Open Water Swimming

Organised Sessions

Cardiff’s iconic reservoirs

Brought to you by Welsh Water

Supervised Open Water Swimming

Are you looking for an exhilarating swimming experience that will leave you refreshed and energised? Look no further than our supervised open water swimming sessions in the stunning Llanishen Reservoir.

Our dedicated supervisors provide peace of mind for swimmers of all levels and ensure a secure environment for you to challenge yourself and push your limits. Under their watchful eyes and expert guidance, you can focus on the sheer joy of swimming while leaving your worries behind.

Indulge in the perfect blend of adventure, fitness and serenity as you embark on a supervised open water swimming experience. Reconnect with nature, embrace the invigorating sensation of the water and enjoy the unmatched thrill of swimming in the reservoir.

Unleash your inner adventurer and book your supervised open water swimming session now.


Lisvane & Llanishen Reservoirs is a SAFE Cymru-Accredited venue.

SAFE Cymru has been developed by Swim Wales in close partnership with Welsh Triathlon and is recognised by Welsh Government, Sport Wales and AWWSG as the pinnacle of safe aquatic facility standards in Wales.

SAFE Cymru is helping us promote and progress open water swimming safely. Swim Wales’ world class standard will provide the appropriate resources and standards which are needed to ensure safe participation in Wales.

Swimmer’s itch

(also known as ‘cercarial dermatitis’)

What is swimmer’s itch?

Swimmer’s itch is an itchy skin rash. It is caused by an allergic reaction to a type of tiny flatworm that is found naturally in open water.

The tiny flatworms that cause swimmer’s itch live all over the world, in natural outdoor or ‘open’ waters, such as lakes, ponds and the sea. They are so small that we cannot see them, so it is not possible to know when they are there.

These flatworms do not infect people but they can cause itching if they come into contact with a person’s skin. The ‘itching’ cannot spread from one person to another, it needs direct contact with the worms. Anyone who is in contact with the flatworms can get swimmer’s itch – this could be when swimming, dipping, wading or paddling in outdoor waters.

How do I know if I have swimmer’s itch?

Swimmer’s itch usually happens within hours (1 to 48 hours) of being in the water. At first, it may cause a tingling, itching or burning feeling of the skin. Small reddish spots may appear, sometimes turning into larger rashes and blisters, with intense itching.

It usually only affects skin which directly touches the water. Skin that is covered by tight swimwear is usually fine.

Swimmer’s itch usually gets better without treatment and goes away by itself in 1-3 weeks. As swimmer’s itch is an allergic reaction, people in the same water can have different reactions. But the more often someone has contact with the flatworms, the more serious (immediate and intense) their reaction may be.

What should I do if I get swimmer’s itch?

People with swimmer’s itch are unlikely to need medical help, as it usually gets better by itself, and there is no test that needs to be done for it. But it is important that you don’t scratch the rash, to stop it getting infected with germs. Speak to your pharmacist if you need help with the itching. It is also important to remember that itching skin and rashes can be caused by lots of other things. So, if you are unsure if you have swimmer’s itch, if your symptoms are getting worse or if you feel unwell after being in outdoor waters, see your GP or pharmacist for advice.

How do I know when swimmer’s itch is a problem in water?

Swimmer’s itch is not a sign of pollution or ‘dirty’ water.  But we are still learning more about why swimmer’s itch is a problem in some waters and not in others, and how this can change over time.

We think that swimmer’s itch is more likely to be a problem when water is warmer, in the Summer, in water where lots of water birds live or visit (e.g. ducks, geese and swans) and in shallower water with lots of plants. It may also be more of a problem in the early morning. Children seem to be more likely to develop swimmer’s itch than adults, probably because they spend more time in shallow waters and may not dry themselves as well as adults do.

How can I reduce my chance of getting swimmer’s itch?

It’s difficult to know when and where swimmer’s itch will be a problem before you go into the water. Even if it has been reported as a problem somewhere, it may not always be a problem there in the future. But if you want to reduce your chance of getting swimmer’s itch:

• Avoid swimming or wading in warmer, shallow waters with lots of plants.

• Avoid swimming or wading where lots of water birds live or visit.

• Think about covering your skin e.g. wearing a full-length wetsuit, swim cap, wet suit gloves and booties. Remember your face will still be bare.

• Towel rub your skin dry straight after leaving the water.

• Where possible, shower straight after leaving the water.

It is also a good idea to rinse your wetsuit in clean fresh water after use.

You can find out more about safe swimming in outdoor waters here.

This advice is based on information from:

DermNet (2021): ‘Swimmer’s itch’

Centers for Disease Control and Prevention (2020): ‘Swimmer’s itch FAQs’

World Health Organization (2021): ‘Guidelines on recreational water quality Volume 1 Coastal and Fresh Waters’

Safety First

We would remind you that unauthorised swimming at any of our reservoirs is prohibited and is extremely dangerous. Our open water swimming sessions will be regulated under the close supervision of our fully-trained team. They will only take place in strictly designated areas of the reservoir during pre-booked organised sessions.

The Dangers Of Unauthorised Swimming in Welsh Water Reservoirs

Automatic equipment located under the surface of the water, which can sometimes operate without obvious warning.

Very cold and deep water that can cause even strong swimmers to find themselves in difficulty.

Most reservoirs are remote or not easily accessible so the chance of rescue is greatly reduced.

Take Care

All of our activities are planned and delivered in such a way as to work with and preserve the very delicate natural environment we have on site. As such, we restrict numbers, access and types of activities to ensure our programme is delivered responsibly. If you have any questions, our team would be happy to explain.