Is it legal?

 Are we allowed to swim here? What happens if we get ‘caught’?

This is a complex topic, and I’m only going to summarise it here. I recommend that you read about this on other sites including the Outdoor Swimming Society. The information here is based on their resources.

It is interesting to compare the situation in England and Wales to that in Scotland. In Scotland there is a clear right to swim, as part of a wider ‘right to roam’. But this does not exist in England and Wales, and the situation feels very muddy.

There are several places that swimming is tolerated, although not encouraged (such as Caroline’s - and here only in one lake). Elsewhere swimming is only officially allowed during organised events, such as at Roundhay Park. The rivers Wharfe and Nidd are very popular with swimmers and there is a general acceptance that when there is a right of way that runs alongside a river, access to the river is part of that. However understandably land owners and residents get frustrated when they perceive that people are negatively affecting their day to day lives, or mistreating the environment, for example through blocking access or littering. Big Bend is a site where both of these issues can cause frustration.

And then there are reservoirs. I now swim in reservoirs frequently. But I’ve had to overcome an ingrained belief that this was ‘wrong’ and dangerous. Most of the reservoirs around us are owned by Yorkshire Water, who are not supportive of open water swimming. Whilst water companies have a legal responsibility to provide recreational access to their sites, they do not usually believe that this extends to swimmers. There is a growing movement to improve swimming access to reservoirs - you can read some of the reasons here (written by the excellent Owen Hayman, friend of FLOWS).

If you do choose to swim in a reservoir, you will notice that despite the signs, the temperature does rise above 12 degrees in the summer. Use the same caution you would use anywhere else, don’t jump in, and avoid any reservoir architecture (towers, dam walls, slipways).

 
Almost everywhere we swim there are ‘No Swimming’ signs, and many of the places have almost no known history of swimming. One of our core aims is to normalise outdoor free swimming in places where it was once a very eccentric thing to do, if not illegal. Not only do we aim to normalise swimming in the eyes of onlookers and gain public support, but normalise it with ourselves too. Through sharing maps and information, and inviting strangers to swim, we break down social and personal barriers. We have a responsibility to proactively care for the places we swim, and try to instil this culture in newcomers. Swimming and environmental responsibility go hand in hand. We work towards a time when the invaluable benefits of swimming and dipping in open water, for people and for the environment, are recognised and valued. Come for a swim!
— Owen Hayman. https://www.outdoorswimmingsociety.com/sixteen-reasons-reservoirs/

If you are challenged whilst swimming, it is best to be polite and leave. You do not have to give your name and address if asked for them.