How Swimmers Can Avoid Polluted Water: A Coach's Guide

One of the less glamorous parts of running open water swimming sessions is paperwork.

Over the years, I have built up a fairly substantial document covering all of the operational procedures for PeteWilbyTriathlon. In the industry, this is known as a Normal Operating Procedure (NOP). Given the risks and responsibilities associated with coaching swimmers in the open water, I find it incredibly valuable to have an experienced external reviewer review my plans each year.

I do this through Beyond Swim. As we're effectively a pop-up venue wherever we operate, I like to think we have every angle covered, but a fresh perspective is always invaluable.

This year's review led to some great discussions with Adrian, who suggested publishing some of the checks and decision-making processes that happen behind the scenes before I give the thumbs-up for a swim session. We agreed that water quality would be a particularly useful topic given the challenges facing our rivers and coastlines today.

So, here's a quick guide to why swimmers should avoid polluted water, the potential health implications, and how to reduce your risk.

Why Does Water Quality Deteriorate?

The most common cause is heavy rainfall.

When large amounts of rain fall in a short period, runoff from roads and farmland enters rivers and streams. This can carry animal waste, slurry, fertilisers and other pollutants into the water system before eventually reaching the sea.

At the same time, our ageing sewer infrastructure can struggle to cope. Many parts of the UK still rely on combined sewer systems that carry both rainwater and household wastewater. During heavy rain, these systems can become overwhelmed, resulting in sewage overflows into rivers and coastal waters.

How Can You Reduce the Risk?

The simplest rule is to be cautious after heavy rain. Many experienced open water swimmers will avoid swimming for 24–72 hours after significant rainfall, depending on local conditions.

The second recommendation is even easier: Download the Safer Seas & Rivers Service app.

The app provides real-time pollution alerts, sewage discharge notifications and water quality information for bathing locations around the UK. It allows swimmers to make informed decisions rather than relying on guesswork.

As a coach, I regularly use this tool to assess whether conditions are suitable for a session.

After Your Swim: Clean Up Properly

What you do after your swim is just as important as the checks you make before getting in.

As soon as possible after leaving the water, shower thoroughly and wash your hands before eating or touching your face. This helps remove any contaminants that may have been present in the water and reduces the risk of illness.

It is equally important to clean and dry all of your swimming equipment, including wetsuits, swimsuits, tow floats, goggles, boots, gloves, and changing mats. Bacteria, viruses, and other contaminants can remain on kit after a swim and may still be present when you next use it.

Regular cleaning of your equipment also helps prevent the spread of invasive non-native species and diseases between different waterways. If you swim in the sea one day and a lake, river, or reservoir the next, contaminated kit can unintentionally transfer organisms between ecosystems.

A few minutes spent cleaning your kit after each swim can make a significant difference to both swimmer safety and environmental protection.

Why Should Swimmers Care?

Bathing water quality is primarily assessed using two types of bacteria: E. coli and intestinal enterococci. Both are indicators of faecal contamination and can suggest the presence of sewage, animal waste, or polluted runoff entering our rivers and seas.

Exposure to elevated levels of these bacteria can increase the risk of:

·       Gastrointestinal illness, including sickness, diarrhoea and vomiting

·       Ear, eye and skin infections

·       Infections of cuts and wounds

·       Respiratory symptoms

·       Serious bacterial infections requiring hospital treatment

·       Long-term health complications

·       Death in rare but tragic circumstances

The risks are not just theoretical.

Many swimmers and surfers can recount stories of becoming unwell after entering polluted water. More seriously, the recent Channel 4 series Dirty Business highlighted the story of Devon surfer and teacher Reuben Santer, who developed labyrinthitis after surfing in polluted water. This ultimately triggered Ménière's disease, a chronic inner-ear condition that left him suffering severe vertigo, hearing loss and tinnitus, forcing him to give up his teaching career.

The programme also revisited the heartbreaking case of eight-year-old Heather Preen, who died after contracting E. coli during a family holiday in Dawlish Warren - our doorstep - in 1999. Her story remains one of the most powerful reminders of why water quality matters and why swimmers should never ignore pollution warnings.

While severe outcomes are fortunately uncommon, the consequences of swimming in polluted water can be life-changing. The good news is that much of the risk can be avoided by checking conditions before you swim and steering clear of the water after heavy rainfall or pollution alerts.

Final Thoughts

The vast majority of swims are completed without issue, and open water swimming remains one of the most rewarding activities you can do.

However, understanding the impact of heavy rainfall, agricultural runoff and sewage discharges can help you make better decisions about when and where to swim.

A quick check of recent weather conditions and the Safer Seas & Rivers Service app could be the difference between a fantastic swim and a week spent regretting it.

The sea doesn't care whether you're an Olympian, a triathlete, a surfer, or a child building sandcastles. Polluted water affects

everyone equally.