SWALLOWING
Ten times the sea water
The Exeter team says surfers swallow up to ten times more sea water than sea swimmers, which makes them more exposed to bacteria that pollute it.
See the findings
WHAT THE RESEARCH FOUND
A mouthful
of the sea.
Every wipeout comes with a gulp of salt water.
Surfers and bodyboarders swallow far more sea water than swimmers, so researchers at the University of Exeter asked a simple question: does that change the bacteria in their guts? Their Beach Bums study found it might, without being a reason to stay out of the water.
10× more water swallowed than swimmers
See the findings- Surfers swallow more
- Bacteria travel in water
- Check before you paddle out
- Informed, not put off
THE SHORT ANSWER
More water in,
more bacteria too.
The study found an association, not proof of harm.
The researchers did not want to put anyone off the sea.
RESISTANCE
Three times more likely
Regular surfers and bodyboarders were three times more likely than non-surfers to carry E. coli that could grow despite cefotaxime, an important antibiotic.
See the numbers
CHECKING
Testing has a season
The Environment Agency tests bathing waters from 15 May to 30 September. Many surfers are in the water all year, outside that window.
Before you paddle out
FOUR THINGS TO CHECK
Know your water
before you go.
Bacteria in sea water come from sources such as sewage, livestock, wildlife and road drainage. These checks come from how the Environment Agency monitors and reports water quality.
Know the testing season
Bathing waters are sampled from mid-May to the end of September. Outside that season, there are no routine bathing water samples to go on.
Look for a pollution risk warning
At some beaches the Environment Agency issues daily pollution risk forecasts, and local authorities put up warning signs when risk is higher.
Be wary after heavy rain
Storm overflow spills are usually linked with heavy rain, and short-term pollution can affect water quality for up to 72 hours.
Check the beach's rating
Each designated bathing water gets a yearly rating, from Excellent to Poor, based on four years of samples. A Poor site has a sign advising against bathing.
TWO NUMBERS WORTH KNOWING
Surfers swallow more,
and most beaches pass.
One figure from the Beach Bums study,
one from England's bathing water results.
up to 10×
Sea water surfers swallow, compared with swimmers
The study asked 300 people, half of them regular UK surfers, to take swabs. Surfers were three times more likely than non-surfers to carry cefotaxime-resistant E. coli.
EXPOSURE · UNIVERSITY OF EXETER
92.9%
England's bathing waters meeting at least the minimum standard
417 of 449 bathing waters measured in 2025. 297 (66.1%) were rated Excellent and 32 (7.1%) were Poor.
WATER QUALITY · DEFRA 2025
Dr Will Gaze, who supervised the study, said the team was not seeking to discourage people from the sea, which has many benefits for exercise, wellbeing and connecting with nature, but wanted people to make informed decisions.
THE STUDY IN FIVE NUMBERS
What did
Beach Bums find?
Pick a finding from the University of Exeter research to see what it means. The bar gives a rough sense of the size of each number.
Based on the University of Exeter's 2018 Beach Bums study (Environment International) and the team's 2015 estimate of exposure in English and Welsh coastal waters. This is research information, not medical advice.
WHY IT MATTERS
Resistance can
travel through nature.
Antibiotic resistance is usually discussed in hospitals and doctors' surgeries. The Beach Bums study was the first to link surfing with gut colonisation by antibiotic-resistant bacteria, adding to evidence that resistance also spreads through natural environments such as the sea.
Bacteria reach coastal water through sewage and waste, including run-off from farmland treated with manure. The researchers hoped their results would help policy-makers, beach managers and water companies make evidence-based decisions to improve water quality further.
Questions
Questions people ask
Do surfers really swallow that much water?
The University of Exeter researchers say surfers swallow up to ten times more sea water than sea swimmers, which is why they studied surfers' gut bacteria.
What did the Beach Bums study find?
9% of surfers (13 of 143) carried E. coli resistant to the antibiotic cefotaxime, compared with 3% of non-surfers (4 of 130), making regular surfers three times more likely to carry them.
Does this mean surfing is unsafe?
No. The study found an association, not illness. Its supervisor said the team was not seeking to discourage people from the sea, but wanted them to make informed decisions.
Is sea water tested in winter?
Routine bathing water sampling in England runs during the bathing season, between 15 May and 30 September, so there are no regular bathing water samples for most of the surfing year.
Where does the bacteria in sea water come from?
The Environment Agency lists sewage, agricultural livestock, wildlife, birds and road drainage. Storm overflow spills are usually associated with heavy rain.
Sources
- University of Exeter (16 Jan 2018): Surfers three times more likely to have antibiotic resistant bacteria in guts
- Leonard et al. (2015), Human recreational exposure to antibiotic resistant bacteria in coastal bathing waters, Environment International (Europe PMC)
- Defra (GOV.UK): 2025 statistics on English coastal and inland bathing waters
- Environment Agency: Bathing Water Quality, help understanding the data
Updated