Is Sewage Really Everywhere?
Separating the Headlines from the Reality for Outdoor Swimmers
If you only followed newspaper headlines, you'd be forgiven for thinking every river, lake and beach in the UK has become an open sewer. Stories about sewage spills dominate the news, social media is filled with alarming maps showing overflow points, and many people now question whether it's safe to swim outdoors at all.
The truth, however, is more nuanced.
There is no denying that sewage pollution is a serious environmental issue that deserves attention and action. But that doesn't mean every waterway is permanently polluted or that outdoor swimming has become impossibly dangerous. Understanding what sewage is, where it comes from, and how pollution behaves can help swimmers make informed decisions rather than being driven by fear.
The Sewage Problem Is Real
Let's start with the obvious.
The UK's ageing sewer infrastructure is under enormous pressure. During periods of heavy rainfall, combined sewer systems can become overwhelmed. To prevent sewage backing up into homes and businesses, combined sewer overflows (CSOs) are designed to release excess wastewater into rivers and coastal waters.
These discharges are a genuine problem. They can affect wildlife, damage ecosystems and, under certain conditions, increase the health risks for people using the water.
Campaigns highlighting these issues have played an important role in forcing governments, regulators and water companies to take greater responsibility. Increased public awareness has already led to better monitoring, greater transparency and more designated bathing waters across England.
But Are All Rivers, Lakes And The Sea Full of Sewage?
No.
This is perhaps the biggest misconception.
Millions of people swim, paddle, kayak and surf in UK waters every year. If every river and lake was constantly contaminated with untreated sewage, participation in outdoor water sports simply wouldn't continue to grow.
Pollution events are usually temporary rather than permanent. Rivers flow, tides move, and contaminants become diluted over time. A sewage discharge at one point doesn't necessarily mean a river remains polluted for days or weeks afterwards.
Likewise, many lakes, reservoirs and stretches of coastline have excellent water quality for much of the year.
The challenge isn't that everywhere is polluted all the time—it's knowing when and where conditions may temporarily become unsuitable.
What Does "Sewage" Actually Mean?
When most people hear the word sewage, they immediately imagine toilet waste.
In reality, sewage is much broader than that.
It includes wastewater from toilets, but also water from sinks, showers, washing machines and household drains. In many sewer systems this mixes with rainwater before reaching wastewater treatment works.
That doesn't mean swimmers should ignore pollution, but understanding what sewage actually contains provides important context when discussing overflows.
The Missing Piece of the Puzzle
One reason the public often feels confused is because of how sewage spills are reported.
Most publicly available maps rely on Event Duration Monitors (EDMs).
These monitors record how long an overflow operates.
They do not tell us:
how much water was discharged
how diluted it was
what bacteria were present
whether the discharge created a significant health risk
A discharge lasting several hours could represent a relatively small, highly diluted overflow—or a much larger pollution event.
Without measuring water quality directly, duration alone cannot tell swimmers whether the water is actually safe.
That's why experts increasingly argue that real-time water quality monitoring is what swimmers genuinely need, rather than simply knowing that an overflow has operated.
Why People Don't Get Ill Every Time They Swim
This is one of the questions many new outdoor swimmers ask.
The answer is simple: exposure and risk vary enormously.
Many factors influence water quality, including:
recent rainfall
river flow
sunlight
temperature
dilution
location of pollution sources
agricultural runoff
wildlife
Even when bacteria are present, illness is never guaranteed. The amount of contamination, the organisms involved and an individual's own immune system all play a role.
That doesn't mean swimmers should become complacent—but it does explain why regular outdoor swimmers often enjoy years of swimming without becoming ill.
Learning to Read the Water
Experienced outdoor swimmers rarely rely on a single source of information.
Instead, they build an overall picture before deciding whether to swim.
Questions worth asking include:
Has it rained heavily?
Heavy rainfall is one of the strongest indicators that pollution risk may have increased because it can trigger sewer overflows and wash contaminants from roads and farmland into waterways.
What does the water look like?
Clear water isn't automatically clean, and murky water isn't automatically polluted.
However, obvious warning signs such as sewage fungus, sanitary products, wet wipes, unusual scums or excessive litter should raise concerns.
Does it smell?
Trust your senses.
If the water smells unpleasant or distinctly of sewage, it's sensible to stay out.
What's happening upstream?
Urban areas, wastewater treatment works and intensive agriculture all increase the likelihood of pollution entering rivers.
Understanding your local catchment helps build a better picture of potential risks.
What are other swimmers saying?
Outdoor swimming communities are remarkably good at sharing local knowledge.
If regular swimmers are avoiding a location because of recent pollution or illness, it's worth listening.
Risk Can Never Be Zero
One of the most important lessons for any outdoor swimmer is accepting that open water always carries some level of risk.
Whether it's cold water, currents, weather, blue-green algae, hidden obstacles or water quality, swimming outdoors requires judgement.
The goal isn't to eliminate every possible hazard.
It's to understand them well enough to make informed decisions.
Good swimmers don't ignore risk—but they also avoid assuming the worst every time they see a headline.
Practical Ways to Reduce Your Risk
You can significantly reduce your chances of becoming ill by following some straightforward precautions:
Avoid swimming immediately after heavy rainfall.
Check available pollution and bathing water information where possible.
Don't swim if the water smells unpleasant or looks obviously contaminated.
Avoid swallowing water.
Wash your hands before eating after your swim.
Shower and wash your swim kit when you get home.
Pay extra attention if you're immunocompromised or swimming with young children.
Small habits can make a significant difference.
We Need Better Information, Not More Fear
The sewage debate shouldn't become a choice between pretending everything is fine or believing every river is toxic.
Neither position reflects reality.
The UK absolutely needs investment in sewer infrastructure, improved environmental regulation and far better real-time water quality monitoring.
At the same time, thousands of beautiful rivers, lakes and coastal locations continue to provide safe and rewarding experiences for outdoor swimmers throughout the year.
The challenge is giving people accurate, timely information so they can make informed choices.
Because confident swimmers aren't those who ignore pollution.
They're the ones who understand it.
By learning how waterways behave, recognising changing conditions and respecting the environment, outdoor swimmers can continue to enjoy the enormous physical and mental benefits of wild swimming while helping drive improvements in the health of our rivers, lakes and seas.
