Stay safe and swim smart
Open water swimming is growing in popularity across the UK, offering a refreshing way to enjoy nature in lakes, rivers, and reservoirs. However, while it can be an enjoyable and rewarding activity, it also comes with potential health risks, particularly from water quality and environmental factors.
This guide provides essential open water swimming safety advice, helping you minimise risks and make informed decisions before entering natural waters.
What is open water swimming?
Open water swimming refers to swimming in natural bodies of water such as:
- lakes
- rivers
- reservoirs
- coastal waters
Unlike swimming pools, these environments are not always monitored or treated for human use, which means water quality can vary significantly.
Health risks of open water swimming
Swimming in untreated water can expose you to harmful micro-organisms and pollutants that may cause illness.
Common risks include:
- gastrointestinal infections (from swallowing contaminated water)
- exposure to sewage or animal waste
- pollution from agriculture or industry
- exposure to toxins from blue-green algae
- increased risk in areas not designated for bathing
Rivers and non-designated swimming locations are primarily managed for wildlife, not human safety. This means contaminants that are safe for ecosystems may still be harmful to people.
Who is most at risk?
While open water swimming can be safe with precautions, certain groups are more vulnerable:
- children are more likely to swallow water
- new or inexperienced swimmers
- people with weakened immune systems
If you fall into one of these categories, it’s especially important to follow safety guidance and choose your location carefully.
How to choose safer places to swim
To reduce your risk of illness:
- choose designated bathing waters (these locations are monitored for water quality and provide a safer environment)
- avoid high-risk conditions, like after heavy rainfall (which increases runoff pollution), near farmland, sewage outlets, or industrial areas
- check water quality before you swim
Use trusted resources to check water quality such as:
Tips to stay safe before, during and after swimming
Before you swim
- Check water quality and weather conditions
- Avoid swimming if you feel unwell or have open wounds
During your swim
- Avoid swallowing water
- Stay aware of your surroundings, currents, and hazards
After Swimming
- Wash your hands before eating
- Shower as soon as possible
- Clean and disinfect any cuts
What to do if you feel unwell
If you become ill after open water swimming:
- seek medical advice promptly
- inform your healthcare provider that you have been swimming in open water
Symptoms of concern may include:
- stomach cramps
- diarrhoea
- vomiting
- fever
Early treatment can help prevent more serious complications.
What to do if you get into difficulty
Even experienced swimmers can encounter unexpected situations in open water, such as strong currents, cold water shock, or fatigue.
Stay calm and act quickly
- Float on your back – this helps you regain control of your breathing and conserve energy
- Signal for help by raising one arm and shouting if possible
- Don’t panic or swim against strong currents – conserve energy and look for the safest way out
- If you’re in trouble near the coast, remember to Float to Live (RNLI guidance)
If you see someone in difficulty
- Call 999 or 112 and ask for the Coastguard (or Fire & Rescue for inland waters)
- Do not enter the water unless trained, use a reach or throw rescue if possible
Being prepared and knowing what to do in an emergency can save lives.
Enjoy open water swimming responsibly
Open water swimming can be a fantastic way to connect with nature and stay active. By following simple safety steps and staying informed, you can significantly reduce your risk and enjoy a safer swimming experience.