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WHY ARE HEALTHY RIVERS IMPORTANT?

Providing drinking water! In the Thames basin, 80% of the water we use comes from rivers, via reservoirs
Supporting incredible wildlife and plants (from kingfishers, otters & eels down to mayfly and watercress)
Culture and history: our local rivers are key players in literature, film and historical events (think the Wind in the Willows, William the Conqueror crossing Wallingford bridge).
Supporting tourism & recreation, which in turn supports the economy
Healthy rivers can buffer against drought and flooding, set to become more frequent with climate change.
Intangible benefits… emotional & spiritual wellbeing.

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RIVERS IN TROUBLE

The Environment Agency classified rivers across England and judges whether a river is in good health every 3 – 5 years.
England = 14% in good ecological health
Thames = 6% in good ecological health
Chemical status: 0% of rivers in England have good chemical status.
Presence of “forever chemicals” (PFAS) is the overwhelming reason for failing good chemical status.
Some of these chemicals are already banned, but take decades to degrade (if they ever do).
Over the last 30 years, many pollutants decreasing (ammonia 85%, phosphate 83%, heavy metals), some increasing (nitrate 23%)

Reference: The Rivers Trust https://theriverstrust.org/ecology-map

What are PFAS?

Per- and poly-fluoroalkyl substances (PFAS) are a class of more than 4000 manufactured chemicals that are not found naturally in the environment. There are many types of PFAS, with the best known examples being perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS). These individual chemicals are collectively referred to as PFAS in the guidance unless specifically mentioned. PFAS are persistent chemicals that do not breakdown and therefore remain in the environment. PFAS have demonstrated the potential for bioaccumulation and biomagnification (i.e. gradual increase in concentration) in humans.

Where do PFAS come from?

PFAS have been used in a wide range of consumer products, including surface treatments to non-stick cookware, solution treatments for carpets and treatment of clothing for stain resistance and water repellence. As a result of this widespread use, PFAS are commonly found in landfills and wastewater treatment plants. They also have been widely incorporated in aqueous film forming foam (AFFF) used to extinguish hydrocarbon fires. As a result, PFAS have been found to contaminate sites where there has been historic use of PFAS-containing firefighting foams. At some sites, these chemicals have migrated through subsurface environments and contaminated surface water, groundwater and adjoining land areas.

Reference: https://www.nhmrc.gov.au/sites/default/files/documents/attachments/PFAS-Guidance-for-recreational-water.pdf

Chemical pollution in 2016, 97% passed the chemical pollution tests, but upgraded methods and including more substances in 2019 meant all failed.

Since 2016, new substances have been added to the assessment list, such as PFOS, a chemical from the PFAS family, and new standards have been developed for contaminants in aquatic wildlife.

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RIVER HEALTH

For a healthy river, you need to have:
Clean water (good water quality)
Enough water (sufficient water quantity)
Places for species to live (good habitat quality)

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WATER QUALITY FOR WILDLIFE

Water quality determines the suitability of a river to support aquatic life.
Water quality is made up of many different components e.g.

pH,
dissolved oxygen,
temperature,
nutrient levels (e.g. phosphorus and nitrogen),
and the levels of many other pollutants e.g. ammonia, heavy metals, manmade chemicals

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WATER QUALITY AT WALLINGFORD

The Thames and its tributaries are split into hundreds of smaller waterbodies, which the Environment Agency test and give a rating for.
Local waterbody: “Thames Wallingford to Caversham”. Link to results.
Overall “moderate” ecological quality…
…but that is only because phosphate is “moderate”, all others “high”. NB: high means high quality, not high levels.
Phosphate originates predominantly from sewage (70%) and agriculture (30%). Too much phosphate can cause the overgrowth of algae -> algae die and decompose -> bacteria use up oxygen (eutrophication).

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BUT WHAT ABOUT PEOPLE?

Rivers in the UK, until very recently, have only been monitored & regulated for ecological health, not the health of humans using them for recreation.
This is despite over 4.1 million adults taking part in open water swimming in the past year (1.9 mil canoeing/kayaking, 1.9 mil paddleboarding, 480k rowing).
Designated bathing water status (DBWS) is the method for protecting open waters for swimming.
In England: 420+ coastal designated bathing waters…
Only 16 river locations…
Only 2 on the Thames…
Wallingford Beach is one of them! Thanks to a campaign by many people (councils, residents, Thames21)

Reference: Sport England https://activelives.sportengland.org/Result?queryId=145919

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DESIGNATED BATHING WATER STATUS

Tests for 2 types of bacteria, E. Coli and intestinal enterococci. These bacteria can be harmful to human health (e.g. stomach upset, skin infection)
20 tests in the summer “bathing season” of mid-May to end of September (approx. weekly).
Each site is given a rating at the end of the season (excellent, good, sufficient or poor).
Strict criteria: if only 1 out of 20 readings too high, whole site is “poor”.
Legal duty to improve the water quality of the site (water company, EA).
Wallingford: 2024 “Poor”
2 dates when above threshold: 8th July 2024, 10^th Sept 2024

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Bacteria at Wallingford 2023…

And so far in 2025…

Real time testing is not yet available at any bathing water… but many people are working on it! This summer, fluidion is being used alongside lab testing.

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CHEMICALS AT WALLINGFORD

“Forever chemicals” PFAS not tested at bathing waters.
Linked with health problems (hormone dysregulation, liver problems, some kinds of cancers) although research ongoing.
Australia has limits for some kinds of PFAS in recreational waters… but the UK does not.

Australia: 2µg/l sum of PFOS & PFHxS (another type of PFAS) in recreational waters.

The Rivers Trust found in 2025 that 94% of river sites tested exceeded proposed EU ecological thresholds… so Wallingford probably would too.
Many organisations calling for a ban on all PFAS manufacture, not just individual chemicals (there are 4700 different ones).
It is a serious problem, but you will be exposed to PFAS in many ways (e.g. takeaway boxes, some cosmetics) and exposure through the skin is considered minimal (currently).

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Concentrations of individual chemicals not critical for public health, but effects of chemical cocktails on wildlife and people unknown

University of York and Surfers Against Sewage – 23 rivers and lakes 7 days – July-August 2024

National Review of bathing water

High levels of AMR genes that could promote anti-biotic resistance bacteria

High levels of pharmaceuticals (e.g. paracetamol)

High levels of coliforms (including E-coli) bacteria (exceeding US standards) from STW

Results for River Thames at Wallingford beach

High levels of PFAS (chemicals that remain in the environment long-term

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TOP TIPS FOR STAYING WELL WHEN SWIMMING IN THE THAMES

Open water swimming has huge benefits to mental and physical health: boosted immune system, increased wellbeing, better sleep, community connection and more.
Poor water quality is just one of the risks of open water swimming.
Ensure you are safe and know your limits, e.g.

Know your exit point before you get in,
Don’t jump into water you haven’t checked for depth/underwater obstructions,
Know what temperature you can tolerate,
Go with somebody else, inform someone of your plan,
If you get into difficulty, float,
Wear a bright hat or take a tow float, especially if there are boats.

This isn’t an exhaustive list. For more information, read advice from the RNLI or the Royal Lifesaving Society.

https://www.swimming.org/openwater/wild-swim-project/

Swimmers who maintained their regular group wild swim sessions for six months or more reported their life satisfaction improved by 25 per cent, their happiness increased by 20 per cent, whilst their feeling of worthiness went up by 23 per cent. Significantly, their anxiety levels decreased by 18 per cent. (July 2024)

A large-scale study has found that wild swimming in lakes, rivers, or the ocean is linked to significantly higher levels of well-being compared to swimming in open-air pools.

Published in the Journal of Environmental Psychology, the study of 1,200 outdoor swimmers spanning 19 countries found that both forms of outdoor swimming were associated with improved mood and reduced stress, but wild swimming appeared to deliver a particularly significant boost to well-being.

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TOP TIPS FOR STAYING WELL WHEN SWIMMING IN THE THAMES (2)

Avoid swimming for 48 hours after heavy rainfall, or after a raw sewage release 10km upstream (use the Oxford Rivers Portal)
Check the most recent bacteria reading before you swim (again, on the Oxford Rivers Portal).
Cover any cuts or broken skin with a waterproof plaster.
Use common sense – don’t go in if it looks/smells “iffy”!
Wash your hands after swimming and before eating or drinking (take hand sanitiser with you if you can’t find fresh water.)
Dry your ears after swimming.
Again, this is not an exhaustive list. Everyone’s body and immune system is different.

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HOW CAN I HELP?

As we probably all know, pollution from sewage is a major stress on the health of the Thames
Physical modifications, pollution from roads and transport and from agriculture/rural areas are also significant.
But there are still things we can do as individuals, households and communities.

RNAGs = “reasons for not achieving good”. Source: Environment Agency.

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HOW CAN I HELP? At home

Bin it, don’t block it
Only flush the 3 P’s : poo, pee, paper.
Everything else is not flushable… Yes, not even “flushable” wet wipes! Put it in the bin.
Put cooking oils and fats in the bin, not down the sink
Get rid of hazardous waste safely
Take chemicals, solvents, engine oil and paint to the local recycling or refuse site.
Medicines and syringes should go to a local pharmacist
Waste wizard for Oxfordshire tells you where and how to recycle/dispose of waste.

Check for misconnections: this is when something that should be plumbed into a foul water drain is plumbed into a surface water drain

e.g. a washing machine outlet plumbed into surface water drain.

Buy and use eco friendly products
E.g. for laundry, dishwashing, cleaning and personal care. Aim for ones with simple, biodegradable ingredients.
Reduce spot-on flea treatments
Chemicals in spot-on flea treatments are being found in rivers, and can devastate aquatic life.
Cut down on how often you treat for fleas, and use pills over spot on treatments.

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Misconnections diagram

More information: https://www.water.org.uk/developers/plumbing-and-drainage-misconnections

(Water UK, misconnections)

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HOW CAN I HELP? Saving water

Hosepipe ban (temporary usage ban) will come into place in 22^nd July
This is because of the prolonged dry period, reservoir levels are lower than they should be. Can’t take more from the River Thames without endangering wildlife.
Please don’t use a hosepipe to:

Water gardens
Wash vehicles
Fill swimming/paddling pools or hot tubs

There are exemptions e.g. food crops. Check the Thames Water website.
Other ways to help: get a rainwater butt, cut down the number of clothes washes per week, reuse water used for washing vegetables.

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HOW CAN I HELP? Reporting pollution and sickness

If you see water pollution, report it immediately to the Environment Agency on 0800 80 70 60 or via the online form.
What should I report?

Wildlife in distress, dead fish or fish gasping for air
Oily sheen, sewage debris, bad smells or discolouration
Suspected illegal fishing or poaching
Blockages to the main river
People taking water from rivers possibly illegally.

They may not be able to attend every incident – but the more reports from an area, the more likely there will be an inspection.
You can also report pollution, leaks and blockages to Thames Water directly using their online report a problem tool.
Sickness after swimming or watersports should be reported to Surfers Against Sewage: submit a sickness report.

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SUMMARY

Healthy rivers are crucial for our health and wellbeing.
Pollution is sadly widespread in rivers nationally and in the Thames basin. We lag behind European neighbours on river health.
Although some pollutants are certainly getting worse, in recent years we have also become aware of a greater range of pollutants.
Check the Oxford Rivers Portal before going for a river swim or doing other watersports.
Take safety precautions before (e.g. planning a route) and after using the river (e.g. washing hands)
Make sure your home is water-wise
If you want to get more involved, please follow Thames21 and the Rivers Trust. Sign up to our mailing list!
Big River Watch and UK Waterblitz September 2025

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