which can be harmful to people’s health. We need action now to clean up the river. We cannot wait!”

Naturalist and television presenter Steve Backshall said, “The continual release of pollutants into the Thames is causing havoc for wildlife and people alike. Events like Henley that have been running for 185 years are at risk, all because of inaction from failing water companies. The British public deserve better. In an election month it’s worth knowing only the Greens and Lib Dem’s are really running with fixing this public disgrace as a part of their manifestos.”

Clean rivers campaigner Feargal Sharkey said, “The Government has allowed Thames Water to accrue £15 billion in debt rather than invest in maintaining and upgrading their sewage infrastructure. This failing corporation and frequent polluter needs to be put into special administration and refinanced without a public bail out, with the new government assuring its 15 million customers they will not pay the price of decades of deregulation and profiteering.”

This General Election River Action asks all candidates to save our rivers through 5 asks:

1.    SEWAGE – Significant reform of OFWAT’s failed regulation of the water industry with increased testing, fines, and investment.

2.    AGRICULTURE – Clamping down on pollution through strengthened regulation of intensive livestock and dairy farming and increasing support for sustainable farming practices. 

3.    PUBLIC HEALTH – Ensuring the Environment Agency properly monitors our rivers and publishes transparent data and guidance about when it is safe to use rivers.

4.    WATER SCARCITY – Building more reservoirs and fixing leaks so we do not run out of water. 

5.    ENFORCEMENT – Properly funding environmental protection agencies instructing them to take firmer action against polluters including by increasing sanctions.

“As voters make up their minds on who should lead the country, we encourage everyone to consider supporting a party that takes on the water polluters and demands reform of our environmental regulators and restructuring failing water companies. Everyone should be able to enjoy our rivers and seas without risking their health,” said the CEO of River Action James Wallace.

Hustings tonight at the Henley River and Rowing Museum

Tonight at 1800, at the Henley River and Rowing Museum, a General Election hustings takes place where candidates from the constituency of Henley and Thame will provide voters with the opportunity to understand how they would address water pollution on the River Thames and how their parties will solve the crisis nationally.  Attending:

  • Caroline Newton, Conservative (confirmed)
  • Jo Robb, Greens (confirmed)
  • Nanda Manley-Browne, Labour (confirmed)
  • Freddie van Mierlo, Liberal Democrats (confirmed)

The hustings are preceded by short talks on water pollution and solutions with River Action, British Rowing, Earthwatch and citizen scientists.


For media interviews call Ian at River Action on 07377 547 362 or email

In the interests of transparency and to encourage openness about data collated on the UK’s rivers, River Action has published the findings of its water quality testing at Fawley Meadows, Henley-on-Thames. The results, verified by Earthwatch, can be found on their website here and on another site by the River Thames Water Quality Testing Group here. For ease of use, you can also download the Earthwatch report website here.

On 23rd May 2024, the Henley and Marlow River Action Group commenced regular water quality testing on the Thames used for the Henley Royal Regatta. Testing continues until 7th July, the last day of the Regatta. Test results between 23rd May and 25th June indicate a mean, from 27 tests, of 1,213 E.coli colony forming units (CFU) per 100ml of water. This excludes our highest recorded spike (19th June) so far which reached 25,000 CFU, more than 27 times the acceptable limit. This reading was verified as a “good” reading by Fluidion, but we have chosen to remove it. The second highest reading reached 8,001 on 16th June. Of the measurements taken in Fawley Meadows, 47% were above 900 cfu/100 mL; meaning that they do not meet the threshold for sufficient water quality based on DEFRA’s Inland bathing water standards. To meet bathing water quality standards, this level should be below 900 CFU per 100ml to meet the lowest water quality deemed safe for swimming. By comparison, the Environment Agency conducts between 3 and 20 water quality tests at official bathing water sites between May and September to decide the status. According to the Environment Agency, an inland water registering 900 CFU or greater is unsafe to swim. 

There will always be slight variations in the readings depending on the water quality testing lab or kit used.  In our case we have used a Fluidion World Health Organization verified E.coli analyser with the results verified by Earthwatch. This coliform incubator – the Alert One – is used by the Olympic team in France to check water quality on the River Seine. It is regarded as highly accurate and reliable and is being used increasingly across Europe and the UK.

We have conducted our testing over the last month very near the Henley sewage treatment works whose final effluent – and untreated discharges – pass Fawley Court and enter the Thames at Fawley Meadow on the Henley Mile used for the Regatta.  Thames Water test upstream of the Henley Mile at Marsh Lock and downstream at Hambledon Lock. They told us they test at those sites because they are easier to reach. We have asked them to test at the Fawley Meadows location, too.

Recordings are bound to be much higher near the sewage treatment works than 2km upstream or 5km downstream when the sewage discharge and final effluent are more dilute. We believe this is why their readings are so vastly different to ours and why, on one occasion, we recorded a reading of 8,000 and another of 25,0000 colony forming units (CFUs) per 100ml, which is more than 27 times higher than what the Environment Agency grades designated bathing waters as poor, the bottom of four categories.  When bathing water is graded ‘poor’ at 900 CFUs, the Government’s advice is against bathing. The testing locations suggest that the source of pollution is from Thames Water discharging final effluent which is not treated for bacteria and untreated sewage directly into the river and its tributaries. There is very little intensive agriculture anywhere near Henley so the likelihood of farming elevating E.coli levels is low.

There is no legal requirement to remove bacteria from treated final effluent. This is known as tertiary treatment. We have asked Thames Water to invest in tertiary treatment at Henley STW and upstream at Wargrave or anywhere else that could be endangering the water quality of Henley-on-Thames.

The E.coli bacterium is found in faeces and can survive in the environment. It can cause a range of infections including urinary tract infection, cystitis (infection of the bladder), and intestinal infection, stomach cramps, bloody diarrhoea, and vomiting. In the worst of cases, some strains of E.coli can lead to life-threatening sepsis (blood poisoning) requiring urgent medical attention.

River Action conducts citizen science on waterways to determine whether there are pathogens present harmful to the health of humans and wildlife. We are on a mission to rescue Britain’s rivers by raising awareness of the crisis facing our rivers, and the failure of Government funded environmental agencies to make water companies invest in their polluting infrastructure and to prosecute illegal business practices that cause river pollution.